Toxicity Identification Evaluation Methods Research Articles

Microscale Toxicity Identification Evaluation (TIE) for interstitial water of estuarine sediments affected by multiple sources of pollution.

Estuaries in the world are affected by different contamination sources related to urbanisation and port/industrial activities. Identifying the substances responsible for the environmental toxicity in estuaries is challenging due to the multitude of stressors, both natural and anthropogenic. The Toxicity Identification and Evaluation (TIE) is a suitable way of determining causes of toxicity of sediments, but it poses difficulties since its application is labour intensive and time consuming. The aim of this study is to evaluate the diagnosis provided by a TIE based on microscale embryotoxicity tests with interstitial water (IW) to identify toxicants in estuarine sediments affected by multiple stressors. TIE showed toxicity due to different combinations of metals, apolar organic compounds, ammonia and sulphides, depending on the contamination source closest to the sampling station. The microscale TIE was able to discern different toxicants on sites subject to different contamination sources. There is good agreement between the results indicated in the TIE and the chemical analyses in whole sediment, although there are some disagreements, either due to the sensitivity of the test used, or due to the particularities of the use of interstitial water to assess the sediment toxicity. The improvement of TIE methods focused on identifying toxicants in multiple-stressed estuarine areas are crucial to discern contamination sources and subsidise management strategies.

Identifying Organic Toxicants in Sediment Using Effect-Directed Analysis: A Combination of Bioaccessibility-Based Extraction and High-Throughput Midge Toxicity Testing.

Toxicity identification evaluation (TIE) and effect-directed analysis (EDA) were integrated to diagnose toxicity drivers in a complex system, such as sediment. In TIE manipulation, XAD resin was utilized as an amending agent for characterizing organic toxicants, which also facilitate a large-volume bioaccessibility-based extraction for EDA purposes. Both raw sediments in TIE and extract fractions in EDA were tested with Chironomus dilutus for toxicity using whole-sediment testing and a high-throughput microplate assay. This allowed for a direct link between whole-sediment TIE and EDA, which strongly strengthened the characterization and identification of toxicants. Sediments amended with XAD resin, as part of the TIE, significantly reduced midge mortality compared with unamended sediments, suggesting that organics were one class of main toxicants. On the basis of bioaccessible concentrations in sediment measured by XAD extraction, a group of previously unidentified contaminants, synthetic polycyclic musks (versalide, tonalide, and galaxolide), were found to explain 32-73% of the observed toxicity in test sediments. Meanwhile, three pyrethroids contributed to an additional 17-35% of toxicity. Surprisingly, the toxicity contribution of musks and pyrethroids reached 58-442 and 56-1625%, respectively, based on total sediment concentrations measured by exhaustive extraction. This suggested that total sediment concentrations significantly overestimated toxicity and that bioavailability should be considered in toxicity identification. Identifying nontarget toxicants sheds a light on application of the integrated TIE and EDA method in defining causality in a complex environment.

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.

Application of toxicity identification evaluation procedure to toxic industrial effluent in South Korea

Toxicity identification evaluation (TIE) was applied to the effluent from a pharmaceutical industrial complex, following the US EPA TIE guidelines. The whole effluent toxicity (WET) test found toxicity greater than 16toxic units (TU) in the effluent. Dissolved non-polar organic compounds were identified as the major contributor to the observed toxicity in the TIE manipulations in phases I and II. Among the 48 organic compounds identified, three compounds (i.e., acetophenone, benzoimide, and benzothiazole) were related to the pharmaceutical production procedure; however, no contribution to toxicity was predicted in the compounds. The results of the ECOSAR model, which predicts toxicity, indicated that the alkane compounds caused significant toxicity in the effluent. The toxicity test and heavy metal analysis, which used IC and ICP/MS, identified that particulate and heavy metals, such as Cu and Zn, contributed to the remaining toxicity, except dissolved organics. The results showed the applicability of the TIE method for predicting regional effluents produced by the industrial pharmaceutical complex in this study. Although the location was assumed to be affected by discharge of pharmaceutical related compounds in the river, no correlations were observed in the study. Based on the results, advanced treatment processes, such as activated carbon adsorption, are recommended for the wastewater treatment process in this location.

