Occurrence of Pyrethroids in Bed and Suspended Sediments in

Chapter 3

Occurrence of Pyrethroids in Bed and Suspended Sediments in California

Downloaded by PURDUE UNIV on November 29, 2016 | http://pubs.acs.org Publication Date: August 19, 2008 | doi: 10.1021/bk-2008-0991.ch003

Michelle L . Hladik and Kathryn M. Kuivila U.S. Geological Survey, 6000 J Street, Sacramento, C A 95819

Pyrethroids have been detected in sediments collected over the past decade from a variety of California locations. While most published studies sampled in close proximity to pyrethroid application, the studies included in this chapter focused on watersheds located farther from pyrethroid sources. The four watersheds in this chapter varied considerably in size (1100,000 km ) and included both agricultural and urban land use. Four pyrethroids (bifenthrin, ^-cyhalothrin, x-fluvalinate and permethrin) were detected in bed and suspended sediments. Bifenthrin and permethrin were detected the most frequently and at the highest concentrations, with maximum concentrations of 24 and 70 ng/g dry weight, respectively. Occurrences of individual pyrethroids were correlated to higher use in some but not all cases. 2

Introduction The Pesticide Fate Research Group of the U.S. Geological Survey (USGS) has been measuring pyrethroid insecticides in bed and suspended sediments in California for years and detected pyrethroids in samples as early as 1997. While the objective of the studies described herein was to understand the transport and © 2008 American Chemical Society Gan et al.; Synthetic Pyrethroids ACS Symposium Series; American Chemical Society: Washington, DC, 2008.

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56 fate of many current-use pesticides, pyrethroids were included in the suite of analytes. Pyrethroids are detected mainly in the sediment because these compounds are hydrophobic (log Koc >5; ref 7) and tend to partition onto particles rather than remain in the dissolved phase. Pyrethroids are highly toxic to aquatic organisms, especially those that live in the sediment; 10-day L C values for Hyalella azteca have been found to range from 0.52 ug/g organic carbon for bifenthrin to 11 ug/g organic carbon for permethrin (2). Sediment toxicity is likely to be of greatest concern close to the pyrethroid application sites and in depositional zones just downstream of those sites. Typically, dilution of sediment-bound pyrethroids occurs as non-contaminated sediments enter from other downstream sources; however, sediment sorting has been shown to cause downstream pyrethroid enrichment in a single-source drainage canal (3). This chapter describes the occurrence of pyrethroids in bed or suspended sediments at four locations in California (Carpinteria Marsh, Mallard Island, Yolo Bypass and Salton Sea) from 1997 to 2005 (see Figure 1 for general locations). The Carpinteria Marsh study focused on bed sediments to monitor coastal marsh contamination from urban inputs. The Salton Sea study combined investigations of both bed and suspended sediments in a watershed that has


5 0

Figure 1. Areas in California where pyrethroids were detected. San Francisco Bay includes Mallard Island and Yolo Bypass.

Gan et al.; Synthetic Pyrethroids ACS Symposium Series; American Chemical Society: Washington, DC, 2008.

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intensive agricultural activity, is home to endangered species and an important ecosystem for the Pacific Flyway. The Yolo Bypass and Mallard Island studies (both located within the San Francisco Bay watershed) focused on suspended sediments that are transported into San Francisco Bay, one of the most economically and ecologically important estuaries in the United States. Sampling, detections and use for each location are summarized in Table I. Other studies have measured pyrethroids in sediments in California, but most have been close to agricultural (4) or urban (5) sources. To achieve a greater understanding of pyrethroid transport and toxicity, watersheds farther from sources need to be monitored; these include larger rivers and estuaries.

Table I. Summary of locations included in this chapter. Location

Year(s)

Carpinteria Marsh Salton Sea

2002, 2003 2001, 2002

Yolo Bypass Mallard Island

2004, 2005 1997

Sediment Matrix bed

Watershed Size (km ) 0.9

bed and suspended

5,359*

suspended

5,036*

suspended

99,587

2

Pyrethroids Environmental Setting Detected bifenthrin, coastal marsh contamination permethrin ecosystem for bifenthrin, Pacific Flyway \cyhalothrin, permethrin fish habitat bifenthrin, Tfluvalinate flows to San bifenthrin Francisco Bay

a

Alamo and New Rivers: 2,428 km ; Whitewater River: 3,931 km

2

h

Willow Slough: 697 km ; Knights Landing Ridge Cut: 4,339 km

2

2

2

Sampling and Analysis Techniques Sample Collection Bed sediment samples were collected with either a stainless steel spoon from the top 2 cm of depositional zone, a 9-inch (22.9 cm) Ekman grab sampler, or a 2-inch (5.1 cm) diameter, Teflon-barreled hand corer. In some cases multiple grabs were required to obtain approximately 0.5 L for each site. Suspended sediment was isolated from large-volume water samples (1001000 L ) . At each site, water was collected with a peristaltic pump into 20-L


58 stainless steel soda kegs and then pumped through a Westfalia continuous-flow centrifuge at 2 L/min within 6 hours of collection.


