用混合细菌作指示生物评价工业废水综合毒性的实验研究

用混合细菌作指示生物，建立了富含重金属工业废水综合毒性的评价方法。结果表明，混合细菌总脱氢酶活性的抑制率（％）随工业废水中重金属浓度的增加而增加，按现行的国家《污水综合排放标准》（ＧＢ８９７８－８８）配制模拟混合废水、其中的重金属（Ｈｇ、Ｃｄ、Ｃｒ＋６、Ａｓ·Ｐｂ）浓度（Ｘ）与细菌总脱氢酶活性抑制率（Ｙ）之间的回归方程为：Ｙ＝－８．５＋２０．６Ｘ．相关系数（ｒ）＝０．９８４．二者呈直线相关性（Ｐ＜０．０１）。用这一回方程评价了长沙市８家工厂生产废水的综合毒性和一家工厂废水外理装置对废水综合毒性的去除效果，这一方法在实际应用上较为理想。     

Bioaccumulation of Polybrominated Diphenyl Ethers by the Freshwater Benthic Amphipod Gammarus pulex

This study reports on the relationship between polybrominated diphenyl ether (PBDE) levels in water, sediment, and the benthic macroinvertebrate Gammarus pulex, which plays a major ecological role in freshwater ecosystems. Samples were taken in a periurban watershed (near Paris, France), and PBDEs were systematically detected in sediment (≤727 ng g(-1) OC) and G. pulex (≤264 ng g(-1) lipids). PBDEs were also occasionally detected in the water column at low levels (∑ PBDEs < 1.5 ng L(-1)). The log values of bioaccumulation factors were in the range 7.8 ± 0.1-8.3 ± 0.4 L kg(-1) for tetra- and penta-BDEs, which were the only ones quantified in the dissolved phase of river water. Meanwhile, levels of individual tri- to hepta-PBDE congeners in G. pulex generally positively correlated with sediment levels, suggesting an equilibrium situation. Biota-to-sediment accumulation factors (BSAFs) of tri-hepta BDEs were congener specific and were in the range 0.5 ± 0.3-2.6 ± 1.2. For several PBDEs, BSAF values deviated from the expected range, likely because of in vivo metabolism.     

Avoidance of polycyclic aromatic hydrocarbon-contaminated sediments by the freshwater invertebrates Gammarus pulex and Asellus aquaticus

Contamination of sediments is a serious problem in most industrialized areas. Sediments are often contaminated with trace metals and organic contaminants like polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Bioassays are often used to determine the effect of contaminants on biota. However, survival or growth may not be the most sensitive endpoints. Behavioral changes often occur at much lower concentrations. Our study aimed to assess the effect of PAHs on habitat choice of two common freshwater invertebrates, the amphipod Gammarus pulex and the isopod Asellus aquaticus. We spiked clean field sediment with a mixture of four PAHs, fluoranthene, pyrene, chrysene, and benzo[k]fluoranthene, to a total concentration of 30 mg PAH/kg dry weight. Both species were offered a choice between PAH-spiked sediments and clean sediments in laboratory experiments. Results show that both species avoid PAH-spiked sediment. Origin of the population, either from a clean reference site or from a polluted site, did not affect habitat choice of either species.     

Evaluation of the Gammarus pulex in situ feeding assay as a biomonitor of water quality: robustness, responsiveness, and relevance

