Effect of concentration on uptake of some trace metals by plants

Abstract

The uptake by plants of somes trace metals at different concentrations was related closely to the decay constant, I. This means that for a 10‐fold increase in applied concentration, the increase in uptake was close to 4. 93 (10^0.693 = 4. 93). With some trace metals the value of Y (10^Y = ratio of uptake for 10‐fold increase in metal concentration was around 1. For generalized conditions the value of Y in the expression, (/ = uptake ratio, for different concentrations and varied around I. Some values of Y for whole plants were Ni, 0.699 with C.V. (coefficient of variation) 12.2%, Cu, 0.468 with C.V. 12.1%, Zn, 0.606 with C V. 31.5%, and Cd, 0.903 with C.V. 10.9%. From soil the values for shoots for Co were 0.855 (C.V. = 14.8%) without EDTA (ethylenediamine tetraacetic acid) and 0. 941 (C. V. = 20. 8%) with EDTA; for Cu with EDTA it was 0. 562 (C. V. = 25.8%). with EDTA; for Cu with EDTA it was 0.562 (C.V. =25.8%).     

生物淋滤去除农用污泥中重金属的效果及工艺

污水处理厂污泥中的重金属含量高是污泥农用的主要障碍。该文针对天津污水处理厂污泥含铜量高的特性,分别以硫酸亚铁和硫粉作为培养基进行生物淋滤对比试验,前者对铜的去除率远远高于后者。以硫酸亚铁作为培养基,研究了投配比、接种污泥量、pH值和温度对污泥中重金属去除效果的影响。结果表明,在硫酸亚铁投配比为10 g/L、污泥接种量为20%、温度为28℃、淋滤时间为4 d时,污泥中重金属Cu、Pb、Cr、Ni、Zn和Cd的去除率分别为89%、38%、61%、76%、72%和57%,其相应残余量分别为116、62.5、98、22、174、1.1 mg/kg。在7～28℃范围内,温度越高,氧化亚铁硫杆菌活性越高,生物淋滤时间越短;28℃和35℃下氧化亚铁硫杆菌活性基本相同。以硫酸亚铁为培养基淋滤处理后污泥中重金属的含量可满足《农用污泥中污染物控制标准》(GB4284-1984)。     

可溶性有机质对凹凸棒土负载铁/镍降解黄棕壤中BDE47的影响

多溴联苯醚(PBDEs)是一类广泛使用的溴代阻燃剂,在大气、水体、土壤、生物体等环境介质中普遍检出,严重威胁环境安全和人体健康。本文以凹凸棒土负载铁/镍材料(A-Fe/Ni)为修复剂,以普遍检出的2,2′,4,4′-四溴联苯醚(BDE47)为模式化合物,开展了可溶性有机质(DOM)存在条件下,A-Fe/Ni对黄棕壤中BDE47的降解动力学过程研究,探讨了DOM对材料降解BDE47的影响机制。结果表明:A-Fe/Ni可高效地降解黄棕壤–甲醇/水体系中的BDE47,降解过程符合假二级动力学方程,BDE47可被降解成一溴~三溴联苯醚和联苯醚。体系中加入3种DOM(胡敏酸、柠檬酸和草酸)后,DOM在Fe/Ni颗粒表面形成钝化层,抑制了降解过程中的传质和电子传递作用,不同程度降低了A-Fe/Ni对黄棕壤–甲醇/水体系中BDE47的降解效率,并影响其降解产物物质的量的组成。实验结果为使用零价纳米铁及零价纳米铁基双金属材料修复污染土壤中PBDEs提供了理论依据和参考。     

Comparison of Ni/Zn Accumulation Ability of Thlaspi japonicum from Three Different Areas in Hokkaido

