Uptake and transport of radioactive nickel and cadmium into three vegetables after wet aerial contamination

Knowledge of radionuclide or trace element retention and translocation to plants following an aerial contamination event, for example, sprinkling with contaminated water, is necessary for the evaluation of human exposure through consumption of contaminated vegetables. The fate of 63Ni and 109Cd in all plant parts of three different vegetables after wet deposition on leaves or on fruits was studied. Lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), and bean (Phaseolus vulgaris L.) grown under controlled conditions in a growth chamber were contaminated with 63Ni and 109Cd either on leaves, by means of two different contamination methods (a single early contamination and a repetitive one), or on bean husks (third contamination method: a single contamination at a late stage). Spiked and nonspiked organs were harvested at maturity and radionuclide contents were measured. The fraction retained was on average 56% of the initially administered doses of 63Ni and 87% of 109Cd. The leaf-to-other organ translocation factor was considerably higher for 63Ni (on average 43% of retained radioactivity) than for 109Cd (8%). Nickel-63 migrated throughout the whole plant following foliar contamination, and mainly toward young leaves, seeds in formation, and sink organs, whereas 109Cd migrated to a much lesser extent and only to the organs that were closest to the spiked one, and not at all into fruit. After a fruit contamination event, both radionuclides were translocated into the seeds of spiked fruits. Radionuclide retention and translocation were not affected by plant species, but principally by the type of organ contaminated.     

Multiyear nutrient removal performance of three constructed wetlands intercepting tile drain flows from grazed pastures

Subsurface tile drain flows can be a major s ource of nurient loss from agricultural landscapes. This study quantifies flows and nitrogen and phosphorus yields from tile drains at three intensively grazed dairy pasture sites over 3- to 5-yr periods and evaluates the capacity of constructed wetlands occupying 0.66 to 1.6% of the drained catchments too reduce nutrient loads. Continuous flow records are combined with automated flow-proportional sampling of nutrient concentrations to calculate tile drain nutrient yields and wetland mass removal rates. Annual drainage water yields rangedfrom 193 to 564 mm (16-51% of rainfall) at two rain-fed sites and from 827 to 853 mm (43-51% of rainfall + irrigation) at an irrigated site. Annually, the tile drains exported 14 to 109 kg ha(-1) of total N (TN), of which 58 to 90% was nitrate-N. Constructed wetlands intercepting these flows removed 30 to 369 gTN m(-2) (7-63%) of influent loadings annually. Seasonal percentage nitrate-N and TN removal were negatively associated with wetland N mass loadings. Wetland P removal was poor in all wetlands, with 12 to 115% more total P exported annually overall than received. Annually, the tile drains exported 0.12 to 1.38 kg ha of total P, of which 15 to 93% was dissolved reactive P. Additional measures are required to reduce these losses or provide supplementary P removal. Wetland N removal performance could be improved by modifying drainage systems to release flows more gradually and improving irrigation practices to reduce drainage losses.     

Sorption and degradation of pesticides in nursery recycling ponds

Knowledge of pesticide distribution and persistence in nursery recycling pond water and sediment is critical for preventing phytotoxicity of pesticides during water reuse and to assess their impacts to the environment. In this study, sorption and degradation of four commonly used pesticides (diazinon, chlorpyrifos, chlorothalonil, and pendimethalin) in sediments from two nursery recycling ponds was investigated. Results showed that diazinon and chlorothalonil were moderately sorbed [K(OC) (soil organic carbon distribution coefficient) from 732 to 2.45 x 10(3) mL g(-1)] to the sediments, and their sorption was mainly attributable to organic matter content, whereas chlorpyrifos and pendimethalin were strongly sorbed (K(OC) > or = 7.43 x 10(3) mL g(-1)) to the sediments, and their sorption was related to both organic matter content and sediment texture. The persistence of diazinon and chlorpyrifos was moderate under aerobic conditions (half-lives = 8 to 32 d), and increased under anaerobic conditions (half-lives = 12 to 53 d). In contrast, chlorothalonil and pendimethalin were quickly degraded under aerobic conditions with half-lives < 2.8 d, and their degradation was further enhanced under anaerobic conditions (half-lives < 1.9 d). The strong sorption of chlorpyrifos and pendimethalin by the sediments suggests that the practice of recycling nursery runoff would effectively retain these compounds in the recycling pond, minimizing their offsite movement. The prolonged persistence of diazinon and chlorpyrifos, however, implies that incidental spills, such as overflows caused by storm events, may contribute significant loads of such pesticides into downstream surface water bodies.     

