重金属Cd在再生水—土壤—蔬菜体系中的迁移

通过小区试验种植了小白菜和萝卜,以再生水灌溉和污泥施肥,采用修正的BCR法测定了再生水、污泥、土壤、蔬菜中重金属Cd的5种形态含量,分析Cd在再生水(污泥)-土壤-蔬菜体系中的迁移和累积特征。结果表明:灌溉用清水和再生水中Cd的总量均未超出国家农田灌溉水质标准(GB5084-2005)的规定,但水样中的Cd主要以水溶态存在,生物有效性系数K≥0.85。经再生水灌溉和污泥施肥后土壤中Cd的形态和总量均发生了变化。蔬菜地上部分中Cd以水溶态B0和可氧化态B3的形式存在,B0>B3;而地下部分以B0、B2和B3为主,B0相似文献   

Nitrate leaching under vegetable field above a shallow aquifer in Slovenia

In the search for new technologies that would ensure optimum yield and environmental sustainability, various irrigation, nitrogen and cropping system management strategies for the production of vegetables with a shorter growing period were assessed at a benchmark site in Slovenia for the years 2006 and 2007. In the studied years four irrigation and fertilization treatments were applied: (1) 50% drip irrigation of plants water requirements ET_crop and the farmer's practice of fertilisation (broadcasting), (2) fertilisation and 100% drip irrigation (fertigation), (3) the farmer's practice of irrigation (sprinkler irrigation using water stored in plastic tanks) and fertilisation, and (4) control (the farmer's practice of irrigation but no fertilisation). An equivalent of 80, 80 and 200 kg ha⁻¹ of nitrogen (N), 50, 50 and 80 kg ha⁻¹ of phosphorous (P) and 120, 120 and 300 kg ha⁻¹ of potassium (K) was added for iceberg lettuce, endive and cabbage, respectively. Nitrogen (N) labelled fertilizer (¹⁵N) was applied to trace the movement of the applied N fertiliser. The tested irrigation and fertilisation techniques for the production of vegetables with a shorter growing period in the Slovenian climate showed that environmentally sustainable practices (split application of nutrients compared to broadcast incorporating fertilisation) should be a practice of choice in water protection zones. The results confirm that fertigation and improved irrigation scheduling can be an effective way of minimizing nitrate leaching, and should be considered for vegetable production in or close to groundwater protection zones.     

Safety issues related to the maintenance operations in a vegetable oil refinery: A case study

The present work was focused on maintenance hazards related to vegetable oil refining. An incident occurred in an Italian vegetable oil refinery was presented to evidence this safety criticality. The incident took place during a maintenance shut down, and was associated to the ignition of the solid residual in a packed column. No fatalities or injuries were reported, but the column was strongly damaged and removed from the plant. A specific experimental characterization of the solid residues accumulated in the column, sampled both from the damaged and undamaged parts of the column, was carried out in order to determine the conditions leading to unwanted combustion of the residues. At the same time, samples taken from the damaged column steelwork were subjected to metallurgical analysis aimed at the thermal and mechanical characterization of the steel, obtaining information about the incident duration and temperature reached during the combustion phenomenon. The study evidenced the need of adequate maintenance procedures and safety management in the generic framework of food industry, identified as key lessons learned.     

遥感指数在湖泊叶绿素a反演研究中的应用

借鉴陆地植被指数的算法,利用MODIS数据的波段组合对太湖叶绿素8浓度进行反演。探讨了差值植被指数DVI、比值植被指数RVI、归一化植被指数NDVI这三种遥感指数形式的反演效果及各自特点。MODIS数据蓝光波段和红外波段的组合是反演太湖叶绿素浓度的最佳波段组合,DVI适合于反演叶绿素浓度高的情况,RVI的反演结果两极分化明显而普适性较差,NDVI适合于反演浓度较低的情况。     

