Sediment Toxicity Identification Evaluation Research Articles

Using spatial and temporal variability data to optimize sediment toxicity identification evaluation (TIE) study designs.

Toxicity tests are an important aspect of sediment quality assessments, but knowledge of the cause of toxicity is needed to determine effective management actions. Toxicity identification evaluation (TIE) methods were developed to meet this need. While TIE method manuals provide information on the procedures, little information on study design is presented. The level of variability associated with performing TIEs and how to account for it is also not addressed. The goal of this study was to collect data on both the spatial and temporal variability associated with sediment TIEs by use of the amphipod Eohaustorius estuarius 10-day survival test and then apply that information to make recommendations for designing future TIE studies. Ten stations were sampled at Consolidated Slip in Los Angeles Harbor, California, with samples collected 2 months apart. In the first stage, TIEs were conducted on whole sediment and pore water from 3 of the most toxic stations. In the second stage, focused TIEs were conducted on whole sediment from all stations. Chemical analysis for metals and organic contaminants was also performed. With a weight of evidence approach, it was determined that pyrethroid pesticides were the likely cause of toxicity, with a lesser contribution from polycyclic aromatic hydrocarbons (PAHs). Results of the individual TIEs fell into 3 broad categories: TIEs in which treatments for organic chemicals and pyrethroids were effective; TIEs in which the treatment for pyrethroids was not effective but the treatment for organic contaminants was effective; and TIEs in which the treatment for pyrethroids was effective but the treatment for organic contaminants was not. This variability was used to calculate that at least 3 TIEs were necessary to make a confident assessment of the cause of toxicity. There was not substantial temporal variability in the TIE outcomes. Other recommendations are made regarding effective TIE study design. Integr Environ Assess Manag 2019;15:248-258. © 2018 SETAC.

A Tropical Amphipod (Grandidierella bonnieroides) Tested with Granulometric Fractions and TIE Materials for Optimization of Toxicity Evaluations

A series of acute toxicity studies exposed G. bonnieroides to different sediment particles (SP), materials used in whole sediment toxicity identification evaluations (TIE), and environmental samples (ES). The results from different experimental steps have confirmed that no significant difference was found between treatments (SP and TIE) and their control samples, thus indicating that the species can be successfully used in this type of experiment. Due to the high survival percentage (97.5% average) observed in all test replicates, the species characteristics that enable it to be used as a standardized species, with high ecological representativeness in tropical ecosystem toxicity tests were discussed. Finally, environmental sample analyses were performed to validate the procedures and confirm the tested amphipod viability and suitability.

Sediment toxicity identification evaluation (TIE phases I and II) based on microscale bioassays for diagnosing causes of toxicity in coastal areas affected by domestic sewage.

Domestic sewage is a major problem in highly urbanized coastal areas worldwide. In the present study, toxicity identification evaluation (TIE) phases I and II were applied to sediment interstitial water from 2 locations along the São Paulo coast in southeastern Brazil: the sewage outfalls from the city of Santos, a densely urbanized area, and the city of Bertioga, a less urbanized area. An adapted microscale sea urchin embryo-larval development bioassay was employed. Phase TIE-I manipulations were 1) ethylenediamine tetraacetic acid (EDTA) addition, 2) aeration at modified pH, 3) C18 solid-phase extraction (SPE), and 4) addition of Na2 S2 O3 . The results of the Santos TIE-I indicated toxicity by sulfides and substances with affinity to C18 resin. In Bertioga, toxicity was the result of NH3 , metals, and arsenic, as well as substances with affinity to C18 resin. Phase TIE-II aimed to specify the causes of toxicity by testing the toxicity of eluates of the sublation and C18 SPE manipulation. The results reinforced the role of both surfactants and nonpolar compounds as causative agents of toxicity in both Santos and Bertioga. Chemical analyses of sediment interstitial water or whole sediment ruled out the influence of polycyclic aromatic hydrocarbons (PAHs) or polychlorinated biphenyls (PCBs) in the toxicity of both sampling sites. Other hydrophobic substances may play a role in the toxicity of Santos and Bertioga effluents. Efforts to remove such substances from sanitary effluents must be prioritized. Environ Toxicol Chem 2017;36:1820-1832. © 2017 SETAC.

