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Evaluation of mercury methylation in fresh and pre dried sediments using ^(203)Hg radioisotope

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Journal of Environmental Sciences 2000年第S1期12卷 66-75页

作者： J.R.Ikingura 1, H.Akagi 2, J.R.D.Guimaraes 3 (1. university of Dar es Salaam, P.O.Box 35052, Dar es Salaam, tanzania 2. Nat. Inst. for Minamata Disease, 4058 Hama, Minamata, 867 Kumamoto, Japan 3. Lab. de Radioisotopos, Universidade Federal Do Rio

Mercury methylation rates in fresh and pre dried river sediments were determined in sediment water systems spiked with 203 HgCl 2 at a level of 0.75—0.95 ppm as Hg. At the end of the incubation period (21—38 days), methylmercury production in the fresh sediments was in the order of 3.0% to 13.75%, whereas in the pre dried sediments the methylation was much lower, at 0.6% to 3.9%. The highest methylation levels were generally recorded in the uppermost, 1 cm layer of the sediment column. Total mercury concentration in water in equilibrium with the 203 Hg spiked fresh sediments was in the range of 44.7 to 634 ng/L, whereas in equilibrium with the pre dried sediments the concentration was in the range of 19.5 to 34.5 ng/L. The proportion of methylmercury to total mercury in the water varied from 9.4% to 66.6% over the fresh sediments, and from 7.1% to 10.8% over the pre dried sediments. In the system consisting of water, sediment and sediment inverterbrates the concentrations of methylmercury were 8.61 to 15.69 ng/g in the sediment, 0.011 ng/ml in the water, and 9.22 to 40.69 ng/g in the inverterbrates. Methylmercury bioaccumualtion factors (BAFs) were in the order of 274 to 8087 relative to the water, and 0.25 to 7.31 relative to the sediment. These results provide further evidence for the tendency of methylmercury to accumulate in high concentrations in aquatic organisms, even at very low total mercury concentration in water.

关键词： mercury methylation rate methylmercury partitioning tropical river sediment

维普期刊数据库

Risk factors for HIV infection among women in Dodoma region,tanzania

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现代妇产科进展 2002年第2期11卷 157-160页

作者： Zhang Shiqian 1,Tagalala WP 2,Hamissi NM 2,Soka HU 2,Massi MM 2,Jiang Sen 1 (1.QiLu Hospital of Shandong university,Jinan China 250012 2.Regional Hospital,P.O.Box 904,Dodoma,tanzania) QiLu HospitalofShandongUniversityJinanChina250012 Regional HospitalP.O.Box904DodomaTanzania

Objective To investigate the risk factors of HIV infection among women in the Dodoma region,*** The protocol were assessed through a population-based cross sectional *** participants were obtained by randomly selecting clusters of 10-households from Unga imited, Babati town and Matufa roadside village which are urban,semi-urban and rural communities *** verbal consent for participation in an interview and in HIV testing was sought from each respondent. Blood samples were collected from each consenting individual for HIV antibody testing using enzyme linked immunosorbent assay(ELISA) and all positive sera were confirmed using repeated ELISA *** on risk factors was obtained through the interview process using a structured *** Of 567 women who gave blood samples, 48(8.5%) were HIV *** HIV seroprevalence rates among women in the urban area,the semi-urban area and in the rural village were 14.4%, 6.9% and 2.3%*** associated with significantly higher HIV seroprevalence were urban residence,history of having travelled out of Dodoma region within tanzania,as well as having travelled abroad,having multiple sexual partners and having sexual intercourse under the influence of *** who reported ever having used condoms had significantly higher probability of being infected with HIV than those who had never used condoms,suggesting that condom use may be a marker of high risk sexual behavior and that condom use was probably not adhered to in a way that consistently protects against HIV *** The results suggest the need for health education interventions aimed at increasing appropriate and consistent condom use and reduction of the number of sexual partners.

关键词： HIV infections Risk factors Women tanzania

Agronomic and Economic Potential of Tughutu and Minjingu Phosphate Rock as Alternative Phosphorus Sources for Bean Growers

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Pedosphere 2007年第6期17卷 732-738页

作者： P.A.NDAKIDEMI Research and Technology Promotion Cape Peninsula university of Technology Cape Town CampusKeizersgrachtP.O.Box 652Cape Town 8000(South Africa).

