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421.
实验研究了蔗糖为碳源,硝酸钠、脲、蛋白胨、硫酸铵和氯化铵等氮源对NIII2发酵产絮凝剂的影响。结果表明,发酵液起始pH值为7.50,以硝酸钠为氮源,发酵液pH会上升,升至7.60~8.34时,NⅢ2菌株开始大量分泌微生物絮凝剂,发酵72 h,产量可达7.5 g/L,该产量是目前报道的克雷伯氏菌产絮凝剂的最高值。脲为氮源,pH则下降,降至5.04~6.49时,大量分泌絮凝剂,发酵72 h产量达5.2 g/L。蛋白胨、氯化铵和硫酸铵等为氮源时,pH下降十分明显,pH小于3.71时有絮凝剂分泌,发酵72 h产量约2.0 g/L或更小。以硝酸钠和脲为氮源时,发酵液中有黄色物质分泌,该黄色物质出现或黄色逐渐加深,是NIII2菌高产絮凝剂的标志。除硫酸铵外,其他氮源发酵所产絮凝剂为O-糖蛋白。当以硝酸钠、脲、蛋白胨、硫酸铵和氯化铵为氮源时,絮凝剂中蛋白的含量分别为9.55%、33.28%、19.39%、13.81%和15.51%,且蛋白含量越高,絮凝剂活性越大。 相似文献
422.
Gao Fuyuan Li Kaiming Zhao Chengzhang Ren Heng Nie Xiaoying Jia Dongyu Li Linfeng Li Qingfeng 《Environmental science and pollution research international》2019,26(20):20469-20474
Environmental Science and Pollution Research - The expansion of poisonous plants can change vegetation community structures and affect grassland ecosystem service values. Stellera chamaejasme is... 相似文献
423.
为了对水中苯酚的去除进行研究,通过离子交换法及液相沉积法在天然沸石上负载Fe3O4制备出一种具有较高反应活性的复合催化剂,采用X-射线衍射仪(XRD)、扫描电镜(SEM)等仪器对其结构和形貌进行表征,并利用复合催化剂进行非均相UV/Fenton反应处理模拟苯酚废水,考察不同因素对苯酚降解效果的影响。实验结果表明,在催化剂投加量为0.4 g/L,H2O2投加量为二分之一理论投加量,pH为3~10且室温的条件下,处理100 mg/L的模拟苯酚废水,60 min之内苯酚去除率可达90%以上。通过对催化剂的稳定性研究,发现经5次循环使用后,苯酚去除率均可保持在90%以上,具有良好的循环使用性能。 相似文献
424.
Zhang Cheng Kun-Ci Chen Kai-Bin Li Xiang-Ping Nie Sheng Chun Wu Chris Kong-Chu Wong Ming-Hung Wong 《Environmental science and pollution research international》2013,20(7):4484-4495
This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05–3.01 mg?kg?1 wet weight (w. wt) and 8.41–22.76 mg?kg?1 dry weight (d. wt), respectively. In addition, the As content was positively correlated (p?<?0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and δ 15N. The slope of the regression (?0.066 and ?0.078) of the log transformed As concentrations and δ 15N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10?4) stipulated by the USEPA. 相似文献
425.
Hongtao Wang Yongfeng Nie 《Journal of the Air & Waste Management Association (1995)》2013,63(2):264-272
ABSTRACT The purpose of this investigation is to evaluate the current status and to identify the problems of municipal solid waste (MSW) management in China to determine appropriate remedial strategies. This is the second of two papers proposed on this topic. Major problems or difficulties identified in MSW management in China include MSW land, air, and water pollution, commingled collection, poor administration, shortage of funds, lack of facilities, and problems of training and public awareness. In order to solve these problems and to improve MSW management in China, remedial strategies in three areas are recommended: institutional reform, technology development, and legislation and administrative improvement. The primary principle involved in institutional reform is unifying legislative responsibilities into one body and developing a market mechanism for handling MSW. Composting, landfills, and incineration should be equally developed in accordance with China's needs. The feasibility of developing technology to handle MSW in China is discussed. Also recommended is the establishment of sound regulatory systems, including a service fee system, a source separation system, and a training program. China is presently undergoing economic and institutional reform at the national and local levels. Results of this study will provide useful information on MSW management in China. 相似文献
426.
427.
Nie M Lu M Yang Q Zhang XD Xiao M Jiang LF Yang J Fang CM Chen JK Li B 《Environmental pollution (Barking, Essex : 1987)》2011,159(1):157-163
In this study, we investigated Phragmites australis’ use of different forms of nitrogen (N) and associated soil N transformations in response to petroleum contamination. 15N tracer studies indicated that the total amount of inorganic and organic N assimilated by P. australis was low in petroleum-contaminated soil, while the rates of inorganic and organic N uptake on a per-unit-biomass basis were higher in petroleum-contaminated soil than those in un-contaminated soil. The percentage of organic N in total plant-assimilated N increased with petroleum concentration. In addition, high gross N immobilization and nitrification rates relative to gross N mineralization rate might reduce inorganic-N availability to the plants. Therefore, the enhanced rate of N uptake and increased importance of organic N in plant N assimilation might be of great significance to plants growing in petroleum-contaminated soils. Our results suggest that plants might regulate N capture under petroleum contamination. 相似文献
428.
Wang Z Nie E Li J Yang M Zhao Y Luo X Zheng Z 《Environmental science and pollution research international》2011,19(7):2908-2917
Purpose
Two series of activated carbons modified by Fe (II) and Fe (III) (denoted as AC/N-FeII and AC/N-FeIII), respectively, were used as adsorbents for the removal of phosphate in aqueous solutions.Method
The synthesized adsorbent materials were investigated by different experimental analysis means. The adsorption of phosphate on activated carbons has been studied in kinetic and equilibrium conditions taking into account the adsorbate concentration, temperature, and solution pH as major influential factors.Results
Maximum removals of phosphate are obtained in the pH range of 3.78?C6.84 for both adsorbents. Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Results suggest that the main phase formed in AC/N-FeII and AC/N-FeIII is goethite and akaganeite, respectively; the presence of iron oxides significantly affected the surface area and the pore structure of the activated carbon.Conclusions
Studies revealed that iron-doped activated carbons were effective in removing phosphate. AC/N-FeII has a higher phosphate removal capacity than AC/N-FeIII, which could be attributed to its better intra-particle diffusion and higher binding energy. The activation energy for adsorption was calculated to be 22.23 and 10.89 kJ mol?1 for AC/N-FeII and AC/N-FeIII, respectively. The adsorption process was complex; both surface adsorption and intra-particle diffusion were simultaneously occurring during the process and contribute to the adsorption mechanism. 相似文献429.
Yuanxin Zhang Fei Li Chaoqiong Ni Song Gao Shuwei Zhang Jin Xue Zhukai Ning Chuanming Wei Fang Fang Yongyou Nie Zheng Jiao 《Frontiers of Environmental Science & Engineering》2023,17(2):21
430.