铜和镉对蝌蚪的联合毒性研究

研究了铜和镉对蝌蚪的急性毒性和联合毒性，结果表明，Cu^2 对蝌蚪的24h，48h、96h和LC50分别为0.201,0.138和0.118mg/L；Cd^2 对蝌蚪的24h，48h和96h的LC50分别为32.1、23.3和18.9mg/L,Cu^2 和Cd^2 共存对蝌蚪的24h,48h和96h联合毒性相加指数（AI）分别为1.03、1.12和1.20。     

Variations between rice cultivars in root secretion of organic acids and the relationship with plant cadmium uptake

To attempt to understand certain mechanisms causing the variations between rice cultivars with regard to Cd uptake and accumulation, pot soil experiments were conducted with two rice cultivars at different levels of Cd, i.e., 0 (the control), 10, 50 mg Cd kg⁻¹ soil. The two rice cultivars differ significantly with regard to Cd uptake and accumulation. Root secretions of low-molecular-weight organic acids (LMWOA) for each treatment were measured with ion chromatography. The results showed that LMWOA concentrations in the soil planted with Shan you 63 (a high soil Cd accumulator) were all higher than those in the soil planted with Wu yun jing 7 (low soil Cd accumulator) at different soil Cd levels, although the magnitudes of the differences varied for individual LMWOA and depend on soil Cd concentrations. For all six LMWOA, there were significant differences at P < 0.05 or < 0.01 levels for soils treated with 10 and 50 mg kg⁻¹ Cd. The magnitude of the differences was greater under soil Cd treatments, especially at relatively low levels (for example, 10 mg Cd kg⁻¹ soil), than in the control. Acetic acid and formic acid constituted more than 96% of the total concentration of the six LMWOA, while citric acid constituted only about 0.1%. The rice cultivar with higher concentrations of LMWOA in soil accumulated more Cd in the plants. The results indicate that LMWOA secretion by rice root, especially in Cd-contaminated soils, is likely to be one of the mechanisms determining the plant Cd uptake properties of rice cultivars.     

Effect of Cadmium on Microbial Activity and a Ryegrass Crop in Two Semiarid Soils

Soil pollution with Cd is an environmental problem common in the world, and it is necessary to establish what Cd concentrations in soil could be dangerous to its fertility from toxicity effects and the risk of transference of this element to plants and other organisms of the food chain. In this study, we assessed Cd toxicity on soil microorganisms and plants in two semiarid soils (uncultivated and cultivated). Soil ATP content, dehydrogenase activity, and plant growth were measured in the two soils spiked with concentrations ranging from 3 to 8000 mg Cd/kg soil and incubated for 3 h, 20 days, and 60 days. The Cd concentrations that produced 5%; 10%;, and 50%; inhibition of each of the two soil microbiological parameter studied (ecological dose, ED, values) were calculated using two different mathematical models. Also, the effect of Cd concentration on plant growth of ryegrass (Lolium perenne, L.) was studied in the two soils. The Cd ED values calculated for soil dehydrogenase activity and ATP content were higher in the agricultural soils than in the bare soil. For ATP inhibition, higher ED values were calculated than for dehydrogenase activity inhibition. The average yields of ryegrass were reduced from 5.03 to 3.56 g in abandoned soil and from 4.21 to 1.15 g in agricultural soil with increasing concentrations of Cd in the soil. Plant growth was totally inhibited in abandoned and agricultural soils at Cd concentrations above 2000 and 5000 mg/kg soil, respectively. There was a positive correlation between the concentration of Cd in the plants and the total or DTPA-extractable concentrations of Cd in the soil.     

生物材料治理镉污染研究进展

近年来,生物材料以其经济、有效和无二次污染等特点,在重金属废水处理和土壤修复方面显示出了众多的优势·可替代传统的镉污染处理方法.综述了目前国内外生物材料在处理镉污染方面的研究进展,并对今后应用生物材料治理镉污染提出了一些建议.     

