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981.
以多级孔ZSM-5分子筛为吸附剂,吸附水中的亚甲基蓝(MB),考察了吸附条件对吸附效果的影响,并探讨了吸附的热力学和动力学特征。实验结果表明:在溶液pH为11、分子筛加入量为800 mg/L、吸附温度为303.15 K、吸附时间为60 min、初始MB质量浓度为20 mg/L的条件下,该分子筛对MB的吸附率达97%;溶液pH为5~12时,吸附率均达89%以上,说明该分子筛具有宽的pH适应范围;该分子筛对MB的吸附热力学符合Langmuir和Freundlich方程,293.15~313.15 K的饱和吸附量达50.51~62.11 mg/g,吸附为吸热、自发过程;吸附动力学符合拟二级动力学方程。 相似文献
982.
Spatial and temporal variations and the factors influencing primary production have been studied in three different mangrove waters (Pichavaram, Ennore Creek and Adyar Estuary) of South India characterised by different anthropogenic impacts. the gross primary productivity in the unpolluted Pichavaram mangrove was 113 g Cm-2yr-1 exhibiting natural variability with the environmental forcing factors. Human activities have elevated primary productivity in the Ennore Creek mangrove (157g Cm-2yr-1) primarily through the direct discharge of fertilizer effluents. By contrast, a combination of domestic and industrial effluent discharges into the Adyar Estuary mangrove has considerably reduced phytoplankton primary productivity 83g Cm-2yr-1 the Redfield N: P ratio varies from 0.96 N: 1P at Ennore Creek, 1.75N: 1P at Adyar Estuary to 15.2 N: 1P at Pichavaram mangroves. This suggests that the Pichavaram mangroves represent a well equilibrated ecosystem with N: P ratio close to steady-state values in contrast to the anthropogenically altered mangrove ecosystems studied. Results show a significant temporal variability in nutrient concentration in the three mangrove areas. Distinct differences in nutrient concentrations between the dry and the wet seasons have been observed. 相似文献
983.
五氯酚(PCP)高效降解菌Psendomonas sp.CS5的研究 总被引:6,自引:0,他引:6
从曾受五氯酚(pentachlorophenol,简称PCP,下同)污染废水的活性污泥中,经驯化富集和分离筛选获得一株PCP降解菌,菌号为CS-W-98-5.在24h内该菌降解w(PCP)=400×10 相似文献
984.
Stephen E. Watts 《Environmental management》1998,22(4):611-616
Artemisia tridentata Nutt.) habitat within the Idaho Army National Guard Orchard Training Area in southwestern Idaho. The purpose of this study
was to determine the short-term (1–2 years) influence of tank tracks on vegetation and microphytic crusts in shrubsteppe habitat.
The two types of tank tracks studied were divots (area where one track has been stopped or slowed to make a sharp turn) and
straight-line tracks. Divots generally had a stronger influence on vegetation and microphytic crusts than did straight-line
tracks. Tank tracks increased cover of bare ground, litter, and exotic annuals, and reduced cover of vegetation, perennial
native grasses, sagebrush, and microphytic crusts. Increased bare ground and reduced cover of vegetation and microphytic crusts
caused by tank tracks increase the potential for soil erosion and may reduce ecosystem productivity. Reduced sagebrush cover
caused by tank tracks may reduce habitat quality for rodents. Tank tracks may also facilitate the invasion of exotic annuals
into sagebrush habitat, increasing the potential for wildfire and subsequent habitat degradation. Thus, creation of divots
and movement through sagebrush habitat by tanks should be minimized. 相似文献
985.
David R. Breininger Mary Jo Barkaszi Rebecca B. Smith Donna M. Oddy Jane A. Provancha 《Environmental management》1998,22(2):315-321
/ We identified and ranked 108 resident and migratory wildlife taxa on John F. Kennedy Space Center (KSC) that were vulnerable to local, regional, or global extinction. We ranked taxa based on their vulnerability to extinction, their potential role for maintaining faunal integrity, and the relevance of KSC for maintaining their populations in the United States and Florida. Several taxa, not listed by agencies, were vulnerable to regional or global extinction. Many taxa not vulnerable to global extinction were vulnerable to local and regional extinction. Top predators were vulnerable to extinction because of small population size, isolation from other populations, and road mortality. Many taxa were dependent on habitat conditions at different geographic locations so that conservation required greater collaboration among land owners, managers, and researchers at local, regional, and global scales.KEY WORDS: Biological diversity; Endangered species; Conservation 相似文献
986.
