新安江上游横江地表水中砷、硒、汞含量变化研究

以安徽省黄山地区新安江上游横江地表水中重金属污染现状及其含量变化的规律特征为研究对象;以该水域地表水中砷、硒、汞含量变化为研究内容,对选取的7个采样点的砷、硒、汞含量进行采样测定,并通过整体分析方法进行研究。结果表明,该水域地表水中砷、硒、汞含量最大值分别为:0.719μg/L、1.400μg/L、0.069μg/L;最小值分别为:0.359μg/L、0.975μg/L、未检出。由此可见,横江地表水中砷、硒、汞含量变化不大,水质较稳定。     

合作市更洒金矿土壤污染调查与评价

金属矿区及周边土壤重金属污染使土壤质量下降，生态系统功能退化，进而威胁人体健康。本研究采集合作市更洒金矿作业影响范围内的300份土壤样品，测定砷、镉、六价铬、铜、铅、汞、镍及氰化物的含量，对矿区环境污染和生态风险进行评估。经现场取样和样品分析，总体来看，研究区土壤中，除砷之外，其余调查物质的含量均低于安全阈值。砷污染严重，污染程度的排序依次为堆浸场>矿区下游>对照点。     

铅锌矿产集中发育区土壤重金属背景值及特征分析

探索铅锌矿产集中发育区土壤重金属背景值及分布特征，并结合受污染耕地、涉重企业分布进行土壤重金属污染成因分析。选取铅锌矿产发育的尤溪县梅仙镇，采用系统均匀布点法，按2.5 km×2.5 km网格布设39个表层土壤监测点位，以土壤环境背景含量顺序统计量的95%分位值获得区域土壤环境背景值，分析高背景值重金属元素的分布特征；结合受污染耕地、涉重企业分布特点，从污染源角度解析农用地的重金属污染分布特征及成因。明确研究区土壤环境背景值为：镉0.294 mg/ kg、汞0.181 mg /kg、砷11.0 mg/ kg、铅269.1 mg/ kg、铬75.2 mg/ kg、铜61.3 mg/ kg、镍35.6 mg/ kg、锌153.0 mg /kg。对比分析显示,铅、铜元素属于区域性高背景重金属元素，同源重金属铅、铜、镉、锌呈现区域性复合污染；从分布上,铅、铜围绕矿产集中分布区富集，铅元素在平面上呈现连片式分布，铜元素在平面上呈现点状式分布。结合高背景值重金属元素分布特征及受污染耕地分布解析，梅仙镇安全利用类耕地分布主要受背景值控制，同时受矿山采选活动叠加影响；严格管控类耕地分布受矿山采选活动影响为主，地质背景的自然因素影响较小。     

ICP-MS法测定土壤6种重金属元素

本文使用王水—微波消解作为土壤前处理方法,利用电感耦合等离子体质谱(ICP-MS)测定土壤中铬、镍、铜、锌、镉、铅6种重金属元素,探讨了ICP-MS测定土壤6种元素的可行性。结果表明,实验室经过对ICP-MS法测定土壤和沉积物中铬、镍、铜、锌、镉、铅的重金属方法进行验证,其中线性关系中相关系数分别为0.999 9、0.999 9、0.999 9、0.999 9、0.999 9、0.999 8;检出限分别为0.2、0.1、0.1、0.4、0.03、0.1 mg·kg~(-1),检出下限分别为0.8、0.4、0.4、1.6、0.12、0.4 mg·kg~(-1);精密度中铬、镍、铜、锌、镉、铅的相对标准偏差分别为1.2%～2.7%、1.1%～3.7%、0.4%～3.5%、0.9%～4%、0.3%～0.3%、1.1%～2.0%;准确度中各指标均在标准物质GSS-25和GSS-12不确定度范围内。线性关系、检出限、精密度、准确度均符合《土壤和沉积物12种金属元素的测定王水提取—电感耦合等离子体质谱法(HJ 803-2016)》要求,ICP-MS测定土壤铬、镍、铜、锌、镉、铅6种重金属元素可行。     

