中国持久性有机污染物污染现状及治理技术进展

介绍了持久性有机污染物的定义、特性及其危害,分析了典型持久性有机污染物在中国土壤、水体、大气、农产品等介质中的污染状况,阐述了对被持久性有机污染物污染的介质进行生物修复、焚烧、物理和化学处理技术及进展,并对中国在此领域发展方向进行了展望。     

基于甜高粱的铅污染农田安全利用技术研究

本研究通过田间控制试验研究甜高粱对铅的富集特征,分析其与土壤铅含量的关系,以期建立基于甜高粱的铅污染农田安全利用技术。结果表明：甜高粱对铅具有较强的耐性,在不同浓度铅处理条件下并未表现出明显的毒害症状,且茎秆含水量和含糖量无显著的变化;甜高粱对铅的吸收与土壤中的铅含量具有显著的线性关系,随着土壤中铅含量的增加,甜高粱体内各部位的铅浓度均显著增加,且各部位铅浓度呈现“根>叶>茎>籽粒”的特征,单株铅积累量最高可达12.4 mg。在此基础上,通过集成先进固态发酵技术和燃烧技术实现对甜高粱植株的安全处置,建立了基于甜高粱的铅污染农田安全利用技术,此技术简便、方法易行,同时可实现生态、经济和社会效益。     

Use geopedological methods for the evaluation of sedimentation rates on river floodplains, southern Québec, Canada

This article pertains to the fluvial dynamics of rivers in southern Québec, in particular to the aggradation and pedogenetic processes observed in floodplains affected by periodic floods. The frequency of flood events, notably along the Saint-François River and its main tributaries, leads to fine materials being frequently deposited on floodplains and affected development of alluvial soils. Particle size and physical and chemical analyses have led to a better understanding of the dynamics involved in the formation of floodplains and the development of soils related to this fluvial environment. Also, sedimentological analyses (layer texture and thickness, microstructure) combined with radiocarbon dating (¹⁴C) and isotopic methods (²¹⁰Pb, ²²⁶Rd) enabled the determination of sedimentation rates along the floodplains. The radiocarbon dating results obtained from the organic layers buried in alluvial soils show relatively variable ages, i.e. between 2210 ± 60 and 30 ± 70 years BP. The data gathered reveal an active overbank deposition, which shows evidence of the high flood recurrence in many rivers of the basin. It is estimated that the annual floodplain aggradation ranges from 1.0 to 7.6 mm yr^− 1 on average, which causes increases in floodplain elevations (vertical accretion). The sedimentation rates obtained using the constant rate supply dating model (²¹⁰Pb) show average values that range from 2.1 to 10.7 mm yr^− 1. Also, the presence of contaminated layers at the lower level (> 100 cm) of the floodplains suggested an active sedimentation rates along the rivers affected by floods.     

淮南粉煤灰处置场周围土壤中若干金属污染调查

通过系统采集高皇和上窑两个贮灰场周围土壤样品,采用ICP-AES分析方法,调查土壤中若干金属元素(Cd、Cr、Cu、Mn、Ni、Pb、Zn)含量,评价淮南市三大热电厂大体积粉煤灰长期处置导致土壤金属污染状况。结果表明:这些元素在土壤中表现积累性富集,Cu、Cd、Cr具有相对高的迁移性。但土壤金属含量除Cu外,均没有超过国家土壤一级质量标准,土壤属无污染或轻微污染类型。因此,有效处置管理措施能够控制淮南粉煤灰中有害金属的环境影响。     

六种野草对土壤中菲的降解研究

研究了六种野草对菲污染土壤的修复作用和降解途径。通过60 d的温室盆栽试验,观察到:对菲浓度为100 mg kg-1的污染土壤,六种野草表现出了不同的去除能力:狐尾草>狗尾草>蟋蟀草>稗草>高羊茅>碱蓬。其中种植狐尾草、狗尾草、蟋蟀草的菲污染土壤菲去除率分别达到了:81.53%,78.02%和76.01%,碱蓬仅为42.86%。利用GC-MS联用仪初步研究了菲的降解途径,结果表明:菲主要按照邻苯二甲酸途径进行降解,降解产物主要有:长链正代烷烃、邻苯二甲酸酯类、长链正代醛和长链有机酸。中间产物最终进入TCA循环,降解为二氧化碳和水。     

Effects of Wastewater Irrigation on Physicochemical Properties of Soil and Availability of Heavy Metals in Soil and Vegetables

The present study investigated the impact of irrigation with wastewater on nutritional property and heavy‐metal concentrations in the soil and consequent accumulation in vegetables at sites having long‐term uses of wastewater for irrigation. Samples of irrigation water, soil, and root and shoot parts of palak plants were analyzed to determine the concentration of heavy metals. Wastewater irrigation led to increases in the total and phytoavailable heavy‐metal concentrations in the soil at all the sites. Heavy‐metal concentrations in soil under wastewater irrigation were negatively and positively correlated with soil hydrogen potential (pH) and organic carbon (OC), respectively. The enrichment factor and metal pollution index were higher at wastewater‐irrigated sites as compared to the clean water–irrigated ones. The study concludes that wastewater irrigation modified the physicochemical properties of the soil, leading to more availability of heavy metals in the soil and consequently to the plant.     

