城市地表汞释放通量时空特征分析

大量研究证实土壤中的汞可以释放到大气中 ,是区域汞多介质环境污染的重要特征之一 .城市是一种特殊的人工生态系统 ,地表覆盖类型与森林土壤存在很大差异 ,其地表汞释放的研究对了解汞的多介质循环有重要意义 ,本文测定了长春市七种不同地表类型的汞释放 ,并分析了其释放规律 .1　样品的采集与测定在长春市区范围内 ,选择七种不同的地表类型 :煤炭堆放地 ,沥青地面 (公路 ) ,裸地 ,草地 ,市区森林土壤 ,郊区森林土壤 ,郊区空旷地 .在不同的气象条件下测定土壤挥发性汞释放通量 .同时 ,采集大气样品与土样 ,测定大气温度、相对湿度等气象参…     

封闭垃圾填埋场通过地表向大气释放汞的测定

利用动力学通量箱及自动测汞仪联用技术,于2004年3月中旬对贵阳市的一座封闭生活垃圾填埋场汞通过地表向大气释放的过程进行了研究。3个采样点的汞释放通量日均值分别为559.1、88.2、53.6ng·m-2·h-1,汞释放通量强度与表层基质中的汞含量密切相关,该测定值高于世界背景地区通量的1~2个数量级,说明封闭垃圾填埋场也是大气汞的潜在来源。汞释放通量呈现明显的昼夜变化规律,白天较高并在午间前后达到最大,而夜间降至最低。气相因子中光照强度与汞的释放过程相关性最高,其次分别是气温、相对湿度、地温和风速。氧化态汞的光致还原作用是可能垃圾填埋场Hg0生成的主要途径,降雨初期能促进地表汞的释放。     

土壤湿度和浇水对紫色土土/气界面汞释放通量的影响

以重庆市的主要耕作土壤——紫色土为研究对象,用动力通量箱与RA-915＋汞分析仪联用技术,通过室内模拟实验研究土壤湿度和浇水对紫色土土/气界面汞交换通量的影响.结果表明,加入外源硝酸汞的土壤汞交换通量大于加入硝酸亚汞的土壤汞交换通量,对照土壤的汞释放通量最小.随着土壤含水量的增加,土/气界面汞交换通量有增加的趋势,在土...     

土壤汞污染研究进展

对国内外学者近些年来对土壤汞污染研究的工作进展作了系统的综述。主要包括土壤汞污染的途径、迁移方式和治理办法。其中重点介绍了大气汞的干湿沉降、土壤汞的释放及生物修复治理土壤汞污染。最后，还介绍了土壤汞形态的分析方法以及土壤挥发性汞释放通量的测量方法。     

凋落物处理对森林地表CO_2通量的影响及其调控机理

全球变化和森林演替可以导致森林地表凋落物数量和质量的变化,从而对森林地表CO2通量产生影响。本实验对亚热带不同演替阶段的3种,即马尾松林(前期)、混交林(中期)和季风林(后期)进行地表凋落物去除、加倍与置换处理,利用静态箱气相色谱法测定地表CO2通量,并同步测定气温、土壤温度和湿度,分析凋落物质量和数量变化对森林地表CO2通量的影响及其调控机理。结果表明,(1)去除凋落物处理显著降低了不同演替阶段的3种森林地表CO2通量,而加倍凋落物处理可以增加森林地表CO2通量,但不同演替阶段增加的幅度不同,依次为:季风林马尾松林混交林。(2)置换凋落物对不同演替阶段的森林地表CO2通量的影响不同,在演替后期的季风林中,置换混交林和马尾松林凋落物处理均增加地表CO2通量;在演替中期的混交林中,置换季风林和马尾松林凋落物均降低地表CO2通量。在演替前期的马尾松林中,置换季风林凋落物增加地表CO2通量,而置换混交林凋落物降低了地表CO2通量(3)结合测定的土壤温度和水分数据分析得出,凋落物处理引起森林地表CO2通量的变化是通过处理凋落物质量和数量后改变森林地表水热条件来实现的。(4)3个林型的各种处理,地表CO2通量与土壤温度均呈显著的指数相关关系,但不同处理不同地改变了森林地表土壤CO2通量对温度的敏感性,即Q10值。     

