Impact of Peat Fire on the Soil and Export of Dissolved Organic

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Impact of peat fire on the soil and the export of dissolved organic carbon in tropical peat soil, Central Kalimantan, Indonesia Kazuto Sazawa, Takatoshi Wakimoto, Masami Fukushima, Yustiawati Yustiawati, M. Suhaemi Syawal, Noriko Hata, Shigeru Taguchi, Shunitz Tanaka, Daisuke Tanaka, and Hideki Kuramitz ACS Earth Space Chem., Just Accepted Manuscript • DOI: 10.1021/ acsearthspacechem.8b00018 • Publication Date (Web): 21 May 2018 Downloaded from http://pubs.acs.org on May 29, 2018

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ACS Earth and Space Chemistry

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Impact of peat fire on the soil and the export of

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dissolved organic carbon in tropical peat soil,

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Central Kalimantan, Indonesia

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Kazuto Sazawa†, Takatoshi Wakimoto†, Masami Fukushima‡, Yustiawati Yustiawati§, M.

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Suhaemi Syawal‖, Noriko Hata†, Shigeru Taguchi†, Shunitz Tanaka§, Daisuke Tanaka†, and

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Hideki Kuramitz†,*

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†

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Engineering for Research, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan

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‡

Department of Environmental Biology and Chemistry, Graduate School of Science and

Laboratory of Chemical Resource, Division of Sustainable Resources Engineering, Faculty of

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Engineering, Hokkaido University, Sapporo 060-8628, Japan

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§Division

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University, Sapporo, Hokkaido 060-0810, Japan

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‖Research

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Cibinong, Bogor 16911, Indonesia

of Material Science, Graduate School of Environmental Earth Science, Hokkaido

Center for Limnology, Indonesian Institutes of Sciences, Jl. Raya Jakarta-Bogor Km.46

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ACS Paragon Plus Environment

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ACS Earth and Space Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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ABSTRACT: Tropical peatlands play an important role in the global carbon cycle, and therefore,

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their stability has important implications for climate change. In this study, we evaluated the effect

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of fire on the physical, chemical, and biological properties of peat soils in Indonesia for three years

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following exposure to fire. The results of the thermal analysis suggest that the organic matter

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contents of surface soils significantly decreased because of peat fires and that charred materials

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were produced in the subsurface layer of the burned soils. The atomic ratios of the burned soils

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and the thermally treated samples indicate that the Indonesian peat soils were dehydrated by these

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low-severity fires. The microbial abundance and phosphatase activity in the burned soils

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significantly decreased compared to those of the unburned soils. Leaching of the dissolved organic

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carbon (DOC) concentration from the burned soils is lower than that from the unburned soils. The

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obtained laboratory results indicate that the concentration of the leached DOC increased drastically

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after heat treatments near the ignition temperature. It was seen that the denaturation of the soil

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organic matter caused by the heat from the fire accelerates the exodus of organic carbon in

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peatlands, which contain huge accumulations of carbon.

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Key words: Peat fire, Soil organic matter, Dissolved organic carbon, Thermogravimetry,

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Three-dimensional excitation-emission matrix, Soil enzyme

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■ INTRODUCTION The total amount of worldwide wetlands consists of only 4%–6% of the global land surface1;

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however, the top 100 cm of peat soils contains approximately 13%–26% of the world’s soil

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carbon stock, which is estimated to be 202–377 Gt.2–5 Peatlands, typically found in wetlands of

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boreal and tropical regions, are formed by the incomplete degradation of root litter, falling leaf


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and branch materials under low microbial activity in anaerobic, acidic and oligotrophic

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conditions. They play an important role in the global carbon cycle; therefore, their stability has

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important implications for climate change. The recent increase in global warming is thought to

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accelerate the decomposition of soil organic matter (SOM).6 Some researchers have emphasized

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that dissolved organic carbon (DOC) leakage from northern peatlands will increase with

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increasing river discharge and elevating atmospheric CO2 levels.7,8 The amount of DOC exported

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from northern peat soil shows a positive correlation with temperature, as well as the lignin

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decomposition enzyme activity, which also accelerates under more aerated conditions.9–11

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Indonesian peatlands are estimated to cover an area of 206,950 km2, accounting for

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approximately 50% of the global tropical peatland area and storing approximately 57.3 Gt of

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carbon.12 The peatlands of the Sumatra and Central Kalimantan (Borneo) islands, Indonesia have

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undergone dramatic ecological and social changes over the past decades, and the stability of the

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peatlands has been disturbed since the early 1980s. In particular, an agricultural land

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development project in Central Kalimantan, called “The Mega Rice Project,” was promoted from

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1995 to 1999 by the Indonesian Government, and more than 4500 km of channels were dug in

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this area. As a result, the drainage from the channels is causing the drying and acidification of

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the peat soil. Dried peat soil is easy to burn.13, and it can also be assumed that the drying of

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peatland led to increase in microbial population and soil respiration. This can result in the release

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of large amounts of CO2 into the atmosphere via wildfires and the decomposition of SOM by

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microorganisms.14 Furthermore, delays in the onset of the rainy season increase the number of

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fire events and accelerate damage to peatlands. For example, during the 1997 El Niño event, an

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extensive area of Indonesian peatland burned (1.45 Mha), approximately 50% of which was on

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Central Kalimantan. It is estimated that between 0.81 and 2.57 Gt of carbon was released into the


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atmosphere from these fires across the whole of Indonesia.15 This is equivalent to 13%–40% of

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the mean annual global carbon emissions from fossil fuels (6.4 Gt-C yr−1). A large number of

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forest fires have been occurring continuously according to the Fire Information for Resources

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Management System website.16 Therefore, tropical forests and peatlands in Indonesia are one of

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the main sources of CO2 emissions arising from land use change anywhere in the world and are

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important in any mitigation efforts to control current global climate change.