López A de Marco I Caballero BM Adrados A Laresgoiti MF 《Waste management (New York, N.Y.)》2011,31(8):1852-1858
In this work, a study of the regeneration and reuse of ZSM-5 zeolite in the pyrolysis of a plastic mixture has been carried out in a semi-batch reactor at 440 °C. The results have been compared with those obtained with fresh-catalyst and in non-catalytic experiments with the same conditions. The use of fresh catalyst produces a significant change in both the pyrolysis yields and the properties of the liquids and gases obtained. Gases more rich in C3-C4 and H2 are produced, as well as lower quantities of aromatic liquids if compared with those obtained in thermal decomposition. The authors have proved that after one pyrolysis experiment the zeolite loses quite a lot of its activity, which is reflected in both the yields and the products quality; however, this deactivation was found to be reversible since after regeneration heating at 550 °C in oxygen atmosphere, this catalyst recovered its initial activity, generating similar products and in equivalent proportions as those obtained with fresh catalyst. 相似文献
987.
南京市大气颗粒物中多环芳烃变化特征 总被引:4,自引:2,他引:2
逐月采集南京市大气中不同粒径的颗粒物,采用HPLC分析了2010年每个月PM_(10)和PM_(2.5)颗粒物样品中的多环芳烃(PAHs)的种类和浓度水平。结果表明:PM_(10)中PAHs年均值为25.07 ng/m~3,范围为11.03~53.56 ng/m3;PM_(2.5)中PAHs年均值为19.04 ng/m~3,范围为10.82~36.43 ng/m~3。PM_(10)和PM_(2.5)中PAHs总体浓度有着相似的变化趋势,呈现凹形变化曲线;在南京市大气颗粒物中吸附的PAHs大部分以5~6环的高环数组分为主,大部分PAHs和∑PAHs的相关性较好,年度变化幅度不大,分析结果表明,颗粒物中PAHs的来源与稳定的排放源相关,机动车排放不容忽视,与北方城市燃煤污染有着较大的区别。 相似文献
988.
989.
A.S. Al-Akel H.F. Alkahem Al-Balawi F. Al-Misned Z. Ahmad E.M. Suliman 《毒物与环境化学》2013,95(10):1865-1878
The influence of dietary copper (Cu) exposure on accumulation, growth, and hematological parameters was investigated in Cyprinus carpio after sub-chronic ingestion of 0, 250, 500, 750 or 1000?mg?kg?1 for 60 days. The profile of Cu accumulation among tissues in C. carpio was dependent on the exposure period and Cu concentration. Liver of C. carpio was the predominant storage tissue and the order of Cu accumulation in tissues was liver?>?intestine?> gill?>?kidney?>?muscle. Cu concentration at >125?mg?kg?1 reduced growth rate, and was inversely related to growth. The RNA?:?DNA ratios were not affected by exposure and there was no correlation between growth rate and RNA?:?DNA ratio in liver and muscle. There were no significant effects of exposure on blood parameters except for magnesium. Cu exposure time and dose increased the serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) activity levels. 相似文献
990.
Ozone and atmospheric nitrogen are co-occurring pollutants with adverse effects on natural grassland vegetation. Plants of the rhizomatous sedge Carex arenaria were exposed to four ozone regimes representing increasing background concentrations (background-peak): 10-30, 35-55, 60-80 and 85-105 ppb ozone at two nitrogen levels: 12 and 100 kg N ha−1 yr−1. Ozone increased the number and proportion of senesced leaves, but not overall leaf number. There was a clear nitrogen × ozone interaction with high nitrogen reducing proportional senescence in each treatment and increasing the ozone dose (AOT40) at which enhanced senescence occurred. Ozone reduced total biomass due to significant effects on root biomass. There were no interactive effects on shoot:root ratio. Rhizome tissue N content was increased by both nitrogen and ozone. Results suggest that nitrogen mediates above-ground impacts of ozone but not impacts on below-ground resource translocation. This may lead to complex interactive effects between the two pollutants on natural vegetation. 相似文献