烟草头孢霉F2对氯化汞解毒作用的研究

烟草头孢霉F_2在含200mg/L HgCl_2的液体培养基中生长16h,汞量减少了90％,此后菌量迅速增加,试验了营养条件、HgCl_2浓度、前培养条件、pH及温度等对F_2菌汞解毒作用的影响,初步研究了解毒作用机理.结果表明,该菌能将HgCl_2还原成为元素汞,据分析,约12％的汞挥发到气相中,7％被菌体吸收,其余以元素汞颗粒的形态沉积在培养液底部.     

Mercury pollution and control in China

Before 1970s the Second Songhua River and Ji Canal of China had been polluted seriously by mercury. During peak pollution period, mercury levels in water, sediment and fish body of these rivers were close to or even higher than that of famous Minamata Bay of Japan. Some residents who live near to the polluted rivers were affected and the methyl mercury values in their blood, hair and urine were higher than normal people obviously . Since the fish had decreased even vanished in these rivers, so the food chain that transfers mercury to human also was out off almostly. However, nervous symptoms of Minamata disease were discovered among fisherman who had eaten more fishes. This report relates the stories about the mercury pollution of the Second Songhua River and Ji Canal.     

北京市区及郊区大气中的汞沉降的估算

以Throughfall法估算出北京市1996年大气汞干沉降率为528．88μg.m^2.a^-1，以沉降速率估算出1998年北京市汞的年沉降量为687．5μg.m^-2.a^-1。     

Neurotransmitter level changes in domestic ducks(Shaoxing duck) growing up in typical mercury contaminated area in China

The neurotransmitter le vel changes of ducks exposed 8-month in a mercury-polluted site(Wanshan, China) and a reference site ( Shanghai, China) were examined. Chemical analyses showed both higher mercury and selenium concentrations in the organ of Wanshan ducks. An increased content of acetylcholine(ACh) in brain and blood and a decreased activity of acetylcholinesterase(AChE) in blood were observed. Moreover, there was an increasing trend for nitric oxide synthase(NOS) activity and nitric oxide(NO) production in duck brain, but a reduction of NOS activity in duck serum. The possible explanations were due to the interactive effect of selenium accumulation and the sublethal exposure level of mercury in Wanshan area. The present study showed that AChE and NOS were sensitive to mercury contamination of real circumstance, suggesting that these two indexes have the potential to be biomarkers in assessment of health effects by mercury contamination.     

青海湖沙柳河流域不同时期地表水与地下水的相互作用

氢氧稳定同位素技术是研究地表水和地下水相互作用的有效手段。依据青海湖沙柳河流域2018年消融期、多雨期和冰冻期所收集的降水、河水和地下水样品中对氢氧同位素组成（δD、δ¹⁸O）的测定结果,识别和量化不同时期高山草原带和高山草甸带地表水和地下水间的补给关系和比例,其目的旨在明确高寒内陆河流域地表水和地下水δD和δ¹⁸O受降水影响的时空差异。结果表明：青海湖沙柳河流域地表水和地下水δD和δ¹⁸O值受降水响应存在时空差异性,δD和δ¹⁸O值在消融期受降水影响最强,冰冻期最弱;在高山草甸带δD和δ¹⁸O值受降水的影响强于高山草原带。消融期的高山草甸带、高山草原带和冰冻期的高山草原带地表水补给地下水的比例分别为80.65%、93.36%和89.44%;多雨期的高山草甸带、高山草原带和冰冻期的高山草甸带地下水补给地表水的比例分别为44.50%、74.85%和88.58%。研究结果可为该流域水资源优化配置和管理提供科学依据。     

岩溶流域地表水和地下水硝酸盐来源定量识别

选取岩溶地区花溪河流域典型农业区为研究对象,运用δ¹⁵N-NO₃^-,δ¹⁸O-NO₃^-和δ¹⁸O-H₂O同位素示踪技术和水化学分析方法,阐明了研究区地表水和地下水中硝酸盐的分布特征,并揭示其来源和形成过程,基于R语言下运行的贝叶斯模型（stable isotope analysis in R）,对研究区水体中各种硝酸盐来源的贡献比例进行了定量识别.结果显示：受碳酸岩盐风化的控制,流域内地表水和地下水的水化学类型以HCO₃-Ca型为主,硝酸盐在研究区水体中的空间分布特征受土地利用类型影响明显;在研究区水体硝酸盐形成过程中,硝化作用起主导作用,水体中的硝酸盐来源主要有化肥、降雨中的氨盐、土壤有机氮、粪便和污水,与地表水相比,地下水中硝酸盐受粪便和污水的影响较大;基于SIAR源解析模型分析,大气沉降、化肥、土壤有机氮和粪便污水对研究区地表水硝酸盐的贡献比例分别为3.97%、26.87%、36.80%和32.37%,对地下水硝酸盐的贡献比例分别为2.83%、13.96%、21.03%和62.18%.     

