Comparison of sediment extract microtox® toxicity with semi-volatile organic priority pollutant concentrations

A total of 105 sediment samples were extracted with acetonitrile and subjected to cleanup with C-18 columns and copper powder. Extracts were analyzed for semi-volatile organic priority pollutants and for acute toxicity using the Microtox® bioassay. Polynuclear aromatic hydrocarbons (PAHs) accounted for 85% of all priority pollutant identifications. The results of statistical comparisons made between PAH concentrations and extract toxicity depended upon the correlation procedures used. Total PAHs were significantly correlated with toxicity using Spearman's correlation procedure, but not correlated using a linear correlation procedure. Many extracts with below or barely detectable levels of priority pollutants were highly toxic. On an individual extract basis, concentrations of priority pollutants were poor indicators of extract toxicity. Toxicity determinations were also made for commonly detected priority pollutants dissolved in dimethyl sulfoxide.     

Distribution of petroleum hydrocarbon in sediment from coastal area receiving industrial effluents in Kuwait

Sediment samples from the coastal area facing Shuaiba industrial area (15 x 1.5 km(2)) were examined for contamination with petroleum hydrocarbons. Aliphatic hydrocarbons in sediment extracts were characterized largely by unresolved complex mixture from nC(22)-nC(33). The sediment samples from the upstream area facing Mina Al-Ahmadi refinery to Shuaiba Harbor were heavily polluted with polycyclic aromatic hydrocarbons (PAHs) possibly due to the higher depth in the area created for a navigational channel to the harbor. PAHs at these locations exceeded the probable effect levels with reference to sediment quality guidelines.     

An Evaluation of the Toxicity of Contaminated Sediments from Waukegan Harbor, Illinois, Following Remediation

Waukegan Harbor in Illinois was designated as a Great Lakes Area of Concern due to high concentrations of sediment-associated polychlorinated biphenyls (PCBs). The objective of this study was to evaluate the toxicity of 20 sediment samples collected after remediation (primarily dredging) of Waukegan Harbor for PCBs. A 42-day whole sediment toxicity test with the amphipod Hyalella azteca (28-day sediment exposure followed by a 14-day reproductive phase) and sediment toxicity tests with Microtox(R) were conducted to evaluate sediments from Waukegan Harbor. Endpoints measured were survival, growth, and reproduction (amphipods) and luminescent light emission (bacteria). Survival of amphipods was significantly reduced in 6 of the 20 sediment samples relative to the control. Growth of amphipods (either length or weight) was significantly reduced relative to the control in all samples. However, reproduction of amphipods identified only two samples as toxic relative to the control. The Microtox basic test, conducted with organic extracts of sediments identified only one site as toxic. In contrast, the Microtox solid-phase test identified about 50% of the samples as toxic. A significant negative correlation was observed between reproduction and the concentration of three polynuclear aromatic hydrocarbons (PAHs) normalized to total organic carbon. Sediment chemistry and toxicity data were evaluated using sediment quality guidelines (consensus-based probable effect concentrations, PECs). Results of these analyses indicate that sediment samples from Waukegan Harbor were toxic to H. azteca contaminated at similar contaminant concentrations as sediment samples that were toxic to H. azteca from other areas of the United States. The relationship between PECs and the observed toxicity was not as strong for the Microtox test. The results of this study indicate that the first phase of sediment remediation in Waukegan Harbor successfully lowered concentrations of PCBs at the site. Though the sediments were generally not lethal, there were still sublethal effects of contaminants in sediments at this site observed on amphipods in long-term exposures (associated with elevated concentrations of metals, PCBs, and PAHs).     

重庆市主城区长江和嘉陵江水中有机污染物对斑马鱼胚胎仔鱼的毒性研究

目的以重庆市主城区大溪沟(嘉陵江)和寸滩(长江)两个点为代表,研究2004~2005年度重庆市水源水中有机污染物的组成和对斑马鱼胚胎仔鱼的毒性。方法固相萃取法萃取水中有机污染物,GC/MS检测有机污染物的种类;将萃取的有机污染物溶于DMSO中,并用斑马鱼胚胎仔鱼实验研究水中有机污染物对斑马鱼胚胎孵化率和仔鱼畸形率的影响。结果四个水样中均可检出有机污染物,污染物的种类以酞酸酯类和多环芳烃类为主;污染物可导致斑马鱼胚胎孵化率降低及仔鱼畸形率增加,其毒性呈现出时间和剂量依赖性;同一采样点中,枯水期水样毒性大于丰水期水样。结论重庆市主城区嘉陵江和长江水中有机污染物对斑马鱼具有降低胚胎孵化率及增加仔鱼畸形率的毒性作用。     

