Modelling cadmium bioaccumulation in Gammarus pulex by using experimental design approach

Recently, although dynamic approaches have been used increasingly to describe metal bioaccumulation in aquatic organisms, the validation of such laboratory-derived modelling is rarely assessed under environmental conditions. The present study aims to evaluate and verify statistical and mathematical models for the bioaccumulation of cadmium (Cd) and to evaluate the suitability of Gammarus pulex as a biomonitor for Cd. To optimise Cd²⁺ ion bioaccumulation conditions a Box–Behnken design was used and whether G. pulex can be used as an estimated tool to assess aquatic quality was investigated. A Box–Behnken experimental design combined with response surface modelling (RSM) was employed for Cd²⁺ bioaccumulation in G. pulex. Independent variables including temperature, contact time and Cd²⁺ ion concentration significance and their interactions were tested using analysis of variance. The selected variables’ optimum values were obtained by solving the quadratic regression model along with by analysing the response surface contour plots. Based on Box–Behnken design, the applied model is significant because model F-value and R² were obtained as 5121.49, 0.9998, respectively. Bioaccumulation of Cd amount was analysed using electrothermal atomic absorption spectrophotometer. The obtained data suggest that G. pulex can be evaluated as Cd biomonitor.     

Chemical speciation and potential ecological risk assessment of heavy metals in volcanic rocks of Southern Qinghai,China

ABSTRACT

Seven volcanic rocks samples were collected from Southern Qinghai to analyze chemical speciation and migration behavior of heavy metals by sequential chemical extraction procedure and column leaching test. The geo-accumulation index, ecological risk index and the risk assessment code were applied to assess the heavy metal pollution and potential environmental effects in this area. Results revealed that the total concentrations of heavy metals did not exceed the background values in soil of this area. Most of the samples produced acid rock drainage. The order of heavy metal migration and transformation sequence in the volcanic rocks of Zhiduo region was Cd?>?Pb?>?As?=?Cu?=?Zn?=?Mn based on the geo-accumulation index and Cd caused heavy pollution, which was also confirmed by the leaching test. Moderate potential ecological risk posed by heavy metals occurred in the study area based on the potential ecological risk index. Cd contributed to most of ecological risk while the remaining heavy metals (except As) exerted medium to high risks to the environment according to the risk assessment code evaluation results. In summary, volcanic rocks possessed potential risks to the surroundings due to potential release of heavy metals. Cd that caused the pollution should be paid special attention.     

Bioaccumulation and toxic effects of copper in common onion Allium cepa L.

The aim of this study was to investigate the potential utility of Allium cepa L. as a bioindicator organism for measuring copper bioaccumulation and toxicity in laboratory conditions. Onions were exposed to increasing concentrations of the metal (0, 0.1, 0.5, 1, 5 and 10 μg mL^?1) for 7 days. Root and leaf development were chosen as biological endpoints, while bioaccumulation was evaluated in roots, bulbs and leaves. Copper caused inhibition of root elongation with increasing effects at the higher doses, growth being reduced by almost 60% at 0.1 μg mL^?1 and up to 95% at 10 μg mL^?1. The elongation of leaves was significantly lower only in specimens exposed at 0.5 μg mL^?1, but a total absence of newly formed tissues was observed at 10 μg mL^?1. A marked bioaccumulation of copper was measured in roots, with values increasing up to almost four orders of magnitude compared to controls; only slight or even no significant differences were observed for copper levels in leaves and bulbs of treated A. cepa. Multiple linear correlations revealed a significant inverse relationship between copper concentrations and tissue length in both the roots and leaves, evidencing a sensitive responsiveness of this biological model. The overall results suggest the suitability of A. cepa as a robust species for easy and simple ecotoxicological bioassays to test the toxic effects and bioavailability of environmental pollutants, especially trace metals.     

Protective action of zinc against lead poisoning in tilapia Oreochromis niloticus

The accumulation of lead (Pb) in tilapias Oreochromis niloticus, acclimatized in cement tanks, and fed once a day with pellets of commercial food with lead nitrate, was investigated by square wave anodic stripping voltammetry (SWV). The head (including head bones, proteins, and brain) was the main target of lead uptake by tilapias, with a small amount in muscle tissue. A high concentration of Pb was found in feces which indicated low absorption by the organism when fed with high Pb concentration. The protective effects of zinc (Zn) against the Pb poisoning, the accumulation of Pb in the heads of the fishes of 107.8?±?3.1?mg?kg^?1 and in the viscera of 57.1?±?2.9?mg?kg^?1 with consequent decrease of calcium (Ca) concentration, were observed. In spite of the experimental time of 16 months and higher Pb concentration in the dietary food of 320?mg?kg^?1, no death of tilapias was observed due to the protective action of Zn.     

Biochemical constituents and bioaccumulation as biomarkers in the green mussel Perna viridis with reference to silver and chromium toxicity

The sublethal effect of silver and chromium on some biochemical constituents was studied in the green mussel Perna viridis. The results revealed an overall reduction in total protein, total DNA, total RNA, glycogen, protein bound sugars and total lipid in the gill, hepatopancreas, and ovary of the mussels exposed to metals individually and in combination when compared with control. It was apparent that mussels exposed to mixtures of metals exhibited highly significant (P?P?P?相似文献   

Mercury distribution,speciation and potential ecological risk assessment in sediments from Lake Taihu,China

