Multivariate discriminant analysis distinguishes metal- from non metal-related biomarker responses in the clam Chamaelea gallina

Molecular biomarkers are among the most sensitive and earliest responses to pollutants. However, lack of detailed knowledge on variability of responses and their possible seasonal variation limit their use. In addition, the seasonality of biological processes modulates the response of organisms to pollutant stressors. Using multivariate statistics, we have studied the influence of environmental and biological factors on the response of a battery of molecular biomarkers in the clam Chamaelea gallina collected along the South-Spanish littoral. Multivariate discriminant analysis clearly distinguished biomarker response between clean and polluted areas, using heavy metals as indicator of pollution. Such differences disappeared when the dataset was normalised for metal content, thus indicating that pollution was the main significant cause of the changes observed between clean and polluted sites. In conclusion, this work shows that, when applying a complete biomarker panel, multivariate statistical tools can be used to discern pollutant- from non pollutant-related responses.     

Stable isotopes and metal contamination in caged marine mussel Mytilus galloprovincialis

Metal concentrations and isotopic composition were measured in different tissues of the mussel Mytilus galloprovincialis in waters of the Balearic Islands (Western Mediterranean) in order to assess pollution levels. The isotopic composition was correlated with lead, cadmium, selenium and nickel obtained from the digestive gland and foot of the mussels. Significant negative correlations were found between cadmium, selenium and zinc and the mussel foot, mainly for ¹³C. Significant correlations were also found between lead and cadmium and the digestive gland. Pearson correlations indicated that the ¹³C isotopic signal in foot is a good proxy for the concentration of metals such as lead, cadmium, selenium and zinc. Similarly, ¹⁵N isotopic signatures in the digestive gland reflected the lead and cadmium concentration.     

Assessment of Trace Metal Contamination of Drinking Water in the Pearl Valley,Azad Jammu and Kashmir

The aim of this study was to assess trace metal contamination of drinking water in the Pearl Valley, Azad Jammu and Kashmir (Pakistan). The objectives were to determine physical properties and the dissolved concentration of five trace metals, i. e., lead, copper, nickel, zinc, and manganese, in drinking water samples collected from various sites of municipal water supply, natural water springs and wells in the valley. Concentrations of the metals in the water samples were determined by flame atomic absorption spectrometry. Results showed physical parameters, i. e., appearance, taste and odor within acceptable limits and pH was between 5.5 and 7.0. The observed concentrations of the metals varied between sources of water samples and between sampling sites. Maximum dissolved concentration observed was 4.7 mg/L for Pb and Mn, 4.6 mg/L for Zn, 2.9 mg/L for Ni and 2.8 mg/L for Cu. The observed concentrations of the metals were compared with the World Health Organization's guideline values for drinking water. Overall, the quality of water samples taken from the water springs at Mutyal Mara and Bonjosa was good; however, the water quality was unsuitable for drinking in Kiraki, Kharick, and Pothi Bala localities particularly. Finally, the authors discuss possible causes for increased concentrations of the trace metals in drinking water in the study area.     

The Potential of Eleocharis acicularis for Phytoremediation: Case Study at an Abandoned Mine Site

Phytoremediation, a plant‐based and cost‐effective technology for the cleanup of contaminated soil and water, is receiving increasing attention. In this study, the aquatic macrophyte Eleocharis acicularis was examined for its ability to take up multiple heavy metals and its potential application for phytoremediation at an abandoned mining area in Hokkaido, Japan. Elemental concentrations were measured in samples of E. acicularis, water, and soil collected from areas of mine tailing and drainage. The results reveal that Pb, Fe, Cr, Cu, Ni, and Mn accumulation in the plants increased over the course of the experiment, exceeding their initial concentrations by factors of 930, 430, 60, 25, 10, and 6, respectively. The highest concentrations of Fe, Pb, Zn, Mn, Cr, Cu, and Ni within the plants were 59500, 1120, 964, 388, 265, 235, and 47.4 mg/kg dry wt., respectively, for plants growing in mine drainage after 11 months of the experiment. These results indicate that E. acicularis is a hyperaccumulator of Pb. We also found high Si concentrations in E. acicularis (2.08%). It is likely that heavy metals exist in opal‐A within cells of the plant. The bioconcentration factors (BCF: ratio of metal concentration in the plant shoots to that in the soil) obtained for Cr, Cu, Zn, Ni, Mn, and Pb were 3.27, 1.65, 1.29, 1.26, 1.11, and 0.82, respectively. The existence of heavy metals as sulphides is thought to have restricted the metal‐uptake efficiency of E. acicularis at the mine site. The results of this study indicate that E. acicularis shows great potential in the phytoremediation of mine tailing and drainage rich in heavy metals.     