Characterization of soil heavy metal pools in paddy fields in Taiwan: chemical extraction and solid-solution partitioning

Background, aim, and scope  Ongoing industrialization has resulted in an accumulation of metals like Cd, Cu, Cr, Ni, Zn, and Pb in paddy fields across Southeast Asia. Risks of metals in soils depend on soil properties and the availability of metals in soil. At present, however, limited information is available on how to measure or predict the directly available fraction of metals in paddy soils. Here, the distribution of Cd, Cu, Cr, Ni, Zn, and Pb in 19 paddy fields among the total, reactive, and directly available pools was measured using recently developed concepts for aerated soils. Solid-solution partitioning models have been derived to predict the directly available metal pool. Such models are proven to be useful for risk assessment and to derive soil quality standards for aerated soils. Material and methods  Soil samples (0–25 cm) were taken from 19 paddy fields from five different communities in Taiwan in 2005 and 2006. Each field was subdivided into 60 to 108 plots resulting in a database of approximately 3,200 individual soil samples. Total (Aqua Regia (AR)), reactive (0.43 M HNO₃, 0.1 M HCl, and 0.05 M EDTA), and directly available metal pools (0.01 M CaCl₂) were determined. Solid-solution partitioning models were derived by multiple linear regressions using an extended Freundlich equation using the reactive metal pool, pH, and the cation exchange capacity (CEC). The influence of Zn on metal partitioning and differences between both sampling events (May/November) were evaluated. Results  Total metals contents range from background levels to levels in excess of current soil quality standards for arable land. Between 3% (Cr) and 30% (Cd) of all samples exceed present soil quality standards based on extraction with AR. Total metal levels decreased with an increasing distance from the irrigation water inlet. The reactive metal pool relative to the total metal content is increased in the order Cr << Ni = Zn < Pb < Cu < Cd and ranged from less than 10% for Cr to more than 70% for Cd. Despite frequent redox cycles, Cd, Pb, and Cu appear to remain rather reactive. The methods to determine the reactive metal pool in soils yield comparable results, although the 0.43 M HNO₃ extraction is slightly stronger than HCl and EDTA. The close correlation between these methods suggests that they release similar fractions from soils, probably those reversibly sorbed to soil organic matter (SOM) and clay. The average directly available pool ranged from less than 1% for Cu, Pb, and Cr to 10% for Ni, Zn, and Cd when compared to the reactive metal pool. For Cd, Ni, Zn, and to a lesser extent for Cu and Pb, solid-solution partitioning models were able to explain up to 93% (Cd) of the observed variation in the directly available metal pool. CaCl₂ extractable Zn increased the directly available pool for Ni, Cd, and Cu but not that of Pb and Cr. In the polluted soils, the directly available pool was higher in November compared to that in May. Differences in temperature, rainfall, and changes in soil properties such as pH are likely to contribute to the differences observed within the year. The solid-solution partitioning model failed to explain the variation in the directly available Cr pool, probably because Cr is present in precipitates rather than being adsorbed onto SOM and clay. Despite obvious differences in parent material, source of pollution, climate, and land use, solid-solution partitioning of Cd in paddy fields studied here was similar to that in soils from Belgium and the Netherlands. Discussion  To assess risks of metals in soils, both analytical procedures as well as models are needed. The three methods tested here to determine the reactive metal pool are highly correlated and either of these can be used. The directly available pool was predicted most accurately by the 0.43 M HNO₃ method. The similarity of metal partitioning in paddy soils compared to well-drained soils suggests that changing redox conditions in paddy fields have a limited effect on the geochemical behavior of metals like Cd, Ni, and Zn. Small but significant differences in the directly available metal pool during the year suggest that redox cycles as well as differences in rainfall and temperature affect the size of the directly available metal pool. The large observed spatial heterogeneity of contaminant levels requires ample attention in the setup of soil monitoring programs. Conclusions  The directly available pool (0.01 M CaCl₂) of Cd, Zn, and Ni in paddy fields can be described well by an extended Freundlich model. For Cu and Pb, more information on dissolved organic carbon is needed to obtain a more accurate estimate of the directly available pool. Recommendations and perspectives  Soil testing protocols and models used in risk assessment consider the availability of pollutants rather than the total metal content. Results from extensive testing indicate that approaches developed for nontropical regions can be applied in paddy fields as well for metals like Cd, Ni, and Zn. This study shows that the chemical behavior under drained conditions in paddy fields is comparable to that observed in soils across the European Union, which allows regions with large scale soil pollution including Taiwan to apply such concepts to derive meaningful experimental protocols and models to assess risks of metals in soils.     