严格依法管理污染物排放标准

本文提出了当前污染物排放标准工作中存在的问题,论述了规范污染物排放标准管理的严肃性和重要性。     

Hydro-geochemical aspects of Mediterranean temporary ponds in western Crete

The hydrologic and geochemical conditions that prevail in Mediterranean temporary ponds (MTPs), create a unique environment for many rare and endangered species. Mediterranean temporary ponds are habitats of high ecological value, which are vulnerable to imminent climatic changes, as well as to human activities. This article examines the hydrology and the nitrogen and phosphorous geochemical cycles of four MTPs in Crete. Field and laboratory studies provided the necessary information for the development of a conceptual understanding of the hydrologic and biogeochemical processes that affect the fate of nitrogen and phosphorous in these MTPs. Their hydrology was driven by deposition, infiltration, and evaporation. The hydroperiod of the ponds varied between 40 and 160 d. Mineralization and nutrient release capacity experiments illustrated the significant role that MTP sediments played in enhancing the geochemistry of the aqueous phase. Such ecosystem functions (i.e., mineralization, nutrient release) exhibited high variability among MTPs necessitating site-specific studies with immediate implications to management. It is very important to understand the local hydrogeochemical and climatic conditions to ensure appropriate environmental measures for their management and conservation.     

区域大气污染总量控制的渐进方法

对污染物实施总量控制是我国当前和今后污染控制和管理的方向。本文对区域大气污染总量控制的一般方法进行了讨论。考虑到污染控制成本和公平性要求 ,采用浓度控制与总量相结合的循序渐进方法 ,并提出了促进环境与经济协调发展的总量控制负荷优化分配模型 ,以期对各地总量控制的实施提供参考和借鉴     

微粒释放对污染物迁移特征的影响

通过砂柱的水敏感性试验,以二价汞离子(Hg2+)和苯酚(C6H5OH)为例,研究了水敏感性过程中微粒释放对重金属离子和有机污染物迁移特征的影响.试验结果表明:单一NaCl溶液淋滤Hg2+污染的砂柱,Hg2+去除率为31.68%,换蒸馏水置换NaCl溶液发生微粒释放,此过程流出Hg2+占总量的67.55%,仅有0.78%的Hg2+残留在砂柱中;同样,在苯酚的去除试验中,上述去除率分别为55.71%和43.43%,残留率为0.86%,即在水力作用和水敏性的共同作用下,砂柱中的Hg2+和苯酚几乎可以被全部去除.单纯的水力作用对两种污染物的去除率差别较大,原因是砂柱中微粒表面带有负电荷,使得带正电的Hg2+被吸附,从而大量滞留于砂柱之中.     

昆明市特征污染物增长的环境库兹涅茨特征研究

本文通过对昆明市主城区2002~2007年人均GDP与城市污染物增长数据进行分析并拟合,计算表明:昆明市主城区工业废水排放倒"U"型曲线的转折点位于人均GDP 24785.72元处,对应的工业废水峰值,约1426.77万吨。SO2排放倒"U"型曲线转折点位于24005元处,而对应的SO2排放峰值,约29417.6吨。说明昆明市工业废水及SO2污染已经越过EKC的理论计算转折点,将来一段时间昆明市污染物排放总量将会继续减缓。     

漆包线生产工艺废气中主要污染物的监测

以活性炭为吸附材料,用ＣＳ２洗脱,用气相色谱对漆包线生产工艺废气中的主要污染物进行了测定。并对不同吸附段的吸附量进行了比较,提出了一段活性炭吸附改进的快速分析方法。     

德阳市污染物排放现状分析及对策

本文通过对近年来德阳市污染物排放量的分析比较,得出全市污染物排放变化规律,提出相应对策。     

流域污染物通量测算方法研究

流域水系内污染物通量不仅能够用于评价各类污染源的水污染物入河负荷,也是对流域污染特征,水污染物在河流水体中复杂迁移、转化过程的最直观反应。准确测算流域水系内污染物跨界通量及其时空分布是进行流域水环境风险预警和风险管理的重要前提之一。针对目前多种污染物通量测算方法在进行污染物年通量估算时,结果不确定性大这一突出问题,以流域水质监测站年内逐日流量、悬浮颗粒物监测数据作为悬浮颗粒物年通量参考值,基于以月、半月、周为周期的监测策略,将逐日流量、悬浮颗粒物监测数据重新筛选抽样构造,由此,系统分析了不同流域集水面积、污染通量监测频次和目前常用通量估算方法对污染物年通量估算不确定性的影响。所得方法和结论可为进一步制定流域污染物通量的测算规范提供方法指引和技术支持。     

我国生活垃圾处理及污染物排放控制现状

生活垃圾已经成为城市环境的主要污染源之一,并成为制约和限制城市发展的重大问题。与其他处理方式相比较,垃圾焚烧处理具有明显的优势,通过采用烟气净化工艺,可将垃圾焚烧烟气污染物排放降至最低。通过对我国垃圾处理现状及垃圾焚烧烟气处理工艺的分析,为进一步提高我国垃圾处理水平及降低污染物排放提供了参考。     

The impact of duckweed growth on water quality in sub-tropical ponds

Field experiments on duckweeds, Lemna aequinoctialis, were carried out to determine the effect of plant characteristics on water-quality variables in ponds. In view of their rapid growth rates and ability to cover water surfaces very quickly, such studies are necessary, especially in sub-tropical countries, in order to develop viable management strategies. Morphological parameters like leaf length, leaf width, and root length of individual plants along with cover percent of Lemna were studied in each pond along with important water-quality parameters. The plant parameters were related to the studied water-quality variables using regression analysis. Equations showed that changes in root length and cover, both easily measurable growth responses of duckweeds, could be used to reflect changes in two important water-quality variables like DO and phosphorus (both total and soluble reactive) concentrations in pond waters and hence be used effectively for routine monitoring. This study also gives an indication that ponds with low cover of duckweeds could possibly be more effective for prediction purposes.     