Causes of highway road dust toxicity to an estuarine amphipod: Evaluating the effects of nicotine

Urban road dust can potentially have adverse effects on ecosystems if it is discharged into receiving waters. This study investigated the causes of highway road dust toxicity by performing sediment toxicity identification evaluation (TIE) tests with an estuarine amphipod, Grandidierella japonica. In addition to metals and polycyclic aromatic hydrocarbons, which are traditionally considered to be the major toxicants in road runoff, we focused on dissolved nicotine as a causative toxicant. The sediment TIE results suggested that organic contaminants contributed to the majority of toxicity, and that the contribution of unionized nicotine to the toxicity was the highest among the chemicals considered. However, additional mortality tests with 48-h pulsed nicotine exposure demonstrated that exposure to nicotine at the same concentration as the baseline level in TIE tests did not cause significant 10-day amphipod mortality. Thus, the road dust toxicity could not be explained only by unionized nicotine, thereby suggesting contributions from joint effects of the measured toxicants and the presence of other unmeasured factors.

Application of sediment toxicity identification evaluation techniques to a site with multiple contaminants.

Sediment toxicity identification evaluations (TIEs) are conducted to determine causes of adverse effects observed in whole-sediment toxicity tests. However, in multiple contaminant scenarios, it is problematic to partition contributions of individual contaminants to overall toxicity. Using data from a site with multiple inputs and contaminants of concern, the authors describe a quantitative approach for the TIE process by tracking toxicity units to determine whether all toxicity is accounted for. The initial step established the level of toxicity associated with the whole sediment and then partitioned sources of toxicity into general contaminant classes (e.g., ammonia, metals, nonpolar organic compounds). In this case, toxicity was largely the result of nonpolar organics, so the sediments were extracted and the extracts added back into dilution water and tested to confirm recovery of toxicity. Individual fractions were then generated using a solvent gradient and tested for toxicity. Fractions of interest were evaluated with gas chromatography/mass spectrometry to identify specific constituents associated with toxicity. Toxicity units associated with these constituents were then evaluated to determine probable associations with cause and whether all toxicity was accounted for. The data indicated that toxicity was associated with 2 contaminant classes, representing legacy compounds and contaminants of emerging concern, with the contribution of each varying across the site. Environ Toxicol Chem 2016;35:2456-2465. © 2016 SETAC.

Navigating the tmdl process: sediment toxicity

A key step in the development of Total Maximum Daily Load (TMDL) allocations for water bodies impaired due to sediment toxicity is the identification of chemicals responsible for toxicity. Sediment toxicity identification evaluation procedures (TIEs) are one of the primary tools used in this process. This project evaluated standardized and recently developed sediment TIE methods developed by the US EPA and others, to determine their utility for identifying chemicals responsible for toxicity. In this study, formulated sediments were spiked with five chemicals: copper, fluoranthene, tetrachlorobenzene, nonylphenol and ammonia. Experiments were conducted using sediments spiked with single chemicals and chemical mixtures. Toxicity tests used the estuarine amphipod Eohaustorius estuarius and the freshwater amphipod Hyalella azteca. TIEs were conducted using solid-phase (whole sediment) and sediment interstitial waters. Our results indicate that the TIE methods are sufficient to characterize and identify toxicity due to single and multiple chemicals using spiked sediments. One key finding from the spiked sediment experiments is that methods to elute chemicals from extraction media used in solid-phase and interstitial water TIEs require further refinement to ensure complete and consistent elution of sorbed chemicals. An additional finding is that both solid-phase and interstitial water TIE procedures provide useful lines of evidence and that both approaches should be used in a weight-of-evidence approach in the sediment TIE process. In the final phase of this project, we evaluated the TIE procedures using ambient samples collected from three marine sites and three freshwater sites. Marine sediments were collected from Switzer Creek in San Diego Bay, Upper Newport Bay in Newport Beach, and Consolidated Slip, in Long Beach Harbor, all of which are sites in southern California. Freshwater sediments were collected from two additional sites in California: San Diego Creek, in Newport Beach, and Alisal Slough, in Salinas. The final freshwater sediment was collected from a site in Indiana Harbor. Multiple solid-phase and interstitial water TIEs were conducted on each sediment and results of these were combined with chemical analyses and other lines-of-evidence to evaluate the methods. The results indicate that sediment TIE methods are sufficiently developed to characterize toxicity due to general classes of chemicals such as cationic metals, organic chemicals, and ammonia. Methods to improve extraction and elution of metal and organic chemicals in highly toxic sediments require further refinement in order to allow identification of specific chemicals responsible for toxicity as part of the Phase II TIE process. These refinements include determining the appropriate masses of solid-phase extraction media to allow complete removal of toxic chemicals from sediments and interstitial waters. In addition, we recommend that additional studies be designed to determine optimal equilibration periods to maximize removal of toxic chemicals using resin amendments in solid-phase sediment TIEs. As in the spiked-sediment TIEs, we observed inconsistent elution of toxic chemicals from extraction media used in solid-phase and interstitial water Phase II TIEs with the ambient samples. These procedures require additional work to ensure that chemicals responsible for toxicity are completely eluted from extraction media. Improvement of the Phase II TIE elution and solvent handling steps should facilitate better identification of chemicals responsible for toxicity, particularly in situations where toxicity is due to highly insoluble chemicals. When these considerations are satisfactorily addressed, the methods evaluated are capable of providing useful lines of evidence that can be combined to successfully identify sediment toxicants. This title belongs to WERF Research Report Series ISBN: 9781843397663 (Print) ISBN: 9781780403786 (eBook)

