Sediment toxicity identification evaluation (TIE) studies at marine sites suspected of ordnance contamination

A sediment quality assessment survey and subsequent toxicity identification evaluation (TIE) study was conducted at several sites in Puget Sound, Washington. The sites were previously suspected of contamination with ordnance compounds. The initial survey employed sea urchin porewater toxicity tests to locate the most toxic stations. Sediments from the most toxic stations were selected for comprehensive chemical analyses. Based on the combined information from the toxicity and chemical data, three adjacent stations in Ostrich Bay were selected for the TIE study. The results of the phase I TIE suggested that organics and metals were primarily responsible for the observed toxicity in the sea urchin fertilization test. In addition to these contaminants, ammonia was also contributing to the toxicity for the sea urchin embryological development test. The phase II TIE study isolated the majority of the toxicity in the fraction containing nonpolar organics with high log K _ow, but chemical analyses failed to identify a compound present at a concentration high enough to be responsible for the observed toxicity. The data suggest that some organic or organometallic contaminant(s) that were not included in the comprehensive suite of chemical analyses caused the observed toxicological responses. Received: 12 December 2000/Accepted: 11 May 2001     

Toxicity Identification Evaluation of Five Metals Performed with Two Organisms (Daphnia magna and Lactuca sativa)

When trying to identify the main toxicants in effluents, natural waters, sediments, soil leachates, and leachates from products, the Toxicity Identification Evaluation (TIE) procedure has proven useful. To enhance the use of this procedure for soil, sewage, and sediment samples, we wanted to evaluate this TIE procedure, regarding metal toxicity, for the 96-h root elongation test performed with Lactuca sativa (lettuce) seeds. We also wanted to evaluate the effect of TIE treatment on the toxicity of Mn and Fe to Daphnia magna. Bioassays were performed with Daphnia magna (48-h immobility) and lettuce seeds (96-h root elongation) to determine the effect concentrations for both organisms of Ag, Cu, Fe, Mn, and Zn. The TIE was then performed at the determined Daphnia 48-h EC₈₄ and Lactuca 96-h EC₅₀ for each metal. Our results showed that the order of the metal toxicity was Ag>Cu>Zn>Fe>Mn, for Daphnia and Ag = Zn = Fe = Cu > Mn for lettuce seeds. We also found that toxicity of the metals for Daphnia magna was reduced according to the prevailing knowledge regarding Cu, Zn, and Ag. However, the toxicity of Ag and Cu for Daphnia was also reduced by filtration through a C18 resin. Toxicity of Mn and Fe was reduced by filtration through a CM resin and increase of pH. For lettuce seeds, toxicity of the metals was reduced by the same treatments as for Daphnia magna with the exception of EDTA addition, which did not affect Cu toxicity to lettuce seeds. No effects were found for filtration through a C18 resin. We suggest that the TIE procedure using lettuce seeds can be used in toxicity identification of metals. However, the effects of pH manipulations were often stronger with lettuce and should be interpreted with care.     

Whole sediment toxicity identification evaluation tools for pyrethroid insecticides: III. Temperature manipulation

Since the toxicity of pyrethroid insecticides is known to increase at low temperatures, the use of temperature manipulation was explored as a whole-sediment toxicity identification evaluation (TIE) tool to help identify sediment samples in which pyrethroid insecticides are responsible for observed toxicity. The amphipod Hyalella azteca is commonly used for toxicity testing of sediments at a 23 degrees C test temperature. However, a temperature reduction to 18 degrees C doubled the toxicity of pyrethroids, and a further reduction to 13 degrees C tripled their toxicity. A similar response, though less dramatic, was found for 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), and dissimilar temperature responses were seen for cadmium and the insecticide chlorpyrifos. Tests with field-collected sediments containing pyrethroids and/or chlorpyrifos showed the expected thermal dependency in nearly all instances. The inverse relationship between temperature and toxicity provides a simple approach to help establish when pyrethroids are the principal toxicant in a sediment sample that could be used as a supplemental tool in concert with chemical analysis or other TIE manipulations. The phenomenon appears to be, in part, a consequence of a reduced ability to biotransform the toxic parent compound at cooler temperatures. The strong dependence of pyrethroid toxicity on temperature has important ramifications for predicting their environmental effects, and the standard test temperature of 23 degrees C dramatically underestimates risk to resident fauna during the cooler months.     

