Distribution of radionuclides in the guano sediments of Xisha Islands, South China Sea and its implication

Several natural and anthropogenic radionuclides (²¹⁰Pb, ²²⁶Ra and ¹³⁷Cs) in guano-phosphatic coral sediments and pure guano particles collected from Ganquan, Guangjin, Jinqing and Jinyin Islands of the Xisha archipelago, South China Sea, were analyzed. The Constant Initial Concentration (CIC) model and the Constant Rate of Supply (CRS) model were applied for age calculation. The average supply rate of ²¹⁰Pb was 126 Bq m⁻² a⁻¹, very close to the flux of northern hemisphere average (125 Bq m⁻² a⁻¹). The activities of anthropogenic radionuclides in the sediments were very low, indicating that human nuclear tests did not notably impact this region. The main source of radionuclides in the sediments was from atmospheric precipitation, and the organic matter derived from plant and produced by nutrient-rich guano could further enhance them.     

微波消解石墨炉原子吸收法测定空气中的锰(铅)

本文介绍了用微波消解技术消解滤膜以测定空气中的锰（铅）的方法，与传统的稀硝酸浸出法、流酸-灰化法相比，微波消解更加简单、快速、节省、准确、沾污少、环境污染少，回收率高。     

Entrainment mortality of Ichthyoplankton: Detectability and precision of estimates

The ability to detect and to develop a precise and accurate estimate of the entrainment mortality fraction is an important step in projecting power plant impacts on future fish population levels. Recent work indicates that these mortailities may be considerably less than 100% for some fish species in the early life stages. Point estimates of the entrainment mortality fraction have been developed based on probabilistic arguments, but the precision of these estimates has not been studied beyond the simple statistical test of the null hypothesis that no entrainment mortaility exists.The ability to detect entrainment mortality is explored as a function of the sample sizes (numbers of organisms collected) at the intake and discharge sampling stations of a power plant and of the proportion of organisms found alive in the intake samples (intake survival). Minimum detectable entrainment mortality, confidence interval width, and type II error (probability of accepting the null hypothesis of no entrainment mortality when there is mortality) are considered. Increasing sample size and/or decreasing sampling mortality will decrease the minimum detectable entrainment mortality, confidence interval width, and type II error for a given level of type I error.The results of this study are considered in the context of designing useful monitoring programs for determining the entrainment mortality fraction. Preliminary estimates of intake survival and the entrainment mortality fraction can be used to obtain estimates of the sample size needed for a specified level of confidence interval width or type II error. Final estimates of the intake survival and the entrainment mortality fraction can be used to determine the minimum detectable entrainment mortality and the type II error.     

铬渣制取铬黄淋滤液中过量铅离子的去除研究

用累托石做吸附剂来处理铬渣淋滤液制铬黄过程中产生的过量Pb^2-。当pH为5．6～7．3,反应时间90min,吸附剂与水量比为24g／L.pbe^2 浓度由2．5mg／L降到0．05mg／L,Pb^2 的去除率最高可达98％,外排废水符合GB8978—1996一级标准。     

Soil Lead at Elementary Public Schools: Comparison Between School Properties and Residential Neighbourhoods of New Orleans

Soil studies, conducted in Maryland, Minnesota and Louisiana, have described the urban pattern of lead contamination. They have shown that the highest amounts of lead cluster within the interior of the largest cities. The results of the New Orleans urban patterns of distribution of soil lead provided the basis for further study. The hypothesis was tested that elementary school properties have the same pattern of soil lead contamination as their neighbouring residential communities. Thirty New Orleans Public Elementary Schools were selected for this study. Surface samples (2.5cm or 1 inch depth) were collected from playgrounds and next to entrances of each school. Results showed that soil lead on school properties follows the same relative contamination patterns (pvalue10^–5) as soil lead on residential properties of neighbouring communities. Schools however, have significantly lower lead contamination than the neighbouring residential properties. Innercity school properties present a higher risk of soil lead exposure than mid and outercity schools. Soils next to innercity school entrances showed the highest lead, with 18.5% having concentrations over 400gg^–1. Systematic landscaping around the school entrances would significantly reduce the hazard from lead dust contaminated soils.     

水泥窑协同处置生活垃圾焚烧飞灰过程中Pb和Zn的迁移转化特性

对某水泥窑协同处置生活垃圾焚烧飞灰系统进行采样分析,研究飞灰中的Pb、Zn在水洗脱氯预处理及水泥窑协同处置过程中的迁移转化特性。结果表明,水洗预处理过程中,飞灰中0.15%Pb和0.015%Zn进入结晶盐,94.05%的Pb和93.17%的Zn留存在水洗灰中,且赋存形态基本不变。水泥窑协同处置飞灰过程中,进入窑内的Pb和Zn少部分在窑内和预热器系统形成内循环,93.84%Pb和81.38%的Zn进入水泥熟料,0.002 7%的Pb进入窑尾烟气,0.001 4%的Pb和0.001 1%的Zn进入窑灰。热力学平衡计算表明,水泥熟料中Pb的主要存在形态是PbO、PbSiO₃,Zn的主要存在形态是ZnO、ZnFe₂O₄、ZnAl₂O₄。窑尾烟气排放指标和水泥熟料性能指标均满足相关规范要求,这说明Pb和Zn在水泥窑中实现了良好的固化,环境风险可接受。本研究结果可为水泥窑协同处置飞灰工艺系统设计优化提供参考。     