Biomonitoring using benthic macroinvertebrates has been used to assess water quality in Europe since the early 20th century. Most methods use community-level measurements, and the use of single-species responses has been limited, despite their potential benefits as sensitive, early warning indicators. Here we evaluate a single-species in situ assay in which the response is feeding inhibition of the freshwater amphipod Gammarus pulex. The assay was deployed in uncontaminated reference sites to quantify background variability in feeding rates and to elucidate sources of this variation. The ability of the assay to detect impacts of point-source discharges was assessed and the ecological relevance of the assay determined by comparing assay responses to aspects of community structure and functioning. Water temperature accounted for 76% of the variation in the feeding rate of animals deployed at uncontaminated sites, and summer deployments had a >90% power to detect a 30% inhibition in feeding. Inhibition of the situ feeding rate of G. pulex deployed downstream of a variety of point-source discharges ranged from 27 to 99.6%. Gammarus pulex is an important detritivore in stream communities, and a strong positive correlation existed between in situ feeding rate measured over 6 d and leaf decomposition measured over 28 d. A positive correlation also existed between in situ feeding and macroinvertebrate diversity and a biotic index. The G. pulex in situ feeding assay is a short-term sublethal biomonitor of water quality that is indicative of community- and ecosystem-level responses occurring over longer time periods. It is robust, responsive, and relevant.     

The Use of the Cyanobacteria, Cyanobium sp., as a Suitable Organism for Toxicity Testing by Flow Cytometry

Cyanobacteria are commonly found in a number of temperate and tropical bioregions, and provide important roles in fuelling many nutrient poor freshwater and marine ecosystems. Although cyanobacteria commonly occur in these environments, little is known about the use of cyanobacteria as suitable organisms for toxicity studies. Here, we propose the use of the unicellular cyanobacteria Cyanobium sp., as a potential species for tropical toxicity testing using flow cytometry. Cyanobium sp. was isolated from a composite sample of sea water in Halifax Bay, North Queensland, Australia. After careful isolation, cleaning and purification, Cyanobium sp. was used to determine the toxicity of copper, cobalt, and nickel at pH 8, and ammonia at pH 7 and 8. EC₁₀/₅₀ values were calculated using growth inhibition data determined via flow cytometry, which was found to provide rapid, accurate results, with the ability to define multiple endpoints. Cyanobium sp. was particularly sensitive to copper, cobalt and nickel, however, thrived at elevated concentrations of ammonia, irrespective of pH value. The results indicate that Cyanobium sp. is a useful test organism for tropical marine metal toxicity studies, however, is unsuitable for nutrient studies, particularly ammonia.     

Population responses of the freshwater amphipod Gammarus pulex (L.) to an environmental estrogen, 17alpha-ethinylestradiol

The effects of the environmental estrogen 17alpha-ethinylestradiol (EE) on mixed populations of 90 individual Gammarus pulex were examined following a 100-d exposure in a flow-through system. Counts of total animal numbers revealed that, in all treatment groups, population size dramatically increased due to recruitment, with neonate and juvenile gammarids the most abundant. At concentrations of 1 and 10 microg/L EE, the recorded mean population sizes of 385 and 411, respectively, were significantly greater (p = 0.018) than the control (169). Mean population sizes in the solvent control (257) and 100 ng/L EE treatment (267) were not significantly different (p > 0.05) from the control. In addition to total counts, detailed image analysis of each individual animal allowed the assessment of length-frequency distributions, adult sex ratio, number of precopula pairs/ovigerous females, and measurement of secondary antenna and gnathopod length (secondary sex characteristics). The sex ratio of adults at 100 ng, 1 microg, and 10 microg/L EE was greater than 2:1 (female:male), and significantly more females (p = 0.008) were recorded at these concentrations compared with the control. The number of male adults, precopula guarding pairs, and ovigerous females did not differ between treatments (p > 0.05). Secondary antennal and gnathopod length in males was consistently greater than in females (p < or = 0.001), but comparison between groups revealed no difference in these parameters.     