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Forest fires not only destroy the surface vegetation but also strongly impact the soil via

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heating. Previously, several excellent field and laboratory studies have investigated the effect of

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forest fires on the physical, chemical, and biological properties of soil.17–23 The deposition of

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peat soil requires long time periods, and the current average accumulation rate for tropical peat

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soil in Indonesia has been estimated to be between 0.04 and 2.55 mm yr−1.24 Therefore, there has

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been concern that the soil ecosystems of peatlands in Indonesia are strongly influenced by the

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rapid loss of peat by fire events. The magnitude and the recovery term of these alterations

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depend on the fire intensity (temperature), the duration of the fire, and the soil texture.22, 23

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The aim of the present study was to evaluate the physical (particle density and combustion

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characteristics), chemical (quantity and quality of organic matter), and biological (enzyme

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activity and microbial population) properties of unburned and burned tropical peat collected from

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Central Kalimantan, Indonesia, over three years. In addition, the effects of peat fire on the

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component fractions and fluorescence properties of the water-soluble organic matter (WSOM) in

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the peat soil were observed. The WSOM is strongly linked to the storage of carbon in catchment

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soil and is quite vulnerable to changes in the environment. However, the observation of the effect

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of peat fires on WSOM has not been reported. To examine the impact of the heating process, the


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denaturation of SOM and WSOM in thermally treated samples was evaluated, and these data

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were compared to field samples.

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■ MATERIALS AND METHODS

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Study Sites and Sampling. The map of the sampling sites of Palangka Raya on Kalimantan

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Island, Indonesia, is shown in Figure 1. Soil samples were collected from unburned sites (UB1–

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3) and burned sites (B1–5) on September 24 and 25 in 2010, September 17 and 19 in 2011, and

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September 11 in 2012. The soil samples were collected from a depth of 30–50 cm (subsurface) in

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2010 and from two soil (surface: 0–20 cm and subsurface: 30–50 cm) in 2011 and 2012. The

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UB1 and UB2 were a relatively intact swamp forest with little drainage.25 Dominant tree species

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included Combretocarpus rotundatus, Cratoxylum arborescens, Buchanania sessifolia, and

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Tetramerista glabra.26 The UB3 was located in secondary forest. Dominant tree species and the

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microtopography of the forest floor resembled those at the UB1 and UB2.25 The B1–5 sites were

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a drained burnt swamp forest. Forest fire were reported at B1–4 in 1997, 2002, 2004 and 2009.

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Fern (Stenochlaena, Blechnum, and Lygodium spp.) and sedge (Cyperus, Scleria and Eleocharis

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spp.) plants were sparsely re-growing at the B1–4. The B5 was burnt in 2011 and surface plants

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were lost. According to some previous reports, the ground water level for the UB1 and UB3 in

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2005–2009 were from 0 to -1.0 m and from -0.5 to -1.5 m, respectively.25 Prior to use, each

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sample was air-dried at room temperature and ground to pass a 2-mm mesh. To assay the

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enzyme activities, 20-g samples were placed in glass vials, and 4 mL of toluene was added at the

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sampling site; these samples were stored at 4°C and were assayed within two weeks of sampling.


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Figure 1. The location of the sampling sites of Palangka Raya on Kalimantan, Indonesia. UB:

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Unburned sites, B: Burned sites.

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Physicochemical Analysis. The pH (H2O), electrical conductivity (EC), and pH (KCl) of the

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soils were measured in slurries (1:10 air-dried soil/distilled water or 1M KCl). The

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concentrations of cations in the slurries were determined using an Advanced Compact IC 761

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(Metrohm Lt., Herisau, Switzerland) after filtration through a 0.45-µm pore diameter membrane

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filter (mixed cellulose ester, ADVANTEC, Tokyo, Japan).27 The moisture content was

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determined from the weight loss after drying at 105°C for 48 h.28 The particle density was

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determined based on Japanese Industrial Standards (JIS A 1202).29 In addition, these samples

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were combusted at 600°C for 2 h to determine the organic content from the weight loss.


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Thermal Analysis. The combustion characteristics of the soil were determined via a

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Thermogravimetry-Differential Thermal Analysis (Thermo plus TG 8120, Rigaku, Tokyo,

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Japan). Approximately 10 mg of samples was heated from 20°C to 500°C at a rate of 3°C min−1.

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Alumina was used as the reference standard.

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Thermal Treatments. In the laboratory, the sample collected from UB1 (2011) at the

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subsurface layer was heated to different temperatures (90°C, 120°C, 150°C, 200°C, 250°C,

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350°C, and 480°C) for 1, 5, 30, 60, and 120 min using a muffle furnace (KDF007Ex, Denken,

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Tokyo, Japan). The heating rate used was 3°C min−1. After cooling down, the thermally treated

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samples were dehydrated under reduced pressure before the analysis was performed.

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Elemental Analysis. The analyses of the elemental compositions of the soils and thermally

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treated samples were carried out at the Center for Instrumental Analysis at Hokkaido University.

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The C, H, and N contents were measured via a Micro Corder JM 10 type CHN analyzer (J-

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Science Lab. Co. Ltd., Kyoto, Japan). The sulfate ions were analyzed using DX-500 type ion

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chromatography (Dionex, Sunnyvale, CA). The percentage of oxygen was determined by

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subtracting the total sum percentage of C, H, N, S, and ash elements from 100.

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Py-TMAH-GC/MS. Soil samples (1 mg) were placed in a deactivated stainless steel cup. A

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25-μL aliquot of tetramethylammonium hydroxide (TMAH) in methanol (40 mg mL−1) and a 10-

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μL aliquot of nonadecanoic acid in acetone (0.06 mg mL−1) as an internal standard (ISTD) were

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then added to the cup. After removing the solvents under reduced pressure, the cup was

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introduced into a PY-2020D type Double-Shot Pyrolyzer (Frontier Laboratories Ltd.,

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Fukushima, Japan) connected to a Shimadzu GC-17A/QP5050 type GC/MS system.30


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Microbial DNA Extracted from Soils and Real-Time PCR Assay. Soil microbial DNA was

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extracted using the MO BIO Ultra Clean Soil DNA isolation kit (MO BIO Lab., Solana Beach,

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CA, USA) according to the manufacturer’s protocol. The abundance of bacteria in the peat soils

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was estimated via real-time PCR, whose amplifications were carried out in a PCR tube (200 μL,

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Hi-8-Tube, Takara Bio, Shiga, Japan) with a total volume of 25 μL using a thermal cycler

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(Takara Bio, Shiga, Japan). Each 25-μL reaction contained the following: 2.0 μL of the DNA

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template, 1.0 μL of the primers 341f and 518r (10 μM),31 12.5 μL of the two-fold SYBR® Premix

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Ex Taq, and 8.5 μL of sterile distilled water. The PCR conditions were as follows: initial

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denaturation at 95°C for 30 s, then 40 cycles with denaturation at 95°C for 5 s, and annealing at

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60°C for 30 s. The effects of fire on the soil microbial populations in the Indonesian peat soil

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were evaluated from the comparative cycle threshold (CT) values of the unburned and burned

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soils.