利用DH-Ⅱ试剂回收电路板蚀刻废液中铜的研究

对电路板生产过程中排放的酸、碱两种蚀刻废液，用DH—Ⅱ试剂催化铁置换法回收金属铜工艺进行了探索，分别考察了催化置换反应pH值及铁屑用量条件。试验结果表明，pH值分别为-2．50和8．50的两种蚀刻废液以一定比例混合，pH值在0.5-2．0之间时，添加DH—Ⅱ试剂和废铁屑搅拌反应30min后，铜以海绵铜的形式沉出。废水中残留铜量约9．0mg／L，铜回收率可达99．99％。该方法工艺简单易行、成本低廉，铜回收率高，是回收处理蚀刻废液的有效方法。     

工业遗留地块重金属污染状况评价研究

为了解重庆市某工业遗留地块重金属污染特征及其潜在生态风险，本文在研究区内采集48组土壤样品和18组地下水样品，分析砷、镉、铜、铅、汞、镍、钴、锰8种重金属元素含量特征，并运用内梅罗指数法和潜在生态风险指数法，评价研究区的土壤与地下水污染状况。结果表明，研究区内土壤处于清洁状态，地下水中锰元素严重超标，地下水呈重度污染，存在很强的生态风险。     

扭转治理水土重金属严重污染的首要举措——记著名环境工程学家、清华大学环境学院傅国伟教授

<正>目前,我国水土重金属严重污染的形势:许多水域中镉、砷、铬、铅、汞的浓度(或含量)超过环境背景值,约有10%以上的土壤巳遭污染,约有10%的市场大米镉超标,一些地方蔬菜、食品中也出现砷、镉、铅超标,人群中出现砷和铅中毒等等。防治重金属污染是十分艰巨的,它涉及许多行业、部门和学科专业,确定防治的基本原则和技术     

原子荧光法测定土壤中汞含量消解方法的改进研究

消解是影响土壤重金属测定结果准确性的关键步骤。本文利用标准方法《土壤质量总汞、总砷、总铅的测定原子荧光法》(GB22105.1-2008),《土壤和沉积物汞、砷、硒、铋、锑的测定微波消解/原子荧光法》(HJ680-2013)和改进后的水浴消解法进行前处理,采用原子荧光法测定土壤样品中的汞含量,对比了3个土壤标准物质的精密度、准确度和回收率。试验发现,三种消解法的精密度、准确度和回收率均能满足土壤的检测要求。但改进后的水浴消解法具有更好的精密度、准确度和回收率,且简化了操作过程,适用于大批量土壤样品的汞含量测定。     

贵州普安铅厂尾库矿土壤污染特征及风险评价

贵州省是矿产资源最为丰富的省份之一.但不合理的矿产资源开采和矿渣堆积,导致周边土壤受到不同程度的污染,并伴生相关生态环境问题.以贵州省普安县铅厂尾库矿周围污染土壤为研究对象,通过详细的现场调查,以及对土壤进行取样测试砷、镉、铜、铅、汞、镍等元素含量,查明了研究区土壤污染源特征和分布.研究结果表明:研究区未发现危险废物,区内废渣属二类固体废物;土壤的污染途径主要包括有毒有害物质及污染物贮存、遗撒引起的扩散迁移以及干湿沉降造成的污染;土壤中砷的所有暴露途径的总致癌风险大于10-6,砷的总危害指数大于1,部分点位超过第二类用地土壤污染风险管控值,地块存在一定的风险.其研究结果可为污染土壤的改性和风险管控措施研究提供参考依据.     

昆明市农村地下水中金属污染分析与评价

为了解昆明市农村地下水水质状况,利用ICP-AES对昆明市匡远镇3个村庄的地下水中Cu、Zn、Mn、Pb进行分析测定。结果表明,4个采样点地下水样品中,金属元素Cu含量0.026 5~0.293 0 mg/L、Zn含量0.036 3~0.047 9 mg/L、Mn含量0.116~1.571 mg/L、Pb含量0.225~0.481 mg/L。通过污染指数P_i可知,P_((Cu))、P_((Zn))均小于1,表明该区域未受Cu、Zn的污染;而P_((Pb))、P_((Mn))大于1,表明该区域地下水受Pb、Mn不同程度的污染,其中Pb为最主要的污染物。长期施用化肥可能是当地地下水产生污染的原因,因此建议合理规划使用化肥。     

