Polycyclic aromatic hydrocarbons and organochlorine pesticides in surface soils from the Qinghai-Tibetan plateau

Eighty eight surface soil samples were collected from the Qinghai-Tibetan Plateau (QTP) for determination of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs), including dichlorodiphenyltrichloroethane and metabolites (DDXs) and hexachlorocyclohexane isomers (HCHs). The measured concentrations were 51.8 ± 38.5 ng g(-1), 0.329 ± 0.818 ng g(-1), and 0.467 ± 0.741 ng g(-1) as means and standard deviations of PAHs, DDXs, and HCHs, respectively, which were 1-2 orders of magnitude lower than those reported for eastern China. Significant differences were also revealed among four sub-areas within QTP. PAHs detected in the samples from the remote sub-areas of T'ang-ku-la/Hoh Xil Mountains and along the Qinghai-Tibet highway in the west and northwest of QTP were 1 order of magnitude lower than those from Lhasa and east Qinghai. The differences in soil OCPs among the sub-areas were 2-7 times. Soil PAHs were significantly correlated with emission density and soil organic carbon content (SOC), while OCPs were correlated significantly with the population density and SOC. Based on the calculated backward air mass trajectories and geographical distributions of emission and population, it was revealed that PAHs and OCPs accumulated in the soils in the west and northwest QTP were primarily from long-range transport and may represent the background levels of East Asia. This part of QTP can also serve as an important receptor area for regional or even global long-range transport study. The elevated concentrations of PAHs and OCPs in Lhasa and east Qinghai were mainly from local sources, while PAHs from adjacent Lanzhou area also contributed considerably to the accumulation of PAHs in east Qinghai.     

2003年夏秋季大气环流异常对西北地区降水的影响

根据2003年6～10月西北地区118站逐日降水资料,对该地区、该时段的大气环流及其对该地区降水的影响进行了分析研究.     

Lead,zinc and copper accumulation and tolerance in populations of Paspalum distichum and Cynodon dactylon

Both Fankou and Lechang lead/zinc (Pb/Zn) mine tailings located at Guangdong Province contained high levels of total and DTPA-extractable Pb, Zn and Cu. Paspalum distichum and Cynodon dactylon were dominant species colonized naturally on the tailings. Lead, zinc and copper accumulation and tolerance of different populations of the two grasses growing on the tailings were investigated. Tillers of these populations including those from an uncontaminated area were subjected to the following concentrations: 5, 10, 20, 30 and 40 mg l(-1) Pb, 2.5, 5, 10, 20 and 30 mg (l-1) Zn, or 0.25, 0.50, 1 and 2 mg l(-1) Cu for 14 days, respectively, then tolerance index (TI) and EC50 (the concentrations of metals in solutions which reduce 50% of normal root growth) were calculated. The results indicated that both Lechang and Fankou populations of the two grasses showed a greater tolerance to the three metals than those growing on the uncontaminated area, which suggested that co-tolerant ecotypes have evolved in the two grasses. P. distichum collected from Fankou tailings had the highest tolerance to Cu while Lechang population the highest tolerance to Pb and Zn among the tested populations, and tolerance levels in P. distichum were related to metal concentrations in the plants. P. distichum had a better growth performance than C. dactylon when both of them were grown on the tailings sites. Tolerant populations of these species would serve as potential candidates for re-vegetation of wastelands contaminated with Pb, Zn and Cu.     

Cadmium contamination in orchard soils and fruit trees and its potential health risk in Guangzhou, China

This study examines cadmium (Cd) contamination in orchard soils and fruit trees in Guangzhou, China, and assesses its potential health risk. Soils and tissues samples of three species of fruit trees were collected from three orchards. The average soil Cd concentration was 1.27, 1.84 and 0.68 mg/kg in orchards I, II, and III, respectively. The carambola (Averrhoa carambola) accumulated exceptionally high concentrations of Cd (7.57, 10.84, 9.01 and 2.15 mg/kg dw in root, twig, leaf and fruit, respectively), being 6.0-24 times and 4.0-10 times the corresponding tissue Cd in the longan (Dimocarpus longan) and wampee (Clausena lansium), respectively. Furthermore, all Cd concentrations (0.04-0.25 mg Cd/kg fw) of the fruits exceeded the tolerance limit of cadmium in foods of PR China (0.03 mg/kg fw). Our results indicate that the carambola tree has high Cd accumulation capacity and might be a Cd accumulator; and its fruit, among the three species of fruits studied, also poses the highest potential health risk to local residents.     

Sorption of tylosin on clay minerals

The equilibrium sorption of tylosin (TYL) on kaolinite and montmorillonite was measured at different solution pH using batch reactor systems. The results showed that all the sorption isotherms were nonlinear and that the nonlinearity decreased as the solution pH increased for a given clay. At a specific aqueous concentration, the single-point sorption distribution coefficient (K_D) of TYL decreased rapidly as the solution pH increased. A speciation-dependent sorption model that accounted for the contributions of the cationic and neutral forms of TYL fit the data well, suggesting that the sorption may be dominated by both ion exchange and hydrophobic interactions. The isotherm data also fit well to a dual mode model that quantifies the contributions of a site-limiting Langmuir component (ion exchange) and a non-specific linear partitioning component (hydrophobic interactions). X-ray diffraction analyses revealed that the interlayers of montmorillonite were expanded due to the uptake of TYL. TYL molecules likely form a monolayer surface coverage.     

