长春市主要蔬菜中农药残留分析

采用速测法和气相色谱法研究了长春市市场销售的主要蔬菜中的农药残留问题。2002年秋季对长春市的9个蔬菜批发市场的16种蔬菜进行抽样检测，蔬菜中有机磷类和氨基甲酸酯类农药平均超标率为11．05％，残留的主要农药种类是甲胺磷、氧化乐果和敌敌畏。检测16种蔬菜中有9种超标。2003年春季同样对9个蔬菜市场的17种蔬菜进行抽样检测，农药残留平均超标率为11．0％，残留的农药主要种类是甲基对硫磷、对硫磷、甲拌磷、敌敌畏、氯氰菊酯和氰戊菊酯等，检测的17种蔬菜中有3种严重超标。由此可见蔬菜中农药残留还是很严重的问题，政府与有关部门仍需加强管理。     

A Bayesian network approach to modelling land-use decisions under environmental policy incentives in the Brazilian Amazon

ABSTRACT

Deforestation driven by agricultural expansion is a major threat to the biodiversity of the Amazon Basin. Modelling how deforestation responds to environmental policy implementation has thus become a policy relevant scientific undertaking. However, empirical parameterization of land-use/cover change (LUCC) models is challenging due to the high complexity and uncertainty of land-use decisions. Bayesian Network (BN) modelling provides an effective framework to integrate various data sources including expert knowledge. In this study, we integrate remote sensing products with data from farm-household surveys and a decision game to model LUCC at the BR-163, in Brazil. Our ‘business as usual’ scenario indicates cumulative forest cover loss in the study region of 8,000 km² between 2014 and 2030, whereas ‘intensified law-enforcement’ would reduce cumulative deforestation to 1,600 km² over the same time interval. Our findings underline the importance of conservation law enforcement in modulating the impact of agricultural market incentives on land cover change.     

Temporal dynamics of arsenic uptake and distribution: food and water risks in the Bengal basin

Abstract

Contaminated food chain is a serious contender for arsenic (As) uptake around the globe. In Nadia, West Bengal, we trace possible means of transfer of As from multiple sources reaching different trophic levels, and associated seasonal variability leading to chronic As uptake. This work considers possible sources-pathways of As transfer through food chain in rural community. Arsenic concentration in groundwater, soil, rice, and vegetable-samples collected detected in different harvest seasons of 2014 and 2016. Arsenic level in shallow groundwater samples ranged from 0.1 to 354?µg/L, with 75% of the sites above the prescribed limit by WHO (10?µg/L) during the boro harvest season. High soil As content (～20.6?mg/kg), resulted in accumulation of As in food crops. A positive correlation in As conc. with increase over period in all sites indicating gradual As accumulation in topsoil. Unpolished rice samples showed high As content (～1.75?mg/kg), polishing reduced 80% of As. Among vegetables, the plant family Poaceae with high irrigation requirements and Solanaceae retaining high moisture, have the highest levels of As. Contaminated animal fodder (Poaceae) and turf water for cattle are shown to contaminate milk (0.06 to 0.24?µg/L) and behoves strategies, practices to minimize As exposure.     

气相色谱法测定蔬菜中多种有机磷农药

探讨同时测定蔬菜中多种有机磷农药残留量的方法.蔬菜样品经前处理后用气相色谱仪测定甲胺磷、敌敌畏、乙酸甲胺磷、氧化乐果、甲拌磷、乐果、马拉硫磷和对硫磷等8 种有机磷农药残留量,测定了方法的回收率和精密度,分析了干扰情况.上述8 种农药的平均回收率分别为99.0%,96.0%,130.4%,101.3%,95.9%,99.4%,92.4%,91.0%,变异系数分别为6.91%,6.09%,9.23%,9.63%,9.18%,7.01%,6.82%,7.50%.该方法操作简便,回收率和精密度较好,干扰少.     

A complete set of procedure for determination of multiresidue of pesticides in vegetables

A complete set of procedure for determination of multiresidue of pesticides in vegetables was presented in this paper.The complete set of procedure included three steps:bioassay,cholinesterase inhibition and GLC analysis.The samples could be identified to be contaminated with pesticides if 5% of house flies was knocked down in 50 tested house flies. Those samples contaminated with pesticides needed to be detected by AChE inhibition method.The qualitative and quantitative analyses were carried out by GLC.Recoveries ranged from 83.7% in Chinese cabbages to 105.6% in tomatoes for pyrethroids,and 84.0% in tomatoes to 102.7% in sweetbell redpeppes for organophosphorus compounds.Coefficients of variations ranged from 0.59% to organophosphorus compounds.Coefficients of variations ranged from 0.59% to 7.87% for pyrethroids. and 0.33% to 9.88% for organophosphorus compounds with vegetables. The complete set of procedure has been used successfully to analyze 7000 samples collected in Beijing. About 1% of the samp     

无公害蔬菜生产基地环境质量研究

无公害蔬菜的产地,必须达到一定的环境质量标准,故生产基地环境质量研究是生产无公害蔬菜的第一关。主要环境要素有：土壤、水质、大气环境,同时检测基地现产蔬菜中农药残留量。     