100 years of high GEM concentration in the Central Italian Herbarium and Tropical Herbarium Studies Centre (Florence, Italy)

Up to 1980s, the most used preservative for herbaria specimens was HgCl₂, sublimating at ambient air conditions; ionic Hg then reduces to Hg⁰ (gaseous elemental mercury, GEM) and diffuses throughout poor ventilated environments. High GEM levels may indeed persist for decades, representing a health hazard. In this study, we present new GEM data from the Central Italian Herbarium and Tropical Herbarium Studies Centre of the University of Florence (Italy). These herbaria host one of the largest collection of plants in the world. Here, HgCl₂ was documented as plant preservative up to the 1920s. GEM surveys were conducted in July 2013 and July and December 2017, to account for temporal and seasonal variations.Herbaria show GEM concentrations well above those of external locations, with peak levels within specimen storage cabinets, exceeding 50,000?ng/m³. GEM concentrations up to ~ 7800?ng/m³ were observed where the most ancient collections are stored and no ventilation systems were active. On the contrary, lower GEM concentrations were observed at the first floor. Here, lower and more homogeneously distributed GEM concentrations were measured in 2017 than in 2013 since the air-conditioning system was updated in early 2017.GEM concentrations were similar to other herbaria worldwide and lower than Italian permissible exposure limit of 20,000?ng/m³ (8-hr working day). Our results indicate that after a century from the latest HgCl₂ treatment GEM concentrations are still high, i.e., the treatment itself is almost irreversible. Air conditioning and renewing is probably the less expensive and more effective method for GEM lowering.     

燃煤烟气污染物控制装置协同脱汞特性研究

采用Ontario Hydro方法对某100MW燃煤机组进行了烟气汞取样测试,获得了选择性催化还原（SCR）脱硝装置、静电除尘器（ESP）和湿法烟气脱硫装置（WFGD）对烟气汞形态转化和脱除特性规律.借助程序升温脱附（TPD）、扫描电子显微镜分析（SEM）和X射线荧光光谱分析（XRF）等方法探究了飞灰对汞的吸附特性及吸附后汞的热稳定性.结果表明,在75% MCR和85% MCR不同的机组负荷下,SCR+ESP+WFGD对烟气总汞（Hg^T）的联合脱除率分别为92.83%、81.66%.SCR对元素汞（Hg⁰）的氧化率与燃煤氯（Cl）含量正相关,Cl含量为500mg/kg时,氧化率高达96.18%.ESP在完全脱除颗粒汞（Hg^P）的同时对Hg⁰和氧化态汞（Hg²⁺）的平均脱除率分别为12.73%和27.79%,ESP飞灰中的未燃尽炭和金属氧化物（Al₂O₃、Fe₂O₃）是吸附气态汞的关键组分,汞在飞灰表面主要以HgCl₂、HgS（红色）和HgO的形态存在,高于190℃时会分解再释放.WFGD对Hg²⁺的平均脱除率为91.10%,并能将部分Hg²⁺还原成Hg⁰,存在明显的汞二次释放问题.     

蓄水对水库下游食物网中汞生物累积影响研究进展

1991年,加拿大学者Verdon首次报道了加拿大拉格朗德二级水库下游鱼体中汞含量显著高于水库库区的现象,发现水库下游是新建水库汞输出的重要场所,因此水库下游鱼类汞升高的风险继水库本身后成为新的关注热点.通过对相关野外研究的回顾,表明蓄水对水库下游食物网的鱼类、浮游生物以及水体中汞的富集产生影响,水生食物网中各组分甲基汞含量和比例随着营养级的升高而增加.蓄水加速了水库的甲基化过程,使水库自身成为巨大的汞源,不仅影响水库自身食物网中汞的分布,而且更加剧烈地影响水库下游食物网中汞的分布.水库既向下游直接输送溶解态和悬浮颗粒态的甲基汞,又向下游输送丰富的、可被杂食性鱼类和动物直接利用和吸食的甲基汞食物源.在下游食物网中,甲基汞有可能通过微型浮游生物网（悬浮颗粒物-浮游植物-浮游动物经典食物链）,或者通过杂食性鱼类主动摄食来自水库直接输送的浮游动物,或者通过杂食性鱼类被动吸食来自水库直接输送的悬浮颗粒物富集途径,向位于更高营养级位置的鱼类进行传递.在我国,水库蓄水对下游汞输送机制以及对下游微型、底层食物网中生物累积和迁移转化的影响需要更加深入的定量研究.      

典型燃煤电厂汞的分布、迁移及释放特征研究

采集安徽不同地区两典型燃煤电厂火力发电中使用的原煤及其产生的3类固体副产物(飞灰,炉渣及脱硫石膏样品),对4类样品中汞含量分别进行测定,以此揭示电厂燃煤过程中汞的分布、迁移及转化规律。此外,采用质量平衡及二次排放模型分别初步估算了电厂燃煤及燃煤固体副产物再利用过程中汞的两次释放特征。结果显示,汞在原煤、飞灰、炉渣及脱硫石膏样品中的含量分别为174~321μg/kg、421~316μg/kg、6~3 143μg/kg和2 988~4 694μg/kg;燃煤过程中有20.9%~23.6%的汞转移到飞灰中,32.6%~59.9%的汞赋存于脱硫石膏中,16.5%~37.4%的汞通过烟囱首次排入大气,仅有0.02%~9.2%的汞残留在炉渣中。二次排放模拟结果显示,燃煤电厂1#和2#中飞灰和脱硫石膏的高温再利用过程将向大气二次释放汞量96.0 kg/a和165.8 kg/a,两次年排放总量分别为189.5 kg和640.8 kg。本研究可为燃煤电厂汞的污染过程控制提供参考依据。