凋落物处理对森林地表CO2通量的影响及其调控机理

全球变化和森林演替可以导致森林地表凋落物数量和质量的变化,从而对森林地表 CO2通量产生影响。本实验对亚热带不同演替阶段的3种,即马尾松林（前期）、混交林（中期）和季风林（后期）进行地表凋落物去除、加倍与置换处理,利用静态箱气相色谱法测定地表CO2通量,并同步测定气温、土壤温度和湿度,分析凋落物质量和数量变化对森林地表CO2通量的影响及其调控机理。结果表明,（1）去除凋落物处理显著降低了不同演替阶段的3种森林地表CO2通量,而加倍凋落物处理可以增加森林地表CO2通量,但不同演替阶段增加的幅度不同,依次为：季风林＞马尾松林＞混交林。（2）置换凋落物对不同演替阶段的森林地表 CO2通量的影响不同,在演替后期的季风林中,置换混交林和马尾松林凋落物处理均增加地表CO2通量;在演替中期的混交林中,置换季风林和马尾松林凋落物均降低地表CO2通量。在演替前期的马尾松林中,置换季风林凋落物增加地表CO2通量,而置换混交林凋落物降低了地表CO2通量（3）结合测定的土壤温度和水分数据分析得出,凋落物处理引起森林地表 CO2通量的变化是通过处理凋落物质量和数量后改变森林地表水热条件来实现的。（4）3个林型的各种处理,地表 CO2通量与土壤温度均呈显著的指数相关关系,但不同处理不同地改变了森林地表土壤 CO2通量对温度的敏感性,即Q10值。     

可溶性有机物对土壤汞向大气释放的影响

通过模拟试验,研究了浸提自稻草、腐殖土和堆肥的可溶性有机物(DOM)对紫色潮土、紫色土和黄壤三种土壤中汞向大气释放的影响.结果表明,DOM尤其是堆肥DOM能有效地抑制土壤汞向大气的释放,且土壤中DOM添加量越高,土壤汞释放量越少,即DOM对土壤汞释放的抑制作用越强;不同土壤类型,DOM的抑制作用不同,三种土壤汞释放量大小顺序均为:紫色潮土紫色土黄壤.     

华南丘陵区针叶林和果园地表N2O通量的日变化

利用静态箱-气相色谱法对华南丘陵区典型土地利用类型(针叶林:马尾松 Pinus massoniana;果园:龙眼Dimocarpus longan Lour)地表N2O通量日变化进行了原位观测.结果表明, 针叶林和果园土壤总体来说为大气N2O的源.地表N2O通量日变化规律不明显,日变化中最大通量和最小通量出现的时间也没有明显的规律.针叶林地表N2O通量日平均值变化幅度为0.02～0.12 mg·m-2·h-1,果园为0.03～0.37 mg·m-2·h-1,最大值一般出现在6-8月.地温和气温对地表N2O通量日变化无明显影响.降雨对地表N2O通量有较大的影响,雨季(4-9月)地表N2O通量大于旱季(10-3月).不同土地利用方式对地表N2O通量有较大影响,果园地表N2O通量较针叶林大.没有发现凋落物对地表N2O通量有明显影响.     