Application of the Ulva pertusa bioassay for a toxicity identification evaluation and reduction of effluent from a wastewater treatment plant

A toxicity identification evaluation (TIE) based on Ulva pertusa spore release was conducted in 3 phases for the identification of the major toxicants in effluent from a wastewater treatment plant (WTP) and the receiving water in an adjacent stream. The toxicity of the final effluent (FE), as compared with raw wastewater, and primary and secondary effluent, showed a greater change over 12-monthly sampling events and appeared to have impacts on the toxicity of the downstream water with a significant correlation (r2 = 0.89, p < 0.01). In Phase I, toxicity characterization indicated that cations were likely to be the responsible toxicants for the FE. In Phase II, cations such as Cu, Ni, and Zn were found in the FE at higher concentrations than the EC50 concentrations determined for the standard corresponding metals. When the concentrations of each metal in the FE samples were plotted against the respective toxicity units, only zinc showed a statistically significant correlation with toxicity (r2 = 0.86, p < 0.01). In Phase III, using spiking and mass balance approaches, it was confirmed that Zn was the major toxicant in the effluent from the WTP. Following a change in the Fenton reagent used, to one with a lower Zn content, the toxicity of the FE greatly decreased in subsequent months. The TIE developed here enabled the toxicity of FEs of the WTP to be tracked and for Zn, originating from a reagent used for Fenton treatment, to be successfully identified as the key toxicant. The TIE method based on U. pertusa demonstrated utility as a low cost and simple tool to identify the risk factors for industrial effluents and provided information on regulatory control and management.

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.

Confirmation of combinational effects of calcium with other metals in a paper recycling mill effluent on nematode lifespan with toxicity identification evaluation method

We used toxicity identification evaluation (TIE) method to confirm the combinational effects of identified toxic metals in a paper recycling mill effluent in inducing the decreased lifespan in nematode Caenorhabditis elegans. Exposure to Ca + Al caused more severely decreased lifespan than that exposed to Ca, or Al; and exposure to Ca + Fe induced more severely decreased lifespan than that exposed to Ca, or Fe. Exposure to Ca+Al+Fe caused more severely decreased lifespan than that exposed to Ca, or Ca+Fe. Moreover, the baseline toxicity on lifespan was doubled by doubling the concentration of combined metals (Ca+Al+Fe) in spiking test in original effluent (oe), and lifespan defects in oe+Ca+Al+Fe exposed nematodes were more severe than that in Ca+Al+Fe exposed nematode. Therefore, Ca+Al+Fe exposure may largely explain the formation of decreased lifespan induced by the examined industrial effluent. Furthermore, the observed reduction of lifespan induced by the combination of high level of Ca with other metals may be at least partially independent of the insulin-like pathway.

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.

Toxicity evaluation in a paper recycling mill effluent by coupling bioindicator of aging with the toxicity identification evaluation method in nematode Caenorhabditis elegans

Toxicity identification evaluation (TIE) can be used to determine the specific toxicant(s) in industrial effluents. In the current study, the authors have attempted to combine the advantages of the model organism, Caenorhabditis elegans, with the virtues of the TIE technique, to evaluate and identify the toxicity on aging from a paper recycling mill effluent. The results indicate that only the toxicities from mixed cellulose (MC) filtration and EDTA treatment are similar to the baseline aging toxicity, suggesting that the suspect toxicants inducing aging toxicity may largely be the heavy metal substances in this industrial effluent. Examination of the accumulation of intestinal autofluorescence in adult animals further confirms that the short lifespans are actually due to accelerated aging. In addition, exposure to fractions of EDTA manipulations cannot result in severe defects of reproduction and locomotion behaviors in C. elegans. Moreover, high levels of Ca, Al, and Fe in the effluent may account for the severe toxicity on aging of exposed nematodes, by TIE assay. The study here provides a new method for evaluating environmental risk and identifying toxicant(s) from the industrial effluent using C. elegans.