Abstract

Twenty-one surface sediments collected from seven surroundings areas of Lake Taihu in two different years were analyzed for total mercury (THg) concentrations, physicochemical characteristics and speciation using a sequential extraction method to assess spatial distribution, sources, and potential ecological risk. Surface sediments from Lake Taihu contained elevated levels of Hg in two sampling years with THg levels ranging from 77 to 346?ng/g (mean 145?ng/g) in October 2010 and ranging from 122 to 573?ng/g (mean 266?ng/g) in November 2012, respectively. The mean THg concentrations in all studied surface sediments exhibited an increasing trend over time. The oxidizable fraction (F3) and residual fraction (F4) were the predominant Hg species in sediments, while more mobile Hg phases of acid-soluble fraction (F1) and reducible fraction (F2) made up less than 0.5% THg. Significant relationships were found between total organic carbon (TOC) and THg and geochemical speciation indicating an important role for organic matter in affecting distribution, mobility, and bioavailability of Hg in sediments. As evidenced by Hakanson’s potential risk index the total ecological risk of Hg was low in the entire Lake Taihu in 2010 but considered moderate in Zhushan Bay, West Coast, and Meiliang Bay in 2012. These findings provide conservation managers with information needed to more effectively regulate the environment of Lake Taihu.     

Occurrence and distribution of organochlorine residues in fish from the magdalena and meta rivers in Colombia

From sexually mature female fish of 32 different species muscle tissues and eggs were collected at four sites in the Magdalena and Meta rivers in Colombia. In most of the fishes, organochlorine residues were found both in the muscle tissues and in the eggs. On a fat basis, the level of SDDT and PCBs in the muscle tissues ranged from 55–10 700 and 5–5610 ng/g lipid weight, respectively. The concentration of these compounds in the fish eggs were generally lower than those in the tissues. The levels of the residues in the fish were highest in the middle and lower part of the Magdalena River, indicating a contamination of the whole fish community. The results show that this river, especially its lower part after merging with the River Bogotá, is heavily influenced by anthropogenic persistent compounds. The pollution of lakes, dams, rivers and coastal areas with sewage, pesticides and industrial wastes is one of the most pressing environmental problems in Colombia. Since there are no statistics or other material that permit a diagnosis of the problem and its magnitude, it is urgent to carry out such investigations to identify sources and take appropriate measures. The responsibility for the use and control of industrial and agricultural chemicals is today shared among many regional corporations. We suggest the establishment of an authority at high technical and govermental level that can initiate monitoring and coordinate actions to alleviate the present situation.     

上海市河网水体中As的分布特征及其生态风险评价

2012年4月,在上海市河网采集表层水和沉积物样品各53个,测定其As含量,并采用潜在生态风险指数法对沉积物As的污染状况进行了评价。研究结果表明,上海市河网表层水和沉积物中As的含量分别为0.47～8.84μg·L-1和3.72～12.65μg·g-1,其中表层水中As的浓度处于中国地表水环境质量标准Ⅰ类水平,沉积物中As的浓度有15个样点超过了上海市土壤背景值,但均低于欧盟标准推荐值;表层水中As的浓度与pH呈显著正相关,说明pH值影响河水中As的迁移和转化;沉积物中As的浓度与总有机碳含量呈显著性正相关,说明沉积物中的As主要与总有机碳结合在一起;潜在生态风险评价结果显示,上海市河网沉积物中的As属于低生态风险。     

气象水文因子对呼伦湖湿地区域植物气候生产潜力的影响

利用呼伦湖湿地50年的气象资料、水文资料和生态环境监测资料,采用迈阿密模型及回归统计分析方法,分析了气象水文因子对呼伦湖湿地区域植物气候生产潜力的影响,结果表明,①50年来该湿地植物气候生产潜力变化趋势总体为下降趋势,减少的气候倾向率为每10年157.7 kg·km-2,峰值时段为1970—1990年,两个谷值时段为1961—1969年、1991—2010年,最大值和最小值与降水量出现的最多值和最少值一一对应。②在15个气象水文因子中有年降水量、年蒸散量、生长季径流量、春季大风日数、水位、春季平均风速、年大风日数、水域面积8个因子达到显著性检验（P〈0.150～0.001）,上述8个因子的排序也是与湿地区域植物气候生产潜力相关程度由大到小的排序。综述表明,呼伦湖湿地区域呈暖干化趋势,并且干旱灾害比较严重,是限制气候生产潜力的重要原因。③气象水文因子协同作用对该湿地区域植物气候生产潜力的影响较大,复相关系数为-0.997,年蒸散量与年平均气温、年降水量、生长季径流量和水位因子对湿地区域植物气候生产潜力的贡献相反,随其减少或增加,湿地区域植物气候生产潜力变化率增加或减少149.7 kg·hm-2。可以看出,该湿地气象水文因子的匹配并不理想,暖干化趋势依然是制约该区光能利用率低下的重要原因。④该湿地区域植物现实的生产力远未达到气候生产潜力,约有近60%的潜力可以开发;光能利用率较小的主要原因：一是现有的生态保护、修复技术及管理水平还比较落后,二是该区域暖干化趋势显著;而提高气候资源利用率的有效途径是加大保护生态环境力度和积极实施人工增雨、节水灌溉工程。     

螯合剂对铜毒性的影响

研究了螯合剂EDTA和DTPA对海州香薷蓄铜能力和铜毒性的影响.结果显示,EDTA和DTPA能抑制植物的生长,使其生物量降低,叶绿素含量下降,同时降低了植物的根系活力.EDTA和DTPA都可引起植物SOD、POD活性上升,在与Cu²⁺共同作用下,EDTA对Cu²⁺毒性影响较小,表现在SOD、POD活性仍按Cu²⁺独立作用下的变化规律而变化,且数值上变化不大.而DTPA则降低了Cu²⁺作用下SOD、POD活性的变化.EDTA使海州香薷地上部分铜浓度增加,DTPA则明显降低了海州香薷的铜含量.