洛阳郊区蔬菜基地土壤中重金属污染现状调查与评价

为研究洛阳郊区蔬菜基地土壤重金属污染现状,采集了洛阳郊区3个主要蔬菜基地的15个土壤样品,分析了土壤中重金属镉、汞、砷、铅、铬、铜、锌、镍的含量,并采用单项污染指数和综合污染指数进行评价。结果表明,3个蔬菜基地土壤中8种重金属含量均未超标,土壤中重金属单项污染指数和综合污染指数均小于1.0。在3个蔬菜基地中,北郊和东郊基地土壤中重金属的综合污染指数分别为0.52和0.60,均小于0.7,处于清洁(安全)水平,而西郊基地土壤中重金属的综合污染指数为0.78处于尚清洁(警戒限)水平。     

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。     

宝应县土壤重金属的污染调查

以宝应县农田土壤重金属调查为依据，采用污染指数法对土壤质量进行评价，分析土壤重金属污染原因，提出防治措施。     

福州市蔬菜基地土壤重金属和多环芳烃的含量及其与土壤磁性指标的关系

蔬菜基地土壤污染状况与人类健康有着密切的关系。本研究对福州市蔬菜基地土壤中6种重金属和15种美国环境保护总署(US EPA)优控的多环芳烃(PAHs)污染状况进行了调查,并分析了污染物含量与土壤磁性指标间的关系。结果表明,土壤中重金属平均含量为Zn 147.0 mg·kg~(-1)、Pb 55.0 mg·kg~(-1)、Cu 45.5 mg·kg~(-1)、Cr 21.3 mg·kg~(-1)、As 16.0mg·kg~(-1)、Cd 0.6 mg·kg~(-1);PAHs的总量范围为324.3~1 838.6μg·kg~(-1)。Cu含量和PAHs总量与土壤磁化率χ都具有显著的相关性(p0.05)。PAHs特征比值和频率磁化率χfd的结果分析表明,土壤中PAHs主要来源于石油泄漏和生物质的燃烧;重金属来源复杂,为混合来源,包括人类活动排放和成土母质固有含量。污染评价结果表明,土壤中Cr和As的含量都未超标,Cu、Zn和Cd的含量均超标;参考荷兰土壤修复标准中的目标值,PAHs含量超标的土壤为11.1%,而参照我国土壤污染状况评价技术规定,PAHs含量超标的土壤为22.2%。     

福州市主栽蔬菜品种对砷的积累及健康风险

为阐明福州市主要蔬菜基地种植的蔬菜中砷积累特征与食用风险水平,对研究区域内蔬菜和对应土壤中砷含量进行了分析检测,采用Monte-Carlo模型法对蔬菜中砷引起的健康风险进行了评价,并探讨了蔬菜和土壤砷含量之间的相关性及不同品种、不同类别蔬菜之间积累砷的差异。结果表明:研究区内菜地土壤没有明显的砷超标,砷含量均未超出国家土壤二级标准(30 mg·kg~(-1));研究区内蔬菜安全状态很好,不存在明显的健康风险;蔬菜中砷与其对应土壤中砷之间无显著相关性;不同类别的蔬菜之间对于砷的累积存在差异性,蔬菜中砷的富集系数顺序为叶菜类根茎类瓜果类,其中茼蒿的富集系数最大,豌豆和辣椒的最小。     

盐城海岸带土壤重金属污染风险评价比较研究

以盐城海岸带为研究区,分别采用地质累积指数法、内梅罗指数法和潜在生态危害指数法对土壤重金属污染进行风险评价,分析不同方法在评价同一研究区时结果的差异性。结果表明,研究区Cr、Ni、Zn、Cd质量浓度平均值超过盐城海岸带环境背景值。地质累积指数法显示研究区土壤重金属在中度污染到强污染;内梅罗指数法显示研究区土壤重金属为重度污染;潜在生态危害指数法显示研究区土壤重金属处于中度潜在生态危害程度。3种方法评价结果的严重程度为:内梅罗指数法地质累积指数法潜在生态危害指数法。3种评价方法均有一定缺陷与局限性,相对于单一方法的污染评价,采用多种方法评价土壤重金属污染可使评价结果更加客观。     

喀斯特地貌土壤重金属污染负荷评价模型研究

为了解决喀斯特地貌土壤重金属污染负荷评价中的难点,在半机理模型 —— 潜在污染指数模型(PPI)的基础上进行了改进.首先,将土地利用指数替换为重金属指数;其次,重金属的选择引入了健康风险理念;第三,考虑到喀斯特地貌土壤重金属的产生、迁移和衰减特性,对重金属指数、径流指数和距离指数的权重系数进行了优化;最后,引入潜在污染...     

