农产品产地土壤重金属外源污染来源解析及防控策略研究

分析了工业生产排放、污水灌溉、矿产资源开发、农业投入品施用、大气颗粒物降尘及固体废弃物堆放等农产品产地土壤重金属主要外源污染来源,在此基础上构建了包括工业过程源、固定燃烧源、灌溉水源、废弃物堆放源、流动源和农业投入品源的来源清单,并从建立健全源头预防和强化过程控制2个方面,提出了加强农产品产地土壤重金属污染监管的相关建议。     

蕃茄转基因受体系统的研究

对蕃茄基因转化的受体系统进行了研究结果表明：在蕃茄离体子叶（或子叶切段）培养中,只加细胞分裂素（Zt或BA）即可使不定芽充分分化,而少量生长素对不定芽的分化反而有抑制作用;在所试验过的多种外植体中,以2／3子叶片处切割子叶所产生的外植体用作转化受体最好;不同蕃茄品种、同一品种的不同外植体及同一外植体的不同培养方式等均对转化频率有一定的影响;通过生长素短期刺激诱导,可解决转基因植物生很困难的问题．     

Arsenic contamination of soils and agricultural plants through irrigation water in Nepal

This study monitored the influence of arsenic-contaminated irrigation water on alkaline soils and arsenic uptake in agricultural plants at field level. The arsenic concentrations in irrigation water ranges from <0.005 to 1.014 mg L(-1) where the arsenic concentrations in the soils were measured from 6.1 to 16.7 mg As kg(-1). The arsenic content in different parts of plants are found in the order of roots>shoots>leaves>edible parts. The mean arsenic content of edible plant material (dry weight) were found in the order of onion leaves (0.55 mg As kg(-1))>onion bulb (0.45 mg As kg(-1))>cauliflower (0.33 mg As kg(-1))>rice (0.18 mg As kg(-1))>brinjal (0.09 mg As kg(-1))>potato (<0.01 mg As kg(-1)).     

Use of toxicity identification evaluations to determine the pesticide mitigation effectiveness of on-farm vegetated treatment systems

Evidence of ecological impacts from pesticide runoff has prompted installation of vegetated treatment systems (VTS) along the central coast of California, USA. During five surveys of two on-farm VTS ponds, 88% of inlet and outlet water samples were toxic to Ceriodaphnia dubia. Toxicity identification evaluations (TIEs) indicated water toxicity was caused by diazinon at VTS-1, and chlorpyrifos at VTS-2. Diazinon levels in VTS-1 were variable, but high pulse inflow concentrations were reduced through dilution. At VTS-2, chlorpyrifos concentrations averaged 52% lower at the VTS outlet than at the inlet. Water concentrations of most other pesticides averaged 20-90% lower at VTS outlets. All VTS sediment samples were toxic to amphipods (Hyalella azteca). Sediment TIEs indicated toxicity was caused by cypermethrin and lambda-cyhalothrin at VTS-1, and chlorpyrifos and permethrin at VTS-2. As with water, sediment concentrations were lower at VTS outlets, indicating substantial reductions in farm runoff pesticide concentrations.     

Natural attenuation of diesel aliphatic hydrocarbons in contaminated agricultural soil

A diesel fuel spill at a concentration of 1 L m(-2) soil was simulated on a 12 m(2) plot of agricultural land, and natural attenuation of aliphatic hydrocarbons was monitored over a period of 400 days following the spill after which the aliphatic hydrocarbon concentrations were found to be below the legal contamination threshold for soil. The main fraction of these compounds (95%) remained at the surface layer (0-10 cm). Shortly after the spill (viz. between days 0 and 18), evaporation was the main origin of the dramatic decrease in pollutant concentrations in the soil. Thereafter, soil microorganisms used aliphatic hydrocarbons as sources of carbon and energy, as confirmed by the degradation ratios found. Soil quality indicators, soil microbial biomass and dehydrogenase activity, regained their original levels about 200 days after the spill.     

城市内河生物修复及其对底泥氮素转化影响的实验研究

对在城市内河底泥有机质与有机氮含量高的特殊环境下进行水体修复的可行性与修复方法进行了探讨.富含高有机氮的城市内河底泥是氮素的重要释放源,采用向水体曝气可以有效地促使总氮与NH3-N的降解,与未曝气相比,10 d后曝气条件下二者的去除率分别达到81%和92%;此时再以土著水生植物进行修复可以显著地提高水体修复的效果、稳定性与修复成功率,并使总氮、NH3-N维持在1 ms/L和0.5 ms/L以下.但应避免城市内河有效光辐射的减少对水体修复影响.     