Industry specialization, diversification, churning, and unemployment in Chinese cities

This paper studies how industry specialization, diversification, and churning affect unemployment rates in Chinese cities. Using a city level panel data set from 1997 to 2006, we find that in contrast to the evidence from developed countries, industry diversity is positively and significantly associated with unemployment rates, possibly due to the high degree of industry churning during the sample period. We also find that the specialization of construction industry and wholesale and retail trade industry can significantly decrease unemployment rate, but specializing in finance industry increases unemployment rate. Urban growth, market maturity measured by the proportion of private sector employment, and human capital can decrease unemployment rate. The effect of industry structure on unemployment instability is also discussed.     

Aging,automation, and productivity in Korea

This paper examines the impact of aging in the Republic of Korea on productivity as measured by labor productivity or total factor productivity (TFP). It also assesses the effect of robot adoption on the relation between aging and productivity using industrial level data. We find that aging is negatively associated with labor productivity and TFP growth. This is true particularly when aging is measured by increases in shares of old workers. If aging is measured by increases in the median age of workers, the negative effect is weaker. Evidence also suggests that robot technology mitigates aging's negative effect on productivity growth, particularly when productivity is measured by TFP. However, there is no evidence that robots are more heavily adopted in aged industries. While robot technology does not directly contribute to higher productivity growth, our findings suggest that the robot adoption can alleviate the negative impact of aging by helping workers in their 50s and 60s contribute less adversly to productivity growth.     

Relationship among personality traits, leadership behavior, and job stress in nurses in Yunlin, Taiwan

This study probes into the relationships among personality traits, leadership behavior, and job stress in nurses in Yunlin, Taiwan. The major questions addressed are as follows： What model precisely portrays the relationships among personality traits, leadership behavior, and job stress？ Exploration of the causal pathways among these variables revealed a suitable model. A structured, self-administered questionnaire with three scales was distributed to the subjects. The questionnaires were submitted to 350 nurses and 284 questionnaires were completed accounting for a response rate of 81.1 percent. The data were analyzed by statistic analysis including frequencies, means, path analysis using computer program SPSS for windows 14.0 and LISREL 8.7. Results demonstrated a significant, direct, and positive effect of personality traits on leadership behavior, as well as a significant negative indirect effect of personality traits on job stress through leadership behavior was also revealed in the findings. All paths in the model were significant （P〈0.1）. After the analysis of LISREL, the suitability of the framework was fine and proved that the model was applicable for the research. The results of this study will be used as a reference to develop strategies for human resource management.     

Prostitutes,Pimps, and Brothels: Intermediaries,Information, and Market Structure in Prostitution Markets

Prostitution is a multi‐billion dollar, globally distributed, low‐concentration service industry that is receiving increasing attention in the economics literature. This article focuses on a widespread, but little studied, feature of this environment—the role of intermediaries (pimps or brothel owners) on market outcomes. Prostitution laws and markets are perhaps unique in that transactions between principals (prostitutes and johns) are legal in many countries, while intermediary activity (pimping) is illegal. After surveying the varying cross‐country legality of agents we develop a simple theoretical model to analyze how the presence or absence of intermediaries shifts the distribution of market surplus. We show that eliminating pimps and brothels may shift surplus in non‐obvious ways, depending on the precise function they perform and on whether equilibrium is pooling or separating across “high quality” and “low quality” market segments. The implications of alternative policy regimes (intermediaries legal or illegal) are considered.     

Devaluation,Debt, and Default in Emerging Economies

We explore the interactions between exchange rate and fiscal policy, and default on external debt. Exchange rate policy affects the supply of short-term debt facing the government. Under a conventional soft peg, it can be optimal for the government to set the exchange rate at a level in which partial default occurs. In this case multiple equilibria exist, with one featuring high interest rate, overvalued exchange rate, low level of output, and default. Default is also an equilibrium under a hard peg, precisely because devaluation is not an option. Under a hard peg, however, there is a unique equilibrium.