Disruption of iron homeostasis and resultant health effects upon exposure to various environmental pollutants: A critical review

Environmental pollution has become one of the greatest problems in the world, and the concerns about environmental pollutants released by human activities from agriculture and industrial production have been continuously increasing. Although intense efforts have been made to understand the health effects of environmental pollutants, most studies have only focused on direct toxic effects and failed to simultaneously evaluate the long-term adaptive, compensatory and secondary impacts on health. Burgeoning evidence suggests that environmental pollutants may directly or indirectly give rise to disordered element homeostasis, such as for iron. It is crucially important to maintain concerted cellular and systemic iron metabolism. Otherwise, disordered iron metabolism would lead to cytotoxicity and increased risk for various diseases, including cancers. Thus, study on the effects of environmental pollutants upon iron homeostasis is urgently needed. In this review, we recapitulate the available findings on the direct or indirect impacts of environmental pollutants, including persistent organic pollutants (POPs), heavy metals and pesticides, on iron homeostasis and associated adverse health problems. In view of the unanswered questions, more efforts are warranted to investigate the disruptive effects of environmental pollutants on iron homeostasis and consequent toxicities.     

基于模糊专家系统的垃圾焚烧底灰重金属污染风险评价

垃圾焚烧处理技术可以实现城市生活垃圾减量化,但底灰中重金属的存在与迁移转化会形成持续的潜在风险。针对重金属Cu、Cr、Pb和Cr对环境的潜在风险进行分析,将模糊专家系统引入潜在生态风险指数法中。首先将重金属的富集系数作为输入,然后应用知识库和推理机制来实现重金属对环境危害快速、不确定信息的准确推理,最后对城市生活垃圾焚烧底灰中重金属对环境的潜在风险进行评价。实验结果验证,该方法能够更快速、准确地做出适当的决定,为底灰的安全处置和再利用提供理论基础。     

Particle size distribution and characteristics of heavy metals in road-deposited sediments from Beijing Olympic Park

Due to rapid urbanization and industrialization, heavy metals in road-deposited sediments(RDSs) of parks are emitted into the terrestrial, atmospheric, and water environment, and have a severe impact on residents' and tourists' health. To identify the distribution and characteristic of heavy metals in RDS and to assess the road environmental quality in Chinese parks, samples were collected from Beijing Olympic Park in the present study. The results indicated that particles with small grain size(150 μm) were the dominant fraction. The length of dry period was one of the main factors affecting the particle size distribution, as indicated by the variation of size fraction with the increase of dry days. The amount of heavy metal(i.e., Cu, Zn, Pb and Cd) content was the largest in particles with small size(150 μm) among all samples. Specifically, the percentage of Cu, Zn, Pb and Cd in these particles was 74.7%, 55.5%, 56.6% and 71.3%, respectively.Heavy metals adsorbed in sediments may mainly be contributed by road traffic emissions. The contamination levels of Pb and Cd were higher than Cu and Zn on the basis of the mean heavy metal contents. Specifically, the geoaccumulation index(I geo) decreased in the order:CdPbCuZn. This study analyzed the mobility of heavy metals in sediments using partial sequential extraction with the Tessier procedure. The results revealed that the apparent mobility and potential metal bioavailability of heavy metals in the sediments, based on the exchangeable and carbonate fractions, decreased in the order: CdZn≈PbCu.     

一株高效产絮菌的筛选、絮凝条件优化及对重金属废水处理性能研究

从活性污泥、水体底泥、植物根系土壤和草莓种植土壤中筛选、分离、纯化,获得了高絮凝活性的菌株,并考察发酵液用量、助凝剂用量以及碳、氮源种类对絮凝活性的影响及菌株对实际重金属废水的絮凝作用。结果表明:以葡萄糖为碳源,酵母膏为氮源,菌体发酵液用量0.2 m L,助凝剂用量0.8 m L时,菌株QB1的絮凝性最高,可达到93%。其对多种重金属废水均具有较好的处理性能,对含铅废水的去除率最高可达99%以上。     

不同土地利用方式下土壤重金属污染修复技术研究

土壤重金属污染的修复问题备受人们的关注,而在不同土地利用方式下受污染的土壤能够通过不同途径对人群健康构成威胁.国内外有关土壤重金属污染修复方法可分为生物修复、化学修复、物理修复以及联合修复,各修复方法适用范围差异较大.结合农业土壤、城市土壤以及矿区土壤中重金属的污染特征能够提出相应的更加合理的修复措施,最终为相关部门环境污染治理的决策提供理论依据.     

便携式X-荧光分析土壤的准确度和质量控制研究

测定标土能反映便携式X-荧光光谱仪的准确度,采用便携式X-荧光光谱仪测定了国内外七种标准土样,计算了测定结果的相对误差,直观地反映了便携式X-荧光光谱仪的准确度和灵敏度.借鉴EPA对便携式X-荧光光谱仪测定结果的质控要求,分析了部分测定结果得不到质量控制要求的原因,结合中国土壤环境质量标准一、二、三级标准,分析了便携式X-荧光光谱仪测定值在不同标准限值时的准确度和灵敏度.选取了铅冶炼周围的土壤,分析了现场测定由于土壤的不均匀性、粒度效应以及湿度给结果带来的误差.为便携式X-荧光光谱仪的质量控制和数据的准确恒量提供了依据.     

