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991.
对用亚甲基蓝分光光度法测定大气中硫化氢的标准溶液、样品的稳定性、温度对试剂空白的影响等问题进行了一些研究。得出:硫化氢标准使用液用磁性锌氨络盐吸收液配制,冰箱保存至少可稳定2个月;温度对试剂空白值有影响,应根据不同显色温度,确定不同显色时间;绘制标准曲线和样品测定应用同一量器迅速加入显色剂,以提高其灵敏度。 相似文献
992.
研究分析了柴窝堡水源地引水工程对周围地区的一系列生态环境影响,提出了若干生态环境保护对策. 相似文献
993.
Yalei Zhang Chunmin Zhang Xuefei Zhou Zheng Shen Fangchao Zhao Jianfu Zhao 《环境科学学报(英文版)》2016,28(8):174-181
Inspired by iron fertilization experiments in HNLC (high-nitrate, low-chlorophyll) sea areas, we proposed the use of iron-rich engineered microalgae for microbial contaminant control in iron-free culture media. Based on the genome sequence and natural transformation system of Synechocystis sp. PCC6803, ftnA (encoding ferritin) was selected as our target gene and was cloned into wild-type Synechocystis sp. PCC6803. Tests at the molecular level confirmed the successful construction of the engineered Synechocystis sp. PCC6803-ftnA. After Fe3 +-EDTA pulsing, the intracellular iron content of Synechocystis sp. PCC6803-ftnA was significantly enhanced, and the algae was used in the microbial contamination control system. In the coupled Synechocystis sp. PCC6803-ftnA production and municipal wastewater (MW, including Scenedesmus obliquus and Bacillus) treatment, Synechocystis sp. PCC6803-ftnA accounted for all of the microbial activity and significantly increased from 70% of the microbial community to 95%. These results revealed that while the stored iron in the Synechocystis sp. PCC6803-ftnA cells was used for growth and reproduction of this microalga in the MW, the growth of other microbes was inhibited because of the iron limitation, and these results provide a new method for microbial contamination control during a coupling process. 相似文献
994.
Changes in visibility with PM2.5 composition and relative humidity at a background site in the Pearl River Delta region 总被引:2,自引:0,他引:2
Xiaoxin Fu Xinming Wang Qihou Hu Guanghui Li Xiang Ding Yanli Zhang Quanfu He Tengyu Liu Zhou Zhang Qingqing Yu Ruqing Shen Xinhui Bi 《环境科学学报(英文版)》2016,28(2):10-19
In fall–winter, 2007–2013, visibility and light scattering coefficients(b sp) were measured along with PM_(2.5)mass concentrations and chemical compositions at a background site in the Pearl River Delta(PRD) region. The daily average visibility increased significantly(p 0.01) at a rate of 1.1 km/year, yet its median stabilized at ~13 km. No haze days occurred when the 24-hr mean PM_(2.5)mass concentration was below 75 μg/m~3. By multiple linear regression on the chemical budget of particle scattering coefficient(b sp), we obtained site-specific mass scattering efficiency(MSE) values of 6.5 ± 0.2, 2.6 ± 0.3, 2.4 ± 0.7 and 7.3 ± 1.2 m2/g,respectively, for organic matter(OM), ammonium sulfate(AS), ammonium nitrate(AN) and sea salt(SS). The reconstructed light extinction coefficient(b ext) based on the Interagency Monitoring of Protected Visual Environments(IMPROVE) algorithm with our site-specific MSE revealed that OM, AS, AN, SS and light-absorbing carbon(LAC) on average contributed 45.9% ± 1.6%,25.6% ± 1.2%, 12.0% ± 0.7%, 11.2% ± 0.9% and 5.4% ± 0.3% to light extinction, respectively.Averaged b ext displayed a significant reduction rate of 14.1/Mm·year(p 0.05); this rate would be 82% higher if it were not counteracted by increasing relative humidity(RH) and hygroscopic growth factor(f(RH)) at rates of 2.5% and 0.16/year-1(p 0.01), respectively, during the fall–winter, 2007–2013. This growth of RH and f(RH) partly offsets the positive effects of lowered AS in improving visibility, and aggravated the negative effects of increasing AN to impair visibility. 相似文献
995.