Toxicity assessment of sediments from the Grand Calumet River and Indiana Harbor Canal in Northwestern Indiana,USA

The objective of this study was to evaluate the toxicity of sediments from the Grand Calumet River and Indiana Harbor Canal located in northwestern Indiana, USA. Toxicity tests used in this assessment included 10-day sediment exposures with the amphipod Hyalella azteca, 31-day sediment exposures with the oligochaete Lumbriculus variegatus, and the Microtox Solid-Phase Sediment Toxicity Test. A total of 30 sampling stations were selected in locations that had limited historic matching toxicity and chemistry data. Toxic effects on amphipod survival were observed in 60% of the samples from the assessment area. Results of a toxicity test with oligochaetes indicated that sediments from the assessment area were too toxic to be used in proposed bioaccumulation testing. Measurement of amphipod length after the 10-day exposures did not provide useful information beyond that provided by the survival endpoint. Seven of the 15 samples that were identified as toxic in the amphipod tests were not identified as toxic in the Microtox test, indicating that the 10-day H. azteca test was more sensitive than the Microtox test. Samples that were toxic tended to have the highest concentrations of metals, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The toxic samples often had an excess of simultaneously extracted metals (SEM) relative to acid volatile sulfide (AVS) and had multiple exceedances of probable effect concentrations (PECs). Metals may have contributed to the toxicity of samples that had both an excess molar concentration of SEM relative to AVS and elevated concentrations of metals in pore water. However, of the samples that had an excess of SEM relative to AVS, only 38% of these samples had elevated concentration of metals in pore water. The lack of correspondence between SEM-AVS and pore water metals indicates that there are variables in addition to AVS controlling the concentrations of metals in pore water. A mean PEC quotient of 3.4 (based on concentrations of metals, PAHs, and PCBs) was exceeded in 33% of the sediment samples and a mean quotient of 0.63 was exceeded in 70% of the thirty sediment samples from the assessment area. A 50% incidence of toxicity has been previously reported in a database for sediment tests with H. azteca at a mean quotient of 3.4 in 10-day exposures and at a mean quotient of 0.63 in 28-day exposures. Among the Indiana Harbor samples, most of the samples with a mean PEC quotient above 0.63 ( i.e., 15 of 21; 71%) and above 3.4 ( i.e., 10 of 10; 100%) were toxic to amphipods. Results of this study and previous studies demonstrate that sediments from this assessment area are among the most contaminated and toxic that have ever been reported.     

Effects of long-chain hydrocarbon-polluted sediment on freshwater macroinvertebrates

High-molecular weight (> C16) hydrocarbons (HMWHs) are common pollutants in sediments of freshwater systems, particularly urban water bodies. No sediment quality guidelines exist for total hydrocarbons; more emphasis is placed on polyaromatic hydrocarbons, the most toxic component of hydrocarbons. A field-based microcosm experiment was conducted to determine whether unpolluted sediments spiked with synthetic motor oil impair freshwater macroinvertebrate assemblages. Total petroleum hydrocarbon (TPH) concentrations of 860 mg/kg dry weight significantly increased the abundance of Polypedilum vespertinus and Cricotopus albitarsis and decreased the abundance of Paratanytarsus grimmii adults (all Chironomidae), whereas TPH concentrations ranging from 1,858 to 14,266 mg/kg produced a significant reduction in the total numbers of taxa and abundance, with significant declines in the abundance of nine chironomid taxa. About 28% of water bodies surveyed in urban Melbourne, Australia, had TPH concentrations in sediments likely to cause ecological impairment, and about 14% of the water bodies surveyed are likely to have reduced species richness and abundance. Therefore, HMWHs can be a significant pollutant in urban water bodies. Freshwater sediment quality guidelines should be developed for this ubiquitous urban pollutant.     