典型农业活动区土壤重金属污染特征及生态风险评价

联合野外采样和室内分析,以典型农田土壤为研究对象,分析土壤中重金属Cr、Ni、Cu、Zn、Cd、Pb、As和Hg的含量及污染特征,并采用单因子污染指数法、内梅罗污染指数法及潜在生态危害指数法,对农田土壤进行生态风险评价,同时利用主成分因子分析法,提取出3主因子,分析土壤重金属可能来源。结果表明,研究区农田土壤各重金属含量均高于背景值,表层污染程度高于底层;各重金属单因子污染指数对应污染等级均为清洁,内梅罗污染指数为0.46,污染等级为安全。潜在生态风险评估结果显示,研究区土壤重金属污染的潜在生态风险危害程度为中等,各重金属的潜在生态危害程度依次为CdHgAsCuPbNiCrZn。主成分因子分析显示,研究区土壤中Hg、As和Cr主要由工业污染源贡献,土壤中Cd、Pb的污染主要来源于不合理的农业生产活动和居民生活,Ni、Zn和Cu与自然成土过程密切相关。综合评价表明,尽管研究区农田土壤目前重金属污染情况较轻,未达到警戒水平,但由于城市化的发展及长期现代化农业耕作活动造成农田土壤重金属的富集,因此,增强农田土壤安全性生产管理、严控土壤污染源与推行标准农业生产是十分必要的。     

基于总量及有效态的铜陵矿区农田土壤重金属生态风险评价

于铜陵矿区采集147个农田土壤样品,分析土壤样品中Cd、Cu、Pb、Zn 4种重金属总量和有效态含量,探讨该地区农田土壤重金属的污染现状、潜在生态风险和来源,并基于不同类型农田土壤有效态重金属的风险评价提出农作物种植建议。结果表明:铜陵矿区农田土壤重金属平均值普遍高于铜陵市土壤背景值,局部地区潜在生态风险极大;4种重金属元素的单项潜在生态危害指数依次为CdCuPbZn,铜陵矿区农田土壤重金属的潜在生态风险程度为中等,Cd为最主要的潜在生态危害因子;基于有效态重金属对不同类型农田土壤进行潜在生态风险评价,春季农田土壤的综合潜在生态危害指数排序为油菜地蔬菜地麦地,秋季农田土壤的综合潜在生态危害指数排序为稻田蔬菜地。基于上述结果,建议在重金属污染程度较高的区域实施小麦-蔬菜轮作,而在蔬菜种植中选择对重金属吸收能力较低的种类或品种。     

琼北火山岩地区水田和旱地土壤中重金属的累积特征比较

为分析琼北火山岩地区土壤中重金属(As、Cd、Cr、Pb、Ni、Hg)的累积特征,采集旱地和水田的土壤表层样品,并对样品理化性质及重金属含量进行了分析,采用单因子污染指数法和内梅罗综合污染指数法对重金属污染状况进行了评价。结果表明,研究区旱地与水田土壤均呈强酸性-酸性,旱地土壤阳离子交换量(CEC)(4.66 cmol/kg)略大于水田土壤CEC(3.42 cmol/kg),表明旱地土壤保持养分的能力优于水田土壤。与海南土壤背景值比较,研究区旱地和水田土壤中Cd、Cr、Pb和Ni 4种重金属均有不同程度的累积,其中Cd累积程度较重。研究区旱地和水田土壤中Cr与Ni均具有较高的正相关关系,说明旱地和水田土壤中Cr与Ni可能同源,且受基性火山岩地质背景的影响较大。内梅罗综合污染指数评价结果表明,研究区旱地土壤重金属污染明显高于水田土壤,水田土壤重金属为轻度污染,而旱地土壤重金属已达到中度污染,尤其是Cr和Ni污染比较严重,应引起重视。     

Site-specific risk assessment in contaminated vegetable gardens

A field survey was carried on in Gy?ngy?soroszi, Hungary, near to an abandoned lead/zinc mine to analyse the metal contamination of flooded and non-flooded vegetable gardens, and to evaluate the health risks to local population. Contamination levels of arsenic, cadmium, lead, mercury and zinc were measured in soil and homegrown vegetable samples and bioconcentration factors and hazard indices were calculated. The high metal contents of flooded vegetable gardens were caused by floods, the results indicated significant differences between flooded and non-flooded vegetable gardens. The most accumulating vegetable was sorrel, the most mobile elements were cadmium and lead. Arsenic was not available for vegetables. The health risk was calculated for two exposure routes: ingestion of soil and ingestion of vegetables. The site-specific exposure parameters were established after a population based survey and a special equation was created to calculate the health risk due to homegrown vegetable consumption. The highest risk was associated with ingestion of vegetables, the most hazardous element being lead. The hazard index did not exceed the threshold value of one in flooded or non-flooded gardens. The analyses of health risk indicated that despite the high metal concentrations of soil the contamination of vegetable gardens does not pose an unacceptable risk to the inhabitants of the village.     