绿色食品蔬菜生产中若干污染物的容许限量

讨论了绿色食品蔬菜中镉和灌溉水中氯化物的限量水平。建议蔬菜中镉的浓度应控制在０．０５ｍｇ／ｋｇ下,滨海地区灌溉水中Ｃｌ＾－含量可不作为限制因素。     

Production of boundary layer ozone from tropical American Savannah biomass burning emissions

Boundary layer ozone and carbon monoxide were measured at a savannah site in the Orinoco river basin, during the dry and wet seasons. CO and O₃ concentrations recorded around noontime show a good linear correlation, suggesting that the higher ozone levels observed during the dry season are photochemically produced during the oxidation of reactive hydrocarbons in the presence of NO_x both emitted by biomass burning. The rate of photochemical ozone production in the boundary layer ozone by biomass burning calculated from the production ratio ΔO₃/ΔCO (0.17±0.01 v : v) and the amount of CO produced by fires (0.26–1.3 mole m⁻² dry season⁻¹), ranges from 0.6 to 2.6 ppbv h⁻¹ for 8 h of daylight. This O₃ production rate is in fairly good agreement with the value derived from RO₂ radical measurements made in the Venezuelan savannah during the dry season. The net boundary layer production of O₃ from all tropical America savannah fires is estimated to range between 0.28 and 0.36 Tmol O₃ per year, which is about 3 times higher than the O₃ produced from pollution sources in the eastern United States during the summer. An extrapolation to all of the world's savannah would indicate a net boundary layer ozone production of about 1.2 Tmol yr⁻¹. This is discussed in the context of the overall global budget of tropospheric ozone.     

宁夏供港蔬菜田土壤重金属分布特征及生态风险评价

农田土壤重金属污染会影响蔬菜作物的生长发育及产量,同时也会影响蔬菜的品质与口感,长期以来通过食物链传递和富集,最终对人体健康造成一定危害.因此为探明宁夏多年多茬种植供港蔬菜后其土壤重金属分布特征,预测其生态风险,分析其污染形成原因,于2019~2021年连续3 a采集了477个宁夏供港蔬菜田表层土壤样本,分析As、Cd、Cr、Hg、Pb、Cu、Zn和 Ni 这8种重金属含量和分布特征,采用单因子污染指数法、内梅罗综合污染指数法、地累积指数法和潜在生态风险指数法对宁夏供港蔬菜田土壤重金属污染状况进行评价,利用Pearson相关分析和主成分分析法解析了宁夏供港蔬菜田重金属来源.结果表明,宁夏供港蔬菜田土壤中As、Cd、Cr、Hg、Cu和Zn含量均值高于宁夏土壤背景值,但8种重金属含量均低于国内农用地土壤风险筛选值;在空间分布上,As、Cr和Ni在研究区西北部、中部以及南部出现连片高值区,Pb、Zn、Cd、Hg和Cu在研究区西北部与南部出现高值响应;单因子指数法和内梅罗综合污染指数法表明,宁夏供港蔬菜田土壤整体处于清洁水平;地累积指数法结果显示研究区污染以Hg和Cd污染为主,污染区域主要集中在研究区西北部和南部;潜在生态风险指数显示Hg和Cd为主要风险元素,其中Hg以中等、较强和很强生态风险为主,分别占比44.65 %、44.65 %和1.26 %,Cd以中等、较强为主,占比65.83 %和3.56 %;综合Pearson相关分析和主成分分析表明,8种重金属污染来源可划分为3类,Ⅰ为自然源:Cu、Zn、Pb、As、Ni和Cr;Ⅱ为农业源:Cd;Ⅲ为工业源和农业源:Hg.综合来看,供港蔬菜田土壤重金属均无超标现象,土壤环境条件良好,宁夏供港蔬菜生产整体处于安全水平.研究结果可为宁夏供港菜田土壤安全利用和供港蔬菜安全生产、合理施肥、农艺运筹以及种植结构调整等提供帮助.     

昭通市农田土壤和蔬菜重金属污染评价及相关性分析

以昭通市农田区域为研究对象,采用点对点协同采样的方法对昭通市农田土壤和蔬菜进行采集,测定了As、Pb、Cu、Zn、Cd和Cr 这6种重金属含量.使用地累积指数和潜在生态风险指数对土壤重金属污染进行评价,利用健康风险模型评估蔬菜对人体产生的风险情况.结果表明,研究区土壤存在Cu、Zn、Pb、Cd和Cr污染,相较于农用地风险筛选值,超标率分别为34.35%、6.87%、2.29%、80.15%和6.11%;蔬菜存在Pb、Cd和Cr污染,相较于食品中污染物限量,超标率分别为6.87%、15.27%和36.64%.土壤污染评价表明,土壤重金属Cd存在强生态风险,其余重金属存在轻微生态风险.人体健康风险评估模型显示,非致癌风险及致癌风险均超过可接受范围,且对儿童的影响更大.相关性分析表明,土壤中的As对蔬菜吸收Cu和Zn具有拮抗作用,而土壤中Cr对蔬菜吸收Cu和Zn具有促进作用.