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371.
Neal K. Broomhead Roshila Moodley 《Journal of environmental science and health. Part. B》2020,55(4):406-415
AbstractCarpobrotus dimidiatus is an indigenous South African medicinal plant species from the Aizoaceae family that bears edible fruit that is consumed for nutritional value. In this study, the elemental distribution in C. dimidiatus fruit and growth soil from fifteen sites in KwaZulu-Natal (South Africa) was determined along with soil pH, soil organic matter and cation exchange capacity, to assess for nutritional value and the effect of soil quality on elemental uptake. The results showed elemental concentrations in fruit to be in decreasing order of Ca (6235–32755?mg kg?1) > Mg (2250–5262?mg kg?1) > Fe?>?Mn?>?Zn (20.9–50.6?mg kg?1) > Cu (3.83–20.6?mg kg?1) > Pb?>?Cr?>?Cd?>?As?~?Co?~?Ni?~?Se and no potential health risk due to metal toxicity from average consumption. For sites that had high levels of Cd and Pb, bioaccumulation occurred from atmospheric deposition. Concentrations of elements in soil were found to be in decreasing order of Fe (1059–63747?mg kg?1) > Ca (1048–41475?mg kg?1) > Mg?>?Mn (9.76–174?mg kg?1) > Cr (1.55–135?mg kg?1) > Zn (0.76–58.2?mg kg?1) > Se?>?Cu?>?Ni?>?Pb?>?Co?>?As?~?Cd with no evidence of heavy metal contamination. This study revealed that the plant inherently controlled uptake of essential elements according to physiological needs and that the concentrations of essential elements in the fruit could contribute positively to the diet. 相似文献
372.
373.
干旱指标及其在新疆阿勒泰地区干旱监测分析中的应用 总被引:2,自引:0,他引:2
干旱是限制新疆阿勒泰地区农牧业生产可持续发展最主要的自然灾害之一,研究适合该区的干旱指标,是进行有效干旱监测的基础。采用新疆阿勒泰地区7个气象站1961-2008年4-10月月平均气温、降水量资料,首先通过Thomthwaite方法计算潜在蒸发量确定K干旱指数,然后对R指数、Z指数、K指数3种干旱指标进行了分析,结果表明,在监测诊断干旱轻重程度上,K指数能较客观地反映出干旱程度,R指数和Z指数监测干旱程度较轻。在此基础上,基于K指数建立的阿勒泰地区干旱监测评价的强度指数和面积指数,对该地区近48年来干旱的变化进行了分析,表明该地区干旱灾害主要集中在春夏季节,春夏连旱几率较高,强度较大;该地区干旱灾害具有阶段性特征,近年来干旱发生的频次有增多的趋势,其中秋季干旱相对较为明显。 相似文献
374.
375.
中国环保产业运行机制论 总被引:1,自引:0,他引:1
本文从环保产业运行机制的理论依据入手,阐述新世纪中国环保产业化的必然性和推进环保产业化的必要性,再从宏观、中观和微观层面设计中国现代环保产业的运行机制。 相似文献
376.
离子色谱法测定水中主要阳离子 总被引:7,自引:0,他引:7
报导了水中阳离子Li^+,Na^+,K^+,Ca^2+〉Mg^2+的离子色谱分析及其分析精密度,准确性和线性范围。与阴离子组分同时测定用于水中离子总量的分析,获得满意结果。 相似文献
377.
采用熔盐法制备了能级位置可控的钾离子掺杂石墨相氮化碳催化剂(g-C3N4),并考察了其在可见光下降解罗丹明B(RhB)性能.采用XRD、UV-Vis、XPS、N2吸附、PL、EIS等手段对催化剂进行了表征.结果表明,钾离子的引入降低了催化剂粒径尺寸,提高了比表面积,改善了光生电子-空穴对的分离效率.不仅如此,通过控制钾离子掺杂量可以实现催化剂的能级位置在一定范围内的任意调变,使有机污染物的氧化降解反应从·O2-单一氧化剂反应变成·OH和·O2-双氧化剂反应,大大提高了降解率.制备的钾离子掺杂g-C3N4的RhB降解速率常数达到0.022min-1,是纯g-C3N4的5倍.不仅如此,通过对能级位置的调控,制备的催化剂对其他多种有机污染物如甲基蓝,苯酚等的降解率也有显著提高. 相似文献
378.
William A. Battaglin Earl M. Thurman Stephen J. Kalkhoff Stephen D. Porter 《Journal of the American Water Resources Association》2003,39(4):743-756
ABSTRACT: Most herbicides applied to crops are adsorbed by plants or transformed (degraded) in the soil, but small fractions are lost from fields and either move to streams in overland runoff, near surface flow, or subsurface drains, or they infiltrate slowly to ground water. Herbicide transformation products (TPs) can be more or less mobile and more or less toxic in the environment than their source herbicides. To obtain information on the concentrations of selected herbicides and TPs in surface waters of the Midwestern United States, 151 water samples were collected from 71 streams and five reservoir outflows in 1998. These samples were analyzed for 13 herbicides and 10 herbicide TPs. Herbicide TPs were found to occur as frequently or more frequently than source herbicides and at concentrations that were often larger than their source herbicides. Most samples contained a mixture of more than 10 different herbicides or TPs. The ratios of TPs to herbicide concentrations can be used to determine the source of herbicides in streams. Results of a two‐component mixing model suggest that on average 90 percent or more of the herbicide mass in Midwestern streams during early summer runoff events originates from the runoff and 10 percent or less comes from increased ground water discharge. 相似文献
379.
Tamie L. Veith Mary Leigh Wolfe Conrad D. Heatwole 《Journal of the American Water Resources Association》2003,39(6):1331-1343
ABSTRACT: A combinatorial optimization procedure for best management practice (BMP) placement at the watershed level facilitates selection of cost effective BMP scenarios to control non point source (NFS) pollution. A genetic algorithm (GA) was selected from among several optimization heuristics. The GA combines an optimization component written in the C++ language with spatially variable NFS pollution prediction and economic analysis components written within the Arc View geographic information system. The procedure is modular in design, allowing for component modifications while maintaining the basic conceptual framework. An objective function was developed to lexicographically optimize pollution reduction followed by cost increase. Scenario cost effectiveness is then calculated for scenario comparisons. The NPS pollutant fitness score allows for evaluation of multiple pollutants, based on prioritization of each pollutant. The economic component considers farm level public and private costs, cost distribution, and land area requirements. Development of a sediment transport function, used with the Universal Soil Loss Equation, allows the optimization procedure to run within a reasonable timeframe. The procedure identifies multiple near optimal solutions, providing an indication of which fields have a more critical impact on overall cost effectiveness and flexibility in the final solution selected for implementation. The procedure was demonstrated for a 1,014‐ha watershed in the Ridge and Valley physiographic region of Virginia. 相似文献
380.