The use of sediment toxicity identification evaluation methods to evaluate clean up targets in an urban estuary

The Ballona Creek Estuary (BCE) in Los Angeles, California, is in a highly urbanized watershed, is contaminated by a variety of chemicals, and has prevalent sediment toxicity. Sediment cleanup targets for BCE have been established for Cu, Cd, Pb, Zn, chlordane, DDTs, PCBs, and PAHs, based on sediment quality guidelines. A sediment toxicity identification evaluation (TIE) was conducted to examine how these targets corresponded to toxicity observed with the estuarine amphipod Eohaustorius estuarius. Whole sediment and porewater TIEs were used to identify the cause of toxicity. Passive samplers were deployed to determine the bioavailable fraction of contaminants. Spiked sediment tests were conducted to determine the thresholds of toxicity for selected constituents. Toxicity was found to be widespread but temporally and spatially variable. Whole sediment and porewater TIEs both indicated pyrethroid pesticides were the most likely contaminant group contributing to the toxicity. Concentrations of the chemicals listed for cleanup were found to often exceed target values but were not observed at concentrations likely to cause toxicity. Bioavailable fractions of the target chemicals quantified using passive samplers did not exceed toxicity thresholds. Spiked sediment tests established 10 day LC50s for 4,4' DDE, 4, 4' DDT, α-chlordane, and cyfluthrin at >3050 μg/g, 266 μg/g, >2120 μg/g, and 0.33 μg/g organic carbon (OC), respectively. The cyfluthrin LC50 was within the range of concentrations observed in the estuary sediments, but LC50s for the other 3 chemicals were orders of magnitude greater than observed levels. The combination of TIE, sediment chemistry and the results from spiked sediment exposures indicate pyrethroid pesticides are more likely the cause of the observed toxicity than any of the contaminants targeted for cleanup. The results of this study indicate the importance of using a TIE approach to determine chemicals of concern and dose-response information to set cleanup targets, rather than using sediment quality guidelines. Integr Environ Assess Manag 2014;10:260-268. © 2013 SETAC.

Application of whole sediment toxicity identification evaluation procedures to road dust using a benthic ostracod Heterocypris incongruens

Road dust is considered to be an important source of sediment contamination in receiving water bodies; however, few studies have evaluated the toxicity of road dust to benthic organisms. This study evaluated the toxicity of road dust to a benthic ostracod, Heterocypris incongruens, using a six-day direct exposure experiment. We applied whole sediment toxicity identification evaluation (TIE) methods to identify the primary group of toxicants in road dust. Three road dust samples from Tokyo caused high ostracod mortality. The addition of hydrophobic adsorbents, Ambersorb and XAD, eliminated toxicity in all samples, suggesting that hydrophobic compounds were the main toxicants in road dust samples. A cation exchange resin, Chelex, also reduced the toxicity of two samples, although the measured concentrations of dissolved heavy metals in the test solution did not exceed the LC50 values in the literature. In addition, the sum of toxic unit (TU=measured concentration/LC50) of each individual metal which predicts the toxicity of the metal mixtures did not exceed 1.0 in all samples, suggesting that heavy metal mixtures did not have additive effects. We hypothesized that the toxicity reduction by XAD and Chelex was due to the removal of hydrophobic compounds, rather than heavy metals. Thus, a toxicity test was conducted on fractions eluted with organic solvents from the XAD and Chelex recovered from one of the road dust samples. Methanol-eluted fractions of XAD and Chelex showed 100 percent ostracod mortality, indicating that the hydrophobic organic compounds removed by these adsorbents were the principal toxicants in the road dust sample.

