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161.
Armitage HF Britton AJ Woodin SJ van der Wal R 《Environmental pollution (Barking, Essex : 1987)》2011,159(1):140-147
The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha−1 yr−1) and a low N deposition site, Ben Wyvis (7.2 kg ha−1 yr−1). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. 相似文献
162.
采用无机羟基铝及阳离子表面活性剂十六烷基三甲基溴化铵对天然蒙脱石进行无机及复合改性。在吸附过程中研究了反应时间、投加量和pH等变量对吸附性能的影响,同时进行吸附动力学及吸附等温线研究,吸附规律符合Langmuir等温方程式。采用X射线衍射、X射线荧光、傅里叶红外光谱等表征手段对未改性及改性蒙脱石进行性能表征。研究结果表明,羟基铝及复合改性蒙脱石对As(V)具有良好的吸附性能,在pH为4~10,初始砷浓度为2 mg/L,改性蒙脱石对As(V)的去除率接近99%。吸附机理主要为羟基铝表面络合吸附和静电吸附。 相似文献
163.
164.
本实验以工业化学合成聚合硫酸铁混凝剂和自制生物聚合硫酸铁为例,考察了铁系混凝剂品种对地表水浊度、TOC和UV254的去除效果,混凝剂品种对混凝-超滤联合工艺处理地表水过程中超滤膜污染的影响。混凝实验结果表明,在10 mg/L(以Fe3+计)最佳投加量下,两类混凝剂对浊度、TOC和UV254的去除率基本相同。超滤膜污染实验结果表明,生物聚合铁预处理水样通量衰减速度略大于化学聚合铁预处理水样;膜污染阻力分析结果显示,随着循环次数的增加,工业化学合成聚合铁预处理水样造成的不可逆污染阻力逐渐增加,而生物聚合铁预处理水样造成的不可逆污染阻力却略有下降;膜污染机理分析表明,2组过滤过程的膜污染类型基本相似,由最初的膜孔堵塞过渡到最终的滤饼层污染。SEM分析表明,生物聚合铁预处理水样的膜污染较为严重。 相似文献
165.
采用浸渍法制备了不同NiO和CuO质量分数的NiO-CuO/ZSM-5催化剂,并以CH4为还原剂研究了NiO-CuO/ZSM-5催化剂对催化裂化烟气的脱硫脱硝活性。XRD分析结果表明,NiO质量分数为4%、CuO质量分数为6%的催化剂4%NiO-6%CuO/ZSM-5中的ZSM-5结构完好,CuO和NiO高度分散在ZSM-5骨架中,表明具有较好的催化活性。4%NiO-6%CuO/ZSM-5的脱硫脱硝起活温度均较低,无氧条件下最高NO转化率和SO2转化率分别为94.7%和95.9%,O2体积分数为1.0%时的NO转化率和SO2转化率分别为97.7%和89.0%。 相似文献
166.
Ruixin Guo Xinkun Ren Hongqiang Ren 《Journal of environmental science and health. Part. B》2013,48(9):883-890
As important members of the zooplankton community and sources of food for fish, rotifers are used extensively in ecotoxicological research to assess the health of the environment and safety of compounds. However, most rotifer toxicity tests are only conducted using rotifer neonates derived from unexposed mothers, thus ignoring the potential transfer of contaminants from mother to offspring. To understand better the mother to offspring exposure, a multigenerational study was conducted using three successive generations (F0, F1 and F2) of the common freshwater rotifer Brachionus calyciflorus to investigate the toxic effects of the widely used organophosphate pesticide, dimethoate (O, O-dimethyl S-methylcarbamoylmethyl phosphorodithioate). When the F0 generation was exposed to five pesticide concentrations, the population growth rate (r) displayed symptoms of hormesis, characterized by the conversion of low-concentration stimulation to high-concentration inhibition. Despite this observation, the exposure to any given concentration of dimethoate reduced the population growth rates of the F1 and F2 generation rotifers. Significant differences existed between the F0, F1 and F2 rotifers for the population growth rate under dimethoate stress: F2 individuals were more sensitive than F1, whereas the F1 individuals were more sensitive than F0. The results indicated that the parental exposure to a given toxic stress could result in increased sensitivity and decreased fitness in the offspring. This study illustrates the utility of multigenerational toxicity tests, which may better reflect and more accurately predict the effects of long-term pesticide exposure to aquatic organisms at the population level. 相似文献
167.