The use of toxicity bioassays to monitor the recovery of oiled wetland sediments

Six toxicity assays were compared to determine their efficacy in assessing toxicity dynamics during a wetland bioremediation study. The toxicity bioassays used were the Microtox 100% elutriate test, Microtox Solid Phase Test (SPT), amphipod assay, P450 reporter gene system, Toxi-ChromoPad test and a Salmonella/microsome assay. Oiled sediments were analyzed for toxicity in the petroleum biostimulation experiment conducted along the San Jacinto River, near Houston (TX, USA). The bioassays were evaluated for their ability to measure acute toxicity, chronic toxicity, and the mutagenic potential of amended oiled plots as compared to oiled and unoiled control plots. Amendments were diammonium phosphate alone or in combination with potassium nitrate, which served as an alternate electron acceptor. With exception of the Toxi-ChromoPad and Salmonella tests, the bioassays exhibited a significant increase in toxicity after oil application. Microtox bioassays detected significant sediment toxicity up to 29 d after oil and amendment application. The Microtox solid phase test results correlated strongly with gas chromatography-mass spectrometry analyses of total target saturate and aromatic hydrocarbons. The amphipod assay detected initial toxicity with a decline to day 70, followed by a significant increase in toxicity on day 140 in plots receiving nutrient amendments, which may be in response to excessive nutrient application. Low levels of enzyme induction were observed with the P450 reporter gene system assay in all oiled sediments throughout the study, suggesting low but persistent levels of polycyclic aromatic hydrocarbons. Of the six tests, the two Microtox tests and the amphipod test showed the most potential in evaluating petroleum toxicity in wetland sediments.     

Comparative Bioaccumulation of Chlorinated Hydrocarbons from Sediment by Two Infaunal Invertebrates

Bioaccumulation of chlorinated hydrocarbons (CHs) from field-contaminated sediments by two infaunal invertebrates, Rhepoxynius abronius (a non–deposit feeding amphipod) and Armandia brevis (a nonselective, deposit-feeding polychaete), was examined and species responses were compared. Sediments were selected over a large geographical area of the Hudson-Raritan estuary to assess the potential for bioaccumulation from a typical urban estuary. Unlike polycyclic aromatic hydrocarbons (PAHs) from these sediments, concentrations of CHs in interstitial water (IW) indicated that partition coefficients (K_oc) were generally as expected, especially when based on predicted, nonsorbed, interstitial water CH concentrations (IW_free). Correlations between amphipod and polychaete tissue residues revealed that these species were responding similarly to a gradient of CH concentrations in sediment. While tissue residues and BAF_loc (lipid/organic carbon normalized bioaccumulation factor) values for the trichlorobiphenyls were similar for both species, accumulation in the polychaete was three to 10 times higher for the more hydrophobic PCBs, which was attributed to differences in the route of exposure. A negative correlation between the bioaccumulation factor (BAF) and total organic carbon (TOC) was found for both species, which was expected according to equilibrium partitioning theory. Because it was assumed that the amphipod was not feeding in these tests and the polychaete was ingesting sediment, comparison of their tissue residues and bioaccumulation factors was useful for highlighting the importance of sediment ingestion, especially for short-term, nonequilibrium exposures. These results may also help elucidate the limitations associated with assessing bioaccumulation and the resultant toxic response in standard 10-day toxicity tests with similar invertebrates. Received: 1 February 1997/Accepted: 30 June 1997     

Sediment toxicity testing with the amphipod Ampelisca abdita in Calcasieu estuary, Louisiana

Discharges from chemical and petrochemical manufacturing facilities have contaminated portions of Louisiana's Calcasieu River estuary with a variety of organic and inorganic contaminants. As part of a special study, sediment toxicity testing was conducted to assess potential impact to the benthic community. Ten-day flow-through sediment toxicity tests with the amphipod Ampelisca abdita revealed significant toxicity at 68% (26 of 38) of the stations tested. A. abdita mortality was highest in the effluent-dominated bayous, which are tributaries to the Calcasieu River. Mortality was correlated with total heavy metal and total organic compound concentrations in the sediments. Ancillary experiments showed that sediment interstitial water salinity as low as 2.5 o/oo did not significantly affect A. abdita's response in the flow-through system; sediment storage for 7 weeks at 4°C did not significantly affect toxicity. Sediment toxicity to A. abdita was more prevalent than receiving water toxicity using three short-term chronic bioassays. Results suggest that toxicity testing using this amphipod is a valuable tool when assessing sediments containing complex contaminant mixtures and for assessing effects of pollutant loading over time. In conjunction with chemical analyses, the testing indicated that the effluent-dominated, brackish bayous (Bayou d'Inde and Bayou Verdine) were the portions of the estuary most impacted by toxicity.     

