安徽某燃煤电厂周边土壤汞分布特征及风险评价

结合当地气象条件,采集了安徽某燃煤电厂周边地区的土壤,采用冷原子吸收法测定其汞含量,应用地统计学和地理信息系统方法分析了电厂周边表层土壤汞含量的空间分布特性,分析了土壤中汞与理化性质之间的相关性,并进行了风险评价。结果表明,电厂周边表层土壤汞含量范围为0.015~0.076 mg/kg,平均值为0.029 mg/kg,虽未超过国家允许的标准,但与当地背景值及安徽省土壤汞含量相比均有一定程度的增加;土壤汞含量的总体分布特征为除距排放源1~2 km的环形区域受影响最大外,污染程度随着与电厂距离的增大而递减,汞含量空间分布受主导风向影响呈现明显的条带分布。相比于单因子污染指数法和地累积指数法,潜在生态危害指数评价法能更好地反映燃煤电厂周围土壤中汞的污染水平和生态风险程度。土壤汞含量与土壤理化性质之间存在不同程度的相关性。     

包头某铝厂周边土壤重金属污染及健康风险评价

以包头市某铝业周边500 m内土壤为研究对象,测定其东北、东南、西北、西南4个方向不同水平距离及深度处土样中Cu、Cd、Pb、Zn、Ni和Cr的含量,并采用地累积指数法和健康风险评价法对重金属污染状况进行评价。结果表明,该区域表层土壤中6种重金属普遍高于内蒙古土壤背景值,且在西南方向50 m处含量最高,人类活动对该区域重金属干扰强烈,而风向对重金属分布影响不大;铝厂周围土壤中Cd、Pb处于中污染-重污染,Cu和Ni处于无污染-中污染,Zn和Cr为无污染,各金属污染程度随土壤深度的增加而减轻;健康风险评价表明,研究区域内Cu、Pb、Ni和Cd均不存在非致癌健康风险,而Cd的致癌危害虽在可接受范围内,但已存在潜在致癌风险,Ni的致癌健康风险指数已超过预警值,应予以高度重视和防治。     

铅冶炼区土壤重金属总量和有效态含量的函数分析

采集铅冶炼企业周边3 000 m范围内220个表层土壤样品,测定了有毒有害元素铅、镉、砷和汞的总量和有效态含量,探讨了它们之间的关系。结果表明:研究区土壤受到汞、砷、铅、镉的污染依次明显严重,土壤重金属的总量和有效态含量的变异系数均大于100%,土壤镉、铅、汞、砷的生物有效性系数平均值分别为25.9%、17.2%、0.58%、0.11%。土壤铅、镉和砷的总量与其有效态含量呈显著正相关(P0.001),而汞的总量与其有效态含量的相关性不显著(P0.05)。土壤铅和镉的总量和有效态含量可以用直线函数和幂函数表达,函数反推的有效态值和对应统计值的变异系数不大于10%。     

燃煤电厂周边大气重金属污染特征及来源解析

为探究燃煤电厂周边大气环境中重金属的污染特征与来源,对广东某山区燃煤电厂周边地区环境和污染源的重金属进行测定,分析其污染特征,采用因子分析法和Pb同位素示踪法对环境中的重金属进行来源解析。结果表明,研究区域室内积尘中重金属浓度水平明显高于土壤重金属,污染空间分布与当地气象条件相关。环境空气TSP中重金属主要来自2个污染源,Cd、Pb、As主要来自电厂燃煤,Ca、Mn、Al、Mg主要来自土壤扬尘。TSP、降尘、积尘样品所含的Pb均与电厂采集的煤、炉渣、粉煤灰样品所含的Pb具有同源性,与其他污染源同源性不明显,说明研究区域大气中Pb污染主要来自电厂燃烧所排放的烟尘,其他污染源影响不大。     