Toxicity identification in metal plating effluent: Implications in establishing effluent discharge limits using bioassays in Korea

Because of complexity and diversity of toxicants in effluent, chemical analysis alone gives very limited information on identifying toxic chemicals to test organisms. Toxicity identification evaluation (TIE) techniques have been widely used to identify toxicants in various samples including industrial wastewater as well as natural waters. In response to new regulation for effluent discharge in Korea, which will be effective from 2011, a necessity of studies emerges that investigates toxicity levels in industrial effluents. This work was a preliminary study examining toxicity levels in effluent from one metal plating factory using Daphnia magna (48 h immobility) and identifying toxicity-causing substances. Toxicity tests showed variability on different sampling occasions and the results of TIE methods indicated that both organic compounds and metals contributed to the observed toxicity in metal plating effluent. Further studies are necessary to help reduce effluent toxicity especially from direct dischargers, who will have to comply with the new regulation.

Marine sediment toxicity identification evaluation methods for the anionic metals arsenic and chromium

Marine sediments accumulate a variety of contaminants and, in some cases, demonstrate toxicity because of this contamination. Toxicity identification evaluation (TIE) methods provide tools for identifying the toxic chemicals causing sediment toxicity. Currently, whole-sediment TIE methods are not available for anionic metals like arsenic and chromium. In the present paper, we describe two new anion-exchange resins used in the development of whole-sediment TIE methods for arsenic and chromium. Resins were shown to reduce whole-sediment toxicity and overlying water concentrations of the anionic metals. Sediment toxicity, expressed as the median lethal concentration, was reduced by a factor of two to a factor of nearly six between amended sediment treatments containing resin and those without resin. Aqueous concentrations of arsenic and chromium in the toxicity exposures decreased to less than the detection limits or to concentrations much lower than those measured in treatments without resin. Interference studies indicated that the anion-exchange resins had no significant effect on concentrations of the representative pesticide endosulfan and minimal effects on concentrations of ammonia. However, the anion-exchange resins did significantly reduce the concentrations of a selection of cationic metals (Cd, Cu, Ni, Pb, and Zn). These data demonstrate the utility of anion-exchange resins for determining the contribution of arsenic and chromium to whole-sediment toxicity. The present results also indicate the importance of using TIE methods in a formal TIE structure to ensure that results are not misinterpreted. These methods should be useful in the performance of marine whole-sediment TIEs.

Determining stressor presence in streams receiving urban and agricultural runoff: Development of a benthic in situ toxicity identification evaluation method

Determining toxicity in streams during storm-water runoff can be highly problematic because of the fluctuating exposures of a multitude of stressors and the difficulty of linking these dynamic exposures with biological effects. An underlying problem with assessing storm-water quality is determining if toxicity exists and then which contaminant is causing the toxicity. The goal of this research is to provide an alternative to standard toxicity testing methods by incorporating an in situ toxicity identification evaluation (TIE) approach. A benthic in situ TIE bioassay (BiTIE) was developed for separating key chemical classes of stressors in streams during both low- and high-flow events to help discern between point and nonpoint sources of pollution. This BiTIE method allows for chemical class fractionation through the use of resins, and these resins are relatively specific for removing nonpolar organics (Dowex Optipore), ammonia (zeolite), and polywool (control). Three indigenous aquatic insects, a mayfly (Isonychia spp.), a caddisfly (Hydropsyche spp.), and a water beetle (Psephenus herricki), were placed in BiTIE chambers that were filled with natural substrates. Acute 96-h exposures were conducted at Honey Creek, New Carlisle, Ohio, USA (reference site), and Little Beavercreek, Beavercreek, Ohio, USA (impaired site). At both sites, significant (p < 0.025) stressor responses were observed using multiple species with polywool or no resin (control) treatments exhibiting < 80% survival and resin treatments with >80% survival. The BiTIE method showed stressor-response relationships in both runoff and base flow events during 96-h exposures. The method appears useful for discerning stressors with indigenous species in situ.