Development and application of whole‐sediment toxicity test using immobilized freshwater microalgae Pseudokirchneriella subcapitata

A method for a whole-sediment toxicity test using alginate immobilized microalgae Pseudokirchneriella subcapitata was developed using spiked sediments and applied to contaminated field sediment samples. For method development, a growth inhibition test (72 h) with algal beads was conducted for the sediments spiked with Cu or diuron. The method was validated by determining dose-response relationships for Cu and diuron in both fine-grained and coarse-grained sediments. The results of a spiked sediment toxicity test suggested that sediment particle size distribution (clay content) had a significant effect on the growth of P. subcapitata. The developed method using immobilized microalgae P. subcapitata beads was applied successfully in the toxicity test and toxicity identification evaluation (TIE) for the four field sediment samples. After a series of extractions with 0.01 M CaCl(2) solution, acetone, and dichloromethane, the extracted sediment, which was shown to be nontoxic to algae, was used as the control and diluent for the same sediment in the whole-sediment toxicity test. The results showed that all investigated field sediment samples were found to be toxic to the immobilized algae P. subcapitata, with their median effective concentration (EC50) values ranging from 41.4 to 79.0% after 72 h exposure. In the whole sediment TIE, growth of P. subcapitata was improved to varying degrees after adding zeolite, resin, or activated charcoal, suggesting different contributions to toxicity from ammonia, metals, and organic contaminants in the tested sediments.

Distribution, magnitude and characterization of the toxicity of Ukrainian estuarine sediments

During the Soviet era, Ukraine was an important industrial and agricultural region of the Soviet Union. This industrial and agricultural activity resulted in contamination of Ukraine’s estuaries with legacy anthropogenic pollutants. Investigations on the toxicological effects of this estuarine contamination have been limited. For this research, we measured the toxicity of contaminated sediments from four Ukrainian estuaries to several aquatic organisms over 3 years. Sediment chemical analyses and whole sediment toxicity identification evaluations (TIEs) were also performed to determine the classes of contaminants contributing to toxicity. Toxic sediments were observed in several of the Ukrainian estuaries and chemical analyses of the sediments demonstrated anthropogenic contaminants were widely distributed. Contaminants were also detected in macrobenthic organisms collected from the sediments. Several lines of evidence, including TIEs, indicated hydrophobic organic chemicals (HOCs) were contributing substantially to observed toxicity. This information can guide environmental managers to prioritize portions of the estuaries requiring remediation.

Assessment of supercritical fluid extraction use in whole sediment toxicity identification evaluations

Supercritical fluid extraction (SFE) with pure CO(2) was assessed as a confirmatory tool in phase III of whole sediment toxicity identification evaluations (TIEs). The SFE procedure was assessed on two reference sediments and three contaminated sediments by using a combination of toxicological and chemical measurements to quantify effectiveness. Sediment toxicity pre- and post-SFE treatment was quantified with a marine amphipod (Ampelisca abdita) and mysid (Americamysis bahia), and nonionic organic contaminants (NOCs) polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured in sediments, overlying waters, and interstitial waters. In general, use of SFE with the reference sediments was successful, with survival averaging 91% in post-SFE treatments. Substantial toxicity reductions and contaminant removal from sediments and water samples generated from extracted sediments of up to 99% in two of the contaminated sediments demonstrated SFE effectiveness. Furthermore, toxicological responses for these SFE-treated sediments showed comparable results to those from the same sediments treated with the powdered coconut charcoal addition manipulation. These data demonstrated the utility of SFE in phase III of a whole sediment TIE. Conversely, in one of the contaminated sediments, the SFE treatments had no effect on sediment toxicity, whereas sediment concentrations of PCBs and PAHs were reduced. We propose that, for some sediments, the SFE treatment may result in the release of otherwise nonbioavailable cationic metals that subsequently cause toxicity to test organisms. Overall, SFE treatment was found to be effective for reducing the toxicity and concentrations of NOCs in some contaminated sediments. However, these studies suggest that SFE treatment may enhance toxicity with some sediments, indicating that care must be taken when applying SFE and interpreting the results.

