锌冶炼区菜地土壤和蔬菜重金属污染状况及风险评价

对黔西北地区某典型锌冶炼区菜地土壤和主要蔬菜进行取样调查,测定了土壤和蔬菜可食用部分Pb、Cd、Zn、Cu、As、Ni 6种重金属的含量,采用单项污染指数和综合污染指数法评价了土壤和蔬菜中重金属的污染状况,并分别采用潜在生态风险指数（RI）和目标危险系数法（THQ）评价了菜地土壤重金属污染的潜在生态风险和蔬菜中重金属对成人和青少年儿童的健康风险.结果表明,该区域菜地土壤已受到重金属的重度污染,且以Cd对综合指数的贡献最大,土壤Cd存在极强生态风险,研究区处于轻微、中等、强和很强的生态风险程度的采样点比例分别为2.0%、14.3%、35.7%和48.0%;在所采集的蔬菜样本中,土豆处于重度污染水平,芸豆处于中度污染水平;复合重金属健康风险指数评价结果表明,食用研究区域蔬菜对成人和青少年儿童健康产生负面影响的可能性很大.     

盆栽条件下常见蔬菜对污染土壤中铀的吸收

通过盆栽实验,研究了胡萝卜、生菜、马铃薯、豌豆4种蔬菜在人工铀污染土壤中的种植情况。结果表明蔬菜吸收铀的能力不同,相同条件下的4种蔬菜可食用部位中铀含量大小顺序为:土豆>生菜叶>胡萝卜>豌豆;平均铀含量分别为:0.26,0.25,0.11,0.09 mg/kg,且均为低铀富集作物。加入铀溶液的土壤所种植的蔬菜样品中铀含量相比对照组土壤均有所升高,但其铀含量未超过国家标准限值,处于安全水平。     

蔬菜水果中的新烟碱类农药残留量与人群摄食暴露健康风险评价

新烟碱类农药是目前被广泛用于农业中的一类作用独特、高效广谱的内吸性杀虫剂,它们在蔬菜水果中的残留对人体健康构成威胁。本研究目的是查明北京市场上蔬菜水果中不同新烟碱类农药的残留量,并对人群摄食暴露健康风险进行评估。从北京市场上采集49种蔬菜和24种水果,采用Qu ECh ERS–高效液相色谱串联质谱(HPLC-MS/MS)法测定蔬菜水果中9种新烟碱类农药的含量。利用测得数据和中国居民膳食结构调查资料,采用蒙特卡罗模拟方法计算了不同年龄段人群的日均经口摄入暴露量的概率分布,并采用商值法计算了新烟碱类农药的非致癌风险。结果显示新烟碱类农药普遍存在于北京市场上的蔬菜水果中。49种蔬菜样品中检出7种新烟碱类农药,其中吡虫啉、啶虫脒和噻虫嗪检出率均达100%,噻虫胺、烯啶虫胺、噻虫啉和呋虫胺的检出率分别为47%、14%、10%和4%。24种水果样品中检出5种新烟碱类农药,其中吡虫啉和啶虫脒的检出率均达100%,噻虫嗪、噻虫胺和噻虫啉的检出率分别为54%、13%和4%。不同新烟碱类农药在蔬菜水果中的含量范围为0.01 ng·g~(-1)~126 ng·g~(-1),均未超过我国食品安全国家标准或美国联邦管理条例中的限量值。小部分(约3%)人群因摄食蔬菜水果暴露于新烟碱类农药的非致癌风险商值大于0.1。新烟碱类农药在蔬菜水果中普遍存在,对人体健康有潜在的风险。     

Assessment of metals in fourteen species of vegetables and crops cultivated in a suburban area using multivariate analyses

Concentrations of seven metals (Cd, Cr, Mn, Ni, Pb, V, and Zn) were determined in 14 plant species including vegetables and crops from an agricultural area located at the Southern part of the Iranian capital, near the Tehran oil refinery. Different statistical methods, especially multivariate ones, were employed for the analysis of the results. Based on the results of agglomerative hierarchical method for clustering of the grid cells, some similarities between the dendrograms of Pb, Ni, and V and, furthermore, between Mn and Cr were observed that could be attributed to their similar distribution sources in the study area. The principal component analysis showed that with respect to accumulation of all the metals in the plant species, two main groups could be identified. The highest mean concentrations of all metals (except for Pb) were found in onions. In all plants the mean concentrations of Cd and Pb were considerably higher than limits stated in international guidelines for human consumption. The levels of the metals in onions exceeded these limits. Moreover, the Cr concentrations in mint and basil and the Zn concentrations in tarragon and parsley were higher than the established limits.     

大围山区野生蔬菜资源及其开发利用

对大围山区野生蔬菜资源调查结果表明:区内现有野生蔬菜隶属于叶菜类、茎芽类、块根类、花菜类、果类、种子类、食用菌类、竹笋类、葱蒜类9大类,共计220余种.阐述了大围山区野生蔬菜资源开发利用现状,提出了开发与保护对策.     