Assessment of Sediment Toxicity Using Different Trophic Organisms

The main aim of the present project is to study the feasibility of using different trophic organisms for evaluating the toxicity of dredged sediments arising in Hong Kong. A total of eight sediment samples (duplicate samples collected from four selected sites: Kowloon Bay, Tsing Yi, Chek Lap Kok, and Double Haven) of Hong Kong coastal waters were analyzed for the total concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, total organic carbon, acid volatile sulfides, simultaneously extracted metals, redox potential, and 12 organic micropollutants. The sediment elutriates were also analysed for the various metal concentrations, as well as contents of ammonia-N, nitrate, total sulfide, sulfate, and total organic carbon. Elutriate Sediment Toxicity Tests (ESTT) were also conducted, using two microalgae (Skeletonema costatum, a diatom and Dunaliella tertiolecta, a flagellate), juvenile shrimp (Metapenaeus ensis) and juvenile fish (Trachinotus obtaus). Two commercially available tests using bacteria (Microtox Test and Toxi-Chromotest) also were employed to test both the solid phase and elutriates of the sediments. The results of Microtox test on the solid phase, and bioassay tests using diatom on the sediment elutriate, especially the former, were correlated significantly (p < 0.05) with a number of physico-chemical properties of sediments and elutriates. It is recommended that a combination of a liquid-phase bioassay using diatom and a solid-phase bioassay using Microtox test should be used for screening a large number of sediment samples. However, the presence of ammonia in the sediments containing a high content of organic matter seemed to interfere the detection of contamination impacts. Received: 12 March 1996/Revised: 27 August 1996     

用彗星实验和微核实验反映土壤有机污染物的联合毒性

目的 利用彗星实验和微核实验反映土壤有机污染物的联合毒性.方法 选取某污灌农田土壤为研究对象(下称“污灌区”),地下水灌溉农田土壤为对照(下称“对照区”),采用超声振荡法提取土壤中的有机污染物,用气相色谱质谱联用仪(GC/MS)对土壤中的有机物进行分析;采用灌胃的方式对小鼠进行染毒,用单细胞凝胶电泳实验和徽核试验检测土壤有机提取物的联合毒性.结果 污灌区土壤检出的主要污染物为烷烃类、苯系物及多环芳烃,有机污染物的种类及含量高出对照区数倍;与试剂对照组和对照区相同染毒剂量组比较,污灌区各组拖尾率、微核率均增高(P＜0.05).结论 该污灌区土壤已受到一定程度的有机物污染,且污染物对小鼠具有一定的毒性.     

Effects of dilution on the exposure in sediment toxicity tests- buffering of freely dissolved concentrations and changes in mixture composition

Some sediment toxicity tests, such as the Microtox test, are conducted by diluting either contaminated sediment or an aqueous phase with clean water. The present study aims to clarify how the dilution procedure affects the exposure of organisms. It is shown that freely dissolved concentrations of hydrophobic compounds are buffered by desorption from the sediment matrix when sediment is diluted with water. The buffering depends on the properties of the sediment matrix and contaminant. Consequently, the composition of a contaminant mixture changes with dilution, and the exposure in a sediment dilution toxicity test is poorly defined. This questions the application and subsequent assessments of such tests. Additionally, the often-observed higher toxicity in sediment dilution tests relative to elutriate dilution tests is not sufficient to claim direct contact exposure, because the enhanced sensitivity in sediment dilution tests also can be explained by buffering from the sediment matrix. In applying these tests, one should be aware of the fundamental differences between the sediment dilution strategy and the dilution of an aqueous phase and of the consequences it has for the outcome of the test.     

