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21.
This paper attempts to discuss the links between the geochemical composition of rocks and minerals and the geographical distribution of diseases in human beings in Nigeria. We know that the natural composition of elements in our environment (in the bedrock, soils, water, and vegetation) may be the major cause of enrichment or depletion in these elements and may become a direct risk to human health. Similarly, anthropogenic activities such as mining and mineral processes, industrial waste disposal, agriculture, etc., could distort the natural geochemical equilibrium of the environment. Thus, the enrichment or depletion of geochemical elements in the environment are controlled either by natural and/or anthropogenic processes. The increased ingestion of toxic trace elements such as As, Cd, Hg, Pb, and F, whether directly or indirectly, adversely affects human health. Of these, Cd has most dangerous long-term effect on human health. Environmental exposure to As and Hg is a causal factor in human carcinogenesis and numerous cancer health disorders. Available information on iodine deficiency disorder (IDD) in Nigeria indicates goiter prevalence rates of between 15% and 59% in several affected areas. There have been reported cases of dental fluorosis resulting from intake of water with fluoride content >1.5 ppm. Dental caries among children shows an overall prevalence rate of 39.9%. Within the Younger Granite province in central Nigeria, cases of cancer and miscarriages in pregnant women have been linked to natural radiation These examples and a number of others from the existing literature underscore the pressing need for the development of collaborative research to increase our understanding of the relationship between the geographical distribution of human and animal diseases in Nigeria and environmental factors. We submit that such knowledge is essential for the control and management of these diseases. 相似文献
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Hansen V Roos P Aldahan A Hou X Possnert G 《Journal of environmental radioactivity》2011,102(12):1096-1104
Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope 129I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environmental mobility is strongly linked to organic matter.Due to its long half-life (15.7 million years), 129I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of 129I and 127I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The different forms of iodine are related to water soluble, exchangeable, carbonates, oxides as well as iodine bound to humic acid, fulvic acid and to humin and minerals. This is the first study to identify 129I in humic and fulvic acid and humin. The results show that 30-56% of the total 127I and 42-60% of the total 129I are associated with organic matter in soil and sediment samples. At a soil/sediment pH below 5.0-5.5, 127I and 129I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 129I was mostly found to be bound to fulvic acid. Anoxic conditions seem to increase the mobility and availability of iodine compared to oxic, while subaerial conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions. 相似文献
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利用碘消除碱性和中性溶液中硫化物及硫代硫酸盐对 Cr+ 6 测定的干扰 ,经实验找出了含硫化物和硫代硫酸盐工业废水中 Cr+ 6的测定方法 相似文献
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This paper deals with some endemic diseases related to selenium, iodine and fluoride in eco-environment. Keshan disease and Kaschin-Beck disease are associated with low selenium, they mainly occur in a belt zone across China ranging from North-East to South-West. Selenium contents in food grains and human hair from the disease affected areas are usually below 0.020ppm and 0.20ppm respectively. The endemic goitre caused by iodine deficiency distributes extensively in China, mainly in mountainous and hilly districts, swamp and peat areas, some sand soil and limestone areas. Also there is another kind of endemic goitre which caused by iodine excess in interior and coast areas. Endemic cretinism usually occurs in the endemic goitre seriously affected areas. Endemic fluorosis is also widely distributed in China, but mainly occurs in dry or semi-dry areas of north China. The fluoride sources for causing endemic fluorisis are drinking water and food grains polluted by coal smoke in the backing process of maize 相似文献
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Preparation of iodine doped titanium dioxide to photodegrade aqueous bisphenol A under visible light
Highly photoactive iodine-doped titanium dioxide (I-doped TiO2) photocatalysts were synthesized to degrade aqueous bisphenol A (BPA) under irradiation by visible light and sunlight. The band gap energies of TiO2 and I-doped TiO2 (I/Ti mole ratio = 0.5%) were 3.01 and 3.04, and the BPA photodegradation rate constants were 1.61, and 5.11 h−1, respectively. The most probable reaction mechanism was proposed to involve IO4− and IO3− as electron acceptors that generate an inductive effect, increasing the photocatalytic efficiency of TiO2. Results indicated that I-doped TiO2 not only acted favorably as a photocatalyst, but also exhibited considerable mineralization effects. In addition, a recycling test after ten experiments demonstrated the stability and reusability of the photocatalyst. 相似文献
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在柠檬酸介质中,I-对KIO3氧化结晶紫的反应有催化效应,据此建立了测定微量I-新的催化动力学光度法.方法的检出限为0.185μg/ml,测定范围为5~70μg/25ml,用本法对环境水样进行了测定,结果满意。 相似文献
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本文研究结果表明,在自然环境缺碘地区持续投放含碘浓度25ppm 的“NaCLI—固”后出生的儿童身高体重发育水平接近对照地区的中等水平;缺碘地区儿童甲状腺激素 T_4、T_3、T_4/T_3比值均在正常范围,甲状腺功能状态基本正常,提示机体内环境缺碘程度已得到纠正;缺碘区儿童 IQ 低下检出率明显高于对照区,血清 Zn 水平则无显著性差异,表明这部分低智儿童与在胚胎期间碘元素相对缺乏有着密切关系. 相似文献
30.
A robust and rapid methodology for the determination of iodine by inductively coupled plasma mass spectrometry in environmental
samples is presented. Data were initially obtained for the validation of the analytical measurements, using 17 commercially
available soil reference materials. The methodology was then tested on soil and water samples collected in Afghanistan where
iodine deficiency and its effects are reportedly prevalent. Sample collections were conducted in Greater Kabul; the iodine
in agricultural soils was determined to be in the range of 1.6–4.2 mg/kg and that in water drawn for drinking and irrigation
was found to range from 9.9 to 22.7 μg/L. Samples were also collected in a second region, Nangarhar province, which is located
to the east of Kabul, where goitres in the local population had been reported. The iodine content in soils and water at this
location was 0.5–1.9 mg/kg and 5.4–9.4 μg/L, respectively. The organic content of soils in Kabul was found to be in the range
of 1.9–4.2%; in Nangarhar, organic content ranged from 1.7 to 4.5%. All of the Afghan soils were slightly alkaline at pH 7.6–8.2. 相似文献