潮间带沉积物中重金属污染评价及生物有效性研究进展

潮间带是一个典型的环境脆弱带和敏感带,极易受到人类活动的破坏.潮间带重金属除了直接对潮间带生物有影响外,还可以通过过食物链的富集和放大作用影响人类健康,同时由于潮间带水动力和生物活动的影响,造成重金属的重新分布和释放,产生重金属的"二次污染",直接危害近岸环境.开展重金属元素在潮间带沉积物中含量、赋存形态、污染评价及其生物有效性已成为目前环境科学领域中十分重要的研究内容和任务,国内外学者均对河流沉积物重金属污染开展了大量的研究.文章从这4个方面阐述了潮间带沉积物重金属研究进展,以期为潮间带沉积物重金属研究提供一定的参考.     

内蒙古地区马铃薯中重金属残留状况与风险评价(英文)

[目的]对马铃薯重金属污染程度和对人体的健康风险展开风险评价。[方法]通过对内蒙古马铃薯样品的重金属监测,分析了马铃薯中的总砷、汞、镉、铅、铬、镍和铜等7种重金属的残留污染状况。[结果]内蒙古产区马铃薯重金属残留符合国家限量标准,重金属污染综合指数小于0.7,属于安全等级。铅和铬的污染相对严重,对综合污染指数的贡献相对明显。7种重金属THQ值及复合污染风险TTHQ值均小于1,表明该地区马铃薯中重金属的污染对人体健康造成的风险不明显。在以马铃薯为主粮的极大摄入水平下,铬的THQ值大于1,通过食用马铃薯摄入的铬含量可能引起人体的健康风险。不同采样区域,马铃薯中重金属对人群的健康风险存在差异性。[结论]该研究为马铃薯质量安全风险管理提供了客观科学依据。     

城乡有机废弃物农用资源化研究进展

综述了城乡有机废弃物农用资源化的优点和潜在风险,旨在为城乡有机废弃物农业利用降低潜在风险.研究表明:城乡生活中产生的有机废弃物作为肥料施入农田后对土壤性质产生了影响,从而间接影响了土壤微生物量和土壤酶活性;有机废弃物中的重金属会在土壤中积累对土壤环境造成的危害,因此有必要对废弃物农用后的土壤环境进行长期研究.     

Effect of slow releasing nitrogen fertilizers on nutrient status across wheat rhizosphere grown on volcanic ash

Abstract

The volcanic ash of the Mount Pinatubo in Philippines was used in this study. The major drawbacks of this ash for growing agricultural crops are nitrogen (N) and iron (Fe) deficiencies with low organic matter contents. The main objective of this study is to investigate the wheat grown on the volcanic ash to and determine the nutrient status across its rhizosphere using a rhizobox system. Either oxamide or polyolefinresin‐coated urea (PORCU) along with potash and phosphate fertilizers was applied to each rhizobox containing the volcanic ash. Plants were grown on the central compartment (CC) of the rhizobox. The nutrient status was examined by the assessment of distribution patterns of NH₄ ⁺‐N, NO₃ ^‐‐N, Ca²⁺, Mg²⁺, K⁺, Cl^‐, SO₄ ^2‐, PO₄ ^3‐, and associated pH. Although NH₄ ⁺‐N in both oxamide and PORCU treatments was accumulated to a somewhat considerable extent of the rhizosphere. The rhizosphere effect was more prominent in oxamide treatment. While NO₃ ^‐‐N concentrations in either of the treatment was low with a mere rhizosphere effect in PORCU treatment and a rugged distribution in oxamide treatment. Dominant anions and cations accumulated in the CC and the near by compartments of oxamide treatment were Cl^‐, SO₄ ^2‐ and Ca²⁺, respectively. In contrast, SO₄ ^2‐ and K⁺ were accumulated in the CC and the adjacent PORCU treated compartments. Thus the overall distribution of nutrients and pH across the wheat rhizosphere was rugged. Despite of this, it seems that with a rugged nutrient distribution and pH, the effects of slow releasing N fertilizers may well ensure the N benefit on plants while growing on the volcanic ash under circumstances of low N content.     