煤矿周边土壤重金属影响评价及来源分析

在麟游县郭家河煤矿下风向500 m范围内布设10个土壤采样点,测定其表层土中Zn、Cr、Pb、Cu、Cd、Hg和As7种元素的质量比,利用土壤综合质量影响指数法和富集因子法评价该煤矿周边土壤重金属影响状况,并应用Spearman相关分析法和主成分分析法分析污染来源。结果表明:Cu、Pb、Zn和Hg 4种重金属的平均质量比均高于陕西省土壤(A层)背景值和麟游县土壤环境背景值;距矿区10 m~150 m范围内7种元素富集状况受人类活动的影响较大;矿区Cu、Zn、Pb、Cd、As和Hg元素均来自煤矿开采导致的"三废"污染及农药、化肥的使用,Cr主要受成土母质的控制。     

重庆市菜地土壤和蔬菜中Hg、Pb的污染特征及相关性分析

通过对重庆市菜地土壤和蔬菜 Hg、Pb的含量分析 ,发现土壤 Hg含量远远大于背景值 ,并且土壤 Hg的含量与菜地周围的环境密切相关 ;土壤 Pb的含量同背景值相差不大。Hg、Pb在土壤和蔬菜中的污染特征表现为主城区 >近郊区 >远郊区 ;并且不同蔬菜品种中 Hg、Pb的含量差异较大 ,在不同蔬菜种类表现为叶菜类 >果菜类 >根菜类。相关性分析表明同一菜地土壤和蔬菜中 Hg、Pb含量无相关性 ;不同菜地土壤和蔬菜 Hg、Pb含量不具有相关性。     

典型铝塑厂周边土壤重金属分布特征与健康风险评价

为探究铝塑园区周边土壤重金属污染情况,选取山东省某城市塑料开发区为研究区,按照分层采样方式获取到80个土壤样品,分别测定土壤中As、Cd、Hg、Cr、Cu、Ni、Pb、Zn含量,运用统计分析法探讨土壤重金属等的分布特征和来源,并利用健康风险评价模型确定了土壤重金属对周边居民的健康风险。结果表明:As、Cd、Hg、Cr、Cu、Ni、Pb和Zn均超出山东省土壤背景值,其中Cd、Hg、Cu和Pb分别超出背景值48. 15%、106. 90%、62. 04%和39. 96%,表明土壤中存在一定程度的重金属积累,在周边140～210 m处最为严重,且受人类活动影响强烈,与风向关系不大;土壤重金属垂直分布特征大致呈现随着深度的增加不断增加,在20 cm深度附近达到最高值,其后不断降低并趋于平稳,Cd、Hg、Cu、Pb和Zn变异幅度大,受到人为干扰较大,As、Cr和Ni主要受成土母质控制,属于自然来源,变动幅度较小;研究区内8种元素不存在非致癌风险,Cr、As、Ni和Cd产生的致癌风险处在可接受范围内,但存在的潜在致癌风险应引起足够的重视。     

内蒙古畜禽养殖场周边土壤重金属污染特征及评价

于2015年5—8月采集内蒙古自治区东部、中部和西部地区32个畜禽养殖场周边共160个土壤样品,分析8种重金属含量。通过单项污染指数法和内梅罗综合污染指数法评价畜禽养殖场周边土壤重金属的污染程度,主成分分析重金属污染的成因和来源。结果表明,除Hg和As外,Cd、Pb、Cr、Cu、Zn和Ni 6种重金属的平均值均高于内蒙古自治区土壤背景值,其中Cd是背景值的2. 14倍。单项污染指数评价表明,重金属Cd在东部畜禽养殖场周边土壤中呈中度污染,在中部和西部地区畜禽养殖场周边土壤中呈轻度污染。不同重金属元素平均污染程度为:Cd Pb Cr(Ni) Zn Cu As Hg。内梅罗综合污染指数评价表明,东部地区畜禽养殖场周边土壤污染最严重,为中度污染,中部和西部地区畜禽养殖场周边土壤均为轻度污染。不同地区畜禽养殖场周边土壤重金属内梅罗综合污染指数大小顺序为:东部地区(2. 27)西部地区(1. 52)中部地区(1. 35)。主成分分析结果显示,内蒙古不同地区畜禽养殖场周边土壤不同重金属的来源存在差异,其中Pb、Cr、Cu、Zn和Ni主要来源于畜禽粪便和冲洗禽舍等污水的不当排放; Hg主要来源于自然源。     