深圳近海区域降水中重金属湿沉降通量及源解析

为了弄清深圳近海区域城市活动对大气降水中重金属浓度及湿沉降通量的影响,2015年6月至2016年5月,对近海3个点位3年降水用ICP-MS测定18种重金属浓度,并对不同点位四季及全年重金属含量分布、湿沉降通量、富集情况与污染来源做了深入探讨.结果表明,近海区域降水中相同季节重金属浓度及沉降通量的空间变化趋势一致,但YT点位金属含量及沉降通量最高;除元素Cu、Sr及Sb外,3个点位四季重金属浓度存在明显季节性差异,且多出现在春夏季,BA点位频次最高,YT点位次之;降水中重金属浓度及年沉降通量空间差异大,但低于国内其他城市却高于国外一些地区,含量最高的地壳元素Na、Ca、Mg、K、Al及痕量元素Zn、Mn占总浓度的98.99%、占总沉降通量的99.62%,其中毒害大的元素Cu、Pb、Cd、As、Mn年沉降通量分别为:2.941、2.714、0.742、1.445、5.921 mg·(m2·a)-1;分别以Al及Na为参考元素得出降水Zn高度富集但空间差异小,高度富集的Sb在BA点位最高、YT点位最小,而富集因子均超过2200的Cd在YT点位高于4100,表明受人类活动影响最大;主成分分析得出重金属污染来源除受近20%海洋源及10%地壳源共同影响外,BA点位还受周边工业生产排放、发电场燃料废气、交通燃料释放的影响,贡献率达46.3%,DP点位与海上交通燃料排放、垃圾焚烧释放及生物质燃烧关系密切,贡献率达51.9%,而YT点位受盐田港及码头燃料燃烧、交通排放及焚烧释放影响大,贡献率达38.1%.     

华南丘陵区针叶林和果园地表CH4通量的日变化

利用静态箱-气相色谱法对华南丘陵区典型土地利用类型(针叶林:马尾松 Pinus massoniana;果园:龙眼Dimocarpus longan Lour)地表CH4通量日变化进行了原位观测.结果表明, 针叶林和果园土壤总体来说为大气CH4的吸收汇.地表CH4通量日变化波动较大,规律不明显.吸收较强的月份为10-11月,较弱的月份为6-9月.针叶林地表CH4吸收通量日平均值变化幅度为-0.093～0.066 mg·m-2·h-1,果园为-0.098～0.146 mg·m-2·h-1.地温和气温对地表CH4通量无明显影响.降雨对地表CH4通量有较大的影响,旱季(10-3月) 地表CH4吸收通量大于雨季(4-9月).凋落物和植被类型对CH4通量没有明显影响.     

Atmospheric mercury emissions from polluted gold mining areas (Venezuela)

Soil, waste rock and mud from mercury-gold amalgamation mining areas of El Callao (Venezuela) are highly enriched in Hg (0.5–500 μg g⁻¹) relative to natural background concentrations (<0.1 μg g⁻¹). Mercury fluxes to the atmosphere from twelve polluted sites of this area were measured in situ (6 a.m. to 8 p.m.) using a Plexiglas flux chamber connected to a portable mercury analyzer (model RA-915+; Lumex, St. Petersburg, Russia). Mercury fluxes ranged between 0.65 and 420.1 μg m⁻² h⁻¹, and the average flux range during the diurnal hours␣was 9.1–239.2 μg m⁻² h⁻¹. These flux values are five orders of magnitude higher than both reported world background Hg fluxes (1–69 ng m⁻² h⁻¹) and the regional values, which are in the range 2–10 ng m⁻² h⁻¹. The flux results obtained in this study are, however, similar to those measured at Hg polluted sites such as chloro-alkali plants or polymetallic ore mining districts (>100,000 ng m⁻² h⁻¹). The results from this study also show that Hg emissions from the soil are influenced by solar radiation, soil temperature and soil Hg concentration. Our data suggest that solar radiation may be the dominant factor affecting Hg° emission since the major species of mercury in polluted soil is Hg° (85–97% of total Hg). The simple release of Hg° vapor is probably the dominant process occurring with incident light in the field. The apparent activation energy for mercury emission indicates that the volatilization of mercury mainly occurred as a result of the vaporization of elemental mercury in soil. The degree of Hg emission differed significantly among the soil sites studied, which may be due to variations in soil texture, organic matter content and soil compaction.     

