Subscriber access provided by CORNELL UNIVERSITY LIBRARY
Article
Bifenthrin causes toxicity in urban stormwater wetlands: Field and laboratory assessment using Austrochiltonia (Amphipoda) Katherine Joanna Jeppe, Claudette Robin Kellar, Stephen Marshall, Valentina Colombo, Georgia May Sinclair, and Vincent J. Pettigrove Environ. Sci. Technol., Just Accepted Manuscript • Publication Date (Web): 11 May 2017 Downloaded from http://pubs.acs.org on May 15, 2017
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 26
Environmental Science & Technology
1
Bifenthrin causes toxicity in urban stormwater wetlands: Field and
2
laboratory assessment using Austrochiltonia (Amphipoda)
3
Katherine J. Jeppe*, Claudette R. Kellar, Stephen Marshall, Valentina Colombo, Georgia M. Sinclair
4
and Vincent Pettigrove
5
Centre for Aquatic Pollution Identification and Management (CAPIM), School of BioSciences, The University of
6
Melbourne, Royal Parade, Parkville, Australia, 3010.
7
KEYWORDS: Austrochiltonia subtenuis, Sediment toxicity, Synthetic pyrethroid
8
ABSTRACT: Stormwater wetlands are engineered to accumulate sediment and pollutants from stormwater and provide
9
environmental value to urban environments. Therefore, contaminated sediment risks causing toxicity to aquatic fauna. This
10
research identifies contaminants of concern in urban wetland sediments by assessing sediment toxicity using the amphipod
11
Austrochiltonia subtenuis. Sediments from 99 wetlands were analyzed for contaminants and laboratory bioassays were performed
12
with A. subtenuis. Wild Austrochiltonia spp. were also collected from wetlands to assess field populations. Random forest
13
modeling was used to identify the most important variables predicting survival, growth and field absence of Austrochiltonia spp..
14
Bifenthrin was the most frequently detected pesticide and also the most important predictor of Austrochiltonia spp. responses.
15
Copper, permethrin, chromium, triclosan and lead were also important. The median lethal effect concentration (LC50) of bifenthrin
16
to laboratory-based A. subtenuis (1.09 (±0.08) µg/gOC) exposed to wetland sediments was supported by a bifenthrin-spiked
17
sediment experiment, indicating A. subtenuis is a suitable test species. Furthermore, Austrochiltonia spp. were absent from all sites
18
that exceeded the calculated bifenthrin LC50, demonstrating the impact of this contaminant on wild populations. This research
19
demonstrates the sensitivity of Austrochiltonia spp. to urban sediment contamination and identifies bifenthrin as a contaminant of
20
concern in urban wetlands.
1 ACS Paragon Plus Environment
Environmental Science & Technology
Page 2 of 26
21
INTRODUCTION
22
The construction of stormwater wetlands is widely recognized as an effective measure to abate stormwater runoff and reduce the
23
environmental impacts of urbanisation.1 Stormwater wetlands serve several purposes, including sedimentation, chemical adsorption
24
and biological filtration (by vegetation and bacteria), while also providing habitat and environmental value to urban environments.2
25
By design, stormwater wetlands accumulate sediment and associated contaminants, protecting downstream receiving waters but
26
potentially harming biota that live in them.
27
Contaminants of concern in urban stormwater wetlands have changed over time.3 In recent decades, the occurrence of pesticides in
28
urban environments has increased. Pesticides are not only used in agriculture but also in residential areas and are common in
29
structural pest control, landscape maintenance and residential home and garden use. The use of synthetic pyrethroids has increased
30
in recent years to replace organophosphate insecticides.4 Since the use of organophosphate insecticides decreased due to high
31
mammalian toxicity, synthetic pyrethroid use has increased as they have relatively lower mammalian toxicity.5,
32
synthetic pyrethroids have recently been shown to be toxic to non-target biota, such as fish and macroinvertebrates, in receiving
33
environments.7-14
34
Metal contamination in the urban environment has been relatively constant over recent years,3 although individual metals have
35
changed with improved regulation. For example, zinc and copper are ubiquitous in urban environments due to their use in
36
manufacturing processes, production of tires and brake pads and galvanization of metal surfaces. Lead has decreased since the
37
phase out of leaded petrol and metals like cadmium, mercury and silver are generally restricted to industrial point sources.15
38
Furthermore, background metal levels are often associated with geology, for example, nickel and chromium concentrations are
39
often higher in basalt than in clay soils but can have a relatively lower bioaccessible fraction and toxicity.16 Hydrocarbons are often
40
associated with road run off and, like zinc, are ubiquitous in urban environments. All these contaminants have been associated with
41
aquatic ecosystem decline due to their toxicity to biota, the extent of which can be established with sediment toxicity tests.6, 17-20
42
Amphipoda are one of the main groups used in sediment toxicity testing.21 Toxicity tests have been developed for several
43
amphipod species, such as Hyalella azteca (in North America) and Gammarus spp. (in Europe) for the assessment of freshwater
44
bodies, and Melita plumulosa for marine environments.22-24 None of these freshwater species, however, occur in Australia.