Lake and reservoir water quality affected by metals leaching from tropical soils, Bangladesh

 The release of metals during weathering has been studied in order to assess its geochemical controls and possible effects on environmental health in Bangladesh. A total of 27 soil samples and 7 surface water samples were collected from four locations covering three major regions in the country. Results show that weathering effects are a strong function of climatic conditions. Surface waters are typically enriched in Al, Mg, Ca, Na, K, As, Ba, Cr, Cu, Ni, Pb and Zn. The solubility of metal ions, organometallic complexes, co-precipitation or co-existence with the colloidal clay fraction are the main processes that lead to metal enrichment in lake and reservoir water. Aluminium concentrations exceed World Health Organization (WHO) drinking-water standards in all samples, and in two regions, arsenic concentrations also significantly exceed WHO standards. The elevated levels of As indicate that arsenic contamination of water supplies in Bangladesh is not confined to groundwater. Received: 4 June 1999 · Accepted: 17 August 1999     

海洋环流模式模拟自然 和核辐射14C的分布

放射性14C在海洋环流研究和人为CO2问题的研究中都有重要地位。本文用海洋环流模式模拟了海洋中自然14C的分布及海洋对核辐射产生的放射性14C的吸收, 以期对海洋吸收人为CO2的能力做一初步的研究。模拟的海洋环流结果与观测相比符合得较好,成功地模拟出了北大西洋深水（NADW）、南极底水 (AABW）等基本特征。对自然14C的模拟揭示出了海洋通风的基本特征。模拟出的沿GEOSECS 路径的南、北垂直截面与观测结果符合得较好。对核辐射14C的模拟表明:模式模拟的沿GEOSECS 路径的南、北垂直截面与观测结果符合得较好;模拟出的海洋表面核辐射浓度与观测值一致,但核辐射14C在海洋中的柱存量和平均穿透深度都比观测结果要小。文中分析了造成这种差异的可能原因。     

耗氧速率(OUR)测量方法的实验研究

目前多采用分批实验法和呼吸测量仪测量耗氧速率,而耗氧速率的测量对于研究活性污泥数学模型中的动力学参数及废水特性鉴定具有重要意义。本文根据OUR测量方法的基本原理设计了1种简易的OUR测量装置,为检验测量装置的有效性,设计了相关实验进行验证。在内源呼吸实验中,测定了所用活性污泥的内源呼吸速率是5.1mgO2/L·h,污泥的衰减系数是0.0137h-1,比文献值略高。基质降解实验对人工配水(葡萄糖和淀粉)的耗氧速率进行了测定,实验结果显示有3个显著不同的耗氧速率,分别为35mg/L·h,13mg/L·h,6mg/L·h,它们各代表葡萄糖降解、淀粉降解和内源呼吸的速率。内源呼吸速率高于前1个实验是由于基质降解过程中污泥量增加所致。并计算出异养菌产率系数Kd为0.63mgVSS/mgCOD,Kd略低于文献值。实验结果证明,该装置能很好的实现测量目的。     

What controls levels of dissolved phosphate and ammonium in surface waters?

Dissolved inorganic nutrient pools are small relative to particulate pools, and dissolved pools turnover rapidly. It has been observed that pools change little from day to day on the sampling scales usually employed. A simple model is presented where uptake and regeneration rates balance to cause a local steady state concentration for dissolved inorganic nutrients. Enrichment and dilution perturbation experiments with lake water support the idea of steady state nutrient concentrations. Although inorganic nutrient concentrations are often controlled by biota, the absolute concentrations present tell little about the activity of that biota.