Metal levels in street sediment from an industrial city: spatial trends, chemical fractionation, and management implications

Background, aim and scope  Street sediment samples were collected at 50 locations in a mixed land use area of Hamilton, Ontario, Canada, and metal levels were analyzed using a sequential extraction procedure for different particle size classes to provide an estimate of potential toxicity as well as the potential for treatment through best management practices (BMPs). Methodology  The street sediment samples were dry sieved into four different particle size categories and a sequential extraction procedure was done on each size category following the methodology proposed by Tessier et al. 1979 using a Hitachi 180-80 Polarized Zeeman Atomic Absorption Spectrophotometer. Results and discussion  Analysis of variance, post hoc least-significant difference tests, and kriging analysis showed that spatially Mn and Fe levels were associated with a well-defined heavy industrial area that includes large iron- and steel-making operations; Cu and Pb were associated with both the industrial and high-volume traffic areas, while Zn tended to be more associated with high-volume traffic areas. The potential bioavailability of the metals, based on the sum of chemical fractions 1 (exchangeable) and 2 (carbonate-bound), decreased in order: Zn > Cd > Mn > Pb > Cu > Fe. Based on aquatic sediment quality guidelines, there is some concern regarding the potential impact of the street sediment when runoff reaches receiving waters. Conclusions  It is possible that a combination of BMPs, including street sweeping and constructed wetlands, could help to reduce street sediment impact on environmental quality in the Hamilton region. The data presented here would be important in developing and optimizing the design of these BMPs.     

Zinc toxicity on N2O reduction declines with time in laboratory spiked soils and is undetectable in field contaminated soils

Denitrification assays in soils spiked with zinc salt have shown inhibition of the N₂O reduction resulting in increased soil N₂O fluxes with increasing soil Zn concentration. It is unclear if the same is true for environmentally contaminated soils. Net production of N₂O and N₂ was monitored during anaerobic incubations (25 °C, He atmosphere) of soils freshly spiked with ZnCl₂ and of corresponding soils that were gradually enriched with metals (mainly Zn) in the field by previous sludge amendments or by corrosion of galvanized structures. Total denitrification activity (i.e. the sum of N₂O+N₂ production rate) was not inhibited by freshly added Zn salts up to 1600 mg Zn kg⁻¹, whereas N₂O reduction decreased by 50% (EC₅₀) at total Zn concentrations of 231 mg Zn kg⁻¹ (ZEV soil) and 368 mg Zn kg⁻¹ (TM soil). In contrast, N₂O reduction was not reduced by soil Zn in any of the field contaminated soils, even at total soil Zn or soil solution Zn concentrations exceeding more than 5 times corresponding EC₅₀'s of the freshly spiked soil. The absence of adverse effects in the field contaminated soils was unrelated to soil NO₃ or organic matter concentration. Ageing (2-8 weeks) and soil leaching after spiking reduced the toxicity of Zn on N₂O reduction, either expressed as total Zn or soil solution Zn, suggesting adaptation reactions. However, no full recovery after spiking was identified at the largest incubation period in one soil. In addition, the denitrification assay performed with sewage sludge showed elevated N₂O release in Zn contaminated sludges (>6000 mg Zn kg⁻¹ dry matter) whereas this was not observed in low Zn sludge (<1000 mg Zn kg⁻¹ dry matter) suggesting limits to adaptation reactions in the sludge particles. It is concluded that the use of soils spiked with Zn salts overestimates effects on N₂O reduction. Field data on N₂O fluxes in sludge amended soils are required to identify if metals indeed promote N₂O emissions in sludge amended soils.     