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Soil Enzyme Assays. This study measured the activities of one oxidase (phenol oxidase (PO;

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EC 1.14.18.1) and eight hydrolases (β-glucosidase (β-Glu; EC 3.2.1.21), β-xylosidase (β-Xyl;

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EC 3.2.1.37), β-galactosidase (β-Gal; EC 3.2.1.23), α-mannosidase (α-Man; EC 3.2.1.24), N-

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acetyl-glucosaminidase (NAG; EC 3.2.1.30), acid phosphatase (AcP; EC 3.1.3.2), alkaline

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phosphatase (AlP; EC 3.1.3.1), and phosphodiesterase (PD; EC 3.1.4.1)). A summary of the

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assay conditions is listed in Table S1. All substrates were obtained from Sigma Aldrich (St

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Louis, MO). The PO activity method used 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)

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diammonium salt (ABTS+) as substrate.32 The results were expressed as mM ABTS+ g dry-soil−1

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min−1 (with the coefficient of the extinction value of ABTS+ ε420 = 18460 M−1 cm−1). The

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enzyme activities of β-Glu, β-Xyl, β-Gal, α-Man, NAG, AcP, AlP, and PD were determined on

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field-moist soil using modifications of the standard methods.33–35 The enzyme activities were


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determined from colorimetric measurements of p-nitrophenol (p-NP) released when the soil was

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incubated (30°C, 1 h) in the optimum buffer solution containing the substrate. The results were

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expressed as mM p-NP g dry-soil−1 h−1. The difference in the enzyme activities of the unburned

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and burned soils was analyzed using Spearman nonparametric correlations; P values of 0.05 or

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less were considered to be significant.

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The Properties of DOC in Water-Extracted Solutions of the Field and Thermally

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Treated Soil Samples. The soil water-extracted solutions were obtained by shaking the 1:10 air-

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dried soil/distilled water solutions at 190 rpm for 24 h at 25°C in the dark and then by filtering

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through a 0.45-µm pore diameter membrane filter. The total concentrations of DOC in the soil

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water-extracted solutions were measured via a TOC analyzer (TOC-5000A, Shimadzu, Kyoto,

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Japan).27 The DOC components were fractionated using the SupeliteTM DAX-8 resin (40 ± 60

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mesh, Supelco, Bellefonte, PA, USA). A total of 6 mL of DAX-8 resin was transferred into

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columns (12 mL, 1 cm × 15 cm, FLEX-column, Kontes, Vineland, NJ) in slurry. The soil water-

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extracted solutions were adjusted to pH < 2 with 2 M HCl, and 15 mL of the samples was

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filtered by gravity through the DAX-8 resin with a flow rate of less than 1 mL min−1. The

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effluent contained hydrophilic (Hp: e.g., fatty acids, sugar acids, hydroxyl acids, and

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polysaccharides) and hydrophobic (HoB: aromatic amines) base fractions (Hp + HoB).36 The

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hydrophobic neutral (HoN: e.g., large cellulose polymers, hydrocarbons, and carbonyl

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compounds) and hydrophobic acid (HoA: humic and fulvic acids) fractions were retained in the

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resin. The HoA fraction was extracted via 0.1 M NaOH at 1 bed volume with a constant flow

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rate of 0.5 mL min−1. The Hp + HoB and HoA solutions were adjusted to pH < 2 with 2 M HCl.

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The DOC concentrations of the Hp + HoB and HoA fractions were measured via a TOC


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analyzer, and the HoN fraction was calculated by subtracting the Hp + HoB and HoA fractions

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from the total DOC.

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To determine the molecular weight of DOC in the soil water-extracted solution, a 20-μL

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aliquot was injected into a Jasco PU-2080 plus Intelligent HPLC pump system equipped with a

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UV-2075 UV/vis detector (Japan Spectroscopic Co., Tokyo, Japan).37 The absorbance value at

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280 nm for the soil water-extracted solution was recorded to calculate E280, which correlated

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strongly with the total aromaticity of the dissolved humic substance.38 The absorptivity at 280

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nm was calculated as E (cm−1 g of C−1) = absorbance value/[DOC (g L−1)] × (%C/100).

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The 3DEEM spectrum of the soil water-extracted solutions was measured using a fluorescence

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spectrophotometer (Mode LS-55, Perkin Elmer, CA, USA). The scanning wave ranges were

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200–600 nm for both excitation (Ex) and emission (Em).27 The relative fluorescence intensity

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(RFI) was calibrated to be evaluated in quinine sulfate units (QSU), 1 QSU = 1 µg L−1, of

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quinine sulfate monohydrate in the solution of 0.05 M H2SO4 at Ex/Em = 355/450 nm.