Development of toxicity identification evaluation procedures for pyrethroid detection using esterase activity

Recent agrochemical usage patterns suggest that the use of organophosphate (OP) pesticides will decrease, resulting in a concomitant increase in pyrethroid usage. Pyrethroids are known for their potential toxicity to aquatic invertebrates and many fish species. Current toxicity identification evaluation (TIE) techniques are able to detect OPs, but have not been optimized for pyrethroids. Organophosphate identification methods depend upon the use of piperonyl butoxide (PBO) to identify OP-induced toxicity. However, the use of PBO in TIE assays will be confounded by the co-occurrence of OPs and pyrethroids in receiving waters. It is necessary, therefore, to develop new TIE procedures for pyrethroids. This study evaluated the use of a pyrethroid-specific antibody, PBO, and carboxylesterase activity to identify pyrethroid toxicity in aquatic toxicity testing with Ceriodaphnia dubia. The antibody caused significant mortality to the C. dubia. Piperonyl butoxide synergized pyrethroid-associated toxicity, but this effect may be difficult to interpret in the presence of OPs and pyrethroids. Carboxylesterase activity removed pyrethroid-associated toxicity in a dose-dependent manner and did not compromise OP toxicity, suggesting that carboxylesterase treatment will not interfere with TIE OP detection methods. These results indicate that the addition of carboxylesterase to TIE procedures can be used to detect pyrethroids in aquatic samples.     

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.     

Causes of Sediment Toxicity to <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> 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.     

Wastewater treatment polymers identified as the toxic component of a diamond mine effluent

The Ekati Diamond Mine, located approximately 300 km northeast of Yellowknife in Canada's Northwest Territories, uses mechanical crushing and washing processes to extract diamonds from kimberlite ore. The processing plant's effluent contains kimberlite ore particles (< or =0.5 mm), wastewater, and two wastewater treatment polymers, a cationic polydiallydimethylammonium chloride (DADMAC) polymer and an anionic sodium acrylate polyacrylamide (PAM) polymer. A series of acute (48-h) and chronic (7-d) toxicity tests determined the processed kimberlite effluent (PKE) was chronically, but not acutely, toxic to Ceriodaphnia dubia. Reproduction of C. dubia was inhibited significantly at concentrations as low as 12.5% PKE. Toxicity identification evaluations (TIE) were initiated to identify the toxic component of PKE. Ethylenediaminetetraacetic acid (EDTA), sodium thiosulfate, aeration, and solid phase extraction with C-18 manipulations failed to reduce PKE toxicity. Toxicity was reduced significantly by pH adjustments to pH 3 or 11 followed by filtration. Toxicity testing with C. dubia determined that the cationic DADMAC polymer had a 48-h median lethal concentration (LC50) of 0.32 mg/L and 7-d median effective concentration (EC50) of 0.014 mg/L. The anionic PAM polymer had a 48-h LC50 of 218 mg/L. A weight-of-evidence approach, using the data obtained from the TIE, the polymer toxicity experiments, the estimated concentration of the cationic polymer in the kimberlite effluent, and the behavior of kimberlite minerals in pH-adjusted solutions provided sufficient evidence to identify the cationic DADMAC polymer as the toxic component of the diamond mine PKE.     

Application of toxicity identification evaluation procedures on wastewaters and sludge from a municipal sewage treatment works with industrial inputs

A comparison of influent and effluent wastewater toxicities to Daphnia magna was undertaken to determine the most representative aqueous fraction for future toxicity identification evaluation (TIE) studies. Wastewater samples originated from a wastewater treatment plant which receives mainly domestic wastewater and industrial effluents. The TIE results reveal that the key toxicant contained in the influent was 2-propylbezaldehyde oxime. Results suggest that greater attention needs to be given to the receiving influent containing 2-propylbezaldehyde oxime to avoid damaging the bacterial populations in the primary activated sludge process. In addition, in order to evaluate the applicability of the reuse of activated sludge as a fertilizer in agriculture, TIE studies were also performed on water extracts from surplus sludge.     

