全自动甲基汞分析系统分析甲基汞的仪器条件优化

通过对比优化了全自动甲基汞仪器分析系统的参数设置,得到当吹扫气N2和载气Ar流速分别为344 mL.min-1和34 mL.min-1,GC柱分离温度在约40℃时,Hg0、MeHg和Hg2＋乙基化（1%NaBEt4溶液）后分离效果和完成时间最佳;在0—100 pg的标准工作曲线范围内,乙基化试剂的最佳投加量为40μL;...     

吹扫捕集-气相色谱/冷原子荧光法联用测定地表水中甲基汞研究

建立了吹扫捕集-气相色谱/冷原子荧光联用测定地表水中甲基汞的方法,具体方法:水样乙基化后转化为易挥发的甲基乙基汞,在线吹扫捕集至Tenax管,在高纯Ar作载气时加热使Tenax捕集管中各种形态的Hg热脱附,进入GC柱分离,在700℃~900℃高温下热解还原为元素汞(Hg0),进入冷原子荧光检测器进行检测.方法检出限为0.08 pg(若水样为40 mL,检出限为0.002 ng/L),相关系数可达0.9999.对不同来源的地表水进行分析,精密度<10%,加标回收率在83.4%~105%,具有操作简单、快速、灵敏度高,满足环境监测要求.     

Effects of phosphorus on uptake and translocation of methylmercury in rice

The aim of this study was to determine uptake and translocation of MeHg in the absence or presence of P in three rice cultivars, named Tianyou196 (TY196), NanJing35 (NJ35), and ZiXiangnuo (ZX). Rice seedlings from each cultivar were divided into two groups. One group was grown in normal P (+P) nutrient solution and the other in absence of P or starvation (?P) nutrient solution for 2 weeks. Both groups were subsequently exposed to 200 mg/L MeHg chloride culture solution and maintained in a greenhouse for 4 weeks. The results showed that the amount of reddish Fe plaque outside rice root was significantly increased by P starvation treatment, but in the +P treatments, rice roots remained white. It is proposed that Fe plaque formed sequestered MeHg and consequently reduced translocation of MeHg from roots to shoots. It is of interest that MeHg content in roots and shoots of TY196 and NJ35 was 11.1%–18.8% and 28.9%–32.3% lower than in ZX, respectively. Therefore, in practice, depletion of P to enhance Fe plaque formation in rice growing area is effective in preventing MeHg translocation from roots to shoots and ensures food safety in mine locations.     

Plausibility of toxicological interaction between lead and methylmercury

Humans are exposed to both lead (Pb) and methylmercury (MeHg), two chemicals known to affect the developing nervous system. It is therefore important to know whether these chemicals interact toxicologically to develop reliable estimates of human health risks. The nature of the potential interaction and how it may change with dose are also critical factors which need to be understood and considered in risk assessment. The available toxicological literature was reviewed and yielded five animal studies which involved combined exposure to both metals. None of these studies examined developmental neurotoxicity, the key endpoint of interest. Doses in these studies were also in the range of 1–100?mg?kg^?1?day^?1, which is far above average exposure levels for Pb and MeHg in the U.S. population. The combined exposure literature is therefore uninformative concerning the potential for Pb–MeHg interaction. A subsequent evaluation of the available mechanistic data was conducted, looking for similarities in proposed modes of action relevant at low doses. Shared biological targets suggesting a potential for low dose interaction include protein kinase C, calcium homeostasis, and apoptosis. Whether interaction actually occurs, and the form the interaction might take, remains to be studied. A phased research program is proposed that may provide data needed to address this significant data gap and permit more robust Pb and MeHg risk assessment.     

三峡水库消落带植物汞的分布特征

以三峡库区重庆段忠县石宝寨、涪陵珍溪和开县汉丰湖消落带为主要研究地点,调查并采集了植物样品,分析样品总汞和甲基汞,探讨三峡水库消落带植物汞的分布特征及植物汞库存量.结果表明,调查区域消落带植物总汞含量在(1.62±0.57)~(49.42±3.93)μg·kg-1范围,植物各部位总汞的含量呈根叶茎的趋势分布;植物甲基汞含量在(15.27±7.09)~(1 974.67±946.10)ng·kg-1范围,植物根部甲基汞含量高于茎和叶.同类植物中,开县汉丰湖消落带植物总汞和甲基汞含量均较忠县石宝寨、涪陵珍溪镇消落带植物略高;不同高程植物总汞及甲基汞储存量存在差异,145~150、150~160、160~170和170~175 m高程的植物总汞储存量分别为145.3、166.4、124.3和88.2 mg·hm-2,甲基汞储存量分别为1.9、2.7、3.6和3.2 mg·hm-2.消落带优势种植物对总汞的富集能力相对较弱(BAF1),而对甲基汞的富集能力相对较强(BAF1).     

