超声提取-气相色谱法测定土壤中的多种有机氯农药残留

有机氯农药是一类高毒性、难分解、易残留的化合物,环境样品中有机氯农药残留量在一定程度上直接或间接反映了土壤、水体、植物的农药污染水平.在20世纪80年代我国已禁用有机氯农药,但许多农业土壤中仍有大量残留,严重影响农产品的质量,所以测定土壤中有机氯农药的残留量,对发展我国的绿色农业、有机农业具有重要的意义.     

Spatial and temporal variation of nitrogen exported by runo from sandy agricultural soils

The eutrophication problem has drawn attention to nutrient leaching from agricultural soils, and an understanding of spatial and temporal variability is needed to develop decision-making tools. Thus, eleven sites were selected to monitor, over a two-year period, spatial and temporal variation of runoff discharge and various forms of N in surface runoff in sandy agricultural soils. Factors influencing the variation of runoff discharge and various forms of N in surface runoff were analyzed. Variation of annual rainfall was small among 11 sites, especially between 2001 and 2002. However, variation of annual discharge was significant among the sites. The results suggest that rainfall patterns and land use had significant effect on discharge. The concentrations of total N, total kjeldahl N （TKN）, organic matter-associated N （OM-N）, NO3- -N, and NHn＋-N in the runoff ranged widely from 0.25 to 54.1, 0.15 to 20.3, 0.00 to 14.6, 0.00 to 45.3, and 0.00 to 19.7 mg/L, respectively. Spatial and temporal variations in the N concentration and runoff discharge were noted among the different sites. Annual loads of N in the runoff varied widely among monitoring sites and depend mainly on runoff discharge. High loads of total N, OM-N, NO3--N, and NHn＋-N in the runoff either in citrus groves or on vegetable farms occurred from June to October for each year, which coincided with the rainy season in the region. This study found that N in surface runoff was related to rainfall intensity, soil N level, and fertilizer use.     

Effects of bile salts and divalent cations on the adsorption of norfloxacin by agricultural soils

The effects of bile salts （sodium cholate and sodium deoxycholate, 0-20 mmol/L）, divalent cations （Ca^2＋, Mg^2＋, Cu^2＋ and Zn^2＋, 0-20 mmol/L） or pH （3.0-10.0） on the adsorption of norfloxacin by three selected soils （Paddy_H, Paddy_G and Red_J） were systematically studied. Soil adsorption of norfloxacin follows a pseudo second-order kinetics model, and the maximum adsorption capacity has been determined from the nonlinear fit of the Langmuir isotherm model to be 88.8, 88.1 and 63.0 μmol/g for the adsorption onto Paddy_H, Paddy_G and Red_J, respectively. The results indicate that norfloxacin has a high adsorption affinity for the agricultural soils tested and that the organic content of these soils have at least a slight influence on this adsorption. The adsorption of norfloxacin to soils was strongly dependent on pH and exhibited a maximum at approximately pH 6. The presence of divalent cations prominently suppressed the adsorption of norfloxacin by paddy soils, which followed an order of Cu^2＋ 〉 Mg^2＋ 〉 Ca^2＋ 〉 Zn^2＋, and by red soil, which followed an order of Cu^2＋ 〉 Zn^2＋ 〉 Ca^2＋ 〉 Mg^2＋. The adsorption of norfloxacin （by the soils studied） sharply decreased as the amount of bile salts was increased. For uncharged norfloxacin at environmentally relevant pH values, such factors as soil type, exogenous divalent cations and macromolecules significantly altered the environmental fate and transport of norfloxacin between aquatic and soil interfaces.     

利用农业土壤固定有机碳——缓解全球变暖与提高土壤生产力

大气CO     

未来气候变化对旱田生态系统

反硝化-分解作用模型（DNDC）能较好地拟合贵州省玉米—油菜轮作田、大豆—冬小麦轮作田和休耕地的N₂O释放通量及其影响因子季节变化模式,采用DNDC模型定量探讨了未来气温、降雨量和降雨中无机N浓度变化对亚热带旱田生态系统N₂O释放的潜在影啊．结果表明,除大亚外,其它作物和休耕地土壤N₂O释放通量对气温变化接近于正响应;玉米地、大豆地和体耕地（对应于玉米生长期）土壤N₂O释放通量对降雨量的变化也接近于正响应;降雨中无机氮浓度的变化对3块实验田NO₂释放通量影响最大．     