Identifying the causes of oil sands coke leachate toxicity to aquatic invertebrates

A previous study found that coke leachates (CL) collected from oil sands field sites were acutely toxic to Ceriodaphnia dubia; however, the cause of toxicity was not known. Therefore, the purpose of this study was to generate CL in the laboratory to evaluate the toxicity response of C. dubia and perform chronic toxicity identification evaluation (TIE) tests to identify the causes of CL toxicity. Coke was subjected to a 15-d batch leaching process at pH 5.5 and 9.5. Leachates were filtered on day 15 and used for chemical and toxicological characterization. The 7-d median lethal concentration (LC50) was 6.3 and 28.7% (v/v) for pH 5.5 and 9.5 CLs, respectively. Trace element characterization of the CLs showed Ni and V levels to be well above their respective 7-d LC50s for C. dubia. Addition of ethylenediaminetetraacetic acid significantly (p?≤?0.05) improved survival and reproduction in pH 5.5 CL, but not in pH 9.5 CL. Cationic and anionic resins removed toxicity of pH 5.5 CL only. Conversely, the toxicity of pH 9.5 CL was completely removed with an anion resin alone, suggesting that the pH 9.5 CL contained metals that formed oxyanions. Toxicity reappeared when Ni and V were added back to anion resin-treated CLs. The TIE results combined with the trace element chemistry suggest that both Ni and V are the cause of toxicity in pH 5.5 CL, whereas V appears to be the primary cause of toxicity in pH 9.5 CL. Environmental monitoring and risk assessments should therefore focus on the fate and toxicity of metals, especially Ni and V, in coke-amended oil sands reclamation landscapes.     

Sequential toxicity identification evaluation (TIE) for characterizing toxicity of Venice Lagoon sediments: comparison of two different approaches

A toxicity identification evaluation phase-I (TIE-1) procedure was carried out on five pore water samples extracted from sediments of the Venice Lagoon previously investigated to assess both chemical contamination and toxic effects on the biota. Two different sequential TIE procedures were tested. A first sequence (TIE-1) provided for adding Na2S2O3, adding Na-EDTA, filtering, elution through a C18-SPE column and removing ammonia using the macroalgae Ulva rigida Agardh 1823, while a second procedure (TIE-2) was set up using U. rigida treatment for ammonia removal as first step, keeping unchanged the sequence of the other manipulations. Two different exposure time to the macroalgae were tested (3-h and 15-h). Sperm-cell toxicity test with the echinoid Paracentrotus lividus and embryotoxicity tests with the bivalves Mytilus galloprovincialis and Crassostrea gigas were performed on pore-water samples to assess the effect of the sequential treatments on the overall toxicity. The results confirmed that ammonia contribution to toxicity is strong in most of the samples and that metals, specially Cu, are of concern at least in three sites. The TIE-2 procedure provided more reliable results for the samples characterized by high ammonia contribution to the overall toxicity, whereas the results of TIE-1 and TIE-2 were equivalent for the samples where ammonia contribution was not prevailing. Chemical analyses and test results showed that a 3-h U. rigida exposure is suitable to remove ammonia toxicity minimizing potential metal up-take.     

Causes of water toxicity to Hyalella azteca in the New River, California, USA

The New River (CA, USA) was created in 1905 to 1907 when the Colorado River washed out diversionary works and flowed into the Salton Basin, creating the Salton Sea. Approximately 70% of the river's current flow is agricultural wastewater from the Imperial Valley. The river is contaminated with pesticides, industrial organic chemicals, metals, nutrients, bacteria, and silt. Monitoring for the State of California Surface Water Ambient Monitoring Program has indicated persistent water column toxicity to the epibenthic amphipod Hyalella azteca. Four toxicity identification evaluations (TIEs), along with chemical analyses, were performed, and the results indicated multiple and varying causes of toxicity. The first two TIEs characterized the causes of toxicity as a combination of metals and organics, but only the second sample contained enough total copper to contribute to toxicity. The third TIE used an emerging method for characterizing and identifying toxicity caused by pyrethroid pesticides. This TIE characterized organics as the cause of toxicity, and a carboxylesterase enzyme treatment further identified the cause of toxicity as pyrethroids. The final TIE used the enzyme and Phase II procedures to identify cypermethrin as the cause of toxicity. The TIE results demonstrate the evolving causes of toxicity in the New River and should assist regulators with implementing the total maximum daily load process for pesticides, particularly pyrethroids. Further research will determine if pyrethroids and other New River contaminants are having an impact on the Salton Sea.     