长江下游典型滨海地区农业土壤重金属污染特征

为揭示长江下游滨海地区农业土壤重金属污染状况,以滨江临海的南通市为例,网格化布点,采集表层农业土壤样品共计334个,对其重金属Cu、Pb、Cr、As、Hg含量进行了测定分析.结果表明,研究区域表层农业土壤中各重金属含量均已超过其背景值,且以Pb污染最为严重;区域性差异较大,以滨海的如东、海门、启东污染最为严重,且以海门、启东As含量最高;各重金属间相关性不显著,来源途径不止一种.从而提出南通市农业土壤重金属污染的防治应立足于防重于治的方针,着重滨海地区,以Pb、As污染源为主,并对污染土壤进行修复.     

新疆典型城-郊-乡梯度带土壤微量元素空间分布与来源

从新疆某地典型城-郊-乡梯度带采集了77个表层(0~20 cm)土壤样品,基于GIS技术与多元统计分析方法,研究各梯度带表层土壤中Hg、As、V、Co、Ni、Cu、Zn、Cd、Pb和Sb等10种微量元素的空间分布特征与主要来源。结果表明:Hg元素在城区、郊区和乡村表层土壤中的平均含量均超出研究区土壤背景值,As元素在城区和郊区表层土壤中的平均含量超出背景值,Zn和Pb元素在城区表层土壤中的平均含量超出背景值,其余元素在3个梯度带表层土壤中的平均含量均低于相应的背景值。研究区表层土壤中,V、Co、Ni、Zn、Cd、Pb和Sb等7种元素的空间分布格局基本相似,均呈现沿城市化梯度带分布的地带性格局;As、Cu和Hg等3种元素的空间分布呈现岛状格局。来源分析结果表明,各梯度带表层土壤中的微量元素的来源各不相同。     

Fractions and leaching characteristics of mercury in coal

A huge amount of coal is always stored in open spaces in coal-fired power plants before combustion. Mercury released from coal by rain or flowing water is an environmental risk and can cause contamination of the soil around the storage area. To better understand mercury pollution and to control mercury emission before combustion, it is necessary to determine the mobility and leaching characteristics of mercury from coal. In this study, we collected ten coal samples from one coal-fired power plant and proposed a sequential extraction procedure to get five fractions of mercury for evaluation. Elemental Hg was found as the most dominant fraction, and sulfate Hg was shown to be the second largest fraction. The mercury in the organic and the soluble fractions were not the major fractions, but they should still be considered because of their high mobility.     

北京市大气气态汞变化特征

采用Tekran 2537X大气汞分析仪在线测量北京市城区大气中气态元素汞(GEM,简称大气汞) 浓度,研究大气汞浓度随不同气象条件的变化特征。通过分析2016年10月—2017年9月大气汞监测数据发现,该监测点全年大气汞浓度为0.48～16.25 ng/m³,均值为(3.41±1.79)ng/m³。春季、夏季、秋季和冬季大气汞浓度均值依次为2.93 、2.95、4.27、3.37 ng/m³,其中,秋季大气汞浓度明显高于其他季节 。秋季大气汞浓度显著偏高可能由不利的大气扩散条件导致。大气汞夜间浓度显著高于白天浓度。同时,将大气汞与SO₂、CO及PM_2.5进行相关性分析,发现大气汞浓度变化趋势与SO₂、CO和PM_2.5呈显著正相关。结合风向和风速进行污染来源分析,得到该点位大气汞在西南和东北方向上受人为排放源影响较大。污染源类型分析表明,冬季大气汞与CO同源性强,主要来自本地供暖用煤。     

基于实测的燃煤电厂烟气中汞排放水平浅析

简述汞污染和控制问题成为环境问题的新热点和前沿研究领域,介绍中国燃煤电厂烟气汞监测试点的基本情况。分析江苏省7家燃煤电厂煤中汞及烟气中汞排放水平,提出利用现有的除尘、脱硫、脱硝设施,能满足《火电厂大气污染物排放标准》中汞的排放限值要求。     

