Biomonitoring of Lead in Atmospheric Environment of An Urban Center of the Ganga Plain, India

Monitoring of atmospheric lead from the Dalbergia sissoo treewas undertaken at Lucknow urban centre of the Ganga Plain, India.Atotal of 26 leaf samples were collected in spring, monsoon and winter seasons from 16 sampling sites and was analysed by Atomic Absorption Spectrophotometry method. Lead concentrations were low in spring season, increased in monsoon to winter seasons and range from 2.1 to 28.2 μg/g (dry wt.). This accumulative response of lead in the tree leaves is directly linked with the exposure time of automobile emission that is considered to be the predominant source for it. Highway localities show higher lead concentrations by a factor of 2 as compared to urban localities. Highest concentration was recorded at Sitapur Road (National Highway No. 24) in winter season. A linear quantitative relationship between urban air-lead levels and lead-in-the Dalbergia sissoo leaves is used to infer the qualitative assessment of present day atmospheric lead pollution. Reported results suggest a drastic reduction in mean lead concentration in Lucknow urban air from 1.32μg/m3 in 1994 to 0.19μg/m3 in 2002. Similarly, mean lead concentration in the tree leaves during winter season also dropped from 17.9 μg/g in 1994 to 8.1 μg/g in 2004. Despite of increasing urban population, urban area, vehicle population and traffic density, the introduction of unleaded-petrol (vehicular fuel) keeps lead level in the urban environment of Lucknow much lower than the past. Like Lucknow, other urban centres of the Ganga Plain are also on way to the exponential increase in pressure of urbanization. An appropriate urban public transport planning is required to provide healthy atmospheric environment for millions of people especially future young generation.     

广东鼎湖山斑岩钼矿区生物地球化学特征

本文对从钼矿区和对照区采集的岩石、土壤和植物样品的研究表明,矿区岩石与土壤中钼含量的相关系数为0.74,土壤与马尾松、桃金娘、鼠刺和芒箕叶片中钼含量的相关系数分别为0.9,0.87,0.98和0.99。在马尾松、桃金娘、鼠刺、芒箕和藤黄檀的叶片中,矿区相对于对照区,前者的最高钼含量是后者的18倍、53倍、12倍、46倍和35倍。钼含量高的土壤中生长的藤黄檀的细胞,在电子显微镜下其结构发生明显变化,主要表现为核膜界限消失,核仁解体,叶绿体结构受到破坏,细胞中有颗粒物存在。钼还会抑制植物叶片对镁的吸收。因此利用生物地球化学特征可以找出隐伏在植被下的矿床。     

慢生根瘤菌DG的分离、鉴定及其与降香黄檀的共生关系

从大果紫檀根瘤中分离到一株慢生型根瘤菌DG,通过其形态特征观察、保守基因序列分析以及生物学特性研究等方面进行种类鉴定,通过结瘤试验了解DG与降香黄檀的共生关系,并探讨其共生固氮能力.16S rRNA、nifH和dnaK系统发育结果表明,该菌株与Bradyrhizobium elkanii同源性最高.菌株DG与B,elkanii USDA76T在碳源利用、抗生素抗性、耐受NaCl等生物学特性上基本一致,而且还能在pH 10.0下良好生长.结瘤试验显示,菌株DG能在降香黄檀根部结瘤;接种DG的降香黄檀幼苗植株的株高、干重以及全氮含量(P<0.05)显著高于对照处理,表明DG能与降香黄檀形成良好的共生关系,且具有高效的固氮能力.图4表2参27