Evaluation of Bleached Kraft Mill Process Water Using Microtox®, Ceriodaphnia dubia, and Menidia beryllina Toxicity Tests

To determine whether a 7- to 10-d embryo toxicity/teratogenicity test with the inland silverside fish, Menidia beryllina, is a sensitive indicator for evaluation of bleached kraft mill effluents, we compared this test with the Microtox? 15-min acute toxicity test and the Ceriodaphnia dubia 7-d chronic toxicity test. Water samples used in each test were collected from three areas in a bleached kraft pulp and paper mill using a 100% chlorine dioxide bleaching process: 1) river water prior to use in the mill; 2) the combined acid/base waste stream from the pulping process prior to biological treatment in the aerated stabilization basin (ASB); and 3) the effluent from the ASB with a retention time of approximately 11 d. Relative toxicity determined by the three tests for each water sampling location was compared. All three toxicity tests were predictive indicators of toxicity; however, the C. dubia and M. beryllina tests were the more similar and sensitive indicators of toxicity. Process water (ASB influent) prior to biological treatment in the ASB was toxic at all concentrations using the Microtox? and C. dubia tests. The fish embryo test showed no toxicity at 1% concentrations, slight toxicity at 10%, and acute toxicity at the 100% ASB influent concentration. Tests with biologically-treated ASB effluent indicated a substantial reduction in observed toxicity to Microtox? bacteria, C. dubia, and M. beryllina. No toxic responses were observed in any test at a 1% ASB effluent concentration which was the approximate effluent concentration in the receiving river following mixing. No relationship was found among any toxicological response and effluent levels of adsorbable organic halides, polychlorinated phenolic compounds, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, total suspended solids, color, chemical oxygen demand, or total organic carbon. Received: 27 February 1996/Revised: 4 September 1996     

Quantitative structure-activity relationships and mixture toxicity of organic chemicals in Photobacterium phosphoreum: the Microtox test

Quantitative structure-activity relationships were calculated for the inhibition of bioluminescence of Photobacterium phosphoreum by 22 nonreactive organic chemicals. The inhibition was measured using the Microtox test and correlated with the partition coefficient between n-octanol and water (Poct), molar refractivity (MR), and molar volume (MW/d). At log Poct less than 1 and greater than 3, deviations from linearity were observed. Introduction of MR and MW/d improved the quality of the relationships. The influences of MR or MW/d may be related with an interaction of the tested chemicals to the enzyme system which produces the light emission. The sensitivity of the Microtox test to the 22 tested compounds is comparable to a 14-day acute mortality test with guppies for chemicals with log Poct less than 4. The inhibition of bioluminescence by a mixture of the tested compounds was slightly less than was expected in case of concentration addition. The Microtox test can give a good estimate of the total aspecific "minimum toxicity" of polluted waters. When rather lipophilic compounds or pollutants with more specific modes of action are present, this test will underestimate the toxicity to other aquatic life.     

Sediment pore water toxicity identification in the lower Fox River and Green Bay, Wisconsin, using the Microtox assay.

Microtox assays with two different methods of osmotic adjustment were used to assess the toxicity of pore waters from 13 sediment samples collected from the Fox River watershed in Wisconsin. No toxicity was observed in Microtox assays osmotically adjusted with NaCl; however, 15-min EC50 values for assays osmotically adjusted with sucrose ranged from 52 to 63% pore water. Un-ionized ammonia accounted for a large part of the observed toxicity, but, based on a toxic units approach, did not account for all observed toxicity. Metals (Cu, Zn) and an unidentified compound(s) may potentially contribute to the observed effects in Microtox assays osmotically adjusted with sucrose. The use of alternative osmotic adjustment techniques in the Microtox assay is one potentially useful tool for elucidating several classes of compounds responsible for effects observed in toxicity assays.     

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.     

Toxicity testing of sediment elutriates based on inhibition of alpha-glucosidase biosynthesis inBacillus licheniformis

An assay based on inhibition of a-glucosidase biosynthesis (AGB) inBacillus licheniformis was used to test the toxicity of sediment elutriates from hazardous waste sites in Florida. The assay gave the same general classification of toxicity as Microtox in 85% of the 66 elutriates screened. For the ten most inhibitory elutriates, the AGB assay consistently gave lower EC₅₀s than Microtox. These samples were the highest in concentrations of cadmium, copper, lead, zinc of all those screened, suggesting that the AGB assay is particularly sensitive to heavy metals.     

