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211.
大坝拦截对河流水溶解组分化学组成的影响分析——以夏季乌江渡水库为例 总被引:6,自引:0,他引:6
以乌江渡水库为主要研究对象,揭示了大坝拦截条件下的夏季水化学特征:阴离子以HCO-3,SO2-4为主,阳离子以Ca2+,Mg2+为主,其余离子含量低于10%,说明了碳酸盐岩的风化对水体化学组成起到了主要控制作用,蒸发盐岩石的风化对水体化学组成影响较小。水库水体存在温度分层现象,形成了不同层位的水体有着不同的水化学组成,即水化学分层。水化学的分层形成了溶解组分在水库垂直深度上的规律分布,比如受藻类的影响,Si和叶绿素随深度成相反的变化特征;HCO-3受光合作用和有机质降解的影响,30 m 以上随着水深的增加而递增,30 m 以下呈现相反趋势;水库泄水方式明显改变了水化学各种参数和离子在水体中的分配。乌江水库两主要支流(息烽河和偏岩河)分别对乌江渡坝前水体中的Ca2+,SO2-4,HCO-3,Mg2+和K+,Na+,Cl-有贡献。网箱养鱼、生活污水、农业施肥、酸性矿山废水以及酸雨沉降都会对水体造成不同程度的污染。 相似文献
212.
Liming Zhang Dongsheng Yu Xuezheng Shi David C. Weindorf Limin Zhao Weixin Ding Hongjie Wang Jianjun Pan Changsheng Li 《Atmospheric environment (Oxford, England : 1994)》2009,43(17):2737-2746
Quantifying greenhouse gas (GHG) emissions from wetland ecosystems is a relatively new issue in global climate change studies. China has approximately 22% of the world's rice paddies and 38% of the world's rice production, which are crucial to accurately estimate the global warming potential (GWP) at regional scale. This paper reports an application of a biogeochemical model (DeNitrification and DeComposition or DNDC) for quantifying GWP from rice fields in the Tai-Lake region of China. For this application, DNDC is linked to a 1:50,000 soil database, which was derived from 1107 paddy soil profiles compiled during the Second National Soil Survey of China in the 1980–1990s. The simulated results show that the 2.34 Mha of paddy soil cultivated in rice–wheat rotation in the Tai-Lake region emitted about ?1.48 Tg C, 0.84 Tg N and 5.67 Tg C as CO2, N2O, and CH4 respectively, with a cumulative GWP of 565 Tg CO2 equivalent from 1982 to 2000. As for soil subgroups, the highest GWP (26,900 kg CO2 equivalent ha?1 yr?1) was linked to gleyed paddy soils accounting for about 4.4% of the total area of paddy soils. The lowest GWP (5370 kg CO2 equivalent ha?1 yr?1) was associated with submergenic paddy soils accounting for about 0.32% of the total area of paddy soils. The most common soil in the area was hydromorphic paddy soils, which accounted for about 53% of the total area of paddy soils with a GWP of 12,300 kg CO2 equivalent ha?1 yr?1. On a regional basis, the annual averaged GWP in the polder, Tai-Lake plain, and alluvial plain soil regions was distinctly higher than that in the low mountainous and Hilly soil regions. As for administrative areas, the average annual GWP of counties in Shanghai city was high. Conversely, the average annual GWP of counties in Jiangsu province was low. The high variability in soil properties throughout the Tai-Lake region is important and affects the net greenhouse gas emissions. Therefore, the use of detailed soil data sets with high-resolution digital soil maps is essential to improve the accuracy of GWP estimates with process-based models at regional and national scales. 相似文献
213.
Dongmei Han Xing Liang Menggui Jin Matthew J. Currell Ying Han Xianfang Song 《Environmental management》2009,44(2):243-255
Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow
systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater δ2H and δ18O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry,
including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water–rock interaction (e.g.,
silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and
locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in
shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. 87Sr/86Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu
River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC,
reveal water–rock interaction processes along different flow paths. This modeling method is more effective for characterizing
flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan
enhances mixing between different groundwater flow systems. 相似文献
214.