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■ RESULTS AND DISCUSSION

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The Effects of Fire on the Physicochemical Properties. The means of the selected

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physicochemical properties of the soils are shown in Table S2. Compared to the UB sites, the

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surface soil sampled immediately after being burned (B5, 2011) indicated higher pH (UB1–3 =

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3.04–3.46; B5 in 2011 = 5.81) and EC (UB1–3 = 0.35–2.70 mS cm−1; B5 in 2011 = 4.34 mS

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cm−1). It is a well-known fact that the cations (K+, Na+, Ca2+, and Mg2+) released from

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combusting SOM can increase soil pH by displacing H+ and Al3+ ions adsorbed on the negative

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charge of the soil colloids.39 The concentration of alkaline cations in the water-extracted solution

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obtained from B5 (2011) at the surface was significantly higher than those at the UB sites at the


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subsurface (UB1–3: K+ = 0.40–4.43 mg L−1, Na+ = 0.64–6.54 mg L−1, Ca2+ = 0.09–0.73 mg L−1,

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and Mg2+ = 0.16–0.72 mg L−1; B5 in 2011: K+ = 14.0 mg L−1, Na+ = 6.91 mg L−1, Ca2+ = 14.9

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mg L−1, and Mg2+ = 25.1 mg L−1). Soil pH and concentration of alkaline cations have been

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reported to increase upon heating at temperatures above 350°C.20 Conversely, one year after the

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peat fire, the concentration of alkaline cations in B5 at the surface indicated pre-fire levels (K+ =

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0.54 mg L−1, Na+ = 1.21 mg L−1, Ca2+ = 0.54 mg L−1, and Mg2+ = 0.96 mg L−1), which suggests

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that the alkaline cations were leached from the burned soil during the wet season.

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In the case of the subsurface layer, the pH and EC values did not change because of the fire. It

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has often been reported that the changes in the soil properties after fire events depend on the

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temperature reached at different soil depths. In fact, a previous field study has reported that the

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temperature of Indonesian peat soils in the 0–5 cm layer increased to 400°C during forest fires,

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while the temperature of the 10–20 cm soil layer did not reach 100°C.40 However, in this study,

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the subsurface burned soils had greater soil particle density (UB = 0.97 ± 0.15 g cm−3, B = 1.16 ±

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0.16 g cm−3, and P = 0.010) and lower ignition loss (UB = 80.5 ± 2.5%, B = 76.9 ± 4.8%, and P

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= 0.025) than did the unburned soils. Rein et al. (2017) investigated the vertical downward

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spread of smouldering fire in column of 30 cm tall moss peat under variable moisture content.

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They found that the downward spread rate of fire continuously increases as peat moisture content

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increases.41 Therefore, the soil aggregates of the subsurface soils in this study sites were affected

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by heating during peat fire.

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The Effects of Peat Fire on the Soil Organic Matter Properties. Thermogravimetry-

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Differential Thermal Analysis (TG-DTA) curves of the soil collected from both layers of B5 and

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the subsurfaces of UB1, UB3 and B3 in 2011 are shown in Figure 2. Both curves show the

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weight loss and the rate of heat released from the soil sample during the pyrolysis process. The


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results of the TG curves indicate that the amount of SOM in the surface soil immediately after a

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fire decreases significantly, whereas the subsurface layer SOM is not changed (Figure 2(a)).

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From the obtained DTA curve for UB1, the ignition temperature (Tv), moisture release (Peak A),

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combustible gas release (Peak B), and the combustion of carbide (Peak C) were determined to be

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at 185.5°C (Tv), 54.4°C, 306.1°C, and 425.4°C, respectively. Compared to UB1 and UB3, the

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Peak B and Peak C values of the B5 surface decreased significantly (Figure 2(b)), and in case of

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the subsurface layer, the peak B value decreased dramatically, whereas the peak C value was

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56% higher than that for UB1. These results suggest that the surface layer of B5 was heated

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strongly at high temperature above 400°C and production of charred materials occurred in the

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burned subsurface soils. Furthermore, the DTA curves of B3 and B5 did not show much

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difference. This indicates that the thermal product remained in the subsurface burned soils over

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two years after the fire.

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Figure 2. (a) Weight loss (TG) and (b) differential thermal analysis (DTA) curves of the

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Indonesian peat soils collected from UB1, UB3 (subsurface), B3 (subsurface), and the site

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sampled immediately after a peat fire (B5 at the surface and subsurface). Tv: ignition temperature


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of the volatile matter, Peak A: moisture release, Peak B: combustible gas release, and Peak C:

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combustion of carbide.

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The elemental composition and atomic ratio (H/C, O/C and C/N) of the UB soil, B soil and the

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thermally treated samples shown in Table S3. The C/N ratio of thermally treated samples

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decreases with increasing heating temperature (50 for 90°C for 60 min, 39 for 200°C for 60 min,

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and 21 for 480°C for 60 min). Conversely, the C/N ratios of subsurface peat soil in the burned

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sites have a tendency to increase compared with those of unburned soils (UB = 42.2 ± 7.0, B =

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81.4 ± 17, and P < 0.001). Several soil samples from burned sites exhibited an intriguingly high

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ratio of C/N of 100, creating serious concerns with respect to the restoration potential of the peat

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soil productivity. In addition, during the three years of observation, not much change was noticed

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in the C/N ratio. In general, the C/N ratios of post-fire soils and thermally treated samples

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(>350°C) are lower than those of unburned soils.19,42 This is due to the heat-induced formation of

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large amounts of condensed structures, including heterocyclic nitrogen forms. The findings of

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this study assume that some of the burned soils were affected by low-severity fires.

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The van Krevelen plot (the H/C versus O/C ratios) of the Indonesian peat soil collected from

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the unburned and burned sites at the subsurface in the period of 2010–2012 and the thermally

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treated samples is shown in Figure 3. The atomic ratios of H/C and O/C obtained from the

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samples that were heated to >190°C for 60 min did not show any change; however, in the

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samples exposed to 200°C and 250°C, the atomic ratios of H/C and O/C decreased when the

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heating time was increased. The H/C and O/C ratios in the samples exposed to 350°C or 480°C

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for 60 min were similar. In addition, the H/C and O/C ratios of the burned soils were lower than

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those of the unburned soils. The solid and dashed lines in Figure 3 indicate the accelerating

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dehydration and decarboxylation reactions. These results reveal that some of the burned soils


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were dehydrated by low-severity fires, which were near the ignition temperature (>200°C), and

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that carbonized soils remain for over three years after a peat fire. According to a previous study,

268

the heat released in a fire is transported faster and penetrates deeper in moist soils than in dry

269

soils.43 That is, the organic matter in high-moisture soils such as peatlands is more strongly

270

influenced by wildfires than that in other types of soils.