An in situ toxicity identification evaluation method part II: Field validation

When sediments are found to be toxic usually there is a mixture of chemicals present. Often it is important to establish which chemicals contribute to the toxicity. Establishing causality can be difficult and often requires fractionation with subsequent toxicity testing. The sample collection and manipulation process can alter chemical bioavailability and toxicity. An in situ toxicity identification evaluation (iTIE) chamber is described that was placed in sediments and fractionated pore-water chemicals into nonpolar chemicals, metals, and ammonia-type groups. This method was field tested and compared to the laboratory-based, U.S. Environmental Protection Agency (U.S. EPA) toxicity identification evaluation (TIE) method. Field studies were performed at three sites contaminated primarily with polycyclic aromatic hydrocarbons (PAHs) (Little Scioto River, OH, USA), polychlorinated biphenyls (PCBs) (Dicks Creek, OH, USA), and chlorobenzenes (Sebasticook River, ME, USA). Both the iTIE and the U.S. EPA TIE methods used Daphnia magna in 24-h exposures. Although the iTIE and TIE were conducted on sediments from the same location, there was significantly more toxicity observed in the iTIE testing. The dominant chemical classes were separated by the iTIE method and revealed which fractions contributed to toxicity. The loss of toxicity in the TIE approach did not allow for subsequent fractionation and stressor identification. Advantages of the iTIE over the TIE method were greater sensitivity and ability to detect causative toxic chemical fractions; lack of sediment collection and subsequent manipulation; and, thus, reduction in potential artifacts, more realistic exposure with slow, continual pore-water renewal in situ, ability to evaluate pore waters in sandy or rocky substrates where pore waters are difficult to collect, and a quicker phase I evaluation. Limitations of the iTIE method as compared to the TIE methods were extensive pretest assembly process, fewer phase I fractionation possibilities, and restriction to shallow waters. The results of these studies suggest that the iTIE method provides a more accurate and sensitive evaluation of pore water toxicity than the laboratory TIE method.

An in situ toxicity identification evaluation method part I: Laboratory validation

Identification of individual chemical groups is critical in evaluating sediment quality and fractionating these groups of chemicals in a mixture is important to determine the primary chemicals causing toxicity. The in situ toxicity identification evaluation (iTIE) is a novel method that was developed to fractionate chemicals in contaminated sediments and waters and assess toxicity organisms. The study objectives were to verify that the iTIE can help identify contaminant chemical classes and improve the toxicity assessment process; and compare the iTIE and U.S. Environmental Protection Agency's (U.S. EPA) toxicity identification evaluation (TIE) methods. The iTIE exposure chamber is powered by a portable air pump that suctions pore water, via a Venturi system, through selective sorption materials. After passing through the sorptive materials, the pore water passes into an exposure chamber containing Daphnia magna. The chemical sorption materials included Ambersorb 563 for nonpolar organic chemical adsorption, Chelex for metals chelation, and multiple zeolite types for ammonia adsorption. The laboratory studies were performed using water and sediments spiked with ammonia, cadmium, and fluoranthene. The laboratory validation of the iTIE approach showed that different classes of compounds readily could be separated via the resin treatments, resulting in significant differences in concentrations and thus exposures to in situ exposed organisms. Ammonia, cadmium, and fluoranthene were significantly removed by zeolite, Chelex, and Ambersorb, respectively. Although there was some cross-adsorption to the other nontarget resins, it was limited and allowed for treatment differences to be detected. Survival in the treatment resins exposed to the target compounds was as high as control survivals. A 24-h exposure period appeared optimal, allowing for replacement of initial culture water with pore waters, while longer exposures occasionally allowed for breakthrough of contaminants. The iTIE was more sensitive than the U.S. EPA TIE method, in that it detected toxicity more readily due to the greater loss of contaminant concentrations in the TIE manipulation process.