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.     

Application of toxicity identification evaluation procedures to an effluent from a nitrogenous fertilizer plant in China

The integrated method combining chemistry and toxicology, toxicity identification evaluation (TIE), was conducted to identify key toxicants in an effluent from a nitrogen fertilizer plant in China. Toxicity characterization, phase I of TIE, revealed that the suspected toxicant in the effluent was an anion that could be changed into a volatile acid. The results of toxicity identification and confirmation procedures indicated potassium cyanide to be the primary toxicant in the effluent.     

Phototoxicity Identification by Solid Phase Extraction and Photoinduced Toxicity to Daphnia magna

The photoinduced toxicity of several environmental pollutants (some Polycyclic Aromatic Hydrocarbons [PAHs]) is a potential threat to aquatic organisms. To identify the cause/s of photoinduced toxicity of a sample, it is not sufficient to simply analyze the content of some known phototoxic compounds; so far too few substances of environmental concern have ever been tested for their photoinduced toxicity. The PAHs as well as other known phototoxic compounds are hydrophobic and are expected to bind to C18 columns. The use of Solid Phase Extraction (SPE) is typically part of the procedure identifying any primary nonpolar toxicant/s, and adding phototoxicity tests to these manipulations would not substantially increase the workload. In this study, therefore, the difference in acute toxicity to Daphnia magna before and after 2 h of UV irradiation was determined for six PAHs. The ratio between EC₅₀ values before and after UV irradiation ranged from 4.6 (for benzo[a]pyrene) to >244 (for 3,4-benzofluoranthene), demonstrating that the UV enhances the PAH-toxicity. A further characterization technique using binding to Sep-Pak SPE C18 columns and recovery with methanol as an eluting agent was then tested in combination with UV irradiation. The mean recovered UV induced toxicity after binding and elution of the six PAHs was 119% according to the phototoxicity tests made. A linear relationship, between the log₁₀ K_ow values for the PAHs and the log₁₀ for the concentration of methanol at peak elution was found. The combined use of C18 column separation and UV activation may, therefore, be used in toxicity identification evaluations (TIE) of organic phototoxic compounds. Received: 8 June 1996/Revised: 17 September 1996     

水体沉积物毒性的评价方法

主要介绍了在水体沉积物毒性评价时常用的3种方法：生物毒性试验、毒性鉴别评价程序（TIE）和沉积物环境质量基准（SQGs）。生物毒性试验较化学分析方法考虑了污染物的生物可利用性,但是未能阐明产生毒性的具体污染物;TIE将常规的化学方法和生物毒性试验相结合,对产生毒性的具体污染物进行逐步鉴定,为制定相应的污染物浓度控制标准提供了依据;SQGs可以快速准确地对污染物的毒性作出判定,然而各种建立方法得到的基准间的差异影响了它的利用价值,需建立更为广泛、可靠的SQGs。将化学分析、毒性试验和现场生物调查结合是今后对沉积物中持久性有机污染物进行毒性评价和复合污染研究的发展方向。     

Use of carboxylesterase activity to remove pyrethroid-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in toxicity identification evaluations

Increases in the use and application of pyrethroid insecticides have resulted in concern regarding potential effects on aquatic ecosystems. Methods for the detection of pyrethroids in receiving waters are required to monitor environmental levels of these insecticides. One method employed for the identification of causes of toxicity in aquatic samples is the toxicity identification evaluation (TIE); however, current TIE protocols do not include specific methods for pyrethroid detection. Recent work identified carboxylesterase treatment as a useful method for removing/detecting pyrethroid-associated toxicity. The present study has extended this earlier work and examined the ability of carboxylesterase activity to remove permethrin- and bifenthrin-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in a variety of matrices, including laboratory water, Sacramento River (CA, USA) water, and Salinas River (CA, USA) interstitial water. Esterase activity successfully removed 1,000 ng/L of permethrin-associated toxicity and 600 ng/L of bifenthrin-associated toxicity to C. dubia in Sacramento River water. In interstitial water, 200 ng/L of permethrin-associated toxicity and 60 ng/L of bifenthrin-associated toxicity to H. azteca were removed. The selectivity of the method was validated using heat-inactivated enzyme and bovine serum albumin, demonstrating that catalytically active esterase is required. Further studies showed that the enzyme is not significantly inhibited by metals. Matrix effects on esterase activity were examined with municipal effluent and seawater in addition to the matrices discussed above. Results confirmed that the esterase retains catalytic function in a diverse array of matrices, suggesting that this technique can be adapted to a variety of aquatic samples. These data demonstrate the utility of carboxylesterase treatment as a viable step to detect the presence of pyrethroids in receiving waters.     