271 272

Figure 3. The van Krevelen plot (the H/C versus O/C ratios) of the Indonesian peat soils

273

collected from unburned and burned sites at the subsurface in 2011 and 2012 and thermally

274

treated samples. The solid and dashed lines indicate the accelerating dehydration and

275

decarboxylation reactions. The accelerating dehydration reaction indicates that the number of H

276

and O atoms decreased by a ratio of 2 to 1 from the H and O values of UB1 in 2011.

277

The total ion chromatograms for the Py-TMAH-GC/MS and the fractions of groups for

278

pyrolysate compounds collected from the field and thermally treated samples are shown in

279

Figures S1, S2, and 4. Table S4 lists the major pyrolysate compounds identified in the


14

Page 15 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


280

chromatograms, which can be classified into the following major groups: lignin-derived

281

compounds (cinnamyl, guaiacyl, and syringyl structures), non-lignin-derived compounds, and

282

fatty acids. The results from the burned soils at two depths show that the relative abundance

283

values of lignin-, non-lignin-, and fatty-acid-derived compounds were decreased by the fire.

284

Similar phenomena were observed in the thermally treated samples. A previous study reported

285

that the peak of the pyrolysis products was significantly decreased by wildfires.19 They

286

concluded that charred “non-pyrolysable” refractory carbonaceous materials formed during the

287

heating. It is known that short-chain fatty acids ( 0.05 level. Variance components

380

significant at P < 0.05 are indicated in bold type. Asterisks represent statistical significance, * P < 0.05, ** P < 0.01, and *** P < 0.001.

381

N.D. = Not determined.

Surface

UB B

PO

β-Glu

β-Xyl

β-Gal

α-Man

NAG

AcP

AlP

PD

2011

1.08 ± 0.5

2.02 ± 0.8

0.21 ± 0.1

0.41 ± 0.07

0.06 ± 0.03

0.65 ± 0.07

28.9 ± 3.8

17.3 ± 1.1

6.92 ± 1.6

2012

0.24 ± 0.1

0.84 ± 0.01

0.45 ± 0.2

0.19 ± 0.02

0.05 ± 0.07

0.39 ± 0.03

11.5 ± 6.1

8.71 ± 2.8

2.61 ± 0.9

2011

0.19 ± 0.1

0.22 ± 0.2

0.22 ± 0.03

0.11 ± 0.08

0.11 ± 0.04

0.18 ± 0.07

0.69 ± 0.2

0.49 ± 0.1

0.17 ± 0.08

2012

0.09 ± 0.03

0.16 ± 0.1

0.22 ± 0.01

0.15 ± 0.03

0.03 ± 0.02

0.30 ± 0.07

0.66 ± 0.2

0.23 ± 0.1

0.44 ± 0.06

***

***

0.0002***

P Subsurface

UB

B

P

0.008

**

0.020

*

0.185

0.020

*

0.815

0.0025

**

0.0002

0.0002

2010

0.10 ± 0.04

0.99 ± 0.2

0.58 ± 0.08

0.39 ± 0.2

N.D.

0.46 ± 0.1

23.2 ± 1.7

7.96 ± 0.6

1.91 ± 0.2

2011

0.42 ± 0.02

0.68 ± 0.3

0.68 ± 0.2

0.06 ± 0.05

0.18 ± 0.08

0.44 ± 0.2

15.1 ± 4.5

9.14 ± 2.6

2.74 ± 0.8

2012

0.20 ± 0.01

0.04 ± 0.03

0.78 ± 0.1

0.35 ± 0.07

0.07 ± 0.05

0.44 ± 0.09

6.20 ± 0.8

5.55 ± 2.5

2.17 ± 0.06

2010

0.09 ± 0.01

0.71 ± 0.1

0.64 ± 0.1

0.16 ± 0.2

0.17 ± 0.1

0.44 ± 0.1

4.22 ± 1.7

4.62 ± 1.1

0.39 ± 0.2

2011

0.22 ± 0.08

0.04 ± 0.04

0.86 ± 0.5

N.D.

0.33 ± 0.1

0.13 ± 0.1

1.66 ± 1.0

1.41 ± 0.4

0.97 ± 0.7

2012

0.50 ± 0.2

0.60 ± 0.2

0.98 ± 0.2

0.24 ± 0.1

1.13 ± 0.1

0.62 ± 0.09

2.39 ± 0.9

2.13 ± 1.5

3.38 ± 1.2

1.000

0.285

0.644

0.285

0.012*

0.667

190°C), the concentration of DOC decreased

405

with increasing heating temperature. Observations of the SOM properties indicate that the


22

Page 23 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


406

Indonesian soils were heated by low-severity fires (>200°C). Therefore, it is clear that the low

407

concentrations of DOC in the burned sites occurred because of the denaturation and leaching of

408

soluble SOM.

409

The average molecular weight (Mw) and E280 of the DOC extracted from the thermally treated

410

samples are shown in Figure 6(c). The Mw values decreased when the samples were heated over

411

90°C, and E280 significantly increased for thermal treatments of 150°C and 175°C for 60 min.

412

The fluorescence properties of the colored dissolved organic matter (CDOM) in the soil water-

413

extracted solutions of the UB1 and thermally treated samples were evaluated using the 3DEEM

414

spectrum (SI, Figure S3). The visible humic-like peak (Ex/Em = 320/445 nm) was detected in all

415

of the water samples.63 The relationship between the heating temperature and the RFI of the visible

416

humic-like/DOC ratio and excitation wavelength of the visible humic-like peak for the water-

417

extracted solutions from the thermally treated samples are shown in Figure 6(d). In the case of the

418

soil samples exposed to temperatures of 175°C, the RFI value of the visible humic-like/DOC was

419

15-fold higher than that of the UB1. In addition, a redshift in the excitation wavelength of the

420

visible humic-like peak occurred for sample heating at 150°C and 175°C for 60 min (Ex/Em = 285–

421

280/445 nm). The peak of the UV humic-like materials was detected at Ex/Em = 260/400–460 nm.63

422

A previous study reported that UV humic-like materials have fewer functional groups (less

423

conjugated electron resonance systems) than do visible humic-like materials.63 The investigations

424

conducted both in the field and in the laboratory reveal that peat fires cause transformations of

425

water-soluble SOM to lower molecular, higher aromaticity, and fewer functional group organic

426

compounds. Therefore, the exodus of CDOM (UV humic-like compounds) in the surface peatland

427

could have occurred during rainfall events after the fire.