Sediment Contaminant Chemistry and Toxicity of Freshwater Urban Wetlands in Southern California1

Brown, Jeffrey S., Martha Sutula, Chris Stransky, John Rudolph, and Earl Byron, 2010. Sediment Contaminant Chemistry and Toxicity of Freshwater Urban Wetlands in Southern California. Journal of the American Water Resources Association (JAWRA) 46(2):367‐384. DOI: 10.1111/j.1752‐1688.2009.00407.xAbstract: Wetlands provide many critical functions in urban ecosystems, including habitat for wetland‐dependent fauna and enhancement of water quality. Interest in restoring or creating wetlands to enhance these functions is increasing due to the scale and extent of wetland loss and water quality problems associated with urbanization. One of the most pressing questions associated with urban wetland restoration is the extent to which urban wetlands tend to concentrate contaminants, and if so, whether an associated risk to wildlife exists. The goal of this study was to better understand these potential risks, and the associated tradeoffs with using wetlands to treat urban runoff. Sediment toxicity, contaminant chemistry, and macroinvertebrate (MI) community metrics were measured in 21 southern California wetlands that receive urban runoff as their primary water source. MI organisms in 18 of the 21 urban wetlands examined were considered to be at risk due to sediment contaminant concentrations and toxicity. Most of the sites were either toxic to the amphipod Hyalella azteca, exceeded a sediment quality guideline, or both. Sediment chemistry and toxicity identification evaluation studies suggest that pyrethroid pesticides may have been responsible for much of the toxicity documented in this study. The mean Probable Effects Concentration quotient (an index of degree of sediment contamination) was found to negatively correlate with MI diversity in these wetlands suggesting that toxicity was affecting organisms at the base of the food chain in these wetlands.

Evaluation of methods to determine causes of sediment toxicity in San Diego Bay, California, USA

Regulation of waterbodies impaired due to sediment toxicity may require development of Total Maximum Daily Load (TMDL) allocations to reduce chemicals of concern. A key step in this process is the identification of chemicals responsible for toxicity, and sediment toxicity identification evaluation procedures (TIEs) are the primary tools used to accomplish this. Several sites in San Diego Bay (CA, USA) are listed as impaired due to sediment toxicity associated with organic chemicals and metals, and due to degraded benthic macroinvertebrate communities. Sediment was collected from one of these sites, at the confluence of Switzer Creek in San Diego Harbor. The sediment was subjected to selected whole-sediment TIE treatments to evaluate the efficacy of these procedures for identifying the causes of toxicity at Switzer Creek. Toxicity was assessed using the estuarine amphipod Eohaustorius estuarius. The results indicated that toxicity of San Diego Bay sediment was likely partly due to mixtures of pyrethroid pesticides. These experiments showed that the effectiveness of the individual TIE procedures varied by treatment. Variability was mainly due to inconsistency between results of samples subjected to various Phase II TIE procedures, including chemical analyses of samples subjected to high-pressure liquid chromatography and direct analyses of acetone extractions of carbonaceous resin. The procedures require further refinement to ensure maximum sorption and complete elution and detection of sorbed chemicals. Despite these inconsistencies, the results indicate the utility of these procedures for identifying chemicals of concern in this system.

The contribution of pyrethroid pesticides to sediment toxicity in four urban creeks in California, USA

As part of a statewide assessment of pyrethroid pesticides and sediment toxicity in urban creeks, sites throughout California were screened, and thirty were chosen to evaluate the potential of pyrethroids to contribute to biological impacts. Sediment samples from four sites containing varied concentrations of pyrethroids were investigated using toxicity identification evaluations (TIEs) to determine causes of toxicity. Treatments were conducted on both whole sediment and interstitial water to determine the role of pyrethroids in the observed toxicity to the amphipod Hyalella azteca, and to evaluate TIE method performance. Whole sediment treatments included the addition of binding resins for organics and metals, and specific treatments designed to alter pyrethroid toxicity, including the addition of carboxylesterase enzyme, the addition of piperonyl butoxide (a pyrethroid synergist), and the testing of sediments at two temperatures. Interstitial water TIEs included solid-phase extraction (SPE) columns to reduce and return toxicity caused by organics and metals, as well as the treatments specific to pyrethroids. Resin and SPE column treatments characterized the causes of toxicity as organic compounds. Results of pyrethroid-specific treatments in whole sediment were variable, but similar treatments in interstitial water demonstrated pyrethroids were contributing to toxicity. Measured pyrethroid concentrations in whole sediment and interstitial water SPE extracts were high enough to have contributed to toxicity. Using both whole sediment and interstitial water TIEs and chemical analysis provided multiple lines of evidence that pyrethroids contributed to toxicity.