Quantification and fractionation of mercury in soils from the Chatian mercury mining deposit,southwestern China

Contents of total Hg and Hg fraction, organic matter, pH, grain size and chemical composition were measured to investigate the pollution characteristics and binding behavior of Hg in soils collected from the Chatian Hg mining deposit (CMD), southwestern China. The average concentration of Hg concentration in the CMD soils was 155 and 1,315 times higher than that in control soils and Chinese soils, respectively, suggesting that the CMD soils were heavily contaminated by the element. The finding was confirmed by Müller geoaccumulation index assessment with 75% very seriously polluted, 6.25% highly to very highly polluted and 18.75% moderately to highly polluted. Hg sources in the region were natural and anthropogenic: in addition to the pedogenic process and original geochemical situation, human mining–refining activities have also seriously impacted the redistribution of Hg in soils, especially in paddy soils. Based on the BCR protocol, soil Hg was divided into exchangeable (EXC), amorphous Fe–Mn oxides (AFe–MnOX), organic-crystalline iron oxides (OM-CFe) and residual (RES) fraction. The average percentage of the four fractions in the CMD followed the trend: RES (85.77%) > OM-CFe (12.44%) > AFe–MnOX (0.93%) ≥ EXC (0.86%), suggesting that the majority proportion of soil Hg in the study area remained of residual form inside the soil mineral matrix. However, their concentrations and percentages significantly varied among different locations and land use types. Soil physico-chemical parameters were key factors affecting the presence of Hg fraction. Generally, Hg fraction concentrations were positively correlated with the sand contents and soil pH values, which was presumably due to the basic anthropogenic input of Hg-containing materials and their similarity to sand in physical characteristics. However, organic matter caused adsorption–fixation and reduction–volatilization to coexist, which had opposite effects on Hg concentrations in soil, consequently exhibiting its dual nature.     

中国南方稻田土壤汞含量及潜在危害评价

选择我国南方水稻主产区安徽、浙江、湖南、湖北以及广西5个省,采集213个稻田土壤样品,探究我国南方稻田土壤中汞的空间分布特征与土壤理化参数(如p H值和有机质)的相关关系及汞富集的潜在危害。结果表明:不同省份的稻田土壤汞含量存在显著的差异(P0.05,n=213),含量范围是0.029~0.326 mg·kg~(-1)(干重),平均值为(0.094±0.036)mg·kg~(-1),与农用地土壤环境质量标准0.30 mg·kg~(-1)(GB15618—1995)相比,除湖北省以外均有轻度汞污染。Pearson相关性分析表明,稻田土壤中的汞含量与有机质含量呈显著正相关关系(P0.01,r=0.445),说明适度偏高的有机质有利于土壤汞的富集。不同省份稻田土壤潜在危害等级除浙江省外均在轻微到中等的范围内,浙江省的为强等级。     

滦河流域不同土地利用类型土壤微生物量C、TN、TP垂直分异规律及其影响因子研究

根据2009年4月份在滦河流域采集的25个土壤样点的数据资料,对不同土地利用类型土壤微生物量C、TN、TP质量分数特征、垂直分异规律、表聚性及与影响因子进行研究。结果表明：土壤微生物量C、TN、TP在土壤表层（0～10cm）的平均表聚系数分别为0.22、0.19和0.14,并且河滩地、林草地的土壤微生物量C、TN质量分数明显高于水稻田和旱田土壤,而农田系统土壤中TP质量分数相对占优。土壤微生物C、TN、TP的剖面分布均表现出从表层向下减少的总趋势,并以40cm为界,不同土地利用类型土壤、同层观测值的显著性差异有所不同。土壤微生物量C、TN与土壤含水率呈极显著正相关（P〈0.01）,与粉粒呈显著正相关（P〈0.05）,与土壤容重呈极显著负相关,与气温、降水量呈负相关。TP与气温、降水量呈极显著正相关,与容重负相关,与其它因子没有明显相关关系。     

Amelioration of mercurial toxicity by manganese. I. A case study in mung bean seedling

Mercury, a non essential element renders inhibitory effect on many physiological activities of plants even at a low concentration. Plants absorb "Hg" from soil through root system. Manganese, an essential element has been found to counter the inhibitory effect of mercury mostly by preventing it's uptake from soil. Mung bean (Vigna radiata L. Wilczek) cv. Pusa Baisakhi grown in individual (1, 10, 100 and 1000 ppm) solution of Hg and Mn showed varied uptake of these heavy metals. However, in combined solutions (1 : 1, 10 : 1 and 1 : 10 ppm Hg : Mn), mercury uptake was mostly prevented in presence of 10 ppm Mn, indicating it's ameliorating effect.     