Thlaspi japonicum is a Japanese Ni-hyperaccumulator plant growing in areas with serpentine soil containing a high level of Ni. In the present study, we investigated the ability of wild Thlaspi japonicum plants inhabiting non-ultramafic soil areas of Hokkaido to accumulate Ni/Zn. Wild T. japonicum plants growing on Rebun Island (Rebun-T) accumulated small amounts of Ni, while the plants cultivated on ultramafic rock soil accumulated large amounts of Ni, like T. japonicum growing on Mt. Yubari (Yubari-T), and this change was also observed for T. japonicum growing on Mt. Tengu (Tengu-T). All the T. japonicum plants transplanted on both ultramaflc soil or Andosol accumulated over 100 mg kg⁻¹ Zn, especially the Ni/Zn content of Tengu-T plants tended to be higher than that of the plants growing in the other two areas. In contrast, transplanting of Yubari-T plants from ultramafic soil with a high level of Ni to soil with a lower-Ni content decrease of the Ni concentration in the leaves. Wild Rebun-T plants showed a smaller biomass than the Yubari-T and Tengu-T plants, and some individuals of the Rebun-T population were smaller than those of the other populations, with tiny radical leaves. Zinc content of the small leaves was not significantly different from that in large leaves. These results suggested that T. japonicum plants are able to accumulate high Ni/Zn accumulation, regardless ecotype, habitat and leaf size.     

The use of microbial parameters in monitoring soil pollution by heavy metals

Microbial parameters appear very useful in monitoring soil pollution by heavy metals, but no single microbial parameter can be used universally. Microbial activities such as respiration, C and N mineralization, biological N₂ fixation, and some soil enzymes can be measured, as can the total soil microbial biomass. Combining microbial activity and population measurements (e.g., biomass specific respiration) appears to provide more sensitive indications of soil pollution by heavy metals than either activity or population measurements alone. Parameters that have some form of internal control, e.g., biomass as a percentage of soil organic matter, are also advantageous. By using such approaches it might be possible to determine whether the natural ecosystem is being altered by pollutants without recource to expensive and long-running field experiments. However, more data are needed before this will be possible. Finally, new applications of molecular biology to soil pollution studies (e.g., genetic fingerprinting) which may also have value in the future are considered.     

The content and toxicity of heavy metals in soils affected by aerial emissions from the Pechenganikel plant

The zoning of the terrestrial ecosystems exposed to the aerial emissions from the Pechenganikel plant (Murmansk oblast) was performed; it was based on the state of the soil cover in 2012. The following parameters were determined: the pH, the contents of heavy metals (HMs) and exchangeable calcium and magnesium, the proportion between the organic and mineral soil components, and the state of the soil micro-biota. Three zones differing in the intensity of the soil pollution were distinguished: the zone of strong pollution (at a distance of 3 km from the source of the emission), the zone of medium pollution (16 km), and the zone of weak pollution (25–30 km to the southwest from the pollution source). In the last ten years, the soil pollution in the zone influenced by aerial emissions from the Pechenganikel plant has remained the same. The amount of bacteria and fungi in the air is directly related to that in the soil. The results obtained point to the bacterial pollution of the atmosphere nearby the industrial center. In the vicinity of the plant, gram-negative bacteria (Gracilicutes) predominate in the air; in remote areas, gram-positive bacteria (Fermicutes) are dominants. In the air nearby the industrial center, potentially pathogenic fungi (Gongronella butleri and Alternaria alternata) were revealed.     

淋洗过程预分离细颗粒悬液重金属去除的研究

研究了4种絮凝剂对在土壤淋洗过程中预分离出来的细颗粒悬液中的Cd、Pb、Zn的去除效果以筛选最佳絮凝剂及其用量。结果表明,随着硫酸铝添加量的增加,悬液中Cd、Pb、Zn浓度呈先逐渐降低后上升的趋势;3种元素浓度均随着聚合氯化铝(PAC)和CaO添加量的增加而迅速降低;随着硫酸亚铁添加量的增加,悬液中Pb、Zn浓度逐渐降低,而Cd浓度先迅速降低后逐渐回升。综合悬液中Cd、Pb、Zn的去除效果,选择硫酸铝、PAC、硫酸亚铁和CaO的最佳添加量分别为:0.25、0.04、1.0、0.3 g/L,此时3种元素浓度均达到农田灌溉水质标准。在最佳添加量下按每万吨悬液处理量换算,4种絮凝剂絮凝成本依次为:硫酸亚铁(4500元)>硫酸铝(1900元)>PAC(1000元)>CaO(900元)。因此,选择CaO作为最佳絮凝剂,相应最佳絮凝pH范围为10～11。     