Cadmium—Towards a rational use of a toxic element

Because of its toxicity, cadmium creates an environmental problem as well as a health hazard for exposed workers. Most cadmium emissions arise from the intentional use of the element. It is therefore mandatory to reduce cadmium consumption to the lowest possible level. Cadmium pigments, mainly used in plastic processing, can be replaced in all applications where the processing temperature does not exceed 300°C. Newly developed polyvinyl chloride stabilizers promise to be an excellent substitute for cadmium stabilizers in even the most demanding applications. Cadmium plating, still extensively used in the United States and the West Germany, has been virtually abandoned in Japan. Improved lead acid batteries are replacing vented nickel cadmium batteries because of their cost effectiveness. While in these applications cadmium use is declining, more and more cadmium is needed for the manufacturing of sealed nickel cadmium batteries. These relatively small electrochemical cells are used mainly by individual consumers. Here cadmium can only be replaced in some marginal applications. The high cadmium content of these batteries (up to 22%) makes them a good candidate for recycling of the heavy metal.     

镉对鲫鱼过氧化物酶活性的影响

对鲫鱼的内脏组织的过氧化物酶（ＰＯＤ）活性正常值作了测定，结果表明：心脏和肾脏的ＰＯＤ活性较高，鳃和肝胰脏次之，肠和肌肉较低，当水中镉离子浓度为１６ｍｇ／Ｌ、３２ｍｇ／Ｌ时，肾脏、鳃的ＰＯＤ活性显著增强，肝胰脏的ＰＯＤ活性在３２ｍｇ／Ｌ组显著增强，心脏的ＰＯＤ活性在３种能离子浓度下影响均不明显。体外试验表明，镉不能直接影响ＰＯＤ活性。水体中加入ＥＤＴＡ（乙二胺四乙酸）可解除或减轻Ｃｄ＾２＋对鱼的毒     

聚合硫酸铁絮凝剂中痕量镉测定的研究

研究了测定聚合硫酸铁絮凝剂中痕量镉的新方法。本法是利用离子选择性电极测定聚合硫酸铁絮凝剂中的镉。研究内容包括测定条件、干扰试验、干扰排除等。本法不需调整 p H值 ,设备简单 ,操作简便 ,测定快速。在测定条件下 ,本法的线性范围为 1 .0× 1 0 - 2 ～ 9.0× 1 0 - 7,回收率为 91 %～ 1 0 7% ,适宜的 p H值范围为 3- 6。本法用于了实际样品测定 ,结果满意。     

成都经济生态区大气降尘中镉赋存形态的研究

重金属的生物毒性不仅与其总量有关．更大程度上由其形态分布所决定，不同的形态产生不同的环境效应。为了解城市大气降尘中的镉污染，采用Tessier连续提取法对成都经济生态区内不同区域的24个大气降尘样中镉的赋存形态进行了研究。结果表明，大气降尘中的镉主要以残留态存在;各形态镉在总镉中所占的平均百分比含量的排列顺序依次为：残留态〉碳酸盐结合态〉交换态〉铁锰结合态〉有机结合态（78．907％、8．917％．6．420％、3．419％、2．365％）;交换态镉、碳酸盐结合态镉具有较高生物有效性，铁锰氧化物结合态．有机结合态、残留态这3种形态镉的生物有效性很低。分析得出：汽油和煤的燃烧，以及工厂排放镉能加大城市大气降尘的镉污染。     

Estimation of heavy metal emission fluxes on the territory of the NIS

As the result of our research, the specific procedures to use emission factor methodology were developed and applied for trace metal emission evaluation into the atmosphere over the territory of the former Soviet Union. The existing data on heavy metal emissions were revised as background information from official sources and expert estimations. Source categories and different initial information as well as the concept of spatial emission distribution were defined and observed. The calculated atmospheric emissions of lead, cadmium and mercury were produced among the main source categories of 12 NIS countries for 1990, 1995 and 1997, using modified emission coefficients.Total cadmium emissions into the atmosphere from determined source categories were estimated as 388.4 tonnes in 1990 for the whole domain with reduction by up to 207.0 tonnes per year for 1997. Mercury emissions were estimated as equal to 303.2 tonnes in 1990 and 159.8 tonnes in 1997. Lead emission amounted to 24903.0 tonnes in 1990, and 9652.5 tonnes in 1997.The results of the evaluation demonstrated the general trends of atmospheric heavy metal emissions with a greater decrease during the first half of the 1990s followed later by the rather stable level to be explained by recession in industrial activity and fuel consumption in NIS in that period. The significant spatial variations of atmospheric emissions over vast territories are described based on the results of their distribution according to 1×1 degree grid with remarkably higher values in the location of industrial cities.