45
Importation is possible but problematic due to strict biosecurity regulation, meaning that these tests could only be run in certified
46
laboratories with strict biocontainment. Furthermore, the responses observed in international species are unlikely to accurately
47
represent indigenous species responses. Indigenous species have physiologically adapted to local conditions (e.g. higher salinity
48
and low phosphorus) and their responses better predict contaminant impacts, as they are not affected by local environmental factors
49
that could confound or mask the effect of a toxicant in non-local species.25 It is also possible that the environmental fate and
6
However,
2 ACS Paragon Plus Environment
Page 3 of 26
Environmental Science & Technology
50
bioavailability of chemicals differ under local environmental conditions. Therefore a native amphipod species is essential for
51
ecologically meaningful bioassays.
52
A common amphipod that occurs in southern Australian is Austrochiltonia subtenuis.26 This species is a benthic shredder and by
53
consuming algae and detritus it provides an important ecological function in freshwater ecosystems. It also provides a food source
54
to many invertebrate and vertebrate species. Given that A. subtenuis is one of the most abundant taxonomic groups in these
55
freshwater ecosystems and is crucial to the function and structure of invertebrate communities it is pertinent to investigate potential
56
toxicity of contaminants to this species. Recently, A. subtenuis has been shown to be sensitive to fungicide contamination in water,
57
however there is little research to date on the impacts of sediment contamination on this species.27
58
This study investigated the toxicity of stormwater wetland sediments using laboratory-based sediment tests with A. subtenuis and
59
field assessment of Austrochiltonia spp. This research aimed to identify sediment contaminants of concern in urban wetlands and to
60
validate Austrochiltonia spp. as a sensitive indicator of environmentally relevant sediment toxicity.
3 ACS Paragon Plus Environment
Environmental Science & Technology
Page 4 of 26
61
EXPERIMENTAL MATERIAL AND METHODS
62
Study area and sample collection. Sediment and field amphipods were collected from 99 constructed wetlands in the Greater
63
Melbourne metropolitan Area (GMA) between February and May 2015 (Figure 1). The geographic coordinates of the sampled
64
wetlands are listed in Supporting Information Table S1. For sediment collection, deposited sediments (top 2 cm) were collected and
65
sieved on site through 63 µm nylon mesh.18 Sediments were then allowed to settle in 10 L buckets, the overlying water decanted,
66
and stored in clean glass jars in the dark at 4 °C until chemical analysis and toxicity testing. For field amphipod collection, the
67
types of aquatic habitat (vegetated, leaf litter or bare substrate) were assessed at each site and each habitat was sampled for 2
68
minutes with a 250 µm dip net. The samples were combined across habitats and picked on site for 30 minutes. Resulting
69
amphipods were then stored in 70% ethanol for later identification. Once in the laboratory, amphipods were identified to genus and
70
counted under a dissecting microscope.
71
Chemical analyses. Sediments were analyzed for a number of chemical parameters, including metals, pesticides, total organic
72
carbon, petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAHs). University of Melbourne Chemistry Department
73
analyzed the sediment for organic contaminants by Gas Chromatography Mass Spectrometry (GC-MS), including personal care
74
products and selected pesticides. This analysis was selected to target the semi- and non-polar contaminants that associate with
75
sediment. Detailed methods for the GC-MS analysis of sediments, including mass spectrometer ion monitoring program and quality
76
control and assurance procedures are presented in Supporting Information 2 (Table S2-S4). Australian Laboratory Services
77
analyzed the sediment for total metals by ICP-AES (method: EG005T), total mercury by FIMS (method: EG035T), total
78
recoverable hydrocarbons (C10-C40) (method: EP080/071), total organic carbon (TOC) (method: EP003) and moisture content
79
(method: EA055). Quality assurance and control for metal and hydrocarbon analysis are displayed in Supporting Information Table
80
S5.