Temporal variability of atmospheric particulate matter and chemical composition during a growing season at an agricultural site in northeastern China

This study presents the observations of PM_(10) and PM_(2.5) concentrations at an agricultural site from April to October 2012 in Dehui city,China.Ambient air was sampled by filter-based samplers and online PM monitors.The filter samples were analyzed to determine the abundance of ionic/inorganic elements,organic carbon(OC) and elemental carbon(EC).The daily PM_(10) concentrations varied significantly over the monitoring period,with an average of168 ± 63(in the range of 52-277) μg/m~3 during the land preparation/planting period(26 April-15 June),85 ± 65(36-228) μg/m~3 during the growing season(16 June-25 September),and 207 ±88(103-310) μg/m~3 during the harvest period(26 September-31 October).PM_(2.5) accounted for44%,56%and 66%of atmospheric PM_(10) during these periods,respectively.The PM_(10) diurnal variation showed a distinct peak from 16:00 to 21:00(LST) during the growing and harvesting seasons,while a gradual increase throughout the daytime until 17:00 was observed during tilling season.Mineral dust elements(Al,Ca,Fe,and Mg) dominated the PM_(10) chemical composition during the tilling season;OC,NO_3~-,SO_4~(2-) and NH_4~+ during the growing season;and carbonaceous species(i.e.,OC and EC) during the harvesting season.Our results indicate that the soil particles emitted by farm tillage and organic matter released from straw burning are the two most significant sources of PM_(10) emissions contributing to the recurring high pollution events in this region.Therefore,development of agricultural PM inventories from soil tillage and straw burning is prioritized to support air quality modeling.     

苦草对水-底泥-沉水植物系统中氮素迁移转化的影响

通过模拟水-底泥-沉水植物(苦草)系统,检测了苦草整个生命周期内总氮及各形态氮含量的变化,以反映N在该系统内的迁移转换.结果表明,在整个研究阶段,空白组和苦草组系统氮含量(水体+底泥+苦草中氮含量)均持续降低,但苦草组(实验始末)氮含量降低幅度明显高于空白组,其中苦草组系统中TN、NH4+-N、NO3--N含量分别减少了41.68%、81.96%、93.34%,分别比空白组提高了11.39%、31.90%、0.28%;苦草组底泥中TN、NH4+-N、NO3--N含量分别减少了43.45%、87.41%、96.50%,分别比空白组提高了13.78%、37.26%、1.68%.苦草的存在促进了底泥氮的释放,显著提升了底泥微生物活性及氮循环菌的数量,从而加快了系统内的氮素循环,并在其生命周期的不同阶段明显改变各形态氮的迁移及转化方式.2012年7~10月,苦草组系统总氮(TN)减少幅度最大,到10月份,水体中氮素含量达到最少.     

热活化过硫酸盐降解三氯生

基于硫酸根自由基（SO₄^·-）的高级氧化技术被广泛应用于土壤和地下水污染修复.本研究系统地考察了三氯生在热活化过硫酸盐高级氧化过程中的动力学、中间产物和降解途径.结果表明,提高反应温度或增加过硫酸盐的浓度,可加快三氯生的降解.三氯生的降解符合假一级反应动力学规律,反应活化能（E_a）为142 kJ·mol^-1.水中的腐殖酸显著抑制了三氯生的降解,而氯离子（Cl^-）对三氯生降解的影响比较复杂.当Cl^-浓度为5 μmol·L^-1时,三氯生的降解受到了轻微的促进;但是当Cl^-的浓度增加至10 μmol·L^-1甚至更高时,三氯生的降解反而受到了抑制.通过质谱分析发现三氯生降解过程中生成了4-氯-邻苯二酚、2,4-二氯苯酚和2-氯-5-（2,4-二氯-6-羟基苯氧基）-1,4-苯醌等6种主要中间产物,并由此推测醚键的断裂和酚环羟基化是三氯生的可能降解途径.本研究为基于SO₄^·-的高级氧化技术去除水中三氯生的应用可行性提供了依据.     

垃圾渗滤液运移过程中相关模型的研究及应用现状

介绍了垃圾渗滤液运移机理与研究现状,综述了国内外关于垃圾渗滤液释放、传输过程相关模型的研究及应用现状,并分析了各模型的优缺点。最后提出了渗滤液在土壤中运移的研究方向。渗滤液中水分在填埋场垃圾介质、包气带土层以及含水层各单一层中迁移转化的研究较全面;由于渗滤液中某种污染物的迁移转化涉及多学科交叉点,该方面的研究仍未成熟,相对滞后于工程技术发展的需要。