Bacillus stearothermophilus as a Model to Evaluate Membrane Toxicity of a Lipophilic Environmental Pollutant (DDT)

The thermophilic eubacterium Bacillus stearothermophilus has been used as a model system to identify DDT-promoted events in biological membranes putatively related with the insecticide toxicity. Two strategies have been approached: a) bacterial growth and viability were followed and the effects of DDT (2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane) determined; b) biophysical studies with fluorescent probes were performed to elucidate the effects of DDT on the organization of the membrane lipid bilayer. The effects of DDT on growth and physical properties of the membrane were also determined in the presence of Ca²⁺ to further identify the interference of the insecticide at the membrane level and its putative contribution to cell toxicity. Growth inhibition by DDT is concentration-dependent, being attenuated or removed by the addition of 2.5-mM Ca²⁺ to bacterial cultures. Consistently, fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its propionic acid derivative (DPH-PA) exhibited opposite effects of Ca²⁺ and DDT on the physical state of bacterial polar lipid dispersions. Growth and viability of bacterial cells are affected by DDT concentrations lower than those able to induce detectable bulk fluidity alterations, indicating high sensitivity of the intact bacterial system to alterations in limited membrane domains not directly probed by fluorescent probes that only report the average behavior of membrane lipid population. Received: 10 September 1996/Accepted: 7 December 1996     

Application of a Benthic Euryhaline Amphipod, Corophium sp., as a Sediment Toxicity Testing Organism for Both Freshwater and Estuarine Systems

The use of an as-yet-undescribed euryhaline Corophium sp. amphipod as a sediment toxicity testing organism was assessed. The species was found to be ubiquitous in many tidal areas of the Hawkesbury River catchment. The salinity of habitat sites ranged from 0.1 to 24 ppt, sediment total organic carbon (TOC) ranged from 0.4% to 3.5%, and the fines content (< 63 μm particle size) of the sediment ranged from 4.3% to 47.6%. Monitored populations ranged from a density of 59 to 6622 individuals per m², with freshwater sites with a sediment fines content greater than 20% having the highest population densities. The sensitivity of the Corophium sp. was assessed by using copper chloride and ammonium chloride as reference toxicants in a 96-h static water-only test and a 10-day static sediment test. The LC50 for copper in freshwater-only exposures was 80 to 86 μg/L, using adult animals collected from the field. In contrast, the LC50 for copper in freshwater sediment and the sediment pore water were 840 mg/kg (dry weight) and 99 μg/L, respectively. The LC50 for ammonia (total) in freshwater-only at pH 7 was 5.5 mg/L. In contrast, the LC50 for ammonia (total) in freshwater sediment and the sediment pore water were 110 mg/kg (dry weight) and 6 mg/L, respectively. Laboratory cultures of 5‰ to 15‰ salinity were optimal for supporting the release of juveniles. Juveniles collected from laboratory cultures had a LC50 for copper in 5‰ and 10‰ salinity of 9 μg/L and 28.5 μg/L, respectively, in water-only exposures. The juveniles would be suitable for use in the development of a chronic sediment toxicity test with growth as the endpoint. Received: 21 February 1997/Accepted: 27 May 1997     

Feeding Behavior of an Aquatic Snail as a Simple Endpoint to Assess the Exposure to Cadmium

One of the aims of ecotoxicology is the assessment of the effects of chemicals on the ecosystems. Bioassays assessing lethality are frequently used in ecotoxicology, however they usually employ supra-environmental toxic concentrations. Toxicity tests employing behavioral endpoints may present a balance between simplicity (i.e., laboratory bioassays) and complexity (i.e., relevant ecological effects). The aim of this study was to develop a feeding behavioral bioassay with the aquatic snail, Potamopyrgus antipodarum, which included a 2 days exposure to cadmium, followed by a 9 days post-exposure observational period. Several behavioral feeding endpoints were monitored, including percentage of actively feeding animals, percentage of animals in food quadrants and a mobility index. The percentage of actively feeding animals was reduced by the four cadmium treatments (0.009, 0.026, 0.091 and 0.230 mg Cd/L) with the stronger effect in the highest concentration. The two highest cadmium concentrations significantly reduced the percentage of animals in food quadrants and the mobility index. Therefore, the percentage of actively feeding animals was the most sensitive endpoint to cadmium toxicity as the four cadmium concentrations caused a significant decrease in this endpoint. It is concluded that feeding behavior is a useful endpoint to detect the exposure of aquatic snails to cadmium.     