Occurrence and assessment of polycyclic aromatic hydrocarbons in soils from vegetable fields of the Pearl River Delta, South China

Surface soil (0-20 cm) samples from nine representative vegetable fields located in Guangzhou, Shenzhen, Zengcheng and Huadu within the Pearl River Delta, South China were collected and analyzed for 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography coupled to mass spectrometry (GC-MS). Total concentrations of 16 PAHs (Sigma(PAHs)) ranged from 160 to 3700 microg kg(-1). Large variations were observed also between concentrations of individual PAHs from different vegetable fields and within the site as well. Acenapthylene, benzo[b]fluoranthene, fluoranthene, benzo[a]pyrene and benzo[k]fluoranthene were consistently the most prevalent individual PAHs. The values of PAH isomer ratios [anthracene/(anthracene+phenanthrene) and fluoranthene/(fluoranthene+pyrene)] indicate that combustion processes are the major sources of PAHs. Concentrations of PAHs were poorly correlated with organic carbon concentrations of soils, suggesting different sources and also indicating that the PAH pollution of this area is recent. The same outcome is confirmed by the predominance of PAHs with fewer rings (相似文献   

A study on production of biodiesel using a novel solid oxide catalyst derived from waste

The issues of energy security, dwindling supply and inflating price of fossil fuel have shifted the global focus towards fuel of renewable origin. Biodiesel, having renewable origin, has exhibited great potential as substitute for fossil fuels. The most common route of biodiesel production is through transesterification of vegetable oil in presence of homogeneous acid or base or solid oxide catalyst. But, the economics of biodiesel is not competitive with respect to fossil fuel due to high cost of production. The vegetable oil waste is a potential alternative for biodiesel production, particularly when disposal of used vegetable oil has been restricted in several countries. The present study evaluates the efficacy of a low-cost solid oxide catalyst derived from eggshell (a food waste) in transesterification of vegetable oil and simulated waste vegetable oil (SWVO). The impact of thermal treatment of vegetable oil (to simulate frying operation) on transesterification using eggshell-derived solid oxide catalyst (ESSO catalyst) was also evaluated along with the effect of varying reaction parameters. The study reported that around 90 % biodiesel yield was obtained with vegetable oil at methanol/oil molar ratio of 18:1 in 3 h reaction time using 10 % ESSO catalyst. The biodiesel produced with ESSO catalyst from SWVO, thermally treated at 150 °C for 24 h, was found to conform with the biodiesel standard, but the yield was 5 % lower compared to that of the untreated oil. The utilization of waste vegetable oil along with waste eggshell as catalyst is significant for improving the overall economics of the biodiesel in the current market. The utilization of waste for societal benefit with the essence of sustainable development is the novelty of this work.     

青岛市餐厨垃圾与菜市场垃圾混合高温厌氧消化研究

在中试规模下,研究青岛市餐厨垃圾与菜市场垃圾混合(质量比1∶1)高温厌氧消化实验,通过监测厌氧消化过程中产气量、气体组成等产气情况和消化液中pH值、SCOD、NH3-H、VFAs含量和组分等化学指标变化,确定混合厌氧消化的最大有机负荷,并分析混合高温厌氧消化技术的可行性,结果表明,(1)青岛市餐厨垃圾与菜市场垃圾混合高温厌氧消化产甲烷具有技术可行性;(2)混合厌氧消化的最大有机负荷可达4.069 kg VS/(m3.d);(3)当系统最大有机负荷时,每天每千克VS最高可产生甲烷量0.346 m3;(4)混合厌氧消化可削减氨氮对餐厨垃圾单独厌氧消化产沼气的影响。     

Efficiency of recycled wool-based nonwoven material for the removal of oils from water

The aim of this study was to highlight the potential use of recycled wool-based nonwoven material for the removal of diesel fuel, crude, base, vegetable and motor oil from water. Sorption capacity of the material in water and in oil without water, oil retention, sorbent reusability and buoyancy in static and dynamic conditions were investigated. The results show high sorption capacity of recycled wool for different kinds of oil. This sorbent also exhibited excellent buoyancy after 24h of sorption as well as a good reusability since the decrease in sorption capacity did not exceed 50% of the initial value after five sorption cycles in oil without water.     