Refrigeration waste heat utilization for drying applications: a review

ABSTRACT

Cold chain industry has a vast potential for waste heat recovery. It is a matter of importance for energy efficiency point of view, as global energy demand is increasing day by day. Ample amount of low-grade energy is either unutilized or underutilized. The heat rejected by a Heat pump or refrigeration system emerged as a promising solution for dehydration by utilizing low-grade waste heat despite higher investment. As compared to solar drying technology, heat pump drying evolved as a reliable method regarding better process control, energy efficiency, and quality of the product to be dried. Energy utilized through the refrigeration system’s waste/exhaust heat recovery in combination with or without renewable energy source enhances the overall efficiency of the system and also reduces the cost. This useful review investigated and compared the research findings of waste heat utilization through heat pump and from condenser of refrigeration system on laboratory, pilot as well as industrial scale for drying of various fruits, vegetables, and agro products. Various drying parameters like drying rate, moisture content, Specific Moisture Extraction Rate (SMER), Coefficient of Performance (COP), Exergy efficiency, and temperature as well as humidity conditions inside the drying chamber were also reviewed to promote the technological advancement of energy utilization by commercial cold storage waste heat recovery.     

Genotypic variations in the accumulation of Cd exhibited by di erent vegetables

It is an important approach to use the Cd-contaminated soils properly by growing low accumulator or excluder plants for Cd to produce safe foods. To find the suitable vegetable species for growing in Cd-contaminated soils, in the present study the variations in the Cd accumulation for twenty eight vegetable species and several cultivars of five common vegetables (cowpea, kidney pea, bitter gourd, cucumber and squash) were investigated in two soil Cd levels (1 and 2 mg/kg Cd). Experimental results showed that highly significant di erences in Cd concentration were evident among 28 vegetables. For example, spinach Cd concentrations were 110-fold and 175-fold higher than that of sweet pea under the 1 and 2 mg/kg Cd exposures, respectively. For Cd accumulation, the order of vegetable species was: leafy vegetables > solanaceous vegetables > kale vegetables > root vegetables > allimus > melon vegetables > legumes. Distinctive di erences were also identified when comparing di erent cultivars of the five common vegetables with an average range of 0.003–0.094 mg/kg Cd. Our results indicated that a large genotypic variation existed among vegetable species or cultivars when subjected to Cd exposure. Therefore, it is important and feasible to elect/breed vegetable species/cultivars with low accumulation of Cd, especially in mildly Cd-contaminated soils.     

广东汕头市农业土壤和蔬菜铅含量及健康风险评估

重金属元素铅的危害已经引起人们的广泛关注,为了得到汕头市土壤及蔬菜铅污染的状况,选取了该市115个土壤样品及34个蔬菜样品进行铅含量分析.研究发现,汕头市土壤样品铅含量差异较大,最高含量为110mg/kg,最低含量则为12.1mg/kg,极差达到97.9mg/kg.56.52%的土壤样品铅含量超过国家土壤环境质量标准,表明该市土壤铅污染存在普遍性,且各区(县)土壤铅含量极不均匀.汕头市蔬菜样品铅含量全部超过国家食品卫生标准(GB 14935-94),不同蔬菜品种对铅的富集能力均较强,蔬菜样品铅最低含量为5mg/kg,最高含量为85mg/kg,分别为国家标准限值的5倍和425倍.经分析认为,该市铅污染源主要来自工业"三废"排放、大量含铅农药的使用、汽车尾气排放以及大气沉降等.还对汕头市民通过食用蔬菜而导致的铅暴露进行了健康风险评估,结果表明该市居民使用蔬菜存在较大的健康风险.     

Monitoring of Organochlorine Pesticide Residues in Summer and Winter Vegetables from Agra, India – A case study

Analysis of summer and winter vegetable samples during 2002–2003 for pesticidal contamination was carried out on Gas Chromatograph-Electron Capture Detector with capillary columns. The contamination levels of winter vegetables (average concentration of 4.57, 6.80 and 5.47 ppb respectively for Lindane, Endosulphan and DDT) were found to be slightly higher than the summer vegetables (average concentration of 4.47, 3.14 and 2.82 ppb respectively for Lindane, Endosulphan and DDT). The concentration of these organochlorine pesticides in summer and winter vegetables were well below the established tolerances but continuous consumption of such vegetables even with moderate contamination level can accumulate in the receptor's body and may lead to chronic effects that could be fatal.     

铅锌尾矿库土壤和蔬菜重金属污染特征及健康风险评价

研究调查了洛阳市西南部某铅锌尾矿库山林区、生活区、农田区表层土壤和农田区蔬菜中8种重金属含量,采用污染指数、潜在生态危害及健康风险进行评价.结果表明：农田区Pb、Zn、Cr、Cd和As重金属平均含量均高于土壤风险筛选值;蔬菜中重金属平均含量均超过食品污染物限量.各功能区内梅罗综合污染指数（PN）和非致癌总风险指数（HI）依次为农田区 > 3 > 生活区 > 山林区 > 2、农田区 > 1 > 山林区 > 生活区 > 0.5.其中,HI_Pb、HI_Cr、HI_As之和分别占成人、儿童致癌总风险HI的43%、58%.各功能区As对单项非致癌风险（HQ）作用明显,分别占成人HQ、儿童HQ的45%、35%;52%、41%;23%、17%.各功能区致癌风险总指数（TCR）均表现为农田区>山林区>生活区>10^-6.蔬菜中As对HI作用明显,均占对成人HI、儿童HI的贡献相同,均为55%、64%、94%和60%.4种蔬菜中重金属致癌与非致癌风险对居民作用依次为白菜 > 花椰菜 > 萝卜 > 甜菜.因此,尾矿库周边土壤及蔬菜重金属污染对周边生态环境和居民健康生活构成严重威胁.