Influence of the environmental behavior and ecological effect of cropland heavy metal contaminants by CO2 enrichment in atmosphere

Recently, the impacts of increasing atmospheric CO2 level on the terrestrial ecological system have been intensively studied. The higher the CO2 concentration, the higher the risk of destabilizing vulnerable carbon pool on ecological safety. Metabolism, biomass, activity, and diversity of microbial communities in soils can be significantly altered by the CO2 enrichment. For instance, it may accelerate carbonate weathering, vary the rhizospheric exudation, and enhance the amount of available C from the upper soil layer. However, how the CO2 enrichment would influence food safety such as species transformation and bioavailability of heavy metals in soils is remained unanswered. The bioavailability of heavy metals is strongly affected by bio-factors in addition to the physiochemical conditions of soils. Different physiological mechanisms and states control plant uptake of heavy metals. The enrichment of CO2 influences physiological functionalities of plants, and in turn, is expected to have impacts on the bioaccumulation of pollutants and the stress adjustment system of plants. Currently, in China soil is heavily polluted, in most cases, combined by organic pollutants and heavy metals. Studies of the environmental behavior and ecological effect of Cu in soil under elevated CO2 levels were conducted in China FACE （Free Air Carbon Dioxide Enrichment） from June to October 2005 using pot experiments. Results showed that the accumulation of Cu and Cd in leaves, stems, roots, and grains of rice growing in Cu contaminated soils was significantly lowered, indicating that the bioavailability of heavy metals in soils decreases with increasing CO2 concentration.     

Heavy metal and arsenic distributions in soils surrounding Palapye, Botswana： An evaluation of environmental impact of coal mining and combustion in a sub-arid region

Coal is an important natural resource in Botswana. The best coals so far found occur in the Morupule coalfield, west of Palapye, where nearly 8000 million tons have been identified （Carney et al., 1994）. In this study we investigate the environmental impact of the mining and consumption of the high-ash, medium-calorific value bituminous coal in the eastern part of Botswana, which may serve as a reference for other coal mines and coal-based power stations around the globe. More than two hundred surface soil samples and three profile soil samples were collected around Morupule Colliery, Morupule Power Station and Palapye.     

Contamination and bioavailability of heavy metals in sediments from the Yangtze River Delta Region

The Yangtze River Delta Region is one of the most important economic development areas in China. In the process of its industrialization and urbanization, a great deal of wastewater is poured into rivers, lakes and coasts. Researches on contamination and bioavailability of heavy metals can help us to assess the ecological risks in the aquatic environment of the Yangtze River Delta. The samples were collected from three environmental compartments including the Yangtze River, Taihu Lake, and the south coast of Jiangsu. The concentrations of heavy metals were determined by ICP-MS. Metal speciation was determined by the sequential extraction procedure modified based on Tessier＇s scheme. Among the seven elements of Cu, Pb, Zn, Cr, Cd, Co, Ni detected, the contents of Cr, Zn did not vary significantly, while Cd and Pb varied significantly. Compared to the background values （loess in the basement）, all metals detected except Co, Cr exceeded the background level. Cd had the greatest exceeding values, reaching 2 to 7 times. Ni and Pb were followed. The contents of Zn were comparatively high in lake sediments, especially in the lake bays. Ni was enriched in fiver sediments and Cu was highest in sediments from the Yangtze River estuary. Cd and Pb were concentrated in the coastal sediments. Comparatively, in space, Cr was associated with the carbonate fractions in the bay of lake. Cu-bound Fe-Mn oxides and Ni in residual form were highest in the open lake. In the river environment, Fe/Mn oxide-bound Pb, exchangeable Cd were the highest fractions. In the estuary environment, Pb and Zn bound carbonates, Cd-bound Fe-Mn oxides are the largest fractions. Cd in the exchangeable fraction, Cu-bound Fe-Mn oxides had the larger proportions in the coast. In general, the bioavailability of Cu and Cd were high in lake environment, the available Pb, Cd were remarked in river environment, and Pb and Zn were easily assimilated by creatures in estuary.     

Enrichment of Cd and Pb and associations with grain size in sediments in Nanjing alluvial island of Yangtze River

Intermittence belts of metal contaminated sediment have been formed along the urban riverside of the Yangtze River because of rapid urbanization and industrial development during the last three decades. Baguazhou Island, the third alluvial island in the lower reaches of the Yangtze River, was chosen to assess the contaminations level of Cd, Pb, Ni, Cr, Cu and Zn in suspended particulate matter （SPM）, recent sediments and sediment-derived soils. The relations between the metal concentrations and the grain size distributions in sediments were analyzed in order to explore the association of heavy metal settling with sediment deposition. The results showed that significantly high levels of Cd and Pb in SPM dominated enrichment factors （EFs） of recent sediments in the area of Baguazhou Island. High levels of Cd and Pb were found both in the riverine sediments and in the soils. However, the average levels of Cd and Pb in sediments were almost as twice as those in soil. About 43% of all sediment samples have EFCd≥1.5 and 14% with EFCd≥2. There are about 21% of the samples with EFPb≥1.5 and none of them has EFPb≥2. Meanwhile, soil samples with EFCd≥1.5 account for 39% of all 64 samples and no one with EFPb≥1.0. Most of the sediment samples contain more than 80% of fine grains lower than 60 μm in size, and few samples located in the site where flow eroding process dominates contain fine grains lower than 30%. Correlation analysis indicated that the concentrations of Cd and Pb in the sediments have significant relationships with grain size.     