三峡库区典型农田小流域水体汞的时空分布特征

以三峡库区典型农田小流域——重庆涪陵王家沟为对象,分别于2012年11月~2013年9月对流域内不同类型水体总汞(THg)和总甲基汞(TMeHg)含量进行为期1 a的监测,探讨汞在农田流域水体中的时空分布特征.结果表明,流域内水体THg、TMeHg浓度范围分别为1.12~64.04 ng·L-1、0(未检出)~4.24 ng·L-1,均值分别为(13.54±10.55)ng·L-1、(0.22±0.42)ng·L-1,各类型水体THg均以颗粒态为主,雨水和池塘水TMeHg以颗粒态为主,井水和沟渠水则相反.在空间分布上,THg表现为雨水最高,池塘次之,井水最低,W2井相较于其他井THg浓度最高,各沟渠点水体THg浓度差异不大;TMeHg表现为沟渠水最高,池塘次之,井水最低,井水TMeHg浓度下游大于上游,各沟渠点水体TMeHg浓度差异大,甲基化率为沟渠水>池塘水>井水>雨水.在时间变化上,各类型水体THg浓度均表现为冷季高于暖季,TMeHg浓度则因水体类型而异.综合分析发现雨水是流域内汞的重要来源;农田流域颗粒物的迁移是汞、甲基汞迁移的主要途径,地表径流是影响流域对水库汞负荷贡献量的重要因素.     

Methylmercury and sulfate-reducing bacteria in mangrove sediments from Jiulong River Estuary, China

Estuaries are important sites for mercury (Hg) methylation, with sulfate-reducing bacteria (SRB) thought to be the main Hg methylators. Distributions of total mercury (THg) and methylmercury (MeHg) in mangrove sediment and sediment core from Jiulong River Estuary Provincial Mangrove Reserve, China were determined and the possible mechanisms of Hg methylation and their controlling factors in mangrove sediments were investigated. Microbiological and geochemical parameters were also determined. Results showed that SRB constitute a small fraction of total bacteria (TB) in both surface sediments and the profile of sediments. The content of THg, MeHg, TB, and SRB were (350 150) ng/g, (0.47 0.11) ng/g, (1.4 1011 4.1 109) cfu/g dry weight (dw), and (5.0 106 2.7 106) cfu/g dw in surficial sediments, respectively, and (240 24) ng/g, (0.30 0.15) ng/g, (1.9 1011 4.2 1010) cfu/g dw, and (1.3 106 2.0 106) cfu/g dw in sediment core, respectively. Results showed that THg, MeHg, TB, MeHg/THg, salinity and total sulfur (TS) increased with depth, but total organic matter (TOM), SRB, and pH decreased with depth. Concentrations of MeHg in sediments showed significant positive correlation with THg, salinity, TS, and MeHg/THg, and significant negative correlation with SRB, TOM, and pH. It was concluded that other microbes, rather than SRB, may also act as main Hg methylators in mangrove sediments.     

甲基汞的大气-水-土壤界面交换通量

通过模拟实验和野外实测,对甲基汞在大气－水和大气－土壤的界面交换进行了初步研究．结果表明,甲基汞释放通量与水中的甲基汞浓度有关,水－气体系中甲基汞释放通量大于水－土－气体系中甲基汞释放通量;甲基汞在大气－土壤界面的释放通量为０．２１～３．０９ｎｇ·ｍ^-2·ｈ^-1;在大气－水界面的释放通量为０．１４～０．７９ｎｇ·ｍ^-2·ｈ^-1．     

春季胶州湾海水汞的形态研究

于2010-04对胶州湾进行定点连续采样,采用现场和室内分离测定的方法,分析了海水中汞的形态及其日变化特征,以进一步认识汞在近海环境中的归宿和环境效应.结果表明,胶州湾表层海水中溶解态元素汞(DEM)浓度为97.5 pg.L-1(38.2～156 pg.L-1),最高值和最低值分别出现在13:00和17:30,主要受潮汐和光照的影响.DEM含量随深度的增加而下降,表层海水DEM主要来源于Hg(Ⅱ)的光致还原.活性汞(RHg)、溶解态汞(DHg)浓度分别为7.94 ng.L-1(4.39～19.3 ng.L-1)和13.9 ng.L-1(7.32～49.1 ng.L-1),均在13:00出现最大值,主要是受潮汐带来污染较重的海水的影响.活性汞和溶解态汞浓度随水深变化的趋势相似,受到光照和水温的影响,表层海水活性汞占溶解态汞的比例最大.海水中活性汞平均占溶解态汞的62%,具有相对较高的活性和生物可利用性,为DEM的形成提供了条件.甲基汞(MeHg)浓度较低,平均为0.30 ng.L-1,部分未检出.     

城市景观水体甲基汞的形成机制及微宇宙模拟研究

汞对环境的危害已经成为研究热点之一,尤其是水体底泥作为污染物的主要储蓄库,其对水质以及生物的影响研究非常重要.本文以合肥市景观水体为研究对象,调查分析底泥中无机汞和甲基汞的污染现状,并采用微宇宙试验模拟"底泥-水-草-鱼"生态系统中无机汞和甲基汞的转化过程及其甲基汞的富集机制.结果表明,合肥市景观水体10个底泥样品中无机汞和甲基汞含量范围分别在11.74~13.12μg·kg~(-1)和0.37~2.23μg·kg~(-1)之间.微宇宙模拟试验显示,随着培养时间增加,底泥中无机汞含量逐渐减小,甲基汞含量先增加后递减至平衡;水体中无机汞和甲基汞含量均呈递增趋势;水蕴草和草金鱼中无机汞的含量呈先增长后下降趋于平衡趋势,但总量较小,而水蕴草和草金鱼对甲基汞均具有较高的富集能力,其中,草金鱼(身)对甲基汞富集能力最强,其富集系数也最大.