428


23


Page 24 of 35

429 430

Figure 6. The DOC fractions and concentrations of the water-extracted solutions from (a)

431

unburned sites (UB1–3), burned sites (B1–5) at the subsurface in 2011, and (b) thermally treated

432

samples. Symbols: ■ = Hydrophobic neutral fraction (HoN), ■ = hydrophobic acid fraction (HoA),

433

■ = hydrophilic and hydrophobic base fractions (Hp + HoB), and ● = ignition loss. (c) Average

434

molecular weight (Mw; ●) and E280 (●) of the water-extracted solutions in the thermally treated

435

samples (90°C, 120°C, 150°C, 175°C, 180°C, 190°C, 200°C, 250°C, and 480°C for 60 min). (d)

436

The relationship between the heating temperature and the RFI of the visible humic-like/DOC ratio

437

(●) and excitation wavelength of the visible humic-like peak (●) for the water-extracted solutions

438

from the thermally treated samples.

439


24

Page 25 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

440


■ CONCLUSIONS

441

This study evaluated the effect of forest fire on the soil physical, chemical, biological properties

442

and the export of DOC from tropical peat land in Central Kalimantan, Indonesia. The organic

443

components in peat surface layer was destroyed by forest fires, and the flame-resistance

444

characteristics of SOM was produced in the subsurface layer of the burned soils. In addtion, the

445

decrease of microbial abundances and enzyme activities were observed in the subsurface layer of

446

the burned soils. The heat released in a fire is transported faster and penetrates deeper in moist

447

soils than in dry soils. Therefore, the organic matter in high-moisture soils such as peatlands is

448

strongly influenced by wildfires. The field and laboratory studies observed that the low-severity

449

fires accelerates the exodus of low molecular weight CDOM from peatlands. The structural

450

changes in DOC consequently will change the bioavailavility of metal and nutrient in the

451

hydrosphere. This study suggested that the denaturation of SOM and DOC strongly affect the

452

carbon cycles in Indonesian peat land, which have a huge accumulation of carbon storage in the

453

world.

454

455

■ ASSOCIATED CONTENT

456

Supporting Information. Supporting information for the assay conditions of the soil enzymes in

457

this study (Table S1), detailed physicochemical properties of the Indonesian peat soils (Table

458

S2), the assignments for the peaks identified in the Py-TMAH-GC/MS analyses of the peat soils

459

and the pyrogram total ion chromatograms from the Indonesian peat soil and thermally treated


25


460

samples (Table S3, Figure S1, and Figure S2), and the 3DEEM fluorescence spectrum of the

461

water-extracted samples in UB1 for the subsurface and thermally treated samples (Figure S3).

462

■ AUTHOR INFORMATION

463

Corresponding Author

464

* Phone & fax: +81 (0)76 445 6669; e-mail: [email protected].

465

■ ACKNOWLEDGMENT

466

Page 26 of 35

This work was supported by the JST/JICA Science and Technology Research Partnership for

467

Sustainable Development (SATREPS) Project entitled “Wild Fire and Carbon Management in

468

Peat-forest in Indonesia” and the Japan Society for the Promotion of Science (JSPS) via a Grant-

469

in-Aid for Scientific Research (80727016).

470

471

472

■ REFERENCES

473

(1) Aselmann, I.; Crutzen, P.J., Global distribution of natural freshwater wetlands and rice

474

paddies, their net primary productivity, seasonality, and possible methane emissions. J. Atmos.

475

Chem. 1989, 8, 307-358.

476

(2) Sjörs, H., Peat on Earth: multiple use of conservation. Ambio 1980, 9, 303-308.


26

Page 27 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


477

(3) Adams, J. M.; Faure, H.; Faure-Denard, L.; McGlade, J. M.; Woodward, F.I., Increases in

478

terrestrial carbon storage from the Last Glacial maximum to the present. Nature 1990, 348, 711-

479

714.

480 481 482 483 484 485 486 487

(4) Eswaran, H.; Van den Berg, E.; Reich, P., Organic carbon in soils of the world. Soil Sci. Soc. Am. J. 1993, 57, 192-194. (5) Batjes, N. H., Total carbon and nitrogen in the soils of the world. Eur. J. Soil Sci. 1996, 47, 151-163. (6) Bellamy, P. H.; Loveland, P. J.; Bradley, R. I.; Lark, R. M.; Kirk, G. J. D., Carbon losses from all soils across England and Wales 1978–2003. Nature 2005, 437, 245-248. (7) Tranvik, L. J.; Jansson, M., Climate change-Terrestrial export of organic carbon. Nature 2002, 415, 861-862.

488

(8) Freeman, C.; Fenner, N.; Ostle, N. J.; Kang, H.; Dowrick, D. J.; Reynolds, B.; Lock, M.

489

A.; Sleep, D.; Hughes, S.; Hudson, J., Export of dissolved organic carbon from peatlands under

490

elevated carbon dioxide levels. Nature 2004, 430, 195-198.

491 492 493 494

(9) Freeman, C.; Ostle, N.; Kang, H., An enzymic ‘latch’ on a global carbon store. Nature 2001, 409, 149. (10) Freeman, C.; Evans, C.; Monteith, D.; Reynolds, B.; Fenner, N., Export of organic carbon from peat soils. Nature 2001, 412, 785.


27


495

Page 28 of 35

(11) Pastor, J.; Solin, J.; Bridgham, S. D.; Updegraff, K.; Harth, C.; Weishampel, P.; Dewey,

496

B., Global warming and the export of dissolved organic carbon from boreal peatlands. Okios

497

2003, 100, 380-386.

498 499 500

(12) Page, S. E.; Rieley, J. O.; Banks, C. J., Global and regional importance of the tropical peatland carbon pool. Global Change Biol. 2011, 17, 798-818. (13) Putra, E. I.; Hayasaka, H., The effect of the precipitation pattern of the dry season on peat

501

fire occurrence in the Mega Rice Project area, Central Kalimantan, Indonesia. Tropics 2011, 19,

502

145-156.

