Physiological effects of tetracycline antibiotic pollutants on non-target aquatic Microcystis aeruginosa

This study aimed to evaluate the aquatic toxicity of three typical tetracycline antibiotics, including tetracycline, oxytetracycline, and chlortetracycline, on the cyanobacterium Microcystis aeruginosa. The cell density, chlorophyll a content, protein content, and enzymatic antioxidant activities were determined. The results showed that the cell growth was significantly inhibited by the three compounds at a low concentration. The chlorophyll a and protein content decreased significantly after exposure to 0.05 mg L^?1 of each compound for 9 d. When exposed to 0.2–1 mg L^?1 of tetracycline, the superoxide dismutase (SOD) activity increased, but peroxidase (POD) and catalase (CAT) activities decreased. In contrast, when exposed to oxytetracycline and chlortetracycline at different concentrations ranging from 0.2 to 1 mg L^?1 and from 0.01 to 0.05 mg L^?1, the SOD activity decreased, but the POD and CAT activities increased. These findings indicate that tetracycline antibiotics influence cell growth and protein synthesis, and they also induce oxidative stress in M. aeruginosa at environmentally similar concentrations. Thus, this study may provide further insights into the toxic effects of tetracycline antibiotics and the controlled use of antibiotics.     

Toxicity of synthetic pyrethroid insecticides to the grass shrimp,Palaemonetes pugio,parasitized with the bopyrid isopod,Probopyrus pandalicola

The grass shrimp, Palaemonetes pugio, plays a large role in the marine ecosystem, serving as a vital link in the food web between many other species. Marine parasites such as the bopyrid isopod, Probopyrus pandalicola, reduce shrimp growth and reproductive output and may also cause P. pugio to be more vulnerable to the lethal effects of contaminants. The purpose of this study was to determine the toxicity of resmethrin and bifenthrin on the grass shrimp, P. pugio, infected with the bopyrid isopod, Probopyrus pandalicola. A 96-h static renewal test was conducted to determine the toxicity of the pyrethroid insecticides resmethrin and bifenthrin to grass shrimp, Palaemonetes pugio, parasitized with the bopyrid isopod, Probopyrus pandalicola. The results were then compared to similar tests utilizing unparasitized P. pugio. Parasitized P. pugio had lower 24-h LC₅₀ (1.08 μg/L) and 96-h LC₅₀ (0.43 μg/L) values for resmethrin than unparasitized P. pugio. However, LC₅₀ ratio tests found that there was no significant difference between parasitized and unparasitized shrimp when affected by resmethrin (p = 0.1751 and 0.1108, respectively). In contrast, an LC₁₀ ratio test indicated that there was a significant difference between parasitized and unparasitized P. pugio after 96 h (p < 0.0001). When subjected to bifenthrin, parasitized P. pugio had a higher 24-h LC₅₀ (0.049 μg/L6) than unparasitized P. pugio. The LC₅₀ ratio test established that the effects of bifenthrin on parasitized P. pugio when compared to unparasitized P. pugio were significantly different at 24 h (p = 0.0065). However, there were no significant differences between parasitized and unparasitized after 96 h (p = 0.4229). In conclusion, both resmethrin and bifenthrin are toxic to the grass shrimp, P. pugio, regardless of parasite presence, and parasitized shrimp may be more susceptible to lower doses of resmethrin (when exposed in the field).     

乙酰甲胺磷对斜生栅藻的毒性及细菌降解研究

采用血球计数法测定斜生栅藻细胞数目,研究了乙酰甲胺磷对斜生栅藻的毒性作用,并通过藻类培养液中接种经过筛选得到的乙酰甲胺磷高效降解菌测定其对乙酰甲胺磷毒性的去除影响。研究结果表明,乙酰甲胺磷对斜生栅藻的抑制中浓度(EC50)大于159 mg/L,急性毒性为低毒。但进一步研究发现,在7 d后,EC50为174.68 mg/L,明显低于24 h的1 128.57 mg/L,存在亚慢性毒性。通过藻类培养液接种高效降解菌Y-6,乙酰甲胺磷对藻类的生长抑制程度减轻。     

Toxicity and metabolism of copper pyrithione and its degradation product, 2,2'-dipyridyldisulfide in a marine polychaete