博斯腾湖排污现状和污染物总量控制

近 4 0年来 ,随着人类社会经济活动强度的不断加大 ,博斯腾湖由于受到高矿化度农田排水和工、矿企业污水的污染 ,水质不断恶化 ,并由此带来一系列严重的环境问题 ,如 :土地盐渍化、湿地退化、芦苇长势退化和水产减产等。本文通过一年多在博斯腾湖 2 6个主要排污口的水质动态监测 ,结合当地的实际情况 ,对博斯腾湖水污染进行了污染物总量计算。结果显示 :监测的 2 6个排污口中有 2 3个排污口需进行排污控制 ,每年需削减 5 8 8× 10 4t污染物的排放 ,并据此计算了各排污口相应的削减量。     

确定大气SO2污染物总量控制目标初探

通过对个旧市２０００年和２０１０年大气ＳＯ２排放量的预测及对环境空气质量的影响预测,提出ＳＯ２污染防治措施以及ＳＯ２削减计划,从而确定出既能满足个旧市环境空气质量功能分区目标,又与国家对酸雨控制区的规划目标一致的个旧市２０００年至２０１０年大气ＳＯ２总量控制目标,以确保酸雨和ＳＯ２污染不断恶化的趋势得到遏制。     

Excel在环境评价中污染物扩散模式上的应用

Excel是办公自动化的重要软件,利用Excel编制程序,结合《环境影响评价技术导则》给出的扩散模式,可方便快捷地计算出环境影响评价中污染物扩散浓度和分布特征,结果准确可靠。这一方法,可供环境影响评价人员参考,以免除环评人员烦琐的运算过程。     

Water-quality effectiveness of a detention/wetland treatment system and its effect on an urban lake

A newly installed combined detention/wetland stormwater treatment facility upstream from Lake McCarrons, Roseville, Minnesota, was monitored for 21 months to evaluate its effectiveness and the response of the lake to decreased phosphorus loads. The treatment facility consists of a 1.0-ha detention pond that discharges into a series of six constructed wetland “chambers.” Data from snowmelt and rainfall events are presented for several pollutants. Results show good reductions for most pollutants. Discussion on the facets of the system's operation are presented. Data from the lake show very little change in its water quality from three years prior to restoration (1984–1986) to three years following restoration (1987–1989): the lake's phosphorus and chlorophyll has actually increased.     

The origin and fate of arsenic in coalbed natural gas-produced water ponds

Coalbed natural gas (CBNG)-produced water contains small amounts of trace metals that can accumulate over time in produced water retention ponds. Within the Powder River Basin (PRB) of Wyoming, high concentrations of trace metals in pond water and their effect on shallow groundwater are potential concerns. A pond with a maximum As concentration of 146 microg L(-1) was studied in detail to determine the potential for groundwater pollution and to explain the cause for the high concentration of As. Infiltration characteristics, subsurface hydrology, our fall and pond water quality, isotope signatures, and trace metal balances were examined to assess the hydrology and geochemistry of the pond. The results indicated minimum or no infiltration of pond water and no measurable contamination of the shallow groundwater. The high As concentrations in the pond were determined to be the result of semi-continuous inputs of CBNG-produced water with low As concentrations (0.20-0.48 microg L(-1)), exasperated by low pond volumes during drought conditions. Because of reduced infiltration and high evaporation rates, As became concentrated over time. Reduced infiltration was most likely caused by the high sodium concentration and high sodium adsorption ratio of the CBNG-produced water, which disrupt soil structure. The findings for the pond and the techniques used may serve as a template for future impact assessments of other CBNG-produced water ponds and are relevant for the approximately 4000 ponds currently permitted in the PRB and for future ponds. Further studies are recommended in the use of playa landforms to store marginal-quality produced water.     

北京市大气污染物排放现状分析及治理对策研究

通过对北京市2000—2004年间大气污染物排放情况的考察和研究,着重分析了二氧化硫等大气污染物的排放现状以及大气污染物排放强度指标变化的原因并与国内主要城市及美国大气污染物排放指标进行了对比。结果表明,北京市大气污染物强度在国内处于较低水平,但与发达国家相比,仍有相当的差距,并提出了治理大气污染的对策。     

综合评分法筛选水污染物排放控制因子

控制因子筛选是工业水污染物排放标准制定的重要环节。控制因子筛选应从工业原材料主要成分、排放污染物种类分析着手,逐步缩小备选名单范围。对进入初始名单的污染物,通过综合评分法评价其毒性和暴露水平两方面因素,选择潜在危害指数、年排放量和环境检出率三个指标,制定评分标准,根据各污染物得分情况确定其在排放标准中加以控制的必要性,并以此为主要参考依据确定控制因子。