铅同位素解析技术在工业园污染溯源中的应用

针对土壤中重金属污染溯源及解析不同污染源对土壤中铅的相对贡献率问题,以陕西西部某工业园区为例,采集土壤样品、铅锌冶炼厂矿石混合样、热电厂煤样及焦化厂混合煤样共40个,用ICP-MS测定样品的铅浓度及铅同位素比值(208Pb/204Pb、207Pb/204Pb、206Pb/204Pb).借助于铅同位素比值散点图来对比分析采样点土壤、背景点土壤和可能的污染源样品的铅同位素特征分布,判定其主要污染来源.用混合多元模型计算不同污染区域各污染源的贡献率,结果表明,土壤中的铅同位素比值落在铅锌矿石、炼焦用煤及热电燃煤及背景点的铅同位素比值之间,说明各端元介质均有可能对工业园区土壤中的铅污染有贡献.在铅同位素比值散点图中土壤铅浓度大于60 mg/kg的采样点的铅同位素比值集中落在热电燃煤与炼焦用煤附近.统计定量解析结果可知,对工业园区土壤铅污染的贡献大小依次为热电厂、焦化厂和铅锌冶炼厂.研究表明,铅同位素指纹解析技术用于定性与定量解析工业园区土壤铅污染效果较为理想.     

改性柚子皮吸附剂对模拟废水中pb2+的吸附性能

以废柚子皮为原料,经ZnCl2浸泡-加热的化学改性手段制备改性柚子皮生物吸附剂,并通过模拟试验研究该吸附剂对废水中pb2+的去除.考察了模拟废水的pH、吸附时间、吸附剂用量和pb2+初始浓度、温度等因素对柚子皮吸附剂去除pb2+的影响,并研究柚子皮吸附剂对pb2+的吸附动力学及吸附特征.结果表明,模拟废水的pH、吸附时间、吸附剂用量和pb2+初始浓度、温度等因素对柚子皮吸附剂吸附废水中pb2+均有显著影响.适宜的吸附条件为pH5.3～6.5,吸附时间1.5h,吸附剂用量10g· L-1,pb2初始质量浓度100 mg·L-1,温度30℃.在该条件下,废水中pb2+去除率在90％以上.柚子皮吸附剂对废水中pb2+的吸附符合动力学二级反应方程,等温吸附规律可用Langmuir、Freundlich和Temkin模型进行较好的描述.     

The concentration of Cu and Pb in the funnel spider Eratigena atrica (C. L. Koch 1843) (Araneae: Agelenidae) and its web

Studies on the heavy metal concentrations on spider webs in relation to the pathways of pollution penetration (external and internal) have yet to be performed. This work assesses the concentration levels of two heavy metals: essential copper (Cu) and toxic lead (Pb) in spider webs and spiders (females, males and juveniles). Spiders divided into three treatment groups were exposed to the heavy metals in their diet as prey (fruit flies and mealworms larvae) were artificially contaminated with Cu and Pb. In general, we found higher rates of Cu compared to Pb concentrations in spiders and their webs. A positive correlation between levels of Cu and Pb in webs and spiders was found. Males had higher concentrations of both metals Cu and Pb in their bodies and webs compared to females. In an additional experiment, washed webs had significantly less metals than unwashed suggesting the dominance of external pollution in the contamination pathway.     

青藏高原东麓贡嘎山东坡土壤中Pb的来源解析

选择青藏高原东麓典型山地——贡嘎山(东坡),根据不同海拔梯度(海拔2 000~4 500 m)差异设置8个采样点,根据土壤发育情况分别采集O层(有机层)、A层(矿物质层)和C层(母质层)样品,分析土壤中w(Pb)的海拔分布特征,并利用FA-MLR(因子回归分析)法、地球化学指标法和Pb同位素三元混合模型定量判识表层土壤中Pb的来源. 结果表明:①各层土壤中w(Pb)表现为O层〔(41.73±4.38)mg/kg〕>A层〔(30.47±2.17)mg/kg〕>C层〔(23.04±1.50)mg/kg〕(P<0.05). 随着海拔的增加,O层和A层中w(Pb)总体呈升高—降低—升高趋势;C层中w(Pb)随着海拔的变化无显著差异,表明贡嘎山东坡土壤中w(Pb)的地球化学背景值基本一致. ②各层土壤中206Pb/207Pb表现为O层208Pb/206Pb表现为O层>A层>C层. ③Pb同位素三元混合模型结果显示,表层(O层和A层)土壤中Pb可能受到化石燃料燃烧和矿物开采及金属冶炼活动的影响;根据FA-MLR法、地球化学指标法和Pb同位素三元混合模型这3种方法,得到O层中污染Pb所占比例分别达到84.9%、66.0%和63.7%,A层中分别为56.6%、27.8%和44.9%;在海拔分布上,Pb的污染在海拔2 770 m以下主要归因于当地化石燃料的燃烧,而在林线(约3 700 m)以上则来自矿物开采及金属冶炼活动.      