巴里富碳酸盐硫化物尾矿中重金属的赋存状态

本文以广西大厂锡石-硫化物矿区巴里尾矿库的富碳酸盐尾矿(堆放了20余年)作为研究对象,采用BCR三步提取法研究Zn、Cd、Pb和As的化学形态分量以及其总含量在该尾矿铅垂剖面中的分布,并结合尾矿的结构构造、次生和原生矿物成分及其变化等分析,探讨在氧化/酸化条件下富碳酸盐尾矿中重金属的释放机制。研究结果表明:(1)尾矿下层原尾矿中重金属主要以稳定或较稳定的残渣态(As、Pb、Zn、Cd)、氧化物结合态(Pb)及硫化物结合态(Zn、Cd)形式赋存。在酸水淋滤作用下,原尾矿中重金属的释放顺序为Cd≈ZnPbAs;(2)尾矿上部厚层状氧化硬层(厚度1~1.5m)中,Zn、Cd以酸可溶态大量富集,具有较强的迁移性;As、Pb主要以残渣态以及氧化物结合态赋存,其迁移性较差。因此,富含碳酸盐的硫化物尾矿经过氧化作用具有释放多种重金属的潜能。由于这类尾矿中各重金属的赋存状态存在差异性,因此对其迁移性及环境效应须具体分析。     

实验室重金属废水处理研究

根据实验室废水中Hg2+和Cr3污染特点,以硫酸亚铁、硫化钠作为还原剂,将废水中的Cr6+还原为Cr3+,Hg2+和Cr3+以沉淀的形式混凝去除。分别考察pH值、反应时间及还原剂投加量对两种重金属去除率的影响,结果表明过低的反应时间不利于Cr6+和Hg2+的去除,pH2.0时,Cr6+和Hg2+的还原效率较高,FeSO4和Na2S加量分别在1 000 mg/L和667 mg/L时,Cr6+和Hg2+具有较高的去除效率。利用正交实验对污染物去除条件进行优化,结果表明,两种无机还原剂投加比例对铬、汞两种重金属离子的去除率影响大,pH值次之,反应时间对去除率的影响最小,在pH为2.0、FeSO4和Na2S加量分别在1 000 mg/L和667 mg/L,反应时间为30 min时,废水中Hg2+和Cr6+的去除率最高,分别达到98.23%、95.97%,处理后废水达到国家污水排放标准。     

太湖东部不同类型湖区疏浚后沉积物重金属污染及潜在生态风险评价

为揭示太湖东部疏浚湖区沉积物中重金属分布特征及其潜在生态风险,于2012年在东太湖与胥口湾共设置5个点位采集沉积物样品,测试了底泥部分理化性质及重金属元素含量(As、Cd、Cr、Cu、Hg、Ni、Pb、Zn),并运用潜在生态风险指数法综合评价了疏浚湖区沉积物的重金属污染现状和潜在风险程度.结果表明,太湖东部不同类型湖区间沉积物的营养盐及重金属含量分布存在差异,总体上胥口湾草型湖区的重金属含量相对东太湖养殖湖区较高,营养盐含量则相对较低;在垂直剖面上,沉积物营养盐和重金属均表现出表层富集的特征.太湖东部湖区各疏浚点位的营养盐和重金属含量均低于未疏浚点位,表明底泥生态疏浚能有效去除沉积物中的营养物质和重金属污染物,但疏浚效果随时间逐渐减弱.各重金属元素及营养盐之间均呈显著正相关关系,表明这些污染物具有较好的同源性.潜在生态风险指数RI的评价结果表明,各点位沉积物的重金属潜在危害程度依次为X1>D1>D3>X2>D2,其中未疏浚点位胥口湾X1的潜在生态风险高于东太湖D1,且X1、D1均属于中等生态风险,而疏浚点位D2、D3、X2属于轻微生态风险,底泥疏浚有效降低了沉积物中的重金属潜在生态风险.     

污泥灰渣中重金属煅烧脱除规律研究及安全性评价

污泥目前被认为是磷酸盐矿的二次资源,焚烧处理可实现污泥中磷资源的浓缩富集,但其中重金属毒性问题尚待解决.该文以污泥焚烧灰渣为研究对象,利用马弗炉进行煅烧实验,通过改变反应时间(从10 min到60 min)、温度(从900℃到1200℃)及CaCl2的添加量(以Cl计,从1.5%到8.0%)研究重金属(Pb、Zn和Cu)的去除率及在煅烧灰渣中的赋存形态.结果表明:Pb有较高的去除率,且其去除率均随温度、时间及Cl含量的升高而升高,在1200℃、Cl含量为5.0%的时候有最大值为82.4%;Zn的去除率受温度的影响较大,高温时Zn有较高的去除率,且在1100℃时有最大值为83.9%;Cu的去除率较低,而在温度为1100℃时有最大的去除率为68.2%.就煅烧灰渣中重金属的赋存形态而言,各种工况下Pb在煅烧灰渣中均以残渣态存在;Zn在煅烧灰渣中主要也是以残渣态存在;Cu在煅烧后还存在一定的酸溶态,在900℃、煅烧10min时煅烧灰渣中酸溶态可达29.2%.增加CaCl2的添加量可以促进重金属的去除,同时使煅烧底渣中的重金属更稳定.地累积指数(Igeo)评价结果显示,煅烧底渣中的这3种重金属的污染程度都降低了.