Establishing cause-effect relationships in hydrocarbon-contaminated sediments using a sublethal response of the benthic marine alga, Entomoneis cf punctulata

A sublethal whole-sediment toxicity test that uses flow cytometry to measure inhibition of esterase activity in the marine microalga Entomoneis cf punctulata was applied to the assessment of hydrocarbon-contaminated sediments and toxicity identification and evaluation (TIE). Concentration-response relationships were developed, and a 20% effect concentration for total polycyclic aromatic hydrocarbons (PAHs) of 60 mg/kg normalized to 1% total organic carbon was calculated. Relationships between toxic effects and sediment organic carbon concentrations, organic carbon forms (e.g., black carbon), and sediment particle size indicated that further normalization of hydrocarbon concentrations to sediment particle size may improve concentration-response relationships. The algal toxicity test was applied as a rapid whole-sediment TIE procedure that involved the addition to sediment of powdered coconut charcoal (PCC), a hydrophobic, carbon-based material that strongly adsorbs PAHs and decreases the pore-water exposure pathway. Sediments with PCC concentrations of up to 15% (w/w) provided acceptable responses in control sediments. For six sediments with total PAH concentrations of 1,060, 4,060, 5,120, 9,150, 9,900, and 15,900 mg/kg, inhibition of E. cf punctulata esterase activity (% of control) was 75, 97, 94, 93, 100, and 97%, respectively. Following a 15% PCC amendment to these sediments, inhibition of esterase activity was 0, 1, 11, 69, 32, and 68%, respectively, indicating a decrease in toxicity in all sediments. Because the alga E. cf punctulata is exposed to toxicants via both pore water and overlying water, the reduction in toxicity achieved by 15% PCC additions can be related to the efficient removal of dissolved hydrocarbons released from sediment particles. The sediment-PCC manipulations coupled with algal whole-sediment toxicity tests provided an effective and rapid TIE method to determine whether hydrocarbon contaminants are responsible for toxicity in sediments.     

The behavior and identification of toxic metals in complex mixtures: Examples from effluent and sediment pore water toxicity identification evaluations

Toxicity caused by heavy metals in environmental samples can be assessed by performing a suite of toxicity identification evaluation (TIE) methods. The behavior of metals during TIEs can vary greatly according to sample matrix. Some approaches and precautions in using TIE to identify metal toxicants in a sample are discussed, using case studies from three effluent and one sediment TIEs. These approaches include responses of metals that erroneously suggest the presence of other toxicants, the bioavailability of metals retained by glass-fiber filtration, and cautionary steps in Phase III to avoid dilution water effects on sample toxicity.Mention of trade names does not constitute endorsement by the U.S. Environmental Protection Agency.     

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.     

Identification of ammonia,chlorine, and diazinon as toxicants in a municipal effluent

A toxicity identification evaluation (TIE) was performed on a municipal effluent, and three toxicants were identified, ammonia, chlorine, and diazinon. Ammonia and chlorine were the only toxicants present at toxic concentrations in all sample sets, and diazinon was present in toxic concentrations in one of the effluent sample sets. Six effluent sets taken over an 8-month period were evaluated in this TIE. The nonpolar toxicity, primarily due to diazinon, was intermittent since it was present at toxic concentrations only once in the 8-month time period.This report illustrates the types of data and logic used in performing a TIE which contains common municipal toxicants. Emphasis in this report was place on the data needed for generating the weight of evidence in toxicant confirmation, Phase III, to support the suspect toxicants identified in the TIE process. Multiple Phase III manipulations, when applied to numerous effluent samples, provided consistent results for generating the weight of evidence for the confirmation of ammonia and chlorine as the primary causes of toxicity in this effluent.