TRANSPORT OF SEDIMENT-BOUND ORGANOCHLORINE PESTICIDES TO THE SAN JOAQUIN RWER,CALIFORNIA1

ABSTRACT: Suspended sediment samples were collected in west-side tributaries and the main stem of the San Joaquin River, California, in June 1994 during the irrigation season and in January 1995 during a winter storm. These samples were analyzed for 15 organochiorine pesticides to determine their occurrence and their concentrations on suspended sediment and to compare transport during the irrigation season (April to September) to transport during winter storm runoff (October to March). Ten organochiorine pesticides were detected during the winter storm runoff; seven during the irrigation season. The most frequently detected organochlorine pesticides during both sampling periods were p,p'-DDE, p,p'-DDT, p,p'-DDD, dieldrin, toxaphene, and chiordane. Dissolved samples were analyzed for three organochiorine pesticides during the irrigation season and for 15 during the winter storm. Most calculated total concentrations of p,p-DDT, chlordane, dieldrin, and toxaphene exceeded chronic criteria for the protection of freshwater aquatic life. At eight sites in common between sampling periods, suspended sediment concentrations and streamfiow were greater during the winter storm runoff - median concentration of 3,590 mg/L versus 489 mg(L and median streamfiow of 162 ft³/s versus 11 ft³/s. Median concentrations of total DDT (sum of p,p'-DDD, p,p-DDE, and p,p'-DDT), chlordane, dieldrin, and toxaphene on suspended sediment were slightly greater during the irrigation season, but instantaneous loads of organochlorine pesticides at the time of sampling were substantially greater during the winter storm. Estimated loads for the entire irrigation season exceeded estimated loads for the January 1995 storm by about 2 to 4 times for suspended transport and about 3 to 11 times for total transport. However, because the mean annual winter runoff is about 2 to 4 times greater than the runoff during the January 1995 storm, mean winter transport may be similar to irrigation season transport. This conclusion is tentative primarily because of insufficient information on long-term seasonal variations in suspended sediment and organochlorine concentrations. Nevertheless, runoff from infrequent winter storms will continue to deliver a significant load of sediment-bound organochiorine pesticides to the San Joaquin River even if irrigation-induced sediment transport is reduced. As a result, concentrations of organochlorine pesticides in San Joaquin River biota will continue to be relatively high compared to other regions of the United States.     

磷酸铁膜对黄铁矿氧化动力学行为的影响

用动态法研究了不同温度ＰＨ值和Ｈ２Ｏ２浓度下,对照和经ＫＨ２ＰＯ４处理的黄铁矿氧化反应的动力学。结果表明,用０．１ｍｏｌ．ｌ＾－１Ｈ２Ｏ２＋０．０１ｍｏｌ．ｌ＾－１ＫＨ２ＰＯ４混合液淋洗黄铁矿后,黄铁矿表面可形成磷酸铁膜。     

华北平原1981～2001年作物蒸散量的时空分异特征

利用土壤-植被-大气传输机理模型(VIP模型),以GIS背景数据库(土地利用图、土壤质地图和数字高程图)为支撑,在NOAA-AVHRRNDVI数据和气象信息的驱动下,连续模拟了1981～2001年华北平原冬小麦和夏玉米生育期的蒸散过程。结果表明:模拟的作物蒸散量与Lysimeter观测值和其他学者的田间试验研究结果具有较好的一致性。华北平原冬小麦多年平均蒸散量空间上呈现南高北低的趋势,其中黄河以北地区和山东半岛的蒸散量在200～400mm之间,南部地区在400～466mm之间。对玉米而言,北部的海河低地平原以及津、冀、鲁的沿海地区多年平均蒸散量变化在230～380mm,其余大部分地区蒸散量在380～470mm。除本区最南端的极少部分地区外,华北平原大部分地区冬小麦生育期内的自然降水都小于蒸散量,水分亏缺量大于200mm,而夏玉米生育期内大部分地区的降水大于蒸散量。     

Modelling the closure-related geochemical evolution of groundwater at a former uranium mine

A newly developed reactive transport model was used to evaluate the potential effects of mine closure on the geochemical evolution in the aquifer downgradient from a mine site. The simulations were conducted for the K?nigstein uranium mine located in Saxony, Germany. During decades of operation, uranium at the former mine site had been extracted by in situ acid leaching of the ore underground, while the mine was maintained in a dewatered condition. One option for decommissioning is to allow the groundwater level to rise to its natural level, flooding the mine workings. As a result, pore water containing high concentrations of dissolved metals, radionuclides, and sulfate may be released. Additional contamination may arise due to the dissolution of minerals contained in the aquifer downgradient of the mine. On the other hand, dissolved metals may be attenuated by reactions within the aquifer. The geochemical processes and interactions involved are highly non-linear and their impact on the quality of the groundwater and surface water downstream of the mine is not always intuitive. The multicomponent reactive transport model MIN3P, which can describe mineral dissolution-precipitation reactions, aqueous complexation, and oxidation-reduction reactions, is shown to be a powerful tool for investigating these processes. The predictive capabilities of the model are, however, limited by the availability of key geochemical parameters such as the presence and quantities of primary and secondary mineral phases. Under these conditions, the model can provide valuable insight by means of sensitivity analyses.     

