氯代苯类化合物在飞灰表面的热分解

密闭体系中,在生活垃圾焚烧飞灰的催化作用下,一氯苯到六氯苯表现出不同的热分解特性.这12种氯苯化合物分别经过300℃、30min加热处理,得到的脱氯/加氢反应产物的总量为初始氯苯化合物的50%-90%;而这些反应底物自身的含量为其原始含量的20%-90%.高氯代苯比低氯代苯更容易发生脱氯/加氢的反应.通过与热力学数据的比较,我们认为氯苯化合物脱氯/加氢反应是由热力学控制的.对于HCB而言,有两条主要的脱氯途径,其比例不相上下:1)HCB→五氯苯→1,2,3,5.四氯苯→1,3,5-三氯苯→1,3-二氯苯→1-氯苯;2)HCB→五氯苯→1,2,4,5-四氯苯→1,2,4-三氯苯→1,4-二氯苯→1-氯苯.     

长沙地区O3污染潜势广义可加模型的季节分异性

基于长沙市2016—2019年臭氧（O₃）浓度的逐时监测资料以及该时段同时次的气象观测数据,首先利用相关性分析和方差膨胀因子相结合的方法排除了相对湿度、太阳辐射、气温、风速、气压之间存在多重共线性问题,进而构建了春、夏、秋、冬四季O₃日最大8 h滑动平均质量浓度（O₃-8 h）与上述气象因子的广义可加模型（GAMs）,分析了O₃污染潜势GAMs模型的季节分异特征。结果表明：①春、夏、秋、冬四季O₃与相对湿度、太阳辐射、气温、风速、气压各变量之间多呈现出非线性关系（自由度大于1）。②春、夏、秋、冬四季多变量GAMs模型方差解释率（IRV）分别为80.7%、60.2%、83.0%、81.4%,调整判定系数R²分别为0.795、0.564、0.819、0.795,即不同季节气象因子在GAMs模型中对O₃的解释能力存在显著差异,秋季最好,冬春季次之,夏季最差。③相对湿度、太阳辐射、气温是决定春、夏、秋、冬四季O₃浓度变化最重要的气象要素,但其重要性排序随季节有所变化,对应的太阳辐射的F统计值分别为140.841、36.606、14.16、46.377,相对湿度的F统计值分别为3.291、4.158、15.82、8.105,气温的F统计值分别为7.030、2.113、15.79、3.340。该结论揭示了气象因子对O₃演化影响的复杂性,并为后续O₃污染潜势的预报奠定了基础。     

藻毒素的性质及其处理研究进展

探讨了藻毒素的结构及其理化性质 ,系统总结迄今为止的各种藻毒素降解方法的研究进展 ,指出今后在藻毒素污染控制和处理方面进一步研究的方向     

多环芳烃降解真菌Fusarium solani对芘的吸收存储和降解特性研究

以芘为唯一碳源,从公路旁污染土壤中分离得到一株芘降解真菌,经鉴定为Fusarium solani(命名为Py F-1),荧光显微镜观察发现其菌丝能吸收储存芘.对该菌株在芘浓度为50 mg·L-1的液体培养基中对芘的吸收储存和降解特性,具体包括芘的生物降解、菌体吸收、菌体吸附和消解总量进行了39 d的动态研究,结果表明:生物降解芘在培养0~14 d内逐渐增加,培养14 d时占芘添加量的15.9%,此后基本达到稳定,培养结束时生物降解芘为芘添加量的17.6%;菌体吸收芘在0~21 d内含量较少且变化不显著,低于芘添加量的3%;而在21~39 d内,菌体吸收芘变化显著,芘的消解总量随着菌体吸收量的变化产生显著波动;培养28 d时,芘的消解总量达到最大值,其中菌体吸收芘占芘消解总量的一半,达到芘添加量的16.0%,菌体吸附芘不足芘添加量的0.5%,在研究中可以忽略不计.因此,培养前期培养基中芘的消解以生物降解为主,培养后期菌体吸收芘的变化是芘消解总量变化的主要原因.     

重庆市大气污染特征及其影响因素分析

该文通过对2002-2007年重庆市环境空气质量资料做统计分析,评价了近几年重庆市区的大气环境污染状况,并分析了重庆市大气污染的主要特征及其影响因素,得出了相应的结论并提出了一些具体的建议。     