Biomonitoring with epiphytic lichens as a complementary method for the study of mercury contamination near a cement plant

The study was focused on understanding the mercury contamination caused by a cement plant. Active and passive biomonitoring with epiphytic lichens was combined with other instrumental measurements of mercury emissions, mercury concentrations in raw materials, elemental mercury concentrations in air, quantities of dust deposits, temperatures, precipitation and other measurements from the cement plant's regular monitoring programme. Active biomonitoring with transplanted lichens Pseudevernia furfuracea (L.) Zopf was performed at seven of the most representative sites around the cement plant and one distant reference site for periods of 3, 6 and 12 months. In situ lichens of different species were collected at the beginning of the monitoring period at the same sites. Mercury speciation of the plant exhaust gas showed that the main form of emitted mercury is reactive gaseous mercury Hg2?, which is specific for cement plants. Elemental mercury in air was measured in different meteorological conditions using a portable mercury detector. Concentrations in air were relatively low (on average below 10 ng m?3). In situ lichens showed Hg concentrations comparable to lichens taken from the background area for transplantation, indicating that the local pollution is not severe. Transplanted lichens showed an increase of mercury, especially at one site near the cement plant. A correlation between precipitation and Hg uptake was not found probably due to a rather uniform rainfall in individual periods. Dust deposits did not influence Hg uptake significantly. Lichens vitality was affected over longer biomonitoring periods, probably due to some elements in dust particles, their alkalinity and the influence of other emissions. Mercury uptake measured in vital transplanted lichens was in a good correlation with the working hours (i.e. emitted Hg quantity) of the kiln. The study showed that selected lichens could be used to detect low to moderate Hg emissions from a cement plant and that the biomonitoring procedure could be further standardized and used as part of an environmental monitoring programme.     

Distribution, accumulation and mobility of mercury in superficial sediment samples from Tianjin, northern China

Seventeen sediment samples at three representative sites (the Yuqiao Reservoir, the Haihe River and the Haihe River Estuary) in Tianjin, northern China, were analyzed to investigate the pollution status, accumulation and mobility of mercury (Hg). The results show that the Haihe River has to be considered as moderate to strongly contaminated with Hg (2 < mean I(geo) = 2.35 < 3), where total Hg contents were ca. 3 to 24 orders of magnitude greater than the regional background value. The sediments collected near a coal-fired power plant in an urban area were found to have very high Hg concentrations, which were significantly related to Hg emissions from coal-fired utility boilers. In the Yuqiao Reservoir, the surface sediments have to be considered as unpolluted with Hg (mean I(geo) = -0.05 < 0) and the Haihe River Estuary sediments have to be considered as unpolluted to moderately polluted with Hg (0 < mean I(geo) = 0.18 < 1). Sediment-bound Hg in the Yuqiao Reservoir and the Haihe River Estuary was found to be predominantly associated with the organo-chelated phase of the sediment (38.3% and 50.5%, respectively). However, unlike the Yuqiao Reservoir and the Haihe River Estuary, Hg in the Haihe River sediments existed mainly as sulfide Hg and elemental Hg, which accounted for 54.2% and 30.7% of total Hg, respectively. The availability of this element seemed restricted. The majority of Hg contamination in the Haihe River sediments had been attributed to historic and modern atmospheric deposition and Hg released from the Haihe River sediments didn't seem to be an important pollutant pathway into the Haihe River Estuary. The results provide new insights into Hg contamination in this region.     

Emission factor of mercury from coal-fired power stations

Mercury emission from coal-fired power stations, situated in Poland in the Silesian region was investigated. The determination methods for mercury in the consumed coal and in combustion gas, used in this research, are described. The mass of mercury emitted into the air from coal combustion in the power station is in constant relation to the mercury content in the consumed coal during the assumed period. A relationship between mercury emission into the air and the mercury content in the consumed coal in electric power stations is derived.     