Relationships between contaminant levels in marine sediments and their biological effects on embryos of oysters,Crassostrea gigas

Abstract-Surface sediment samples from 10 coastal locations were analyzed with respect to their physical and chemical characteristics as well as their biological quality. The toxicity of the decanted fresh and freeze-dried sediments and of their elutriates was assessed by bioassays with embryos of the oysters Crassostrea gigas. The concentration inhibiting normal embryogenesis in 20% of the larvae (EC20) was used as a measure of toxicity and compared with the physical and chemical properties of the sediments and elutriates by principal components analysis. Decanted whole sediments were one to four orders of magnitude more toxic than their elutriates because the latter have lower contaminant concentrations. The biological effects of decanted whole sediment depended mostly on the levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs), while in the case of the elutriates, the toxicity was mainly correlated with the concentrations of total ammonia and of dissolved organic carbon (DOC). Freeze-dried sediments and their elutriates were up to one order of magnitude more toxic than fresh sediments and elutriates, respectively, presumably because the freeze-drying procedure increases pollutant bioavailability or causes a release of unidentified organic compounds having toxic effects.     

Toxicity of saline and organic solvent extracts of sediments from Boston Harbor,Massachusetts and the Hudson River-Raritan Bay estuary,New York using the Microtox® bioassay

The toxic effects of organic and saline extracts of sediment samples collected from 16 sites in Boston Harbor, Massachusetts and from 17 sites in the Hudson River-Raritan Bay estuary, New York were tested with the Microtox^® bioassay. This bioassay measures changes in light production by bioluminescent marine bacteria exposed to sediment extracts. Organic solvent extracts of all 33 sediments showed some degree of toxicity, with sediment samples from sites in the urban areas of the bays being significantly more toxic than those from less urbanized areas of the bays. Saline extracts, however, were less toxic, only seven of 33 saline extracts produced a significant response using the recommended method of data analyses. The proportional decrease in bacterial light production at the highest concentration of saline sediment extract in the reaction mixture compared to the bacterial light production in the controls (saline light change—SLC) appeared to be a better indicator of sediment toxicity than generating a saline EC₅₀ (the amount of sediment required to reduce bioluminescence 50%) value; 16 of 33 saline extracts produced a significant response (?10% reduction in bioluminescence). Organic extracts of sediments previously extracted with saline were also always toxic in the Microtox^® bioassay but were less toxic than sediments not previously extracted. Organic EC₅₀ and SLC were inversely related to concentrations of sediment contaminants, principally low- and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs). This relationship was strongest for the organic solvent extracts of sediments tested in the bioassay. Organic solvent extracts of sediments from Boston Harbor were also significantly more toxic in the Microtox^® bioassay than those from the Hudson-Raritan estuary, even though sediment concentrations of PAHs, a measure of anthropogenic contamination, were similar. The cause for the differential toxicity is unknown at this time, but chemical contaminants other than chlorinated hydrocarbons (CHs) and PAHs may be contributing to the observed toxicity in the Microtox^® bioassay using organic extracts of sediment. Testing sediment toxicity using organic extracts of sediment with the Microtox^® bioassay provides better estimates of toxicity due to sediment contaminants than using saline extracts of sediments.     

Ecotoxicological evaluation of cork-boiling wastewaters

Toxicity tests with Vibrio fischeri, Daphnia magna, and Lemna minor were used to evaluate acute and chronic toxicity of cork-boiling wastewaters and correlation analysis was performed with physicochemical parameters. Acute toxicity values (EC₅₀) ranged from 2.3% to 24.2% in the Microtox test and from 4.4% to 29.5% in the Daphnia test. According to these values, 78% of the samples were classified as acutely toxic to the most sensitive species (V. fischeri). Significant correlation was obtained between EC₅₀ and chemical oxygen demand, biochemical oxygen demand after 5 days, total organic carbon, tannin and lignin and total solids. No significant correlation was found between the two acute tests. The D. magna chronic test showed significant differences between all tested concentrations and the control, with an EC₅₀ of 0.32%. An EC₅₀ value of 26.0% was calculated for L. minor. For the analysis of cork-boiling wastewater toxicity and routine biomonitoring, the use of the Microtox test is suggested, to afford greater environmental protection.