We conducted acute toxicity tests and sediment toxicity tests for copper pyrithione (CuPT) and a metal pyrithione degradation product, 2,2′-dipyridyldisulfide [(PS)₂], using a marine polychaete Perinereis nuntia. The acute toxicity tests yielded 14-d LC₅₀ concentrations for CuPT and (PS)₂ of 0.06 mg L⁻¹ and 7.9 mg L⁻¹, respectively. Sediment toxicity tests resulted in 14-d LC₅₀ concentrations for CuPT and (PS)₂ of 1.1 mg kg⁻¹ dry wt. and 14 mg kg⁻¹ dry wt., respectively. In addition to mortality, sediment avoidance behavior and decreases in animal growth rate were observed; growth rate was the most susceptible endpoint in the sediment toxicity tests of both toxicants. Thus, we propose lowest observed effect concentrations of 0.3 mg kg⁻¹ dry wt. and 0.2 mg kg⁻¹ dry wt. for CuPT and (PS)₂, respectively, and no observed effect concentrations of 0.1 mg kg⁻¹ dry wt. for both CuPT and (PS)₂. The difference in the toxicity values between CuPT and (PS)₂ observed in the acute toxicity test was greater than the difference in these values in the sediment toxicity test, and we attribute this to (PS)₂ being more hydrophilic than CuPT. In addition to the toxicity tests, we analyzed conjugation activity of several polychaete enzymes to the toxicants and marked activity of palmitoyl coenzyme-A:biocides acyltransferase and UDP-glucuronosyl transferase was observed.     

Comparative Toxicity of Prymnesium parvum in Inland Waters1

Brooks, Bryan W., Susan V. James, Theodore W. Valenti, Jr., Fabiola Urena-Boeck, Carlos Serrano, Jason P. Berninger, Leslie Schwierzke, Laura D. Mydlarz, James P. Grover, and Daniel L. Roelke, 2010. Comparative Toxicity of Prymnesium parvum in Inland Waters. Journal of the American Water Resources Association (JAWRA) 46(1):45-62. DOI: 10.1111/j.1752-1688.2009.00390.x Abstract: Numerous studies have examined the impacts of Prymnesium parvum to aquatic life, but the majority of information available is from experiments or field studies performed at salinities of marine and coastal ecosystems. Ambient toxicity of P. parvum has been characterized with in vitro and in vivo models because reliable quantitation of P. parvum toxins in environmental matrices is often precluded by a lack of available analytical standards. Hemolytic activity and fish mortality assays have been used most frequently to characterize toxic conditions; however, relatively few in vivo studies employed standardized methods. Because the relative sensitivities of different taxa to P. parvum toxins in inland waters were undefined, we assessed the comparative toxicity of P. parvum filtrate from a laboratory study (20°C, 12:12 light:dark cycle, f/8 media, 2.4 psu) to several common standardized in vitro and in vivo models. After exposure to cell-free filtrate hemolytic activity (1 h EC₅₀ = 13,712 cells/ml) and juvenile fish (Pimephales promelas) survival (48 h LC₅₀ = 21,754 cells/ml) were the most sensitive assay responses examined, followed by rotifer (Brachionus calyciflorus) population growth rate [48 h no observable adverse effect levels (NOAEL) = 19,072 cells/ml] and cladoceran (Daphnia magna) reproduction (10-day NOAEL = 47,680 cells/ml). Green algae (Pseudokirchneriella subcapitata) growth (96 h) was not adversely affected but was instead significantly stimulated by P. parvum toxins. We further propose an initial species sensitivity distribution approach for P. parvum, which may be used to support future environmental management decisions. Our findings from these laboratory studies indicate that although fish kills are increasingly associated with P. parvum blooms occurring in inland waters, further study is required to define the influences of toxin sensitivities of phytoplankton, zooplankton, and fish communities on P. parvum bloom initiation and termination.     

自然堆存下的飞灰污染物浸出毒性研究

测定了飞灰的主要组成成分和重金属元素含量。生活垃圾焚烧飞灰在2年期的自然堆存下，通过分析不同时期污染物浸出特性，以研究飞灰污染物自然老化特征。结果表明：飞灰的主要组成元素有Ca、Si、Al、S、K、Na、Fe、Mg和Cl等，其重金属元素含量大约占1%。飞灰自然老化后，Pb 、Zn 、Cr^6＋、Hg和氰化物的迁移性大大降低；Cu 、As和Cd变化不明显，Cr的浸出略有增加；飞灰中的重金属元素在低pH下仍不具有长期稳定性，因而具有较大的环境风险。     

