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161.
1950-2009年洞庭湖流域农业水灾演变特征及分异规律 总被引:1,自引:0,他引:1
洞庭湖流域为我国重要农业生产区,而农业水灾却一直是制约农业可持续发展的最大障碍因素。以1950-2009年水灾统计资料为依据,用定性与定量相结合的方法,系统分析了该流域农业水灾演变特征及区域分异。结果表明:①年年发生流域性或区域性的农业水灾,其中重灾、特大水灾频率呈增大趋势;②在长时间尺度演变过程中,受灾率异常指数岀现2个波峰期和4个波谷期,成灾率异常指数岀现3个波峰期和3个波谷期,且水灾受灾率与成灾率大体上呈同步变化,但短时间內受灾率与成灾率却呈反向波动;③农业水灾具有突变性,但总体演变呈增加趋势;④受孕灾环境、洪涝致灾因子及经济发展水平组合差异的制约,农业相对灾情与绝对灾情在空间上的分布均呈明显的南北分异与东西分异。 相似文献
162.
Potential particulate pollution derived from UV-induced degradation of
odorous dimethyl sulfide 总被引:1,自引:0,他引:1
UV-induced degradation of odorous dimethyl sulfide (DMS) was carried out in a static White cell chamber with UV irradiation. The
combination of in situ Fourier transform infrared (FT-IR) spectrometer, gas chromatograph-mass spectrometer (GC-MS), wide-range
particle spectrometer (WPS) technique, filter sampling and ion chromatographic (IC) analysis was used to monitor the gaseous and
potential particulate products. During 240 min of UV irradiation, the degradation e ciency of DMS attained 20.9%, and partially
oxidized sulfur-containing gaseous products, such as sulfur dioxide (SO2), carbonyl sulfide (OCS), dimethyl sulfoxide (DMSO),
dimethyl sulfone (DMSO2) and dimethyl disulfide (DMDS) were identified by in situ FT-IR and GC-MS analysis, respectively.
Accompanying with the oxidation of DMS, suspended particles were directly detected to be formed by WPS techniques. These
particles were measured mainly in the size range of accumulation mode, and increased their count median diameter throughout
the whole removal process. IC analysis of the filter samples revealed that methanesulfonic acid (MSA), sulfuric acid (H2SO4) and
other unidentified chemicals accounted for the major non-refractory compositions of these particles. Based on products analysis and
possible intermediates formed, the degradation pathways of DMS were proposed as the combination of the O(1D)- and the OH- initiated
oxidation mechanisms. A plausible formation mechanism of the suspended particles was also analyzed. It is concluded that UV-induced
degradation of odorous DMS is potentially a source of particulate pollutants in the atmosphere. 相似文献
163.
This study compares the accumulation of Cr(VI) and biochemical changes (total chlorophyll, carotenoid, protein, malondialdehyde
(MDA) and cysteine contents) and roles of antioxidant enzymes (superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate
peroxidase (APX)) in tolerance to metal induced stress in Cucumis utillissimus L. grown in Cr contaminated soil (CS) with garden
soil (GS). Furthermore, Cr bioavailability was enhanced by ethylene diamine tetra-acetic acid (EDTA) addition to the soil to forecast
the plant’s accumulation pattern at elevated Cr environment. Accumulation of Cr in the leaves of the plant increased with increase in
substrate metals concentration. It further increased with the addition of EDTA by 1437% and 487% in GS and CS, respectively at the
highest treatment level. The lipid peroxidation increased proportionately with increase in Cr accumulation in the leaves. All the activity
of antioxidant enzymes (SOD, GPX and APX) and the level of cysteine increased with dose dependant manner. SOD and cysteine were
observed to be higher in the GS than in CS, but APX and GPX were found to be higher in CS than in GS. The increase in GPX and APX
activities with the increase in Cr concentration could be assumed that these two enzymes have a major role in the defense mechanism
towards stress induced by Cr in C. utillissimus. 相似文献
164.
Sedimentary record of polycyclic aromatic hydrocarbons in Lake Erhai,
Southwest China 总被引:1,自引:0,他引:1
Jianyang Guo Zhang Liang Haiqing Liao Zhi Tang Xiaoli Zhao Fengchang Wu 《环境科学学报(英文版)》2011,23(8):1308-1315
The temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was investigated in a sediment core from Lake Erhal in Southwest China using gas-chromatography/mass spectrometry (GC/MS) method.The total organic carbon (TOC) normalized total PAHs concentrations (sum of US Environmental Protection Agency proposed 16 priority PAHs) ranged from 31.9 to 269 μg/g dry weight (dw),and were characterized by a slowly increasing stage in the deeper sediments and a sharp increasing stage in the upper sediments.The PAHs in the sediments were dominated by low molecular weight (LMW) PAHs,suggesting that the primary source of PAHs was low- and moderate temperature combustion processes.However,both the significant increase in high molecular weight (HMW) PAHs in the upper sediments and the vertical profile of diagnostic ratios pointed out a change in the sources of PAHs from low-temperature combustion to high-temperature combustion.The ecotoxicological assessment based on consensus-based sediment quality guidelines implied that potential adverse biological impacts were possible for benzo(ghi)perylenelene and most LMW PAHs.In addition,the total BaP equivalent quotient of seven carcinogenic polycyclic aromatic hydrocarbons (BaA,CHr,BbF,BkF,BaP,DBA and INP) was 106.1 ng/g,according to the toxic equivalency factors.Although there was no great biological impact associated with the HMW PAlls,great attention should be paid to these PAH components based on their rapid increase in the upper sediments. 相似文献
165.
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168.
氧化亚铜(Cu2O)与H2O2组成的类Fenton体系能很好的氧化降解印染废水中的有机物.实验用Cu2O类Fenton氧化降解染料活性艳蓝KN-R,研究表明,Cu2O类Fenton能很好的氧化降解染料活性艳蓝KN-R.在KN-R的溶液初始pH值为2,水浴温度为50℃的条件下,用0.429 g Cu2O(0.3 mmol)和0.1 mL、质量分数为30%的H2O2处理50 mL、质量浓度为100mg/L的KN-R溶液1 h,其脱色率为95.09%,TOC去除率为56.38%. 相似文献
169.
为研究阜阳污水处理厂近几年来污泥产量与进水水质之间的关系,对自2007年1月份以来的产泥量与进水水质的基础数据进行了整理.并通过建立各个数据之间的相互关系图表来分析产泥量与进水水质之间的关系。 相似文献
170.
通过叶菜类蔬菜垃圾中温批式厌氧消化实验,比较了含固率(3%、5%、7%)和接种比(1.5、2.5、3.5)对产甲烷效果的联合影响.结果表明,在研究实验参数范围内,含固率越低、接种比越高,越有利于缩短产甲烷反应迟滞期,平均日产甲烷速率越快.经过52d的培养,在含固率为3%、接种比为3.5的工况中,平均日产甲烷速率最快,达到9.5mL/(gVS·d),日最大产甲烷速率最快,达到49.8mL/(gVS·d),最早进入快速产甲烷期.当接种比为3.5时,随着含固率的升高,产甲烷速率下降,迟滞期延长,但单位底物累计产甲烷量增大,含固率7%时单位底物累计净产甲烷量为481mL/gVS.而当接种比为1.5时,含固率为5%和7%的工况均无法启动甲烷化反应,含固率为3%的工况的产气迟滞期达15d.挥发性有机酸的累积抑制甲烷化反应的启动,迟滞期随着液相中有机酸浓度的增加而延长,当有机酸浓度低于1260mg/L,甲烷化反应没有明显的迟滞期. 相似文献