Development of New Toxicity Identification Evaluation by Assessing Toxicity Reduction on Adsorption and Ion-exchange Treatments

A new toxicity identification evaluation method for water exhibiting toxicity has been suggested by evaluating toxicity reduction resulting from adsorption and ion-exchange treatments. Adsorption using various adsorbents such as activated carbon, chitosan and zeolite, and ion-exchange using cationic and anionic ion-exchange resins were performed. In addition, toxicity was evaluated by a cell survival test using human liver cancer origin cells (HepG2), and the dose response data was applied to treatment characteristics. The amount of toxicity adsorbed by the various adsorbents was defined based on adsorption isotherm. Parameters of the toxicity adsorption isotherm provided information that allowed us to identify the toxicity-controlling chemicals in environmental water containing various chemicals. The method is promising for water quality management because it can be used to identify toxicity-controlling chemicals among various environmental pollutants.

Development of New Toxicity Identification Evaluation by Assessing Toxicity Reduction on Adsorption and Ion-exchange Treatments

Abstract A new toxicity identification evaluation method for water exhibiting toxicity has been suggested by evaluating toxicity reduction resulting from adsorption and ion-exchange treatments. Adsorption using various adsorbents such as activated carbon, chitosan and zeolite, and ion-exchange using cationic and anionic ion-exchange resins were performed. In addition, toxicity was evaluated by a cell survival test using human liver cancer origin cells (HepG2), and the dose response data was applied to treatment characteristics. The amount of toxicity adsorbed by the various adsorbents was defined based on adsorption isotherm. Parameters of the toxicity adsorption isotherm provided information that allowed us to identify the toxicity-controlling chemicals in environmental water containing various chemicals. The method is promising for water quality management because it can be used to identify toxicity-controlling chemicals among various environmental pollutants.

Causes of sediment toxicity to Mytilus galloprovincialis in San Francisco Bay, California.

Since the San Francisco Regional Monitoring Program (RMP) sampling began, elutriate samples prepared with sediment from the Grizzly Bay monitoring station have been consistently toxic to bivalve larvae (Mytilus galloprovincialis). An investigation into the cause of toxicity was initiated with a Phase I Toxicity Identification Evaluation (TIE) using bivalve embryos. TIE results and chemical analyses of elutriate samples suggested that divalent metals were responsible for the observed toxicity. Following the initial characterization of trace metals as toxicants, additional TIEs were performed on elutriates prepared from three additional Grizzly Bay samples collected between 1997 and 2001. Additional TIEs included ethylenediamine tetraacetic acid (EDTA) treatments in a sediment-water interface (SWI) exposure system, and the use of a cation exchange column with serial elution of sample fractions with hydrochloric acid of increasing normality. EDTA significantly reduced toxicity in overlying water in the SWI system. The cation exchange column reduced both toxicity and concentrations of trace metals, and serial elution of the column added back both toxicity and specific metals contained in individual acid fractions. Chemical analyses of three elutriate samples demonstrated copper concentrations were within the range toxic to bivalves. Results of Phase I TIEs, additional Phase II treatments, SWI exposures, and metals analyses indicate the potential for metal toxicity in sediments from this estuarine site. When combined with the results of standard TIE methods, a solid-phase cation extraction and elution approach identified copper as the most probable cause of toxicity.