Wei Liu YiHe Jin Xie Quan Kazuaki Sasaki Norimitsu Saito Shoji F. Nakayama Itaru Sato Shuji Tsuda 《Environment international》2009,35(4):737-742
Samples of precipitation events (snow and rain) in Dalian, a typical coastal town in China, were analyzed for perfluorosulfonates (PFSAs) and perfluorocarboxylates (PFCAs) to investigate atmospheric contamination by these compounds. In the snow event on December 16, 2006, samples were collected from 21 different sites and in another 6 precipitation events, samples were collected from a single location. Four PFSAs (C4, C6, C8, C10) and seven PFCAs (C6–12) were analyzed. Among the homologues, perfluorooctane sulfonate (PFOS) concentrations were the highest with a geometric mean (GM) of 145 ng/L (n = 21) during the snow event on December 16, 2006, followed by perfluorooctanoate (PFOA) with a GM of 24.7 ng/L (n = 21). Concentrations of perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS) and perfluoroheptanoate (PFHpA) were more than two orders of magnitude lower than that of PFOS. Other PFSAs and PFCAs were found to be below the limit of detection in all the samples. In other 6 precipitation events, PFSAs and PFCAs were detected approximately in the same order of magnitude in both snow and rain. The results indicate that wet deposition may be a potential transport mechanism of perfluorinated chemicals in the environment. 相似文献
215.
CaO/SiO2对流化床焚烧飞灰熔融过程中重金属挥发的影响 总被引:1,自引:1,他引:0
对掺煤混烧的流化床焚烧飞灰熔融过程中重金属在气相(吸收率)中和固相(固定率)中的分布进行了研究,并采用HNO3-NaOH2级吸收方式对气相重金属进行了吸收.结果表明,CaO/SiO2(摩尔比)对重金属的迁移行为有重要影响,CaO/SiO2降低,Cd、Pb固定率总体呈上升趋势;2级吸收对气相重金属的吸收有限,大部分重金属主要溶解在HNO3吸收液中,但NaOH吸收液对Cr的吸收效果好于HNO3吸收液;氯对重金属的挥发有重要影响,当重金属以氯化物形式存在时,其挥发受到SiO2的限制.随着SiO2含量增加,挥发率降低. 相似文献
216.
新型TCAS吸附树脂对水中Cd2+的吸附去除研究 总被引:4,自引:3,他引:1
通过静态吸附试验,研究一种由超分子受体化合物磺化硫杂杯芳烃(TCAS)与树脂结合的产物——新型TCAS吸附树脂对重金属Cd2+的吸附去除性能,并初步探讨了吸附机理。试验研究结果表明,TCAS吸附树脂对Cd2+的饱和吸附量为14.45 mg/g。当温度为20℃,0.5 g TCAS吸附树脂对10 mL浓度为5 mg/L的Cd2+溶液吸附60 min时, Cd2+的去除率可达到99%以上。pH值是影响TCAS吸附树脂吸附效果的重要因素,在pH=5~9时,Cd2+的去除率随着pH值的升高而增大。在试验范围内,TCAS吸附树脂对Cd2+吸附符合Freundlich方程。吸附在TCAS吸附树脂上的Cd2+可洗脱回收,TCAS吸附树脂也可再生利用。 TCAS吸附树脂对重金属Cd2+的吸附机理主要归因于TCAS对Cd2+的络合作用。 相似文献
217.
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220.
稀土在废水处理中的应用进展 总被引:3,自引:1,他引:2
综述了国内稀土金属在废水处理中的最新应用进展,总结了稀土复合吸附剂的制备方法及其在含磷、氨氮、砷、氟、铬、镉等废水处理中的效果,讨论了稀土复合混凝剂和稀土催化剂在染料、助剂、化工等高浓度有机废水处理中的应用,为找到高效环保的处理工业废水的方法提供了依据. 相似文献