The influence of drainage networks on patterns of soil respiration in a desert catchment

Hydrologic flow and connectivity act as important determinants of ecological pattern and process in heterogeneous landscapes. Here we examine how the routing of water through the drainage network of an upper Sonoran Desert basin influences landscape patterns of soil respiration (SR) at both seasonal and event-based timescales. At seasonal timescales, SR varied up to 13-fold with downstream position in the drainage network, and annual estimates of CO2 efflux ranged from 185 g C x m(-2) x yr(-1) to 1190 g C x m(-2) x yr(-1) for sites arrayed along the same flow path. Spatial patterns of SR were unrelated to the carbon and water content of surface soils, but rather tracked changes in plant size and productivity, which in turn reflect downstream increases in groundwater availability. The relative importance of precipitation and temperature as drivers of SR also changed with landscape position, with the latter becoming more important in downstream locations. At the scale of individual precipitation events, SR increased up to 30-fold upon rewetting but typically returned to background levels within 24 h, even when soil moisture remained elevated. Unlike patterns observed at seasonal scales, event-based losses of CO2 varied across the landscape as a function of the organic-matter content in surface soils. Results from labile carbon amendments confirm that CO2 losses following precipitation pulses are initially constrained by substrate availability, not soil drying. By mediating spatial patterns of vegetation structure and soil resource availability, drainage networks represent an important physical template upon which belowground processes are organized in desert basins.     

An Operationally Defined Method to Determine the Speciation of Mercury

This paper presents a modified method of an operationally determined speciation of mercury in soil. The analytical work was mainly concerned to suit properly with inductively coupled plasma-atomic emission spectrometry (ICP-AES). Soil samples analysed in this study were selected from open areas around a crematorium, a waste incinerator, and two power plants. Results show that both topsoil and subsoil samples were dominated by elemental mercury Hg(0) and mercuric sulphide (HgS). The significant correlation between sulphur concentration and HgS was found in topsoil samples.     

西安东郊某废弃钢铁厂油松年轮记录的重金属含量变化过程

以西安市东郊某废弃钢铁厂为例,采用石墨炉原子吸收法、电感耦合等离子体原子发射光谱法、原子荧光法测定了废弃钢铁厂两棵油松(Pinus tabulaeformis Carr.)树盘及其根部土壤中重金属Cr、Mn、Hg、Zn、Pb、Cd和类金属As以及P等8种元素的含量.土壤测定结果表明,该地区Cr、Zn、As等元素含量超过了西安市郊区土壤背景值,Cr、Mn等元素易在深层土壤中积累,Hg、Zn等元素不易在深层土壤中积累.两个树盘年轮中这8种元素的含量随着年代的推移总体呈现上升的趋势,这表明该地区由这些元素引起的污染状况日益加重.Hg、Pb、Cd等元素于1996年左右吸收达到最高峰,与该钢铁厂生产历史相一致.这两个树盘中Mn、Hg、Zn、As、P等元素自1993年后均呈现比较一致的增长趋势.通过计算各元素的自相关系数,从统计学角度发现这8种元素在油松年轮中的迁移特征:Mn、Zn、As等元素均存在着3年的横向迁移趋势,Pb、P存在2年的迁移趋势,Hg、Cd有1年的迁移,而Cr几乎不迁移,其中Zn、Cd、P等元素在油松中的迁移趋势与西安市西部某地区椿树和桐树中的迁移趋势表现一致.     

Associations of trace elements in aerosol at the south Adriatic coast

We applied statistical methods to the data of a 5-year sampling period to characterize the features of trace elements in airborne particulate matter at the South Adriatic Coast. The analysis of surface soil samples was also performed. The data were processed by cluster analysis, enrichment factor determination and receptor rose statistics. It is shown that the principal element association consists of Fe, Mn and Ti originating from surface material resuspension. Hg and Se were shown to originate from more complex natural and anthropogenic processes. A strong emission source of Cd and Se was identified in the SSE direction.Selected article from the Regional Symposium on Chemistry and Environment Krusevac, Serbia, June 2003, organized by Dr. Branimir Jovancicevic.