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对1990-2000年新疆铁路沿线地区220个大风灾害日和2000-2010年300个大(暴)雪日灾情进行了分析,以1961-2008年年均冬季最大雪深、1961-2010年年均最大风速和致灾性大风日数及承灾体脆弱性作为铁路沿线雪风灾评价指标,基于GIS空间分析对拟建铁路沿线地区的雪风灾进行了区域划分和致灾性定量分析。结果表明:①冬春季是铁路沿线雪灾高发季。拟建铁路阿勒泰-富蕴段、塔城-额敏段为重雪灾区。在铁路弯道设计、防风墙建设方面应进行严格科学论证,作好积雪防护。②大风致灾事件多发生在4-6月。拟建铁路吐鲁番境内柴窝铺-了墩段位于大风高值区,年均大风日60 d以上,哈密-若羌段40 d左右,塔什库尔干-阿克陶段25 d左右。建议在大风地区修建"挡风墙"并修建防护林带和保护铁路沿线现有稀疏植被。 相似文献
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针对污水处理生化出水高磷酸盐浓度对水体富营养化影响的问题,采用阴离子交换树脂(AER)为基质材料,利用树脂上—NH2官能团中的N原子与Fe3+发生配位聚合,制备了除磷聚合配位交换吸附剂(Fe—PLE)。并采用Langmuir和Freundlich等温吸附方程对Fe—PLE和原AER进行了比较,发现Fe—PLE更加趋向化学吸附类型,且Fe—PLE最大吸附容量达到93.05 mg/g,比AER提高了47.98%。通过SEM、EDS、FT-IR及TGA对吸附前后Fe—PLE和AER的表征比较,认为通过配位作用形成Fe—O配位键是Fe—PLE的可溶性无机磷吸附效率提高的主要原因。通过静态吸附实验考察了吸附时间、pH和竞争性阴离子对AER和Fe—PLE吸附的影响,结果显示,Fe—PLE吸附平衡时间为1.5 h,比AER稍高;2种吸附填料都在pH 7.0时效率最高,AER的磷吸附效率对pH较为敏感,Fe—PLE能够在相对较宽的pH范围内保持高去除率;竞争性阴离子对AER磷吸附的负面影响较大,而Fe—PLE依靠其Fe—O的配位作用具有一定的抗干扰能力。通过4次循环再生实验,Fe—PLE表现出良好再生能力的同时磷有较高的回收利用率。 相似文献
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Effect of liming and seasonal variation on lead concentration of tea plant (Camellia sinensis (L.) O. Kuntze) 总被引:1,自引:0,他引:1
Tea is a widely consumed beverage. However, recent studies revealed that there were an increasing number of cases of tea products exceeding the former maximum permissible concentration (MPC) in China for Pb (2 mg kg(-1)). Tea Pb contamination is an issue affecting trade and consumer confidence. Root uptake of Pb could contribute significantly to Pb accumulation in tea leaves due to the strong acidity of many tea garden soils. We conducted pot and field experiments to evaluate the effect of liming on Pb uptake by tea plants on two highly acidic soils (pH3.6). Additions of CaCO(3) significantly increased soil pH by up to 1 unit and decreased soil extractable Pb by up to 32%. Liming resulted in a decrease in the proportion of Pb in the exchangeable and carbonate-bound fractions, with a concurrent increase in the fractions bound to Fe/Mn oxides and residues. Liming significantly decreased Pb concentrations of fine roots, stems and new shoots of tea plants in the pot experiment. In the field experiments, the effect of liming was not significant during the first year following CaCO(3) application, but became significant during the second and third years and Pb concentration in the new shoots was decreased by approximately 20-50%, indicating that liming of acidic tea garden soils is an effective way to reduce Pb contamination of tea. The study also reveals a distinct seasonal variation, with Pb concentration in the new shoots following the order of spring>autumn>summer. 相似文献
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A novel strategy utilizing the phenyls interaction and the hydrophobic affinity of available siloxane surface in the interlayer of bentonite was proposed to improve the sorption capabilities of organobentonites for water soluble aromatic contaminants. A unique organobentonite (65BTMA) was synthesized by intercalating benzyltrimethylammonium cation (BTMA+) into the interlayer of a reduced-charge bentonite with cation exchange capacity (CEC) of 65 cmol kg−1. Phenol, aniline and toluene were used as model compounds of water soluble aromatic contaminants. Their respective removal efficiencies by 65BTMA were achieved at 83.3%, 89.2% and 97.3% at the initial concentration of 20 mg l−1. To reveal the sorption mechanism, sorption characteristics of aromatic contaminants to 65BTMA were compared with that of aliphatic contaminants in similar molecular size. And various organobentonites were prepared by combining TMA+ (tetramethylammonium), BTMA+, HTMA+ (heptyltrimethylammonium) and CTMA+ (cetyltrimethylammonium) with two bentonites (CEC = 108 and 65 cmol kg−1). To 65BTMA, sorption magnitudes of aromatic contaminants were much greater than that of aliphatic compounds with similar size; and dramatically higher than those to other organobentonites at low pollutant concentrations. These observations revealed that the strong phenyls interactions contributed significantly to sorb the aqueous soluble aromatic contaminants to 65BTMA (>90%), and which favored to design uniquely powerful sorbents. 相似文献
289.
Seymour Colleen L. Gillson Lindsey Child Matthew F. Tolley Krystal A. Curie Jock C. da Silva Jessica M. Alexander Graham J. Anderson Pippin Downs Colleen T. Egoh Benis N. Ehlers Smith David A. Ehlers Smith Yvette C. Esler Karen J. O’Farrell Patrick J. Skowno Andrew L. Suleman Essa Veldtman Ruan 《Ambio》2020,49(6):1211-1221
Ambio - A horizon scan was conducted to identify emerging and intensifying issues for biodiversity conservation in South Africa over the next 5–10 years. South African biodiversity... 相似文献
290.
以模拟啤酒废水为底物在IC反应器中进行厌氧污泥颗粒化培养,并对污泥颗粒化过程中胞外多聚物(EPS)的主要成分变化及其与细胞表面疏水性和Zeta电位之间的相互关系进行分析,以此来阐述EPS对污泥颗粒化成核的作用。研究结果表明,好氧剩余污泥在经过56 d的培养后,平均粒径由接种时的54.72μm增长到103.46μm,实现了厌氧污泥颗粒化成核过程;EPS蛋白质含量(PN)在颗粒化过程中逐渐由接种时的18.1 mg/g增至54.3 mg/g,而EPS多糖含量(PS)则无明显变化;此外,PN/PS与污泥平均粒径、细胞表面疏水性(RH)以及Zeta电位之间呈正相关关系,相关系数分别为0.9727、0.9593和0.9274。由此可推测:厌氧污泥颗粒化成核过程的主要作用成分为胞外蛋白质,其可以改变污泥细胞表面疏水性和Zeta电位,从而在厌氧污泥颗粒化过程中有着重要的促进作用。 相似文献