城郊菜地土壤重金属浓度及芦蒿吸收特征

A total of 222 surface soil samples and 40 plant samples were collected to investigate the spatial distribution and possible sources of soil heavy metals and to know the uptake and translocation of heavy metals from roots to different plant parts in a representative vegetable production area in the Baguazhou Island, a suburb of Nanjing City, East China. The arithmetic mean values of total Cd, Cr, Cu, Ni, Pb, and Zn concentrations in the soils were 0.314, 133, 41.0, 58.0, 31.8, and 114 mg kg^-1, respectively. All of these values were above the topsoil background values in the Nanjing area. Multivariate and geostatistical analyses showed that soil Cd contamination was derived mainly from agricultural practices. In contrast, Cu and Zn were derived mainly from soil parent materials and Pb from atmospheric deposition from highway gasoline stations. Artemisia selengensis, a locally important specialty vegetable, accumulated heavy metals primarily in the edible leaves. The general distribution of heavy metal concentrations in this plant species showed that the highest occurred in the leaves, intermediate in the stems and lowest in the roots. Cd had the highest concentration factor (root-to-soil ratio) and may pose increased health risks in the future to the local population through the consumption of contaminated vegetables.     

EDTA与EDDS螯合诱导印度芥菜吸取修复重金属复合污染土壤研究

盆栽试验比较研究了EDTA和易降解的EDDS对复合污染土壤中Cu、Zn、Pb、Cd的活化能力及印度芥菜对4种重金属的吸收与转运特征。结果表明:施用量相同的条件下,EDDS活化土壤Cu的能力与EDTA相当;而EDDS活化土壤Zn、Pb、Cd,尤其是活化土壤Pb、Cd的能力小于EDTA,这与两种螯合剂与不同重金属形成螯合物的稳定常数相一致。向复合污染土壤中施入3mmol/kg和6mmol/kgEDDS均可诱导印度芥菜叶中超量积累Cu。本研究中3mmol/kgEDDS的不同施用方式(单次施,分2次和4次施)对印度芥菜叶片Cu含量的影响差异不显著。各处理印度芥菜叶中的重金属浓度要远高于茎中的浓度,茎中的Cu浓度随土壤溶液Cu浓度线性增加,而叶中Cu的浓度随土壤溶液Cu浓度先增加后下降。     

Effects of heavy metals on the litter consumption by the earthworm Lumbricus rubellus in field soils

Aim of this study was to determine effects of heavy metals on litter consumption by the earthworm Lumbricus rubellus in National Park the “Brabantsche Biesbosch”, the Netherlands. Adult L. rubellus were collected from 12 polluted and from one unpolluted field site. Earthworms collected at the unpolluted site were kept in their native soil and in soil from each of the 12 Biesbosch sites. Earthworms collected in the Biesbosch were kept in their native soils. Non-polluted poplar (Populus sp.) litter was offered as a food source and litter consumption and earthworm biomass were determined after 54 days. Cd, Cu and Zn concentrations were determined in soil, pore water and 0.01 M CaCl₂ extracts of the soil and in earthworms. In spite of low available metal concentrations in the polluted soils, Cd, Cu and Zn concentrations in L. rubellus were increased. The litter consumption rate per biomass was positively related to internal Cd and Zn concentrations of earthworms collected from the Biesbosch and kept in native soil. A possible explanation is an increased demand for energy, needed for the regulation and detoxification of heavy metals. Litter consumption per biomass of earthworms from the reference site and kept in the polluted Biesbosch soils, was not related to any of the determined soil characteristics and metal concentrations.