Accuracy of seven vapour intrusion algorithms for VOC in groundwater

Background, aim and scope  During the last decade, soil contamination with volatile organic contaminants (VOC) received special attention because of their potential to cause indoor air problems. Moreover, research has shown that people spend 64% to 94% of there time indoors; therefore, the indoor air quality is of a primary importance for exposure to VOC. Human health risks to VOC—in cases of soil contamination—are often dominated by the exposure route ‘inhalation of indoor air’. Exposure is often a result of vapour transport from the soil or groundwater to the indoor air of the building. Within human health risk assessments, a variety of algorithms are available that calculate transfer of soil gas to the indoor air. These algorithms suffer from a relatively high uncertainty due to a lack of representation of spatial and temporal variability. For such an application, these algorithms need to be further verified empirically against field observations so that they can be sufficiently reliable for regulatory purposes. This paper presents the accuracy for seven algorithms by using observed and predicted soil and indoor air concentrations from three sites, where the groundwater had been contaminated with aromatic and chlorinated VOC. Materials and methods  The algorithms for vapour intrusion that are frequently used in European countries were included in this study and were Vlier–Humaan (Flanders), CSoil (Netherlands), VolaSoil (Netherlands), Johnson & Ettinger (USA), Risc (United Kingdom), and the dilution factor (DF) algorithms from Sweden and Norway. Three sites were investigated in more detail and samples were taken synoptically from the groundwater, soil and indoor air on four occasions. On the petroleum sites, the aromatic hydrocarbons benzene, toluene, ethylbenzene and xylenes were analysed and, on the dry cleaning sites, the chlorinated hydrocarbons tetrachloroethylene, trichloroethylene and cis 1,2-dichloroethene. To increase spatial resolution, measurements in groundwater and soil air were taken in three different zones at each site, in the close proximity of or in the building. During sampling, several relevant soil properties were measured like the bulk density, water and air filled porosity, soil temperature and depth of the groundwater. Also, building properties like the dimensions of the building and the quality of the floor were registered. The seven algorithms were applied to compare that observed with the predicted concentrations in soil and indoor air. The groundwater concentrations were used as a source contamination. The results from the algorithms were compared by using performance criteria to assess the accuracy of each algorithm. Results  All calculations are presented in a box plot that contains the predicted soil or indoor air versus the observed concentrations. Results from the applied criteria are presented for each algorithm. Discussion  Differences between predictions and observations were up to three orders of magnitude and can be partially related to the amount of parameters included in each algorithm and the mathematical concept used. For example, the inclusion or exclusion of a capillary fringe or temperature correction for the Henry constant: it is not clear why all algorithms tend to over-predict the soil air concentration. The prediction mostly starts with the calculation of a soil air concentration related to the Henry constant, followed by diffusive and/or convective transport to the soil surface and zone of influence around the building foundation. Further research is needed to investigate the over-predictions and the use of the Henry constant to calculate the soil air concentration should be reviewed. Conclusions  The algorithms with the highest accuracy were the Johnson and Ettinger and the Vlier–Humaan algorithms. The DF algorithms from Sweden and Norway resulted in higher over- and underpredictions than others. Results for the indoor air showed that all the algorithms calculate high and low concentrations in the indoor air when compared to observations. The algorithms with the highest accuracy were JEM, Vlier–Humaan and CSoil. The DF algorithm from Norway calculated concentrations that were frequently higher than observed concentrations and the Swedish DF algorithm showed frequent higher and lower concentration than observed. The conservatism of the most accurate algorithms is sufficient for regulatory purposes, and they can trigger an integrated programme of field observations (monitoring) or/and modelling. Recommendations and perspectives  The dataset used for this paper was derived from three sites with groundwater contamination and further verification of these algorithms should be done for other sites that have a vadose zone contamination.     

肠衣加工过程中微生物的污染状况分析及其分离鉴定

为了研究肠衣加工过程中微生物的污染状况,试验对生产过程中的肠衣样品、工人卫生以及加工环境中的菌落总数进行测定,再采用平板划线分离方法对肠衣产品中的主要微生物菌群进行分离,根据16S rDNA序列分析等对试验菌株进行鉴定。结果表明,刮肠后的菌落总数较多,腌制后的肠衣菌落总数明显下降,产品的菌落总数随着储藏时间的延长呈上升趋势。加工环境中腌制台的菌落总数很低,而空气、工人的手和袖套的菌落总数较多且相似。低温储藏3个月的肠衣产品中含有的主要微生物有蜡样芽孢杆菌和陆地罗氏菌,而低温储藏10个月的肠衣产品中含有的主要微生物有蜡样芽孢杆菌、巨大芽孢杆菌、地衣芽孢杆菌和巴氏葡萄球菌。