81
Laboratory-based bioassay. Laboratory-based amphipod bioassays, using Austrochiltonia subtenuis were used to assess the
82
toxicity of wetland sediments compared to reference sediment (Deep Creek, Bulla Rd, Bulla, Victoria). The A. subtenuis culture
83
used in these exposures originated from the reference site. The culture was maintained in glass aquaria containing cotton gauze as
84
substrate and a standard artificial media (SAM) modified from Borgmann.28 The SAM consisted of reverse osmosis water with
85
4.71 mM of NaCl, 2.3 mM of NaHCO3, 1.73 mM MgCl2 hydrous, 0.61 mM of CaCl2 hydrous, 0.48 mM NaBr, 0.32 mM of MgSO4
86
and 0.09 mM of KCl. Cultures were maintained at 21 ± 1°C under a 16:8 h light:dark photoperiod. The culture was fed powdered
87
fish food (Tetramin®) and supplemented with conditioned Pomaderris sp. leaves. Leaves were air-dried for 7 days at room
88
temperature and conditioned in nutrient-enriched water at a rate of 1 g/L (reference site water with 5 mg/L phosphorous as
89
K2HPO4 and 20 mg/L nitrogen as (NH4)2SO4) for 2 weeks, with water renewed after 7 days.
4 ACS Paragon Plus Environment
Page 5 of 26
Environmental Science & Technology
90
For the experiment, ten 7-14 day old juveniles were added to each experimental replicate. Each replicate was composed of a 450
91
mL beaker containing 40 g (wet weight) of sieved (< 63 µm) sediment and ~350 mL SAM. The bioassays were run in 4 batches of
92
25 sites each, with 4 replicates for each site and 8 for the reference (Deep Creek, Bulla Rd, Bulla, Victoria). Batches were timed so
93
that sediment was never held for more than 3 weeks between collection and bioassay commencement. The bioassays were run on a
94
semi-automated flow-through system, which renewed approximately 120 ml of water twice daily. Amphipods were fed three times
95
a week with powdered fish food and ground Pomaderris sp. leaves at a rate of 0.5 mg of each food type per amphipod per day. For
96
quality assurance and control, electrical conductivity, pH, dissolved oxygen and total ammonia concentrations were measured at
97
the end of the assay. Copper reference toxicity tests were also run for A. subtenuis larvae from the same cultures used in the
98
laboratory test to ensure that cultures were appropriately sensitive to a standard stressor. Water quality and copper reference test
99
results are displayed in in Supporting Information, Table S6 and Table S7, respectively. After the 21 d exposure, amphipods were
100
removed from each replicate by sieving the sediment and water through a 250 µm sieve. If less than ten amphipods were retrieved,
101
the remaining sediment (>250 µm) was stained with Rose Bengal and sorted under a dissecting microscope to locate any remaining
102
survivors. Amphipod head length was then measured under a dissector microscope to establish growth during the 3-week exposure.
103
Validation experiment. The results from the laboratory-based bioassay prompted a validation experiment to demonstrate the
104
toxicity of bifenthrin to Austrochiltonia subtenuis. Sediment from an uncontaminated wetland (Bittern Reservoir, Bittern) was
105
spiked to a high concentration (100 mg/kg dry weight bifenthrin, 99% purity, ChemService, USA) using acetone as the solvent
106
carrier (2 mL in 1 kg wet weight sediment). This sediment was mixed open in a fume hood for 10 min per day with a stainless steel
107
spatula to evaporate the acetone and then rolled for 1 h per day for a week. The stock sediment was then diluted with unspiked
108
sediment to provide 13 treatments (measured concentrations: 57 µg/kg, 27 µg/kg, 22 µg/kg, 11 µg/kg, extrapolated concentrations
109
(below detection of analysis) 8.25 µg/kg, 6.19µg/kg, 4.64 µg/kg, 3.48 µg/kg, 2.61 µg/kg, 1.96 µg/kg, 0.98 µg/kg, 0.49 µg/kg). The
110
TOC of spiked sediment was 2.1% and field sediments ranged from 1.07% to 13.91%). Treatment sediments were shaken for 30
111
seconds each day and rolled for 1 h per day for 5 days before experiment setup. A solvent control (2 mL in 1 kg wet weight
112
sediment), treated as the stock sediment, and an unspiked control, treated as diluted sediments, were included. Four replicates were
113
conducted for each spiked treatment and eight replicates were conducted for the two control treatments. Before the experiment
114
commenced, water was renewed twice in all beakers and the experiment was run on a semi-automated flow-through system under
115
conditions described for the laboratory-based bioassays. Water quality and copper reference test results for the validation
116
experiment are displayed in Supporting Information, Table S8 and Table S9, respectively.
117 118
Statistical analysis. All statistical analysis was performed in R (version 3.3.0, The R Foundation for Statistical Computing). For
119
modeling, sediment contaminant concentrations were adjusted for limits of detection (LOD). Values below the LODs were reported
120
as 50% of the LOD and trace detects were reported as 75% the LOD. To account for differences in bioavailability due to organic
5 ACS Paragon Plus Environment
Environmental Science & Technology
Page 6 of 26
121
carbon in the