Accumulation,release, and tissue distribution of 110mAg from natural food (Gammarus pulex) by the common carp,Cyprinus carpio L.

The bioaccumulation of zinc by the freshwater shrimp Gammarus pulex (L.) and adsorption by its food, conditioned horsechestnut leaves (Aesculus hippocastanum L.), in two zinc exposure concentrations were studied in the laboratory. The bioconcentration factors (BCF), uptake and elimination rate constants, and assimilation rate from food were calculated for one exposure concentration using a two-trophic-level model of a food chain. The BCF of the conditioned horse chestnut leaves was more than five times higher than that of G. pulex, and the assimilation rate of zinc from food by Gammarus was only 1.4%. As with many other animals, G. pulex was able to regulate its total body zinc level, and to accumulate most of the metal from water rather than from its food.     

Chemical Analysis and Sediment Toxicity Bioassays to Assess the Contamination of the River Lambro (Northern Italy)

This study consisted of a 10-day whole sediment toxicity test with the chironomid Chironomus riparius and a 28-day sediment toxicity test with the oligochaete Tubifex tubifex at seven sites to assess the quality of the River Lambro (Italy), one of the most contaminated rivers of the Po Basin. Endpoints measured were survival and growth for chironomids and cocoon deposition and development of young worms for tubificid oligochaetes. Responses were evaluated in relation to the occurence of organic micropollutants (PCBs, DDT, HCB, and HCH) representative of the industrial and agricultural contamination of the area. Though survival of the organisms remained unaffected, sublethal effects were observed at all sites. The sediment sampled at the farthest upstream site differed from the control only in the number of cocoons deposited by the worms. Both test species in the next three sediments, where concentrations of PCB and DDT were in the range 21.9–39.5 ng g^–1 DW and 0.6–1.3 ng g^–1 DW, respectively, experienced greater toxicity in terms of growth and reproduction. Contamination was particularly high in the site closest to Milan, where the river receives untreated urban and industrial discharges. Levels of total PCBs and total DDT here were up to two orders of magnitude higher than those found at the other sampling locations, and chironomid growth and the reproductive endpoints of tubificids were significantly lower than in the control and the other sites. The test results for the next two stations showed improvement relative to that of Milan, although contamination was still evident. Sublethal effects were in agreement with the measured concentrations of the principal persistent organic pollutants and should be included as part of environmental monitoring efforts as a basis for assessing the recovery of the river. Received: 9 June 2002/Accepted: 24 January 2003     

Understanding the Chronic Impacts of Oil Refinery Wastewater Requires Consideration of Sediment Contributions to Toxicity

Previous studies at an oil refinery in Saint John, New Brunswick, Canada, found a diminished fish community downstream of the effluent outfall that appeared to be associated with periodic low dissolved oxygen concentrations due to episodic discharges of contaminated transport vessel ballast water. This study was initiated after the ballast water was removed from the effluent to further investigate the potential causes of residual effects in the study stream, Little River. We used field caging of fish, laboratory bioassays, and chemical analysis of effluents and sediments from the field site to determine if the effluent or contaminated sediments were affecting the recovery of the fish community in Little River. The field studies suggested that exposed, caged fish were affected, displaying >40 % increases in liver sizes and increased liver detoxification enzyme activity (cytochrome P450 1A, CYP1A); however, similar responses were absent in laboratory exposures that used effluent only. Adding sediments collected from the vicinity of the refinery’s outfall to the laboratory bioassays reproduced some of the field responses. Chemical analyses showed high concentrations of PAHs in sediments but low concentrations in the effluent, suggesting that the PAHs in the sediment were contributing more to the impacts than the effluent. Application of effects-based monitoring is suggested as beneficial to identify impacts to fisheries where refinery effluents of this type are involved.