中国部分地区铅暴露儿童健康风险评价

通过解析我国现有血铅浓度数据,采用无阈值剂量效应曲线,计算了我国部分地区轻度智力发育迟缓(MMR)的发生概率.最后利用MMR发生率以及生命周期表,计算了相应的伤残调整寿命年.结果表明:我国儿童血铅浓度几何均值和几何标准差分别为5.94,1.58μg/dL,超标率为12.74%,而由于铅暴露污染所导致的儿童MMR发生率和伤残调整寿命年(DALYs)分别为0.78%和0.10a.计算结果表明,我国儿童的铅暴露风险低于非洲,南美以及部分中东地区,远高于北美以及欧洲,与除日本以外的其他亚洲国家基本持平.     

基于化学分析和气象信息综合表征大气铅污染

对天津市1998年11月-1999年2月期间21个玻璃纤维滤膜大气颗粒物样品,采用稀酸浸出法溶解后,测量了ρ(Pb),w(Pb)和同位素丰度比206Pb/207Pb.采用IDAS软件对样品进行聚类分析,分组的结果表明,在不同的天气条件下,各种污染源排放的贡献也不同.48 h反向风迹图提供了大量详实的气象信息,结合ρ(TSP),ρ(Pb),w(Pb)和同位素丰度比的数据,可用于综合表征铅污染的状况.      

Concentrations and Pools of Heavy Metals in Urban Soils in Stockholm,Sweden

The concentrations of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb andZn) and arsenic (As) were surveyed and the metal pools estimatedin soils in Stockholm Municipality. The sampling sites were distributed all over the entire municipality with a higher sampling density in the city centre. Soils were sampled to a maximum depth of 25 to 60 cm. Soil texture, total-C content, electrical conductivity and pH were analysed. Heavy metal concentrations were determined after wet digestion with boiling7 M HNO₃.The results showed a wide range in heavy metal concentrations, as well as in other soil properties. The city centre soils constituted a rather homogeneous group whereas outside this areano geographical zones could be distinguished. These soils were grouped based on present land use, i.e. undisturbed soils, public parks, wasteland (mainly former industrial areas), and roadside soils. The city centre and wasteland soils generally hadenhanced heavy metal concentrations to at least 30 cm depth compared to park soils outside the city centre and rural (arable)soils in the region, which were used to estimate background levels. For example, the mean Hg concentration was 0.9 (max 3.3)mg kg^-1 soil at 0–5 cm and 1.0 (max 2.9) at 30 cm depth in the city centre soils, while the background level was 0,04 mg kg^-1. Corresponding values for Pb were 104 (max 444) and135 (max 339) mg kg^-1, at 0–5 and 30 cm, respectively, while the background level was 17 mg kg^-1.The average soil pools (0–30 cm depth) of Cu, Pb and Zn were 21,38 and 58 g m^-2 respectively, which for Pb was 3–4 timeshigher and for Cu and Zn 1.5–2 times higher than the backgroundlevel. The total amount of accumulated metals (down to 30 cm)in the city centre soils (4.5^*10 ⁶ m² public gardens and green areas) was estimated at 80, 1.1, 120 and 40 t for Cu, Hg, Pb and Zn, respectively. The study showed (1) thatfrom a metal contamination point of view, more homogeneous soilgroups were obtained based on present land use than on geographicdistance to the city centre, (2) the importance of establishing a background level in order to quantify the degree of contamination, and (3) soil samples has to be taken below the surface layer (and deeper than 30 cm) in order to quantify theaccumulated metal pools in urban soils.     