涨渡湖湿地保护与渔业生产优化模式探讨

涨渡湖湿地渔业进行人力的利用起始于1952年,渔业生产主要是以人工投放、天然生长为主,鱼类资源自然增殖为辅的粗放型管理模式。1992～2004年每年平均投放大规格鲢、鳙鱼种量为279 014.8 kg,平均捕捞量为755 439 kg,平均捕捞收入为3 329 143.52元,产量变幅范围为36 691～506 135 kg,其中有9个年份变幅在100 000 kg以上。涨渡湖湿地渔业利用存在产权与经营权分离、沉水植物急剧消退、菱角资源未加合理利用、灌江纳苗与分洪调蓄不能协调等方面问题。从常规鱼类放养型渔业、名优鱼类精养型渔业以及综合型渔业方面对涨渡湖湿地生态渔业可持续发展生产模式进行了相关探讨,提出了建立江湖联系机制的4点建议;并在优化生产模式、合理利用资源、调整产业结构、促进经济发展、严格控制污染、搞好综合治理、加强宣传管理、促进湿地恢复等方面提出了针对涨渡湖湿地的一系列保护对策。     

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO_2 anodes were prepared by thermal decomposition to examine the influence',of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol.The physicochemical properties of the Sb-SnO_2 coating were markedly influenced by different amounts of Sb dopant.The electrodes,which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks,compared with Ti/Sb-SnO_2 electrodes containing 10% or 15% Sb dopant,which exibited larger mud cracks and pores on the surface.However,the main microstructure remained unchanged with the addition of the Sb dopant.No new crystal phase was observed by X-ray diffraction(XRD).The electrochemical oxidation of 4-chlorophenol on the Ti/SnO_2 electrode with 5% Sb dopant was inclined to electrochemical combustion;while for those containing more Sb dopant,intermediate species were accumulated.The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm~2 for 180 min;and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%,respectively.     

Nitrogen interception in floodwater of rice field in Taihu region of China

A field experiment located in Taihu Lake Basin of China was conducted,by application of urea or a mixture of urea with manure, to elucidate the interception of nitrogen(N)export in a typical rice field through"zero-drainage water management"combined with sound irrigation,rainfall forecasting and field drying,N concentrations in floodwater rapidly declined before the first event of field drying after three split fertilizations,and subsequently tended to retum to the background level.Before the first field drying,total particulate nitrogen(TPN)was the predominant N form in floodwater of plots with no N input,dissolved inorganic nitrogen(DIN)on plots that received urea only,and dissolved organic nitrogen(DON)on plots treated with the mixture of urea and manure.Thereafter TPN became the major form.No N export was found from the rice field,but total nitrogen(TN)of 15.8 kg/hm~2 was remained,mainly due to soil N sorption.The results recommended the zero-drainage water management for full-scale areas for minimizing N export.     

Effect of nitrification inhibitor DMPP on nitrogen leaching, nitrifying organisms, and enzyme activities in a rice-oilseed rape cropping system

DMPP （3,4-dimethylpyrazole phosphate） has been used to reduce nitrogen （N） loss from leaching or denitrification and to improve N supply in agricultural land. However, its impact on soil nitrifying organisms and enzyme activities involved in N cycling is largely unknown. Therefore, an on-farm experiment, for two years, has been conducted, to elucidate the effects of DMPP on mineral N （NH4^＋- N and NO3^--N） leaching, nitrifying organisms, and denitrifying enzymes in a rice-oilseed rape cropping system. Three treatments including urea alone （UA）, urea ＋ 1% DMPP （DP）, and no fertilizer （CK）, have been carded out. The results showed that DP enhanced the mean NH4^＋-N concentrations by 19.1%-24.3%, but reduced the mean NO3^--N concentrations by 44.9%-56.6% in the leachate, under a two-year rice-rape rotation, compared to the UA treatment. The population of ammonia oxidizing bacteria, the activity of nitrate reductase, and nitrite reductase in the DP treatment decreased about 24.5%-30.9%, 14.9%-43.5%, and 14.7%-31.6%, respectively, as compared to the UA treatment. However, nitrite oxidizing bacteria and hydroxylamine reductase remained almost unaffected by DMPP. It is proposed that DMPP has the potential to either reduce NO3^--N leaching by inhibiting ammonia oxidization or N losses from denitrification, which is in favor of the N conversations in the rice-oilseed rape cropping system.     

软水中富里酸对铜管/磷酸盐体系溶解性铜释放影响

通过静态模拟试验研究了在软水体系中富里酸对铜管/磷酸盐缓蚀行为的影响,结果表明,富里酸含量、软水pH值、停留时间影响磷酸盐对铜管的缓蚀作用;高浓度的富里酸(16mg/L,以TOC计)明显增加溶解性铜释放,且从新铜管释放溶解性铜浓度高于老化6个月和12个月的铜管;在富里酸存在下,pH值较低时显著增加溶解性铜的释放,随着pH值的增大,富里酸对溶解性铜的释放影响降低;在96h的停留过程中,溶解性铜的释放浓度不断发生变化,表明富里酸与铜离子形成的络合物影响磷酸与铜的相互作用,从而影响磷酸盐对铜管的缓蚀效果.