Comparative analysis of whole sediment and porewater toxicity identification evaluation techniques for ammonia and non-polar organic contaminants

Porewater and whole sediment toxicity identification evaluations (TIEs) were performed on contaminated Illinois River sediment and compared using two standardized toxicity-testing organisms ( Ceriodaphnia dubia and Hyalella azteca). Results suggested that the choice of testing matrix (porewater versus whole sediment) significantly influenced characterization of toxicity. The porewater TIE suggested that ammonia was the major source of toxicity, while the whole sediment TIE indicated that non-polar organics, specifically polycyclic aromatic hydrocarbons, were the primary contributor to toxicity, with ammonia being a secondary contributor to toxicity. While the choice of test organism may have played a smaller role in the discordance between the TIEs, the data suggest that this factor alone could play a prevalent role in characterizing toxicity in other TIE assessments. Because porewater and whole sediment TIEs examine sediment toxicity differently, using both TIE approaches as part of a risk assessment may provide a more accurate risk estimate of sediment toxicity.

Identifying the causes of sediment‐associated contamination in the Illinois River (USA) using a whole‐sediment toxicity identification evaluation

Whole-sediment toxicity identification evaluation (TIE) techniques were employed on the Illinois River Complex (IRC), USA to identify the sources of sediment toxicity that may have contributed to the decline in benthic invertebrate populations. The TIE focused on three classes of contaminants: ammonia, metals, and organics. Sediment toxicity was assessed using the amphipod Hyalella azteca, and the focus of the TIE was on assessing spatial and temporal patterns of contamination. Past studies suggested that ammonia was the major source of contamination in IRC sediments. However, the present study suggested that polycyclic aromatic hydrocarbons (PAHs) were the primary contributor to sediment toxicity. Phase I testing showed 46% of the site trials (12 of 26) exhibited increased H. azteca survival (p < 0.05) with the addition of powdered coconut charcoal (organic amendment), whereas zeolite (ammonia amendment) and Resin Tech SIR 300 (cationic metals amendment) did not increase H. azteca survival. Phase II testing revealed PAH concentrations were high enough to cause the observed toxicity, confirming phase I results. Spatially, sediment toxicity as well as pore-water ammonia concentrations declined with distance downstream from suspected contaminant sources, indicating a potential dilution or remedial effect. Temporally, pore-water ammonia, metals, and PAH concentrations varied among sampling periods over an annual cycle for some sites near urbanized areas, while remaining temporally consistent at others. The results of the present study provide new information on the sources of toxicity within the IRC, and demonstrate the importance of evaluating spatial and temporal aspects in sediment TIEs. This is particularly important for evaluations in riverine systems in which hydrologic processes can result in large variation in sediment toxicity on temporal and spatial scales.

Identification of water soluble and particle bound compounds causing sublethal toxic effects. A field study on sediments affected by a chlor-alkali industry

A combination of cost effective sublethal Daphnia magna feeding tests, yeast- and cell culture-based bioassays and Toxicity Identification Evaluation (TIE) procedures was used to characterize toxic compounds within sediments collected in a river area under the influence of the effluents from a chlor-alkali industry (Ebro River, NE Spain). Tests were designed to measure and identify toxic compounds in the particulate and filtered water fractions of sediment elutriates. The combined use of bioassays responding to elutriates and dioxin-like compounds evidenced the existence of three major groups of hazardous contaminants in the most contaminated site: (A) metals such as cadmium and mercury bound to sediment fine particles that could be easily resuspended and moved downstream, (B) soluble compounds (presumably, lye) able to alkalinize water to toxic levels, and (C) organochlorine compounds with high dioxin-like activity. These results provided evidence that elutriate D. magna feeding responses can be used as surrogate assays for more tedious chronic whole sediment tests, and that the incorporation of such tests in sediment TIE procedures may improve the ability to identify the toxicity of particle-bound and water-soluble contaminants in sediments.