Uptake and Translocation of Copper in Brassicaceae

Abstract

Ten cvs. of four Brassicaceae species were tested to evaluate their copper (Cu) uptake and translocation. Germination and root length tests indicated that Brassica juncea cv. Aurea and Raphanus sativus cvs. Rimbo and Saxa were the species with the highest germinability and longest roots at Cu concentrations ranging from 25 up to 200 µM. Raphanus sativus cv. Rimbo grown in hydroponic culture at increasing Cu concentrations (from 0.12 up to 40 µM) for 10 days produced a relatively high biomass (17.2 mg plant^?1) at the highest concentration and had a more efficient Cu translocation (17.8%) in comparison with cvs. Aurea and Saxa. The potential of cv. Rimbo for Cu uptake was then followed for 28 days at 5, 10, and 15 µM Cu. In comparison with the control, after 28 days of growth the 15 µM Cu‐treated plants showed a reduction in the tolerance index (?40%) and in the above‐ground dry biomass (?19%). On the contrary, an increase in the below‐ground dry weight was observed (+35%). Copper accumulated during the growth period both in the below‐ and above‐ground parts (about 14 and 4 µg plant^?1 at 10 and 15 µM Cu, respectively), but the translocation decreased from 50 to 30% in the last week at all the concentrations used. In addition, cv. Rimbo grown in a multiple element [cadmium (Cd), chromium (Cr), Cu, lead (Pb), and zinc (Zn)] naturally‐contaminated site accumulated all elements in the above‐ground part in a range from 5 to 62 µg plant^?1.     

Comparative evaluation of residual and total metal analyses in polluted soils

Abstract

Two digestion procedures, employing aqua regia‐HF (ARHF) and HNO₃‐HCIO4‐HF (HHH), were used to analyze residual metals (following a chemical fractionation scheme) and total metal content of two soils, one moderately polluted by municipal sludge applications and the other a grossly‐contaminated sample (20.8% Pb) from a battery recycling site. Although commonly used in sequential extraction analyses, the ARHF method solubilized only 53% (significant at p = 0.05) of the HHH‐determined residual Pb in the battery soil. For the sludge‐amended soil, residual Cd, Pb, and Zn were not statistically different by the two methods. For the battery soil, a single ARHF extraction also underestimated total Pb and Cu relative to HHH, but both methods gave statistically‐similar total Cd, Cu, Pb, and Zn for the sludge‐amended soil. As the sample metal concentration increased, the ability of ARHF to solubilize HHH‐equivalent metal quantities generally decreased. Since the degree of contamination is often unknown for environmental samples, the HHH method is more reliable for assessing residual and total metals in polluted soils     

农田重金属土壤健康钝化技术研究及应用趋势

受农用品投入、固体废弃物堆放、污水农灌及大气沉降等因素影响,导致农田土壤退化、农产品安全等问题愈发严峻,重金属污染通过食物链严重威胁人体健康,成为中国农业环境领域亟待解决的关键问题之一。针对中国农田重金属污染现状,从有机、无机钝化材料、土壤钝化健康技术出发,对农田土壤重金属污染健康修复技术进行深入梳理、分析,提出目前农田重金属土壤修复中存在的主要关键瓶颈问题,从有机、无机联合钝化、绿色农产品投入、土壤质量健康提升等方面进行展望发展趋势,为土壤重金属逆境的生态治理、农田废弃物循环利用及土壤健康可持续发展提供理论及技术依据。     

盘州市三大茶区土壤重金属和砷的监测与评价

为了研究盘州市老厂、火铺、保基3个乡镇土壤中铜(Cu)、铬(Cr)、镉(Cd)、铅(Pb)、汞(Hg)5种重金属和砷(As)的浓度及污染水平,用多点采集混合法制得72份土样进行测定、分析。结果表明,盘州市三大茶区大部分的土壤质量符合无公害茶园土壤环境标准,但个别区域因重金属和砷的含量较高,不宜种植无公害有机茶叶。火铺、老厂2个乡镇茶区土壤的单因子污染指数和综合污染指数均<1,表明其土壤未受到重金属和砷的污染,属安全、清洁水平;保基乡茶园土壤因重金属(Cd)单项污染指数>1,综合污染指数介于0.7～1.0之间,即茶区土壤和作物已被重金属(Cd)轻度污染,综合污染级别属警戒范围。