Speciation and mass-balance of mercury from pulverized coal fired power plants burning western Canadian subbituminous coals

This report summarizes the results of a study carried out on six pulverized coal-fired power plants in western Canada burning subbituminous coal for the mass-balance and speciation of mercury. The main objectives of this study were to: determine the total gaseous mercury (TGM) emitted from stacks of power plants using the Ontario Hydro method; identify the speciation of emitted mercury such as metallic (Hg(0)) and gaseous elemental (GEM) mercury; and perform mass-balance calculations of mercury for milled-coal, bottom ash, electrostatic precipitators (ESP) fly ash and stack-emitted mercury based on three tests. Sampling of mercury was carried out using the Ontario Hydro method and mercury was determined using the USEPA method 7473 by cold vapor atomic absorption (CVAAS). The sample collection efficiencies confirmed that both oxidized and the elemental mercury had been successfully sampled at all power plants. The total gaseous mercury emitted (TGM) is 6.95-15.66 g h(-1) and is mostly in gaseous elemental mercury (GEM, Hg(0)) form. The gaseous elemental mercury is emitted at a rate of 6.59-12.62 g h(-1). Reactive gaseous mercury (RGM, Hg(2+)) is emitted at a rate of 0.34-3.68 g h(-1). The rate of emission of particulate mercury (Hg(p)) is low and is in the range 0.005-0.076 g h(-1). The range of mass-balances for each power plant is more similar to the variability in measured mercury emissions, than to the coal and ash analyses or process data. The mass-balance calculations for the six power plants, performed on results of the three tests at each power plant, are between 86% and 123%, which is acceptable and within the range 70-130%. The variation in mass-balance of mercury for the six power plants is mostly related to the variability of coal feed rate.     

Biochemical responses in tree foliage exposed to coal-fired power plant emission in seasonally dry tropical environment

A biomonitoring study was conducted to investigate the responses of plants exposed to power plant emission in a dry tropical environment. For this purpose, five sampling sites were selected in the prevailing wind direction (NE) at different distance to thermal power plant (TPP) within 8.0 km range and a reference site was selected in eastern direction at a distance of 22.0 km. The two most common tree species, Ficus benghalensis L. (Evergreen tree) and Dalbergia sisso Roxb. (deciduous tree) were selected as test plants. Ambient sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), suspended particulate matter (SPM), respirable suspended particulate matter (RSPM), dust-fall rate (DFR) and plant responses such as leaf pigments (chlorophyll a, chlorophyll b and carotenoids), ascorbic acid, sugar and sulphate-sulphur (SO4(2-)-S) contents were measured. Ambient SO(2), NO(2), SPM, RSPM and DFR showed significant spatial and temporal variation at different sites. Considerable reduction in pigment (chlorophyll a, chlorophyll b and carotenoids) and sugar contents were observed at sites receiving higher pollution load. Ascorbic acid exhibited significant positive correlation with pollution load. Accumulation of SO4(2-)-S in leaf tissue showed significant positive correlation with ambient SO(2) concentration at all the sites. At the same time, SO4(2-)-S showed significant negative correlation with pigment and sugar content. D. sisso Roxb. tree was found to be more sensitive as compared to F. benghalensis L. tree.     

郑州市土壤与绿色植物中汞的分布特征

汞污染具有生物积累性,因而得到社会广泛关注。研究监测和评估了郑州市城区土壤和绿色植物叶片中汞浓度、分布、污染水平等。研究发现郑州市主城区土壤总汞浓度为0. 150～0. 958 mg/kg,平均浓度为0. 448 mg/kg;郑州市主城区绿色植物叶片总汞浓度为0. 017～0. 249 mg/kg,平均浓度为0. 107 mg/kg;土壤和叶片中汞浓度按功能区排序为交通枢纽区工业区商业区行政区高教区住宅区。采用地累积指数法对郑州市80个土壤样品的汞污染水平进行评估,结果显示60%受到轻度污染,35%受到偏中度污染,5%受到中度污染。研究较为全面地分析了土壤汞污染的现状及浓度,为郑州市土壤汞污染防治提供参考。