蔬菜对大气汞和土壤吸收的研究

通过田间观测和盆栽试验研究了蔬菜富集汞的特性及土壤、大气对蔬菜汞的贡献。对田间 11种蔬菜的研究发现 ,蔬菜根和叶的含汞浓度高于茎和果 ;在自然条件下 ,蔬菜所吸收的汞 60 %以上分布于地上部的可食部分。盆栽试验结果表明 ,在气汞浓度为 5 7.6± 14.7ng· m- 3条件下 ,红萝卜、莴苣叶 (可食部分 )的含汞浓度超过了食品卫生标准 ;气汞、土壤汞对蔬菜汞的贡献率分别为 70 .4～ 90 .7%、9.3～ 2 9.6% ,气汞较土壤汞是蔬菜更为重要的汞源     

杭州市区蔬菜基地蔬菜重金属含量研究

通过对杭州市区主要蔬菜基地蔬菜中8种重金属含量监测分析与评价，结果表明，江干区蔬菜基地除茄果类蔬菜外，其他种类蔬菜中部分重金属指标均存在超标现象。下沙经济开发区蔬菜基地蔬菜中重金属含量均未超标。     

锐劲特在菜地生态系统中的残留动态研究

建立了青菜、土壤中锐劲特及其代谢物的气相色谱毛细管柱残留分析的方法。对锐劲特及其降解产物在菜地生态系统中的残留动态进行了研究,明确了锐劲特在青菜和土壤中的残留和消解情况,锐劲特在土壤中的降解半衰期为7．88d,在青菜中的降解半衰期为2．58d。     

若干蔬菜和菜区土壤的重金属含量调查

本文介绍了杭州市菜区土壤及部分蔬菜重金属含量状况及分布规律。其中土壤中汞的平均含量是对照点的2.6倍,铅增加69.5％,铜增加58.17％,砷和锌增加19％左右,镍和镉与对照点含量接近。蔬菜中主要积累元素为铅汞。文章还扼要提出了防止菜区重金属污染的对策。     

Mercury in soil, vegetable and human hair in a typical mining area in China: Implication for human exposure

Concentrations of total mercury(T-Hg) and methylmercury(MeHg) in soil, vegetables, and human hair were measured in a mercury mining area in central China. T-Hg and MeHg concentrations in soil ranged from 1.53 to 1054.97 mg/kg and 0.88 to 46.52 μg/kg, respectively.T-Hg concentrations was correlated with total organic carbon(TOC) content(R~2= 0.50, p0.01)and pH values(R~2= 0.21, p0.05). A significant linear relationship was observed between MeHg concentrations and the abundance of sulfate-reducing bacteria(SRB)(R~2= 0.39, p0.05) in soil.Soil incubation experiments amended with specific microbial stimulants and inhibitors showed that Hg methylation was derived from SRB activity. T-Hg and MeHg concentrations in vegetables were 24.79 – 781.02 μg/kg and 0.01 – 0.18 μg/kg, respectively; levels in the edible parts were significantly higher than in the roots(T-Hg: p0.05; MeHg: p0.01). Hg species concentrations in rhizosphere soil were positively correlated to those in vegetables(p0.01), indicating that soil was an important source of Hg in vegetables. Risk assessment indicated that the consumption of vegetables could result in higher probable daily intake(PDI) of T-Hg than the provisional tolerable daily intake(PTDI) for both adults and children. In contrast, the PDI of MeHg was lower than the reference dose. T-Hg and MeHg concentrations in hair samples ranged from 1.57 to 12.61 mg/kg and 0.04 to 0.94 mg/kg, respectively, and MeHg concentration in hair positively related to PDI of MeHg via vegetable consumption(R~2= 0.39, p0.05), suggesting that vegetable may pose health risk to local residents.     

蔬菜废物的两相厌氧消化产气研究

从Holbak丹麦废物处理厂收集的蔬菜废物进行了两相厌氧消化产气的研究。对水解条件，接种物质的添加，pH，及甲烷母液对消化产气的影响进行了考察。结果显示沥液循环实验的COD产率为67．9g／kg湿物质，VFA产率为44．7g/kg湿物质，产气为44．7g/kg湿物质；水冲实验的COD产率为128．2g/kg kg湿物质，VFA产率为128．0g／kg kg湿物质，产气为1281／kg湿物质，牛粪的添加使得蔬菜废物COD及VFA产率提高了30％。还发现以牛粪作为甲烷母液，在pH低于6．8时可以有高的甲烷初始产率。