地震堰塞湖人工排泄断面优化初探

汶川8.0级特大地震诱发了以唐家山堰塞湖为典型的大量堰塞湖,对上下游人民生命财产安全造成了严重的威胁和危害。对震后堰塞湖的处置成为今后次生山地灾害减灾的一大关键性课题。在回顾和总结唐家山堰塞湖的应急排险经验的基础上,对泄流槽纵、横断面的优化进行了初步的探讨。同时在开挖过程中,也应考虑堰塞体组成物质、抗冲稳定性、施工设备等因素选择泄流槽体型。震后5～10年是泥石流、滑坡灾害的活跃期,发生大规模泥石流、滑坡堵江事件的可能性也随之增加,期望研究能够为堰塞湖的排险处理提供一定的技术参考。     

酸、碱废水的中和絮凝作用

通过模拟实验研究了酸、碱矿水的中和絮凝作用,并对酸、碱矿水中和絮凝过程中的最佳混合比、重金属污染物的去除,尾矿砂颗粒的作用,以及凝聚颗粒的沉降规律等进行较详细的论述。研究结果表明,利用碱性矿水中和酸矿水及去除金属污染物,对于恢复矿区污染河流的水质具有重要的实际意义     

基于多叉树的遍历算法在数字水系拓扑关系计算中的应用

数字水系中各网格或子流域之间的拓扑关系是正确反映洪水演算顺序的重要环节。针对目前流域拓扑关系计算中存在的问题,提出了一种基于多叉树的流域拓扑关系计算方法,该算法将流域中的网格或子流域概化成树形结构的结点图,运用后序遍历递归算法,可快速自动建立反映洪水演算顺序的拓扑结构,解决了复杂流域洪水的演算集成问题,为分布式水文模型的开发研制奠定了坚实的基础,具有较强的实用价值。     

Evaluation of the Impact of Acid Mine Drainage on the Chemistry and the Macrobenthos in the Carolina Stream (San Luis – Argentina)

The purpose of this study was to evaluate the impact of acid mine drainage on the chemistry and the macrobenthos of the Carolina stream (San Luis – Argentina). Samples were obtained in the years 1997–1998 at two sites: site C₁, located 200 m upstream of the drainage, and site C₂, located 800 m downstream. The system buffer capacity was evaluated in the non – contaminated site by means of the buffer index calculation. The physico – chemical changes observed as a consequence of the contribution of acid mine drainage (AMD) were: a decreasing of pH and an increase in the ionic concentration, especially sulfate and Fe coming from the oxidation produced by chemiolithotrophic bacteria. The values obtained indicated a low buffer capacity and a high intrinsic vulnerability of the system to resist the impact originated by the AMD, producing a remarkable decreasing of pH of the receiving stream. These changes caused modifications in the original benthic community that was replaced by organisms more tolerant to the acid stress. A reduction in the abundance and in the taxonomic richness of the benthic macroinvertebrates was observed when compared with the reference station. An increase in the proportion of Chironomidae and of Acari and a decrease in the proportion of the remaining taxa were observed. The most sensitive groups were Ephemeroptera, Trichoptera and Mollusca. The community was mostly affected by the following variables: pH, conductivity, sulfate and dissolved total Fe.     

沸石芦苇床除氮中试研究

对沸石芦苇床去除农田回归水和农村生活污水组成的混合污水中的氮进行了中试研究.结果表明,在0.6m/d的水力负荷下,系统对总氮、氨氮、硝酸盐氮、亚硝酸盐氮的平均去除率冬季和春季分别为38.9%和58.2%,93.11%和78.84%,10.01%和48.99%,38.81%和98.45%.春季运行效果明显好于冬季.在相同条件下,总氮、氨氮、硝酸盐氮去除率比砾石芦苇床分别高28%、67%、35%.沸石对氨氮的吸附、离子交换,微生物的哪硝化、反硝化作用是沸石芦苇床系统去除氮的主要途径.     

甘肃省1960—2008年潜在蒸散量时空变化及其影响因子

基于甘肃省27个气象站点1960—2008年逐日气温、 降水、 风速、 日照时数、 太阳总辐射和相对湿度数据,应用Penman-Monteith模型和Kriging插值法,分析其潜在蒸散量的时空变化及其影响因子。结果表明:近49 a来,甘肃省不同气候区年均潜在蒸散量变化除河西走廊外均呈上升趋势,并以甘南高寒湿润区上升最显著,变化率为10.36 mm/10 a(α=0.001);在四季变化中,夏季最大,春秋次之,冬季最小,各气候区变化趋势有别。潜在蒸散量空间差异显著,表现为自西北向东南递减,且甘南高原最小,河西暖温带最大。河西、 陇南、 陇中、 甘南及祁连山区年均潜在蒸散量分别与平均风速、 太阳总辐射和最高气温正相关最显著,典型站点与之一致,且辐射项主要受太阳辐射影响,动力项主要受风速影响。