503

(14) Hirano, T.; Segah, H.; Harada, T.; Limin, S.; June, T.; Hirata, R.; Osaki, M., Carbon

504

dioxide balance of a tropical peat swamp forest in Kalimantan, Indonesia. GCB Bioenergy 2007,

505

13, 412-425.

506

(15) Page, S. E.; Siegert, F.; Rieley, J. O.; Boehm, H. -D. V.; Jayak A.; Limink, S., The

507

amount of carbon released from peat and forest fires in Indonesia during 1997. Nature 2002, 420,

508

61-68.

509 510 511

(16)

Fire

Information

for

Resources

Management

System

Website;

https://earthdata.nasa.gov/earth-observation-data/near-real-time/firms (17) Neary, D. G.; Klopatek, C. C.; DeBano, L. F.; Fgolliott, P. F., Fire effects on

512

belowground sustainability: a review and synthesis. For. Ecol. Manage. 1999, 122, 51-71.

513

(18) DeBano, L. F., The role of fire and soil heating on water repellency in wildland

514

environments: a review. J. Hydrol. 2000, 231-232, 195-206.


28

Page 29 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


515 516

(19) Gonzalez-Perez, J. A.; Gonzalez-Vila, F. J.; Almendros G.; Knicker, H., The effect of fire on soil organic matter-a review. Environ. Int. 2004, 30, 855-870.

517 518 519 520 521 522 523 524 525

(20) Certini, G., Effects of fire on properties of forest soils: a review. Oecologia 2005, 143, 110. (21) Knicker, H., How does fire affect the nature and stability of soil organic nitrogen and carbon? A review. Biogeochemistry 2007, 85, 91-118. (22) Mataix-Solera, J.; Cerda, A.; Arcenegui, V.; Jordan, A.; Zavala, L. M., Fire effects on soil aggregation: A review. Earth-Sci. Rev. 2011, 109, 44-60. (23) Almendros G.; Gonzalez-Vila, F. J., Wildfires, soil carbon balance and resilient organic matter in Mediterranean ecosystems. A review. Spanish J. Soil Sci. 2012, 2, 8-33. (24) Page, S. E.; Wust, R. A. J.; Weiss, D.; Rieley, J. O.; Shotyk, W.; Limin, S. H., A record

526

of Late Pleistocene and Holocene carbon accumulation and climate change from an equatorial

527

peat bog (Kalimantan, Indonesia): implications for past, present and future carbon dynamics. J.

528

Quaternary. Sci. 2004, 19, 625-635.

529

(25) Hirano, T.; Segah, H.; Kusin, K.; Limin, S.; Takahashi, H.; Osaki, M., Effects of

530

disturbances on the carbon balance of tropical peat swamp forests. Glob. Change Biol. 2012, 18,

531

3410-3422.

532

(26) Tuah, S.J.; Jamal, Y.M.; Limin, S., Nutritional characteristics in leaves of plants native to

533

tropical peat swamps and heath forests of Central Kalimantan, Indonesia. TROPICS 2003, 12,

534

221-245.


29


535

Page 30 of 35

(27) Sazawa, K; Tachi, M.; Wakimoto, T.; Kawakami, T.; Hata, N.; Taguchi, S.; Kuramitz, H.,

536

The evaluation for alterations of DOM components from upstream to downstream flow of rivers

537

in Toyama (Japan) using three-dimensional excitation-emission matrix fluorescence

538

spectroscopy. Int. J. Environ. Res. Public Health 2011, 8, 1655-1670.

539

(28) Takakai, F.; Morishita, T.; Hashidoko, Y.; Darung, U.; Kuramochi, K.; Dohong, S.;

540

Limin, S.H.; Hatano, R., Effects of agricultural land-use change and forest fire on N2O emission

541

from tropical peatlands, Central Kalimantan, Indonesia. Soil Sci. Plant Nutr. 2006, 52, 662-674.

542

(29) Japanese Industrial Standards Committee (1999) Test method for density of soil particles

543

JIS A 1202, Japanese Standards Association (in Japanese).

544

(30) Fukushima, M.; Yamamoto, M.; Komai, T.; Yamamoto, K., Studies of structural

545

alterations of humic acids from conifer bark residue during composition by pyrolysis-gas

546

chromatography/mass spectrometry using tetramethylammonium hydroxide (TMAH-py-

547

GC/MS). J. Anal. Appl. Pyrolysis 2009, 86, 200-206.

548

(31) Muyzer, G.; de Waal, E. C.; Uitterlinden, A. G., Profiling of complex microbial

549

populations by denaturing gradient gel electrophoresis analysis of polymerase chain reaction-

550

amplified genes coding for 16S rRNA. Appl. Environ. Microbiol. 1993, 59, 695-700.

551 552 553

(32) Floch, C.; Alarcon-Gutierrez, E.; Criquet, S., ABTS assay of phenol oxidase activity in soil. J. Microbiol. Methods 2007, 71, 319-324. (33) Tabatai, M. A.; Bremner J. M., Use of p-nitrophenyl phosphate for assay of soil

554

phosphatase activity. Soil Biol. Biochem. 1969, 1, 301-307.(34) Eivazi, F; Tabatabai, M. A.,

555

Phosphatases in soils. Soil Biol. Biochem. 1977, 9, 167-172.


30

Page 31 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

556 557


(35) Eivazi, F; Tabatabai, M. A., Glucosidases and galactosidases in soils. Soil Biol. Biochem. 1988, 20, 601-606.

558

(36) Leenheer, J. A., Comprehensive approach to preparative isolation and fractionation of

559

dissolved organic carbon from natural waters and wastewaters. Environ. Sci. Technol. 1981, 15,

560

578-587.

561

(37) Kuramitz, H.; Sazawa, K.; Nanayama, Y.; Hata, N.; Taguchi, S.; Sugawara, K.;

562

Fukushima, M., Electrochemical genotoxicity assay based on a SOS/umu test using

563

hydrodynamic voltammetry in a droplet. Sensors 2012, 12, 17414-17432.