On-farm experiments were conducted in farmers' fields at 6 different sites in Western Usambara Mountains(WUM)in northern tanzania during the 2000-2001 cropping *** objectives were to study the effects of Tughutu(Vernonia subligera ***)pruning in combination with Minjingu phosphate rock(MPR)or triple super phosphate(TSP)supply on the concentration of P in the tissues and seed yields of common bean,and to assess the economic returns of these different technologies to *** experimental design was a randomized complete block with each of the 6 farmers' fields used as a *** treatments included:control,MPR or TSP each at 26 kg P ha^(-1),Tughutu at 2.5 t ha^(-1), and Tughutu at 2.5 t ha^(-1)combined with MPR or TSP at 26 kg P ha^(-1). Addition of MPR or TSP alone significantly raised P concentration in bean shoots from 1.27 mg g^(-1)to 1.70 and 1.95 mg g^(-1)*** MPR or TSP with Tughutu increased P concentration above the proposed deficiency level of 2 mg g^(-1).The relative agronomic effectiveness(RAE)of MPR ranged from 12.5% to 45.0%.Seed yields of common bean was markedly increased by 28%-104% from MPR or TSP supply alone,and 148%-219% from Tughutu application combined with 26 kg P ha^(-1)of MPR or TSP relative to the *** Tughutu alone,seed yield increased by 53%. From economic analysis,the increase in seed yield with the supply of MPR or TSP combined with Tughutu translated into a significantly(P≤0.001)higher marginal rate of return and dollar profit for common bean farmers in WUM in northern *** is concluded that Tughutu and its combined application with MPR or TSP is an appropriate integrated nutrient management strategy that may increase bean yields and dollar profit to the rural poor communities in tanzania.

关键词： integrated nutrient management marginal rate of return P concentration profit relative agronomic efficiency

维普期刊数据库

坦桑尼亚农业地域差异的经济地理分析——热带非洲农业地理的一例

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热带地理 1988年第1期8卷 82-93页

作者：姜忠尽南京大学地理系

坦桑尼亚地处赤道南侧热带地区,介于南纬0°59′～11°44′、东经29°19′～40°30′之间,面积近94万平方公里,人口2000多万。全境属于东非高原的南半部分,起伏的地形使水热条件垂直差异明显打破了生物气候水平地带性的分布规律。境内... 详细信息

坦桑尼亚地处赤道南侧热带地区,介于南纬0°59′～11°44′、东经29°19′～40°30′之间,面积近94万平方公里,人口2000多万。全境属于东非高原的南半部分,起伏的地形使水热条件垂直差异明显打破了生物气候水平地带性的分布规律。境内热量资源丰富(全年各月平均温度在16℃以上)、雨量较多(全国80%的地区年雨量在600毫米以上)、植物种质资源多达3000～3500种。但地广人稀(每平方公里仅22人)、且分布极不均衡,在国土边缘分布相对集中,而广大内陆则人烟稀少;部族众多、分布集中,各自保持着传统的社会结构、文化和土地利用方式。殖民统治时期,大批欧洲移民强占境内的良田沃土,发展了高度商品化的出口农业。坦桑尼亚农业地域差异就是在这种复杂的地理背景下形成的。

关键词：坦桑尼亚经济地理分析农业地理地域差异

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某地区铀矿远景区矿产勘查地球物理方法应用

能源研究与管理 2021年第1期 110-117页

作者：刘承志东华理工大学

非洲地区矿产资源丰富,铀资源储量十分巨大,但经济条件较差,各种勘探手段较为落后,因此在非洲一些国家从事铀矿勘探成为了各国矿产勘探人员的一个新方向。根据坦桑尼亚某地区已有资料,通过放射性勘探方法进行分析、筛选,找出了铀矿关系... 详细信息

非洲地区矿产资源丰富,铀资源储量十分巨大,但经济条件较差,各种勘探手段较为落后,因此在非洲一些国家从事铀矿勘探成为了各国矿产勘探人员的一个新方向。根据坦桑尼亚某地区已有资料,通过放射性勘探方法进行分析、筛选,找出了铀矿关系密切的断层和含矿地层。并依托已有的物探数据资料,对研究区的地球物理数据资料进行成图、分析、解释,圈定成矿有利地段及有找矿意义的异常,揭露部分基岩中具有高铀含量、低钍含量的特征,并在断裂附近发现氡气异常显示,证明了放射性勘探方法在远景区预测矿产深部铀矿方面具有一定潜力,也为研究区下一步异常查证、矿产勘查提供工作依据

关键词：坦桑尼亚地区深部铀矿放射性勘探远景区预测

Genetic diversity and phylogenetic relationship of wild type and cultivated kenaf germplasm as revealed by ISSR analysis

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Genetic diversity and phylogenetic relationship of wild type...