996.
基于对江苏省太湖流域农村生活污水处理设施的全面调研,统计分析了江苏省太湖流域农村生活污水处理设施现状,包括建设数量、建设规模、处理工艺、运维模式、经费来源等,探讨了江苏省太湖流域农村生活污水处理设施存在的问题并提出建议。结果表明:目前江苏省太湖流域农村生活污水处理设施以中小规模(<100 t/d)为主,主要采用生物生态耦合处理技术,出水一般执行(GB 18918-2002)《城镇污水处理厂污染物排放标准》中的一级B标准,以属地管理的运维模式为主。应加快制订符合江苏省太湖流域的农村生活污水处理设施建设标准,并形成责任主体明确、监管制度完善、资金投入有保障的长效稳定运行体制。 相似文献
997.
998.
畜禽养殖废弃物及农业氮磷流失造成的环境面源污染已经成为太湖流域湖泊和水体污染的主要来源之一.通过现场勘查、文献查阅、实地调研等方法,对以太仓为代表的江苏太湖流域畜禽养殖及农业氮磷流失造成的农村生态环境污染问题进行了分析,研究提出了污染防治示范区构建的指导思想、基本原则、技术路径、技术及模式创新点,用五大发展新理念指导污染防治示范区构建,创新畜禽养殖废弃物及农业氮磷污染防治的产业化模式、区域分散畜禽粪便收集服务的社会化体系、覆盖农业氮磷污染防治全程的可控化技术体系. 相似文献
999.
The tap water samples were collected from the users' ends in several areas of Shanghai, which is located in Taihu Lake basin, Eastern China. Source water samples were also collected from two municipal source water facilities at the same time. Samples were assayed by three different short-term mutagenicity test systems: Salmonella/microsome assay (Ames test), the Arabinose resistance test (Ara test) and the SOS/umu test. The data showed that two source water samples did not display direct mutagenic potentials. Two tap water samples from city north, which were directly from Yangtze River, were also not mutagenic. Water samples from city south and middle which used source water originating from Taihu Lake were proved to be contaminated with mutagenic potentials by three different assay techniques. The boiled water displayed an even stronger mutagenic potential compared to its original tap water. The molecular mechanism of mutagenicity was associated with a reading frame-shifting potential. GC-MS analysis of tap water extracts from city middle and corresponding source water was compared. Qualitatively similar spectra were observed except for the peaks of three chlorinated aromatic hydrocarbon compounds, which existed only in the tap water. Since the water source has been polluted, raw water was heavily chlorinated in order to sterilize. More toxic compounds, including mutagens, might form during the multi-chlorination. Caution about the possibility of elevated cancer risks in the population that consumes heavily chlorinated water should be kept in mind. A cohort study in the residents of Shanghai is required. 相似文献
1000.
Degradation of 4-CP in an internal electrolysis system 总被引:1,自引:0,他引:1
The characteristic and mechanism of parachlorophenol (4-CP) degradation in an internal electrolysis system were investigated. The degradation rate of 4-CP was higher in acid solution than that of in neutral or alkaline solution. Addition of activated carbon could make 4-CP easier be degraded by the surface contact catalysis. The dissolved oxygen in solution could take part in the electrode reaction and intensify the degradation of 4-CP. By the analysis of intermediates of degradation of 4-CP, it could be conferred that 4-CP was broken through the bond beside hydroxy firstly, then the bond beside chloride was broken and the chloride was dechlorinated simultaneously. Most intermediate products were glycerine, ethane diacid and acetic acid, while very few 1, 4-butanedial and alcohols were found. 相似文献