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

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

低浓度下4个取代苯污染物与硝酸铅的混合对发光菌的联合毒性

多种污染物混合特别是低浓度下的混合对生物的联合毒性是生态毒理学研究的热点之一。选择了3类污染物苯酚、间甲基苯酚、苯胺、对硝基苯胺、硝酸铅，采用美国微板光度计测定了它们对发光菌青海弧菌．Q67（Vibrio-qinghaiensissp-Q67）的单一及联合毒性。应用非线性拟合技术模拟了这5种物质及其混合物的剂量．效应曲线，硝酸铅可用Logit模型模拟，其它4个物质能用Weibull模型准确描述，所有拟合相关系数在0．98以上，均方根误差在O．02以下。根据纯物质的EC50值，获得这5个物质的毒性强弱顺序：硝酸铅〉对硝基苯胺〉间甲基苯酚〉苯酚〉苯胺。混合实验设计了各物质在EC50、EC1、无观察效应浓度（noobserved effectcon centration，NOEC）比例的混合。用浓度加和（doseaddition，DA）和独立作用模型（independentaction，IA）对混合物毒性进行预测。IA基本准确预测了这5个物质在各自EC50混合的毒性。DA与队模型都稍微过高地预测了以EC。及NOEC浓度比例混合的联合毒性，但都在毒理学实验容许的范围之内。这5个物质以NOEC混合时对测试生物Q67没有产生明显毒性，但是还不能判定这些物质在此浓度下混合是安全的。污染物在各自的NOEC浓度下混合是否对其它生物有潜在的威胁还需更多毒理学实验支持。     

In silico prediction of Tetrahymena pyriformis toxicity for diverse industrial chemicals with substructure pattern recognition and machine learning methods

There is an increasing need for the rapid safety assessment of chemicals by both industries and regulatory agencies throughout the world. In silico techniques are practical alternatives in the environmental hazard assessment. It is especially true to address the persistence, bioaccumulative and toxicity potentials of organic chemicals. Tetrahymena pyriformis toxicity is often used as a toxic endpoint. In this study, 1571 diverse unique chemicals were collected from the literature and composed of the largest diverse data set for T. pyriformis toxicity. Classification predictive models of T. pyriformis toxicity were developed by substructure pattern recognition and different machine learning methods, including support vector machine (SVM), C4.5 decision tree, k-nearest neighbors and random forest. The results of a 5-fold cross-validation showed that the SVM method performed better than other algorithms. The overall predictive accuracies of the SVM classification model with radial basis functions kernel was 92.2% for the 5-fold cross-validation and 92.6% for the external validation set, respectively. Furthermore, several representative substructure patterns for characterizing T. pyriformis toxicity were also identified via the information gain analysis methods.     

Aquatic toxicity of cartap and cypermethrin to different life stages of Daphnia magna and Oryzias latipes

Cartap and cypermethrin, which are among the most widely used pesticides in many countries, are considered safe because of their low mammalian toxicity and their low persistence in the environment. However, recent findings of endocrine-disrupting effects and developmental neurotoxicity have raised concerns about the potential ecological impacts of these pesticides. We evaluated the aquatic toxicity of cartap [S,S′-(2-dimethylaminotrimethylene) bis(thiocarbamate), unspecified hydrochloride] and cypermethrin [(RS)-alpha-cyano-3-phenoxybenzyl-(1RS,3RS,1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate], both individually and combined, on different life stages of the freshwater cladoceran Daphnia magna and a freshwater teleost, Japanese medaka (Oryzias latipes). The 96-hr Daphnia median effective concentrations (EC50s) for cartap and cypermethrin were 91.0 μ g/L and 0.00061 μ g/L, respectively. Rapid recovery of Daphnia was observed after short-term pulsed exposure to cartap and cypermethrin; there were no adverse effects on reproduction or survival 20 d after a 24 hr exposure to cartap up to 1240 μ g/L and cypermethrin up to 1.9 μ g/L. Chronic continuous exposure (for 21 d) of 7-d-old Daphnia to cypermethrin significantly reduced the intrinsic population growth rate in a concentration-dependent manner. However, because the intrinsic population growth rates were all above zero, populations did not decrease even at the highest experimental concentration of 200 ng/L. Exposure of Daphnia neonates (< 24 hr old) to cypermethrin for 21 d caused significant, sub-lethal reproduction-related problems, such as increased time to first brood, reduced brood size, and reduced total brood number, at 0.0002, 0.002, and 0.2 ng/L cypermethrin, but the intrinsic population growth rate was not significantly affected. Oryzias latipes was relatively more resistant to both pesticides. In particular, embryos appeared to be more resistant than juveniles or adults, which may be partly due to the protective role of the chorion. The incidence of larval fish deformity was significantly higher after a 96 hr exposure to as low as 250 μ g/L of cartap or 40 μ g/L of cypermethrin. The mixture of both compounds showed no synergistic toxicity. The extremely high acute-to-chronic ratio suggests that the standard acute lethal toxicity assessment might not reflect the true environmental hazards of these frequently used pesticides. Ecological hazard assessments of long-term low dose or pulsed exposures to cartap and cypermethrin may reveal more realistic consequences of these compounds in surface water.