Extraction and Quantitation Sediment samples were homogenized before microwave-assisted solvent extraction. Sediment samples were extracted wet, at approximately 50% moisture. Matrix was removed from the extract using either a carbon cartridge or stacked carbon and alumina cartridges and sulfur was removed with gel permeation chromatography. Samples were analyzed on a Varian Saturn iontrap gas chromatography/mass spectrometry in M S and M S / M S mode. Further details for both pyrethroid methods and the procedure to measure percent organic carbon can be found elsewhere (6,7). The specific pyrethroids analyzed varied by study, as more pyrethroids were added over time to reflect new compounds of interest. A l l studies included bifenthrin, cyfluthrin, cypermethrin, X-cyhalothrin, esfenvalerate and permethrin. The Yolo Bypass study also included deltamethrin, fenpropathrin, sumithrin and T-fluvalinate. All concentrations were quantified on a sediment dry weight basis. Method detection limits, based on the standard deviation of seven replicate samples, were 1-2 ng/g for the pyrethroids measured (6,7); however, the calculated limit of detection for bifenthrin using the M S / M S mode method for the Mallard Island samples was 0.2 ng/g.

Carpinteria Marsh Carpinteria Marsh is a restored estuarine wetland located east of Santa Barbara, California, along the coast of the Pacific Ocean. This 0.9 k m marsh receives pesticide inputs from applications on nurseries, greenhouses, orchards, row crops and residential areas within the watershed. A creek channel on the west side of the marsh was sampled along a transect beginning at the edge of the marsh (Figure 2). Four stations (A-D) were sampled along the transect in July of 2002 and August of 2003. At each station, bed sediments were collected at different channel depths to account for tidal inundation cycles: the creek channel (low), creek bank (mid), and the vegetated marsh edge (high) (Figure 2). Typically, the creek channel was saturated throughout the tidal cycle, the intertidal bank was flooded intermittently, and the marsh edge was rarely flooded. Two pyrethroids, bifenthrin and permethrin, were detected in the bed sediments. Bifenthrin was detected at stations A and B in 2002 (Figure 3a) and at all stations (A-D) in 2003 (Figure 3b). In 2002, similar concentrations were found at stations A and B (14 to 22 ng/g) and the distribution was throughout the 2



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Figure 2. Diagram of sampling at Carpinteria Marsh. Stations were located along a transect that increased in distance from the input. Additionally each station had a cross-section sampled.

channel but no bifenthrin was detected downstream of station B . In 2003, maximum concentrations decreased along the transect from 24 ng/g at station A to 1.3 ng/g at station D , with distributions once again being found in varying portions of the channel. Bifenthrin concentrations did not show a clear elevation pattern along the transect of the channel in either year. Percent organic carbon for sediments containing bifenthrin ranged from 0.8 to 4.1 percent. Calculated LC50's for Hyalella azteca in sediments with similar organic carbon concentrations (using 0.52 ug/g organic carbon; ref 2) ranged from 4 to 21 ng/g. O f the eleven bifenthrin detections, six exceeded the corresponding LC50. Permethrin was only detected at station A in 2002 (Figure 3a) and stations A and B (Figure 3b) in 2003, with concentrations ranging from 20 to 69 ng/g. Permethrin was detected in the creek channel and bank, but not on the marsh edge. Percent organic carbon in the sediment for the permethrin detections ranged from 0.6 to 2.8 percent; therefore, calculated L C ' s for Hyalella azteca in these sediments (using 11 ug/g organic carbon; ref 2) were 60 to 300 ng/g. None of the permethrin detections exceeded the L C . Overall, bifenthrin and permethrin show different patterns of detection by elevation suggesting different transport during high and low flows, possibly dependent on timing or location of application. Differences in degradation rates on the marsh edge versus the- channel could also influence their fate. Bifenthrin is more stable than permethrin; half-lives for bifenthrin range from 277 to 770 days versus 99 to 141 days for permethrin (8). 5 0

5 0


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Figure 3. Concentrations of bifenthrin and permethrin at Carpinteria Marsh in a) 2002 and b) 2003. Four stations were sampled along a transect and within stations a cross-section was sampled at the high, mid and low portions of the channel


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Salton Sea Located in Southern California, the Salton Sea is a closed-basin lake that receives runoff from the surrounding areas. Three rivers drain into the Salton Sea: the Alamo and New Rivers from the south and the Whitewater River from the north (Figure 4). Within the Imperial Valley, the Alamo and New Rivers drain an area of 2,428 k m that is primarily agricultural. In contrast, the Whitewater River watershed, 3,931 km , is a mixture of agriculture, urban and undeveloped upland areas. Pesticides in water, suspended sediments, and bed sediments were measured at the three river outlets (Figure 4). Samples were collected in the fall of 2001 and the spring and fall of 2002. Details of the sampling times and locations can be found elsewhere (7). Three pyrethroids, bifenthrin, A,-cyhalothrin, and permethrin, were detected in the suspended and bed sediments. For each sampling period, the con centrations for ^-cyhalothrin and permethrin are plotted in Figure 5. Bifenthrin had only one detection of 7.5 ng/g in bed sediments from the Whitewater River in the fall of 2001. The Alamo River had the highest number of detections 2


2

Figure 4. Locations of sampling sites for the Salton Sea.


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Occurrence of Pyrethroids in Bed and Suspended Sediments in

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