1960年代以来西北地区暴雨气候变化特征

为了揭示西北地区暴雨的时空演变特征,利用该地区109个站44年（1961—2004年）的日降水资料,采用小波分析等方法研究了该地区暴雨的气候变化。研究指出,西北地区平均每年有40站次的暴雨;暴雨频次最少的地方在中西部,最多的地方在东部;4—11月都可能出现暴雨,其中6—9月占93．1％。暴雨开始和结束的时间年际差异较大,最早可发生在4月初,最迟到7月中旬发生;最早8月初结束,最迟11月中旬结束。区域性暴雨平均每年发生4．7场次,主要发生在6—9月;第一场区域性暴雨平均日期为7月2日,最早出现在4月初,最迟在9月下旬;最后一场区域性暴雨平均日期为8月31日,最早结束于6月中旬,最迟结束于10月中旬。     

基于DEA模型的区域生态环境建设绩效评价——以江苏省苏州市为例

选取生态系统服务价值、生态绿当量、人均生态足迹赤字和环境质量综合指数作为区域生态环境质量表征指标,借助DEA模型对区域生态环境建设过程中劳动力投入、资金投入、技术投入和资源投入的绩效进行评价,结果表明:(1)苏州市10年来生态环境建设总体而言绩效良好,DEA有效年份占30%,弱有效年份占20%,无效年份占50%,并且无效年份的效率指数都在0.97以上;(2)导致苏州市最近5年生态环境建设DEA无效的原因主要是乔资源投入不足,生态用地成为区域生态环境建设刚性约束;(3)通过调整生态环境建设要素投入比例,各种生态环境指标值都将有所提高,区域生态环境质量也将显著改善;(4)地区生态环境建设绩效下降还受地区人口数量增加、人均生态占用增长、生态环境累积效应影响.最后从促进区域社会经济与生态环境协调发展的角度提出相关建议.     

滇池流域水资源综合平衡管理研究

随着滇池治理的进展,在今后一个时期内,恢复滇池饮用水环境功能,成为滇池治理的首要目标和任务。围绕滇池流域水资源供求平衡,采用水资源全要素配置框架下的三次平衡分析理论,从整体上分析了滇池流域水资源供求平衡关系及存在的主要问题,提出了以需求为导向,建立滇池流域水资源综合平衡管理目标和措施。分析表明：在滇池治理的基础上,通过建立滇池流域水资源综合平衡管理体系,落实管理措施,从总量平衡的理论上能够充分发挥引水工程的作用,恢复滇池饮用水环境功能,实现水量、水质供求的综合平衡。建议进一步开展量化分析和模拟实验研究,为在滇池流域实施综合平衡管理提供可靠依据和建议     

鄱阳湖湿地植物生态系统结构及湖水位对其影响研究

通过对鄱阳湖水文过程和湖盆地形特点的分析,利用3S技术对鄱阳湖湿地进行了分类,研究了各种类型湿地植物生态系统的生境、主要植物群落结构和分布规律。结果表明,鄱阳湖湿地植物生态系统结构复杂,生物多样性极其丰富。湿地植物是以根茎为主要繁殖器官的克隆繁殖植物,以集群分布为主要特点。在宏观尺度上受地形高程、湖水位和洲滩出露时间制约,不同植物群落沿水分梯度分布;在景观尺度上受到土壤含水量、地下水埋深和土壤结构影响,形成水平镶嵌结构;微观尺度上还与微地形和土壤养分密切相关,部分区域表现为复合体结构。湿地植被对水分梯度的敏感性,导致湿地植物生态系统的易变性和脆弱性。近年来,鄱阳湖水位过低且持续时间长,使生态系统遭受一定损害。     

基于GIS和USLE的小流域土壤侵蚀定量评价

通过气象数据分析、实地调查、野外采样及室内分析、DEM计算、遥感解译等,建立了南水北调中线水源地丹江口水库区典型小流域地理数据库,确定了计算USLE因子指标的方法。在ArcGIS支持下,模拟了小流域土壤侵蚀强度的空间分布。将模拟结果分为微度、低度、中度、强度、剧烈侵蚀5级,建立土壤侵蚀与土地利用/土地覆盖类型及坡度之间的关系。结果表明：研究区年均土壤侵蚀量2414 t/hm2,远超该地区容许土壤流失量5 t/（hm2·a）。96%的侵蚀区及95%的土壤侵蚀总量位于<25°区域。就土地利用/土地覆盖类型而言,陡坡耕作区是主要的土壤流失区。研究结果为水源区的土壤侵蚀治理提供参考意见,同时为USLE在无土壤类型图地区的应用提供一种方法借鉴