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941.
为研究石家庄市冬季道路积尘PM2.5中金属元素污染特征及来源,利用移动式采样法收集石家庄市不同类型铺装道路积尘,使用ICP-MS和ICP-OES分析测定PM2.5中Cr、Zn、Mn、Cu、Pb、Ni、Sn、As、Sb、Co、Mo、Cd、Al、Mg、Ca、Fe共16种元素的质量分数.结果表明:石家庄市冬季道路积尘PM2.5中金属元素质量分数之和依次为支路>快速路>主干道>次干道,与车流量、车辆类型、道路类型等影响因素有关,w(Mg)、w(Ca)、w(Cr)、w(Cu)、w(Ni)、w(Zn)、w(Pb)、w(Sn)、w(Sb)、w(Mo)、w(Cd)的平均值均高于当地土壤背景值,是背景值的1.2~40.5倍,其中Cr、Zn、Cu、Pb、Sn、Sb、Mo、Cd等元素中,除Pb的富集因子(9.38)接近10外,其他均高于10,来源于人为污染.Igeo(地累积指数)评价结果显示,Cr、Sn(Igeo为4~5)达到强-极强污染水平;Cd、Cu(Igeo为3~4)达到强污染水平;Sb、Mo、Zn(Igeo为2~3)为中-强污染水平,Pb(Igeo为1~2)为中污染水平.多元统计分析结果表明,石家庄市冬季道路积尘中金属元素来源可分为四大类:As、Mo、Zn、Cd、Ni、Pb主要来自机动车和大气中的燃煤沉降;Mn、Co、Sb来自于自然来源、机动车尾气的排放和焊接材料及轴承的磨损;Cr、Cu、Sn主要来自于工业排放的沉降和机动车刹车片磨损;Al、Ca、Mg、Fe主要来自绿化带或机动车携带的土壤尘.研究显示,石家庄市冬季道路积尘PM2.5中金属元素污染严重,主要来源于交通排放. 相似文献
942.
943.
Yuping Wu Walter W. Piegorsch R. Webster West Dengfang Tang Maureen O. Petkewich Wei Pan 《Environmental and Ecological Statistics》2006,13(1):125-141
We develop and study multiplicity adjustments for low-dose inferences in environmental risk assessment. Application is intended
for risk analysis studies where human, animal, or ecological data are used to set safe levels of a hazardous environmental
agent. A modern method for making inferences in this setting is known as benchmark analysis, where attention centers on the
dose at which a fixed benchmark level of risk is achieved. Both upper confidence limits on the risk and lower confidence limits
on the “benchmark dose” are of interest. In practice, a number of possible benchmark risks may be under study; if so, corrections
must be applied to adjust the limits for multiplicity. In this note, we discuss approaches for doing so with continuous, nonquantal
response data. 相似文献
944.
采用三峡水库坝下宜昌水文站1956—2017年日径流监测数据和长江上游80个国家气象站年均降水量长系列资料,利用一元线性分析法、滑动平均法、线性趋势回归法、非参数统计检验法、Mann-Kendall秩次相关、累积距平法和滑动T检验法分析三峡工程运行前后坝下径流的变化特征,其成果可为三峡工程调度提供参考。结果表明:三峡水库坝下宜昌水文站径流量变化趋势具有显著阶段性。三峡水库蓄水运行前宜昌水文站径流量和上游降水量相关性超过90%,该时期径流量主要受上游天然来水影响。三峡水库运行后,径流量主要受人类活动影响。宜昌水文站径流年际变化减少趋势不显著,长江上游降水量呈显著减少趋势。坝下径流量和上游降水量在2002年发生了突变且变化趋势相同,但径流量减少趋势不显著。径流年内分布发生了一定变化,其中汛期径流量占年径流总量百分比从72%下降到66%,枯期径流量占年径流量总量百分比从11%增加到15%。三峡工程调蓄是人类活动的直接表现,枯期宜昌水文站径流量增大是三峡工程生态效益的具体体现。 相似文献
945.
The solid-solution partitioning of heavy metals (Cu,Zn, Cd,Pb) in upland soils of England and Wales 总被引:12,自引:0,他引:12
Tipping E Rieuwerts J Pan G Ashmore MR Lofts S Hill MT Farago ME Thornton I 《Environmental pollution (Barking, Essex : 1987)》2003,125(2):213-225
Ninety-eight surface soils were sampled from the uplands of England and Wales, and analysed for loss-on-ignition (LOI), and total and dissolved base cations, Al, Fe, and trace heavy metals (Cu, Zn, Cd, Pb). The samples covered wide ranges of pH (3.4-8.3) and LOI (9-98%). Soil metal contents measured by extraction with 0.43 mol l-1 HNO3 and 0.1 mol l-1 EDTA were very similar, and generally lower than values obtained by extraction with a mixture of concentrated nitric and perchloric acids. Total heavy metal concentrations in soil solution depend positively upon soil metal content and [DOC], and negatively upon pH and LOI, values of r2 ranging from 0.39 (Cu) to 0.81 (Pb). Stronger correlations (r2=0.76-0.95) were obtained by multiple regression analysis involving free metal ion (Cu2+, Zn2+, Cd2+, Pb2+) concentrations calculated with the equilibrium speciation model WHAM/Model VI. The free metal ion concentrations depend positively upon MHNO3 and negatively upon pH and LOI. The data were also analysed by using WHAM/Model VI to describe solid-solution interactions as well as solution speciation; this involved calibrating each soil sample by adjusting the content of "active" humic matter to match the observed soil pH. The calibrated model provided fair predictions of total heavy metal concentrations in soil solution, and predicted free metal ion concentrations were in reasonable agreement with the values obtained from solution-only speciation calculations. 相似文献
946.
947.
Francek MA Makimaa B Pan V Hanko JH 《Environmental pollution (Barking, Essex : 1987)》1994,84(2):159-166
This study evaluates the relationship between household Pb levels and four variables (home age, distance to road, traffic volume adjacent to the home, and the amount of exposed soil) for 42 homes in a small city. As a whole, Pb levels for the Mt. Pleasant sample were very low compared to large cities. Home age appeared to have the greatest impact on Pb levels as determined by atomic absorption soil = 65 microg g(-1), vacuum dust = 620 microg g(-1), window sill = 291 microg m(-1), indoor play area = 22 microg m(-1), and home entrance = 291 microg m(-1). The correlation coefficient for increasing home age and soil Pb level was r=0.63 (p<0.000). An inverse relationship (r=-0.45, p=0.003) occurred between soil Pb levels and distance from the road. Household Pb levels generally increased both with higher traffic volumes and greater amounts of exposed soil although both trends were not statistically significant. Study participants kept their home in a good to excellent state of repair and resided on lightly trafficked streets; as such, Pb deposition through the weathering of Pb-based paint and the former combustion of leaded gasoline was minimized. 相似文献
948.
949.
对钢铁厂、化工厂、制药厂、煤气焦化厂、煤矿废水COD进行了剖析分析,结果表明,废水中SS和可溶性无机物对COD有着重要贡献,不同类型或同一类型的工业废水,两者对COD贡献不同,且差值较大。SS贡献最大和最小者分别为61.1%和12.4%。可溶性无机物最大和最小贡献者分别为28.4%和14.6%。原水澄清或过滤测得COD明显偏低。同时,试验了GC法测得有机物总量与澄清水和原水COD的关系,前者呈相关,r为0.8183(n=7),后者无相关性,r仅为0.379(n=7)。 相似文献
950.