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331.
泾阳、临猗地震的地下流体异常特征 总被引:5,自引:3,他引:5
总结了1998 年泾阳Ms4.8 及临猗Ms 4.6 级地震的地下流体异常特征, 结果表明: 异常点数量有随震中距的增大而减少的趋势, 同时又受构造条件的制约; 异常时间以短临为主, 短期异常主要集中在震前3 个月左右, 临震异常出现在震前10 d 左右; 异常幅度与地震三要素关系不明显。 相似文献
332.
333.
为系统分析合肥市长时间序列空气质量变化特征,对合肥市2001—2020年SO2、NO2和PM10,以及2013—2020年CO、O3和PM2.5的浓度特征开展研究。采用Mann-Kendall(M-K)时间趋势检验法分析了6项污染物的时间变化规律,同时考虑了人为活动对污染物小时浓度的影响。结果表明,PM2.5和O3是目前影响合肥市空气质量的首要污染物。2014年以来,合肥市PM10、PM2.5、CO和SO2年均浓度均呈逐年下降趋势,但NO2和O3污染有加剧趋势。合肥市SO2和颗粒物浓度表现为冬春季节高、夏秋季节低;O3浓度变化趋势与之相反;NO2和CO浓度呈秋冬季节高、春夏季节低。 相似文献
334.
335.
为了评估2018年春节期间(2月15—16日)京津冀及周边地区“2+26”城市烟花禁限放措施的效果,采用浓度特征对比、ρ(PM2.5)/ρ(CO)等方法,对“2+26”城市的ρ(PM2.5)、ρ(PM10)、ρ(SO2)、ρ(NO2)进行分析,并定量估算了除夕夜烟花燃放对ρ(PM2.5)和ρ(SO2)的贡献率.结果表明:“2+26”城市烟花的集中燃放会导致ρ(PM2.5)、ρ(SO2)显著增长,出现以PM2.5为首要污染物的重污染时段,2018年12月16日03:00区域内14个城市ρ(PM2.5)达到重度及以上污染水平,呈区域性污染特征;与2017年同期(1月27—28日)相比,2018年春节期间(2月15—16日)14个城市烟花燃放对ρ(PM2.5)平均贡献量呈下降趋势,其中,淄博市、济南市、北京市降幅最大,分别下降了85.2%、74.6%和65.2%,表明烟花禁限放措施起到了显著的污染削峰作用;与城区相比,周边郊县ρ(PM2.5)显著高于城区,呈“农村包围城市”的现象,说明城区监测点位受到郊县等周边地区烟花燃放的传输影响.研究显示,虽然城区烟花禁限放措施起到了显著的削峰作用,但城区监测点位空气质量仍受到郊县等周边地区烟花燃放的传输影响,导致大气重污染的发生. 相似文献
336.
植物络合素及其合酶在重金属抗性中的功能研究进展 总被引:12,自引:0,他引:12
Under heavy metal stress, higher plants initiate a set of defense responses, among which biosynthesis of phytochelatins (PCs) is important. PCs are rich in cystein and biosynthesized by phytochelatin synthase. The chemical structure of PCs and their ability to form complexes with a large range of metal ions is clear. Up to now, these peptides are known to play an important role in both endogenous metal ion homeostasis and heavy metal ion detoxification. The mechanism of cadmium tolerance is illustrated in detail. A model of this mechanism suggested that the detoxification process of cadmium include such steps as PCs induction, transport of cadmium into the tonoplast, formation of the HMW-Cd-PCs complexes and sequestration in vacuole. At the same time, PCs also have other functions, such as detoxification of arsenic, protecting enzyme from metal ion inhibition and supplying metal ion as a cofactor to the enzyme potentially. However, a lot of questions about its biological function remain to be answered. In 1999, three independent labs isolated the genes encoding the PCs synthase. This breakthrough of plant heavy metal tolerance research gave us a chance to further study the heavy metal tolerance mechanism. All the results from the reserch of PCs have a ffreat application potential in phytoremidation. Fig 1, Ref 25 相似文献
337.
The performance of 11 reed-wetland beds for municipal wastewater treatment is described in this paper. The interrelation between pollutants removal (BOD5, SS, N and P) and hydraulic loading rate, organic loading rate, hydraulic retention time as well as the seasonal variation could be found in this study. The treatment efficiencies of reed beds are better than the secondary treatment standards with high and steady nitrogen and phosphorus removal. The total nitrogen and phosphorus of the final effluent are less than 10 mg/L and 0.5 mg/L, respectively. 相似文献
338.
2016年冬季使用单颗粒气溶胶质谱仪(SPAMS)于在北京市平谷区西柏店村进行大气颗粒物的在线观测.以m/z18[NH4]+为特征离子提取含铵盐颗粒物,分析其时间变化特征、粒径分布、化学组分、混合状态和可能来源.含铵盐颗粒物约占观测期间所有颗粒物的31%,分为NH4-OC(49.9%),NH4-EC(5.6%),NH4-ECOC(8.9%),NH4-HOC(1.4%),NH4-K(9.3%),NH4-NaK(21.7%)和NH4-FeK(2.5%)7种主要类别.铵盐主要以硫酸铵、硫酸氢铵和硝酸铵的形态存在,且更易于和含碳类物质发生内混.煤炭和生物质燃烧是铵盐颗粒物的主要来源.后向轨迹分析表明,清洁期气团主要来自采样点北方和西北方的长距离传输,灰霾期气团主要来自西北向的区域传输.潜在源贡献因子分析(PSCF)表明含铵盐颗粒物主要来自本地和周边区域的排放,以及西北方向的长距离传输. 相似文献
339.
QIN Xiaofei XIA Xijuan LI Yan ZHAO Yaxian YANG Zhongzhi FU Shan TIAN Mi ZHAO Xingru QIN Zhanfen XU Xiaobai YANG Yongjian 《环境科学学报(英文版)》2009,21(12):1695-1701
To understand potential ecotoxicological e ects of electrical and electronic equipment waste (e-waste) recycling and polybrominated
diphenyl ethers (PBDEs) bioaccumulation in loaches, a semi-field experiment using Chinese loach (Misgurnus anguillicaudatus) as
experimental fish was performed. Larval loaches were kept in net-cage for three months in an e-wastes recycling site and a reference
site in Southeastern China. There was significant di erence of the survival rate between the loaches from the e-wastes recycling site
(27%, 19/70) and from reference site (70%, 49/70). Histopathological responses were also found in all the livers examined in loaches
from the e-wastes recycling site. These results showed that mixed pollutants resulted from e-wastes recycling led to ecotoxicological
e ects on loaches. The bioaccumulation of polybrominated diphenyl ethers (PBDEs), the main pollutants in e-waste, in loaches was
also studied, the mean concentration of total PBDEs in sediment was 6726.17 ng/g wet weight and in water samples was 4.08 ng/L
(dissolved phase). BDE 209 was the dominant congener in sediment and with relatively high concentration in water. Relatively low
concentration of BDE 209 (less than 0.01% of total PBDEs) and high concentration of BDE47 (up to 39.34% of total PBDEs) were
detected in loaches. 相似文献
340.
Zhang Wenjie Mi Yongbao Jiao Weiguo 《Environmental science and pollution research international》2022,29(49):74038-74050
Environmental Science and Pollution Research - High-pressure rotary jetting (HPRJ) remediation is a recent-applied technology for in situ remediation of contaminated soils. The effectiveness of... 相似文献