The potential of cost-effective coconut husk for the removal of toxic metal ions for environmental protection

Coconut (Cocos nucifera) husk, an agricultural waste, has been thoroughly investigated for the removal of toxic Cd(II), Cr(III) and Hg(II) ions from aqueous media. The parameters like nature and composition of electrolyte, concentration of toxic ions, dosage of coconut husk, and equilibration time between the two phases were optimized for their maximum accumulation onto the solid surface. The effect of common ions on the uptake of metal ions has been monitored under optimal conditions. The variation of retention of each metal ion with temperature was used to compute the thermodynamic quantities DeltaH, DeltaS and DeltaG. The values 18.1+/-0.6 kJmol(-1), 74+/-2 Jmol(-1)K(-1), and -3.8+/-0.04 kJmol(-1) at 298 K; 10.8+/-0.8 kJmol(-1), 48.8+/-2.7 Jmol(-1)K(-1), and -4.6+/-0.3 kJmol(-1) at 298 K; and -37.4+/-2k Jmol(-1), 105+/-7 Jmol(-1)K(-1) and -2.58+/-0.5 kJmol(-1) at 298 K were obtained for Cd(II), Cr(III) and Hg(II) ions, respectively. The sorption data were analysed by applying different sorption isotherms. The sorption capacity and energy were evaluated for each metal ion. The values of the Freundlich constants 1/n and C(m) were 0.92+/-0.04 and 52.6+/-22.2 mmolg(-1); 0.85+/-0.05 and 56.0+/-0.03 mmolg(-1); and 0.88+/-0.03 and 6.84+/-0.45 mmolg(-1) for Cd(II) Cr(III) and Hg(II) ions, respectively. Similarly, the Dubinin-Radushkevich (D-R) constants beta, X(m,) and E were evaluated for the three metal ions. To check the selectivity of the sorbent, sorption of a number of elements was measured under similar conditions. Separation of Zn(II) from Cd(II); Cr(III) from I(I), Zr(IV), Se(IV), and Hg(II) from Se(IV) and Zn(II) can be achieved using this sorbent. This cheap material has potential applications in analytical chemistry, water decontamination, industrial effluent treatment and in pollution abatement.     

不同重金属在烤烟中的累积分配特征研究

研究了重金属Hg、As、Pb在烤烟中的累积分布。结果表明:烤烟对Hg、As、Pb的耐受力较强;Hg抑制K326根系的生长,Pb、As对K326的生长有一定的促进作用。随着重金属浓度的增加,各部位重金属含量和烟株累积总量多呈增加趋势。在不同的处理下,3种重金属的含量在根系中最高;在相同的处理下,重金属在烟叶各部位的含量按大小顺序均为下部叶>中部叶>上部叶。随着处理浓度的增加,分配在根系中的重金属元素的比例不断增加,而在叶片中的分配比例不断降低;按重金属元素在叶片中的分配比例排序为Hg>As>Pb。     

典型Pb/Zn矿区土壤重金属污染特征与Pb同位素源解析

以我国典型的铅锌矿区——湖南水口山铅锌矿区及其周围地区为研究对象,分析自然土壤(A层和C层)样品中不同重金属(Pb、Zn、Cr、Cu、Cd、Hg)的污染特征和Pb同位素组成.结果表明,受铅锌选矿和冶炼活动的影响,研究区域A层土壤明显受到重金属的污染,尤其是在中心区域(水口山矿区),土壤中Pb、Zn、Cr、Cu、Cd、Hg含量最高达3966.88、 2086.25、 135.31、 185.63、 56.15、 16.434 mg/kg;受原生地质环境的影响,C层土壤重金属含量虽然变化很大,但基本反映土壤背景值.土壤中不同重金属的潜在生态危害大小顺序为Cd>Hg>Pb>Cu>Zn=Cr.中心区域多重金属综合潜在生态危害明显高于周围区域,其34%、 33%、 11%、 22%的采样点分别属于轻微、中等、强和很强生态危害,而周围区域属于轻微、中等、强和很强生态危害的采样点比例分别为68%、 16%、 10%、 6%.与C层Pb同位素相比(²⁰⁶Pb/²⁰⁷Pb为1.168～1.246,²⁰⁸Pb/²⁰⁶Pb为2.014～2.130),由于人为Pb源的污染A层土壤中²⁰⁶Pb/²⁰⁷Pb值(1.166～1.226)低而²⁰⁸Pb/²⁰⁶Pb值(2.043～2.135)高.与铅锌选矿、冶炼废水和烟尘中Pb同位素比值对比表明,A层土壤铅污染主要来自于冶炼厂烟气粉尘的沉降.