典型设施农业土壤酞酸酯污染特征及其健康风险

采用超声提取、气相色谱-质谱技术和CalTOX模型,分析了南京城郊典型设施菜地土壤中6种酞酸酯的污染特征、污染负荷及其健康风险.结果表明,所有的土壤样品中均检测出酞酸酯,6种酞酸酯的总量为0.15~9.68mg/kg,其平均含量为2.21mg/kg;邻苯二甲酸二丁酯(DnBP)、邻苯二甲酸(2-乙基己基)酯(DEHP)和邻苯二甲酸二辛酯(DnOP)为该地区设施农业土壤的主要酞酸酯种类,其检出率分别为88.2%、100%和79.8%,含量范围分别在n.d.~1.83、0.02~9.03、n.d.~1.74mg/kg之间;土壤pH值和有机碳含量与土壤酞酸酯含量之间无显著相关性,研究区域土壤酞酸酯总体污染负荷为4.31kg/hm2;健康风险评价结果表明DnBP和DEHP的潜在健康风险较高,设施农业从业者的主要暴露途径通过皮肤接触;设施菜地土壤酞酸酯含量、污染负荷以及健康风险均显著高于周边地区露天菜地土壤.     

广东省典型区域农业土壤中六六六(HCHs)和滴滴涕(DDTs)的残留及其分布特征

2002年10月—2005年11月采集广东省典型区域(汕头市、湛江市、东莞市、惠州市、中山市、珠海市和佛山市顺德区)的农业土壤表层(0～20 cm)样品444个,采用气相色谱方法对土壤中六六六(HCHs)和滴滴涕(DDTs)进行分析,初步揭示广东省农业土壤中有机氯农药的分布及残留情况. 结果表明:HCHs的检出率为95.9%,w(HCHs)为未检出～104.38 ng/g,平均值5.90 ng/g;DDTs的检出率为95.7%,w(DDTs)为未检出～157.75 ng/g,平均值为10.18ng/g. HCHs的4种异构体中,w(β-HCH)最高,平均值为2.96 ng/g,而p,p′-DDE是3种DDTs异构体中含量最高的,平均值为5.09 ng/g. 不同土壤利用类型中,有机氯农药残留总量为水稻田>菜地>香蕉地>旱坡果园地>甘蔗地,汕头市土壤中有机氯农药残留总量明显高于该研究区的其他地方. 与国内外其他地区农业土壤中的DDTs和HCHs含量和我国土壤环境质量标准(GB15618-1995)相比,广东省典型区域污染程度较低.      

于都县农业土壤养分调查与评价

以江西省于都县为例,分析赣南地区农业土壤中有机质、全氮、全磷、全钾元素含量的空间分布特征及其影响因素,并依据《土地质量地球化学评价规范》(DZ/T0295-2016)对该地区农业土壤养分丰缺状况进行了调查与评价.结果 表明:研究区土壤的pH值为酸性,土壤中有机质、全氮、全磷、全钾含量的变异系数小于50％,属于中等强度变...     

遵义东南部地区农业土壤重金属污染预警模型

于2003-2008年对遵义东南部地区耕作区的土壤重金属含量进行检测,选取Cd、Pb、Cr、Hg、As 5种重金属,将改进型层次分析法和时间序列法相结合建立农业土壤重金属污染趋势预警模型和恶化速度预警模型,采用二次指数平滑法预测未来农业土壤重金属综合污染指数及恶化速度.结果表明,如无人为保护措施,自2008年起再过37 a该地区土壤重金属含量将达轻度污染.校验结果表明预测值与实测值较为符合,平均相对误差小于6%.该模型适用于未受过人为大量污染的、重金属含量变化较为稳定的农业地区.     

珠江三角洲典型区域农业土壤中镍的含量分布特征

对珠江三角洲典型区域农业土壤取样调查表明:研究区农业土壤中镍的含量范围在2.29～112.00mg·kg-1之间,平均值(27.79±18.39)mg·kg-1,有24.9%土壤样品的镍含量超过国家土壤环境质量标准(GB15618—1995)的二级标准;土壤中镍的含量主要受成土母质的影响,滨海沉积物和三角洲冲积物发育的土壤中镍含量明显高于其它成土母质的土壤;可能受到富含镍的西江和北江沉积物质的影响,西江和北江三角洲沉积区土壤中镍含量明显高于东江三角洲沉积区。调查结果为研究区域的土壤环境质量调查、评价和治理提供重要的基础资料和决策依据。