Combining forms of heavy metal elements in Dianshan Lake sediments and their spatial and temporal variations

Dianshan Lake is one of the important water supply sources for Shanghai City. The contents of heavy metals in the sediments are obviously higher than those in the overlying water body. The contents of Pb in the sediments vary seasonally; with increasing depth, the contents of Cd, Pb, Cu, Cr and Fe show no variation generally, but Mn varies in the peak pattern. Cd, Pb, Cu, Cr and Fe in the sediments are present predominantly in sludge phase, but iron and manganese oxide form of Pb and organic matter-sulfide form of Cu are their respective preferential combining forms. Manganese is present largely in exchangeable form, iron-manganese oxide combined form and sludge form. The contents of the various forms of Cd, Pb, Cu, Cr and Fe tend to vary with changing season and depth. The contents of exchangeable forms of Fe and Mn vary with depth in the peak-like pattern.     

Calibration of Four Species of Tillandsia as Air Pollution Biomonitors

Many organisms have been used as bioindicators of atmospheric contamination, with moss and lichen species being the most common. However, studies using epiphytic vascular species of Tillandsia have shown a good correlation between the presence of pollutants and the bioindicator's response. Therefore, the aim of our investigation was to calibrate and compare the response of four Tillandsia species of Argentina to ascertain whether they could be used as atmospheric contamination biomonitors. For this, we analysed the correlation between the levels of heavy metals in total atmospheric deposition samples and: a) their rate of enrichment; b) the physiological response of the plant samples. Tillandsia samples collected from a non contaminated area in the province of Córdoba were transplanted to four areas in the capital city with different sources of pollution (industrial or traffic emissions). They were exposed for a period of 3 to 6 months after which the concentrations of Pb, Ni, Fe, Zn, Cu and S as well as the physiological parameters of foliar damage were determined. Simultaneously samples of total atmospheric deposition were also taken.The highest level of metal enrichment was found in T. capillaris followed by T. tricholepis, T. permutata and T. retorta. Also, the use of a foliar damage index proved to be effective and could be a useful tool to evaluate different levels of atmospheric quality in these species. The rate of heavy metal deposition was higher in the industrial area for all metals except for Zn whose values were higher in areas with high levels of traffic.     

江都市土壤重金属分布特征及污染评价

江都市土壤重金属含量分布及污染现状评价结果显示,江都市土壤环境质量总体良好,但局部地区土壤污染严重,其中通扬运河以北地区土壤环境质量优于通扬运河以南地区。土壤中镉、汞、锌含量空间分布不均匀,局部土壤含量超过国家土壤二级标准,由点源污染所致,其中镉、汞为江都市土壤主要致污染因子,导致局部土壤严重污染。建议对不同污染程度土壤土地采取不同利用方式,需进行合理调整规划。     

雷暴低空风切变中大雨对飞行的影响

分析了雷暴低空风切变中大雨滴冲击飞机的机身和机翼而引起的水平和垂直动量损失，估算了大雨累计在机身和机翼上的水膜厚度，并讨论了因遇到大雨雨滴冲撞而粗糙化的机体所产生的阻力。结果表明：雷暴低空风切变中大雨雨滴的冲击作用是明显的，被粗糙化的机体所产生的阻力能显著改变飞行轨迹，并能影响飞行安全；累计在机身和机翼上的水膜厚度造成的飞机质量的增加对飞行的影响可以忽略。     

2004年末黄淮暴雪的特点分析和数值模拟

利用多普勒天气雷达资料和中尺度数值模式模拟分析了2004年12月20日夜里起到22日黄淮出现的大范围暴雪天气过程。发现黄淮地区暴雪天气形成的原因和特点明显不同于梅雨锋暴雨。多普勒雷达探测资料可以很好地反映这场暴雪的特点:对流高度不高,平均高度3~4km左右,最高不超过8km。在强降雪时近地面925hPa附近伴有很强的超低空急流,东北偏东风,风速达12~14m·s-1。高低空垂直切变明显,有很强的斜压性。高分辨率的中尺度数值模式可以很好地模拟出这次过程的演变和特点。     

东风低空急流暴雨的中尺度分析

东风低空急流暴雨在湖北比较少见。使用卫星云图、武汉多普勒雷达资料和地面中尺度资料，针对2004年6月4～5日发生在湖北中东部地区的一次东风低空急流暴雨过程进行了中尺度分析，得到：（1）东风低空急流暴雨是在有利的大尺度背景场条件下，在特定的地域触发产生的；（2）东风低空急流在暴雨的形成和发展中起到重要的作用；（3）东风低空急流暴雨是由中尺度回波团和中尺度复合体造成的；（4）东风低空急流暴雨是在多种尺度天气系统相互作用的情况下发生发展的，而中小尺度系统是其产生的最直接的系统。