广东乐昌铅锌尾矿的酸化潜力

利用净产酸试验(NAG)和净产酸潜力试验(NAPP)方法,研究了广东乐昌铅锌尾矿的产酸潜力.该尾矿的黄铁矿的硫和总硫含量分别为12.57%和18.68%,NAG和NAPP值分别为H₂SO₄ 220 kg·t^-1和326 kg·t^-1,NAG和NAPP的试验结果都表明该尾矿有着很高的产酸潜力.由于黄铁矿硫不会完全被氧化,NAG比NAPP可更为准确地预测尾矿的产酸潜力.2个剖面的分析表明,因氧化难以进入尾矿深部,酸化主要发生在尾矿表面0～20cm,且对下层尾矿的影响很小.尾矿的pH值与EC值显著负相关,表明酸化促进乐昌尾矿中盐分的溶解和重金属的迁移,在酸化的表层,有效态Pb、Zn、Cu和Cd含量显著高于未酸化的下层,而Pb、Zn、Cu和Cd的总量却显著低于未酸化的下层.     

Impact of Atmospheric Long Range Transport of Lead,Mercury and Cadmium on the Swedish Forest Environment

Emissions of Hg, Pb, and Cd to air aretransported over wide areas in Europe and deposited far awayfrom their sources. About 80% of the atmospheric depositionof these metals in south Sweden originate from emissions inother countries. As a result of the increased anthropogenicdeposition the concentrations of Hg, Pb, and Cd in the morlayer of forest soils have increased considerably, mainlyduring the 20th century. Although the atmosphericdeposition of these elements has declined during the mostrecent decades, the reduction of the input of Hg and Pb isnot sufficient to prevent a further accumulation. Theconcentrations of Hg and Pb are still increasing by ca. 0.5and ca. 0.2% annually in the surface layer of forest soils.In contrast, the Cd concentration is currentlydecreasing in a large part of Sweden as a result of bothdeposition decreases and enhanced leaching induced by soilacidification. The accumulation factors of Hg and Pb,especially in the forest topsoils of south Sweden, arealready above those at which adverse effects on soilbiological processes and organisms have been demonstrated instudies of gradients from local emission sources andlaboratory assessment. There are also indications of sucheffects at the current regional concentrations of Hg and Pbin mor layers from south Sweden, judging from observationsin field and laboratory studies. There is an apparent riskof Pb induced reduction in microbial activity over parts ofsouth Sweden. This might cause increased accumulation oforganic matter and a reduced availability of soil nutrients.At current concentrations of Hg in Swedish forest soils,effects similar to those of Pb are likely. Increasedconcentrations of these elements in organs of mammals andbirds have also been measured, though decreases have beendemonstrated in recent years, related to changes inatmospheric deposition rates. As a result of current andpast deposition in south Sweden, concentrations of Hg infish have increased about fivefold during the 20thcentury. This implies risks for human health, when fish frominland waters are used for food. Although the concentrationof Hg in fish has decreased ca. 20% during the last decade,probably as a result of the reduced deposition, the levelstill exceeds the general limit (0.5 mg kg^-1) in about half(ca. 40 000) of the Swedish lakes. In order to reduceconcentrations in fish to the level recommended, and avoidfurther accumulation of Hg in soils, the atmosphericdeposition has to be reduced to ca. 20% of the current deposition rate. This can only be achieved by international co-operation.     

新型二氧化铅电极处理硝基苯废水

采用高压塑片的方法制备了一种PbO₂电极,用X衍射、扫描电镜、火焰原子吸收分光光度法对该电极性能进行了考察,并探讨了该电极降解硝基苯的机理和工艺条件.结果表明,该电极与普通石墨电极相比,COD_Cr去除率更高,电解5 h COD_Cr去除率最高可达65%.由于PbO₂电极具有较高的析氧电位,在阳极极化下,PbO₂电极表面易生成·OH,这是其电解效率高的主要原因.该电极电解硝基苯的最适条件:ρ(硝基苯)为501.5 mg/L,电极间距为3 cm,溶液pH为7.利用该电极处理含磷酸盐和氯离子的硝基苯废水效果尤为突出,但由于阴极的还原作用,电解过程中硝基苯不能被完全氧化.