应用表面活性剂-生物柴油微乳液去除污染土壤中多环芳烃

针对修复焦化厂高浓度多环芳烃污染土壤高成本的现实,采用以非食用性植物油、生物柴油、表面活性剂及其乳化合成的微乳液为淋洗剂,比较不同淋洗剂的淋洗效果。结果表明乳化合成的微乳液对焦化厂土壤中多环芳烃的总去除率高于单独使用表面活性剂为淋洗剂对土壤中多环芳烃的总去除率,说明生物柴油及植物油与表面活性剂乳化形成的微乳液对原污染土壤中的多环芳烃具有显著的增溶作用。1%TW-80和2.5%TW-80对土壤中多环芳烃总去除率分别为11%和14%;以2.5%TW-80为原料乳化合成的微乳液的淋洗去除率较以1%TW-80为原料乳化合成的微乳液高,总去除率分别为15%～30%和11%～18%;以生物柴油为原料乳化合成的微乳液的淋洗去除率较以植物油为原料乳化合成的微乳液高,分别为17%～30%和15%～23%,且对多环芳烃的去除率与其辛醇水分配系数(logKow)呈线性相关关系。     

青岛市菜市场垃圾的高温厌氧消化研究

在中试规模下进行菜市场垃圾高温厌氧消化试验,通过监测消化过程中的产气情况和消化液的pH、可溶解性COD(SCOD)、挥发性脂肪酸(VFA)、NH3-N、碱度等变化,确定菜市场垃圾厌氧消化的最大有机负荷,并分析对菜市场垃圾进行高温厌氧消化处理的可行性.结果表明,在中试规模下,菜市场垃圾高温厌氧消化的最高有机负荷可达6.2...     

Formation of methyl mercury in an aquatic macrophyte

In the nature, inorganic forms of mercury (Hg) may be transformed to the organic, very toxic, methyl-Hg. Occasionally methyl-Hg has been detected in plants, also so in the aquatic macrophyte water spinach (Ipomoea aquatica), which is a popular vegetable in tropical regions. The objectives of this study were to investigate if methyl-Hg is formed and/or degraded in water spinach. Water spinach plants were exposed to inorganic Hg via spiked soil or spiked nutrient solution. Tests were performed in a climate chamber and in experimental units, one for each individual plant, that were equipped with separated shoot and root compartments. Plant tissues were analysed for total- and methyl-Hg. The results showed that methyl-Hg was accumulated in water spinach, especially in young metabolically active parts, when exposed to external inorganic Hg, even at sterilized conditions. Results also showed that methyl-Hg was formed in water spinach in the absence of external Hg, i.e., during recovery in a not Hg-spiked medium following after HgCl₂-exposure. There was however, no sign of demethylation. Summarizing, most of the Hg that is taken up by the plants is bound in the roots, but of the comparatively small amounts of Hg that reach the young growing shoots, a part will be methylated. Since the young shoots of this plant make a delicious and very appreciated vegetable, Hg in I. aquatica may contribute to human health problems.     

Linkage of a geographical information system with the gleams model to assess nitrate leaching in agricultural areas

The GLEAMS (Groundwater Loading Effects of Agricultural Management Systems, Version 2.10) model was linked with a Geographical Information System (GIS) to evaluate the risk of nitrate pollution in an area of 230 km2 near Valencia (Spain). Under Mediterranean conditions, GLEAMS was calibrated and validated using results from field experiments on citrus orchards and vegetables grown in that area. A graphical user interface (GUI) was implemented in the GIS-model system to allow a non-specialist to run the model, and to represent simulation results as a thematic map. In order to execute the GLEAMS model, data must be grouped in five basic layers: four layers correspond to the base maps (soils, climate, land use, NO3 content in irrigation water), and the fifth layer corresponds to agricultural management practices, introduced in the system interacting to the GUI. To illustrate system capabilities. two rotations with crops in the vegetable area (potato/lettuce/onion/cauliflower, and artichoke/artichoke in 2 years rotation each), and orange trees in the citrus area, were simulated to determine the N leached in the study area. Pollution risk maps show that vegetable crops and areas irrigated with groundwater have the highest potential risk of groundwater nitrate pollution. Further analysis identified potato and artichoke (in the first year) to be the crops with the higher risk.     

Primary biodegradability of mineral base oils in relation to their chemical and physical characteristics.

The primary biodegradability of 32 mineral base (i.e., unformulated) oils of paraffinic nature was evaluated using the CEC L-33-A-93 test. These oils were refinery products obtained by varying manufacturing processes. Biodegradation percentages ranged between 15% and 75%, i.e., below the commonly accepted standards for environmentally-compatible lubricants. Biodegradability values were compared to the overall chemical composition and main physical properties of base oils. Biodegradability decreased with increasing levels of aromatic and/or polar compounds in the tested oils. For most oils, the biodegradation percentage increased with the viscosity index, but was a decreasing function of the kinematic viscosity (KV), the pour point, the flash point (FP) and the refractive index (RI). Linear relationships between biodegradability and FP or RI values were observed. These results show that, beside chemical features such as the contents in polar and aromatic compounds, simple physical magnitudes such as KV and RI, commonly used to characterize lubricant properties, may be useful parameters for predicting the biodegradability of mineral base oils.