稻草制浆黑液生物+混凝处理试验 总被引:4,自引:0,他引:4
通过对稻草制浆黑液厌氧、好氧、混凝处理组合工艺的试验研究,探索该工艺的可行性,考察了不同温度、不同有机负荷下,该类废水的生物处理效果以及后续混凝效果。结果表明:中温35℃是厌氧阶段最佳处理温度,好氧阶段不同负荷条件下,CODCr去除率基本相同;经厌氧-好氧处理,黑液CODCr和木质素去除率分别为80%和30%,色度去除不明显;混凝阶段CODCr和木质素去除率分别为70%和90%,色度去除率达90%以上,出水达到国家标准。 相似文献
168.
Yu Ren Aijun Ding Tao Wang Xinhua Shen Jia Guo Jiamin Zhang Yan Wang Pengju Xu Xinfeng Wang Jian Gao Jeffrey L. Collett 《Atmospheric environment (Oxford, England : 1994)》2009,43(9):1702-1711
Measurement of ambient gas-phase total peroxides was performed at the summit of Mount Tai (Mt. Tai, 1534 m above sea level) in central-eastern China during March 22–April 24 and June 16–July 20, 2007. The hourly averaged concentration of peroxides was 0.17 ppbv (± 0.16 ppbv, maximum: 1.28 ppbv) and 0.55 ppbv (± 0.67 ppbv, maximum: 3.55 ppbv) in the spring and summer campaigns, respectively. The average concentration of peroxides at Mt. Tai, which is in a heavily polluted region, was much lower than hydrogen peroxide measurements made at some rural mountain sites, suggesting that significant removal processes took place in this region. An examination of diurnal variation and a correlation analysis suggest that these removal processes could include chemical suppression of peroxide production due to the scavenging of peroxy and hydroxy radicals by high NOx, wet removal by clouds/fogs rich in dissolved sulfur dioxide which reacts quickly with peroxides, and photolysis. These sinks competed with photochemical sources of peroxides, resulting in different mean concentrations and diurnal pattern of peroxides in the spring and summer. A principal component analysis was conducted to quantify the major processes that influenced the variation of peroxide concentrations. This analysis shows that in the spring photochemical production was an important source of peroxides, and the major sink was scavenging during upslope transport of polluted and humid air from the lower part of the planetary boundary layer (PBL) and wet removal by synoptic scale clouds. During the summer, highly polluted PBL air (with high NOx) was often associated with very low peroxides due to the chemical suppression of HO2 by high NOx and wet-removal by clouds/fogs in this sulfur-rich atmosphere, especially during the daytime. Higher concentrations of peroxides, which often appeared at mid-nighttime, were mainly associated with subsidence of air masses containing relatively lower concentrations of NOy. 相似文献
169.
NaCl和KCl对厌氧污泥抑制的动力学研究 总被引:2,自引:0,他引:2
在厌氧颗粒污泥和厌氧絮状污泥系统中,进行盐质量浓度(NaCl或KCl质量浓度,下同)对厌氧污泥抑制动力学的研究,得到不同拟合的COD降解动力学方程及参数.实验结果表明:当盐质量浓度为10~30 g/L时,KCl对厌氧污泥的COD比降解速率的抑制程度大于NaCl;当盐质量浓度由0 g/L增至10 g/L时,半速率常数逐渐增加;当盐质量浓度由10 g/L增至30 g/L时,半速率常数逐渐减小;在厌氧污泥系统中,NaCl抑制作用下的盐抑制常数高于KCl,且颗粒污泥的盐抑制常数高于絮状污泥. 相似文献
170.
Stefanie Grund Eric Higley René Schönenberger Marc J-F. Suter John P. Giesy Markus Hecker Henner Hollert 《Environmental science and pollution research international》2011,18(3):446-460