Use of Ulva lactuca to identify ammonia toxicity in marine and estuarine sediments

Toxicity identification evaluation (TIE) methods are being developed for use with whole sediments. Although a phase I TIE method has been developed to characterize ammonia toxicity in aqueous samples using the marine macroalga Ulva lactuca, the relationship between amphipod and mysid mortality and uptake by U. lactuca of bedded sediment ammonia had not been explored. Additionally, it was not known how interactions in whole sediments between metal and organic contaminants with U. lactuca and ammonia would affect TIE interpretation. The current study showed that ammonia toxicity to amphipods and mysids was reduced significantly in marine sediments in the presence of U. lactuca. The alga slightly affected metal concentrations but did not alter the concentration of organic contaminants in either overlying or interstitial waters. Conversely, ammonia uptake by U. lactuca was not affected by the presence of metal or organic contaminants in the sediments. When used with other TIE manipulations, U. lactuca can be utilized in a whole-sediment, phase I TIE to remove toxicity due to ammonia.

Development of a toxicity identification evaluation procedure for characterizing metal toxicity in marine sediments

A multiagency effort is underway to develop whole sediment toxicity identification evaluation (TIE) methods. Whole sediment TIE methods will be critical tools for characterizing toxicity at hazardous waste sites (e.g., Superfund sites) and in the conduct of environmental risk assessments. The research approach is based on the predominance of three classes of toxicants in sediments: ammonia, nonpolar organic chemicals, and metals. Here we describe a procedure for characterizing acute toxicity caused by metals in whole marine sediments. The procedure involves adding a chelating resin to sediments, resulting in the sequestration of bioavailable metal while not stressing testing organisms. Within the testing chambers, the presence of resin resulted in statistically significant reductions in the overlying and interstitial water concentrations of five metals (cadmium, copper, nickel, lead, and zinc) generally by factors of 40 and 200. Toxicity to both the amphipod Ampelisca abdita and mysid Americamysis bahia (formerly Mysidopsis bahia) of sediments spiked with the five metals was decreased by approximately a factor of four when resin was present. While very effective at reducing the concentrations and toxicity of metals, the resin has only minor ameliorative effects on the toxicity of ammonia and a representative nonpolar toxicant (Endosulfan). Resin and accumulated metal were easily isolated from the testing system following exposures allowing for the initiation of phase II TIE (identification) procedures. This procedure using the addition of a chelating resin provides an approach for determining the importance of metals to the toxicity of marine sediments. Work is continuing to validate the method with environmentally contaminated sediments.

Use of toxicity identification evaluation methods to characterize, identify, and confirm hexavalent chromium toxicity in an industrial effluent

A toxicity identification evaluation (TIE) was conducted on effluent from a major industrial discharger. Although initial monitoring typically showed only slight, intermittent, chronic toxicity to Ceriodaphnia dubia, a later sample showed substantial acute toxicity to C. dubia (48-h lc 50=9%). Acute phase I toxicity characterization tests were conducted on this acutely toxic sample; none of the phase I manipulations reduced sample toxicity. The toxic effluent sample was then treated with activated carbon, and cation, anion, and mixed-bed ion exchange. Acute toxicity was not reduced by treatment with activated carbon or cation exchange, but was completely removed by anion and mixed-bed ion exchange. Based on these data, we concluded that the causative toxicant(s) was likely an inorganic anion(s); chemical analysis detected hexavalent chromium (Cr[VI]) at concentrations sufficient to account for the observed acute toxicity. Although Cr[VI] could clearly explain the presence of acute toxicity, subsequent confirmation testing was designed to determine whether Cr[IV] was responsible for the low-level chronic toxicity more typical of the effluent. Concurrent chronic tests conducted on unaltered and anion-exchanged effluent showed that the presence of chronic toxicity was associated with chronically toxic concentrations of Cr[VI]. The source of Cr[VI] in the effluent was traced to a malfunctioning heat exchanger; after this malfunction was corrected, neither chronic toxicity nor appreciable Cr[VI] was observed in the effluent again.