Evaluation of phase II toxicity identification evaluation methods for freshwater whole sediment and interstitial water

Phase I whole sediment toxicity identification evaluation (TIE) methods have been developed to characterize the cause of toxicity as organic chemicals, metals, or ammonia. In Phase II identification treatments, resins added to whole sediment to reduce toxicity caused by metals and organics can be separated and eluted much like solid-phase extraction (SPE) columns are eluted for interstitial water. In this study, formulated reference sediments spiked with toxic concentrations of copper, fluoranthene, and nonylphenol were subjected to whole sediment and interstitial water TIE treatments to evaluate Phase I and II TIE procedures for identifying the cause of toxicity to Hyalella azteca. Phase I TIE treatments consisted of adding adsorbent resins to whole sediment, and using SPE columns to remove spiked chemicals from interstitial water. Phase II treatments consisted of eluting resins and SPE columns and the preparation and testing of eluates for toxicity and chemistry. Whole sediment resins and SPE columns significantly reduced toxicity, and the eluates from all treatments contained toxic concentrations of the spiked chemical except for interstitial water fluoranthene. Toxic unit analysis based on median lethal concentrations (LC50s) allowed for the comparison of chemical concentrations among treatments, and demonstrated that the bioavailability of some chemicals was reduced in some samples and treatments. The concentration of fluoranthene in the resin eluate closely approximated the original interstitial water concentration, but the resin eluate concentrations of copper and nonylphenol were much higher than the original interstitial water concentrations. Phase II whole sediment TIE treatments provided complementary lines of evidence to the interstitial water TIE results.

Using the Sediment Quality Triad to characterize baseline conditions in the Anacostia River, Washington, DC, USA

The Sediment Quality Triad (SQT) consists of complementary measures of sediment chemistry, benthic community structure, and sediment toxicity. We applied the SQT at 20 stations in the tidal portion of the Anacostia River from Bladensburg, MD to Washington, DC to establish a baseline of conditions to evaluate the effects of management actions. Sediment toxicity was assessed using 10-day survival and growth tests with the freshwater amphipod, Hyalella azteca and the midge, Chironomus dilutus. Triplicate grabs were taken at each station for benthic community analysis and the Benthic Index of Biotic Integrity (B-IBI) was used to interpret the data. Only one station, #92, exhibited toxicity related to sediment contamination. Sediments from this station significantly inhibited growth of both test species, had the highest concentrations of contaminants, and had a degraded benthic community, indicated by a B-IBI of less than 3. Additional sediment from this station was tested and sediment toxicity identification evaluation (TIE) procedures tentatively characterized organic compounds as the cause of toxicity. Overall, forty percent of the stations were classified as degraded by the B-IBI. However, qualitative and quantitative comparisons with sediment quality benchmarks indicated no clear relationship between benthic community health and contaminant concentrations. This study provides a baseline for assessing the effectiveness of management actions in the Anacostia River.

Identifying the cause and source of sediment toxicity in an agriculture‐influenced creek

Del Puerto Creek, an agriculturally influenced stream in northern California, USA, with a history of sediment toxicity, was used as a case study to determine the feasibility of using sediment toxicity testing and chemical analysis to identify the causative agent for the toxicity and its sources. Testing with the amphipod Hyalella azteca confirmed historical toxicity and identified a point along the creek at which there was an abrupt increase in sediment toxicity that persisted for at least 6 km downstream. Three recently developed whole sediment toxicity identification evaluation manipulations, temperature reduction, piperonyl butoxide addition, and esterase addition, were applied to sediment from one site and were suggestive of a pyrethroid as the cause for toxicity. Utilizing published median lethal concentration (LC50) values in a toxic unit analysis, the pyrethroid insecticide bifenthrin was identified as the primary contributor to toxicity in nearly all sites at which toxicity was observed, with occasional additional contributions from the pyrethroids lambda-cyhalothrin, esfenvalerate, and cyfluthrin. Most agricultural drains discharging to Del Puerto Creek contained bifenthrin in their sediments at concentrations near or above acutely toxic concentrations. However, only one drain contained sediments with bifenthrin concentrations approaching the concentrations measured in creek sediments. This fact, along with the proximity of that particular discharge to the location in the creek with the highest concentrations, suggested that one drain may be responsible for much of the toxicity and pyrethroid residues in creek sediments. The methods employed in this study are likely to be of considerable value in total maximum daily load efforts in Del Puerto Creek or other California surface water bodies known to have pyrethroid-related aquatic toxicity.