564 565 566 567 568

(38) Peuravuori, J.; Pihlaja, K., Molecular size distribution and spectroscopic properties of aquatic humic substances. Anal. Chim. Acta 1997, 337, 133-149. (39) Arocena, J. M.; Opio, C., Prescribed fire-induced changes in properties of sub-boreal forest soils. 2003, Geoderma 113, 1-16. (40) Usup, A.; Hashimoto, Y.; Takahashi, H.; Hayasaka, H., Combustion and thermal

569

characteristics of peat fire in tropical peatland in Central Kalimantan, Indonesia. Tropics 2004,

570

14, 1-19.

571 572

(41) Huang, X.; Rein, G., Downward spread of smouldering peat fire: the role of moisture, density and oxygen supply. Int. J. Wildland Fire 2017, 26, 907-918.

573

(42) Almendros, G.; Knicker, H.; Gonza´lez-Vila, F. J., Rearrangement of carbon and nitrogen

574

forms in peat after progressive isothermal heating as determined by solid-state 13C- and 15N-NMR

575

spectroscopies. Org. Geochem. 2003, 34, 1559-1568.


31


Page 32 of 35

576

(43) Choromanska, U.; DeLuca, T. H., Microbial activity and nitrogen mineralization in forest

577

mineral soils following heating: evaluation of post-fire effects. Soil Biol. Biochem. 2002, 34, 263-

578

271.

579 580 581 582 583 584 585 586

(44) Almendros, G.; Martın, F.; Gonza´lez-Vila, F. J., Effects of fire on humic and lipid fractions in a Dystric Xerochrept in Spain. Geoderma 1988, 42, 115-127. (45) Fritze, H.; Pennanen, T.; Pietikainen, J., Recovery of soil microbial biomass and activity from prescribed burning. Can. J. For. Res. 1993, 23, 1286-1290. (46) Warcup, M.G.; Horne, D.J., Occurrence of dormant ascospores in soil. Nature 1963, 197, 1317-1318. (47) Eivasi, F.; Bayan, M. R., Effects of long-term prescribed burning on the activity of selected soil enzymes in an oak-hickory forest. Can. J. Forest Res. 1996, 26, 1799-1804.

587

(48) Hernandez, T.; Garcia, C.; Reinhardt, I., Short-term effect of wildfire on the chemical,

588

biochemical and microbiological properties of Mediterranean pine forest soils. Biol. Fertil. Soils

589

1997, 25, 109-116.

590

(49) Ajwa, H. A.; Dell, C. J.; Rice, C. W., Changes in enzyme activities and microbial biomass

591

of tallgrass prairie soil as related to burning and nitrogen fertilization. Soil Biol. Biochem. 1999,

592

31, 769-777.

593 594

(50) Boerner, R. E. J.; Brinkman, J. A., Fire frequency and soil enzyme activity in southern Ohio oak-hickory forests. Appl. Soil Eco. 2003, 23, 137-146.


32

Page 33 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

595


(51) Gutknecht, J. L. M.; Henry, H. A. L.; Balser, T. C., Inter-annual variation in soil extra-

596

cellular enzyme activity in response to simulated global change and fire disturbance.

597

Pedobiologia 2010, 53, 283-293.

598

(52) Sinsabaugh, R. L.; Antibus, R. K.; Linkins, A. E.; Rayburn, L.; Repert, D.; Weiland, T.,

599

Wood decomposition in a first order watershed: mass loss as a function of exoenzyme activity.

600

Soil Biol. Biochem. 1992, 24, 743-749.

601

(53) Sinsabaugh, R. L.; Antibus, R. K.; Linkins, A. E.; McClaugherty, C. A.; Rayburn, L.;

602

Weiland, T., Wood decomposition: nitrogen and phosphorus dynamics in relation to

603

extracellular enzyme activity. Ecology 1993, 74, 1586-1593.

604 605 606 607 608 609 610

(54) Speir, T. W.; Cowling, J. C., Phosphatase activities of pasture plants and soils: relationship with plant productivity and soil P fertility indices. Biol. Fert. Soils 1991, 12, 189-194. (55) Dinkelaker, B.; Marschner, H., In vivo demonstration of acid phosphatase activity in the rhizosphere of soil-grown plants. Plant Soil 1992, 144, 199-205. (56) Nakas, J. P.; Gould, W. D.; Klein, D. A., Origin and expression of phosphatase activity in a semi-arid grassland soil. Soil Biol. Biochem. 1987, 19, 13-18. (57) Tarafdar, J. C.; Claassen, N., Organic phosphorus compounds as a phosphorus source for

611

higher plants through the activity of phosphatase produced by plant roots and microorganisms.

612

Biol. Fert. Soils 1988, 5, 308-312.


33


Page 34 of 35

613

(58) Saa, A.; Trasar-Cepeda, M. C.; Gil-Sotres, F.; Carballas, T., Changes in soil phosphorus

614

and acid phosphatase activity immediately following forest fires. Soil Biol. Biochem. 1993, 25,

615

1223-1230.

616

(59) Zhang, Y.-M.; Wu, N.; Zhou, G.-Y.; Bao, W.-K., Changes in enzyme activities of spruce

617

(Picea balfouriana) forest soil as related to burning in the eastern Qinghai-Tibetan Plateau. Appl.

618

Soil Eco. 2005, 30, 215-225.

619 620 621 622

(60) Tabatabai, M. A.; Bremner, J. M., Arylsulfatase activity of soils. Soil Sci. Soc. Am. J. 1970, 34, 225-229. (61) Skujins, J. J., Enzymes in soil. In Soil Biochemistry Vol.1; McLaren, A. D., Peterson, G. H., Eds.; Dekker, New York. 1967; pp 371-414.

623

(62) Turner, B. L.; Haygarth, P. M., Phosphatase activity in temperate pasture soil: Potential

624

regulation of labile organic phosphorus turnover by phosphodiesterase activity. Sci. Total Environ.

625

2005, 344, 27-36.

626 627

(63) Coble, P.G.; Del Castillo, C. E.; Avril, B., Distribution and optical properties of CDOM in the Arabian Sea during the 1995 Southwest Monsoon. Deep-Sea Res. II 1998, 45, 2195-2223.

628


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629 630


Table of Content (TOC)

631


35

Impact of Peat Fire on the Soil and Export of Dissolved Organic

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