利用树叶监测空气中污染物铅的探讨

以植物树叶为材料和原子吸收光谱法,测定上海市不同特征地段污染物铅的含量,其中化工区,交通流量大的地段污染物明显大。住宅区,学校较小。本方法建立目的是为了更好地监测大气中的污染物,为政府提供决策依据。本法是以植物叶子的光合作用来吸附大气中污染物,达到测定污染物含量的目的。通过本法测定结果发现本法具有可靠性和可比性,讨论了利用植物叶子监测污染物铅的指示作用。

铅污染的危害及其国槐净化大气中铅污染物的研究

本文分析了铅对人体健康的影响,研究了国槐吸收净化大气中铅化合物的作用.

铅大气污染物环境保护标准限值研究

铅因其对公众健康的影响,其大气污染物标准限值的合理性倍受关注.论文对比分析了国内外铅大气污染物环境质量与排放标准,通过计算提出基于保护环境空气质量的排放标准理论限值及建议限值.分析发现,目前国际上铅环境空气质量标准浓度限值为0.00015~0.0015 mg·m^-3,但多采用世界卫生组织(WHO)的年均浓度限值0.0005 mg·m^-3;建议我国今后修订标准时对铅年均浓度和季均浓度限值进一步加严.与发达国家相比,我国铅环境空气质量季均浓度限值水平已显落后;国际上目前各类排放源铅大气污染物排放浓度限值在0.04~2 mg·m^-3之间,金属冶炼源等主要源的排放浓度限值在1~2 mg·m^-3,其他排放源均在0.5 mg·m^-3以下;我国铅、锌熔炼源正在执行的排放浓度限值(8 mg·m^-3)较为宽松,而其他源的铅大气排放浓度限值与国际上的限值基本一致.通过计算认为,保护公众健康的铅大气污染物的理论排放限值为1.2~2.4 mg·m^-3.考虑到我国的经济技术水平,建议铅、锌熔炼源的铅大气污染物新建企业排放浓度限值为2 mg·m^-3;其他源的新建企业排放浓度建议限值为0.5 mg·m^-3.经过过渡期,现有企业应达到新建企业的排放控制要求.铅的企业边界浓度排放限值是保护企业边界附近公众健康的有效屏障,但鉴于铅的污染特性,对于具体建设项目应加强环评力度,提出更具体明确的排放控制要求,并加强对企业周边环境敏感点的环境监测等,采取综合措施保护公众健康.

Absorption capacity of major urban afforestation species in north-eastern China to heavy metal pollutants in the atmosphere

Totally 24 arbor tree species and 6 shrub species were measured on their absorption capacities to heavy metal Pb, Cd, Cr, and Hg by collecting and analyzing the leaves of trees along different streets in Harbin city in Sept. to Oct. of 2003. The results showed that all the measured species had certain absorbency to the pollutants (Pb, Cd, Cr and Hg), but there existed significant difference in absorption capacity for different species to different pollutants. The measured tree species were classified into three categories by their absorption quantum of heavy metal pollutants. Among the species measured,Betula platyphylla, Ulmus pumila var.pendula, andPrunus persicaf.rubro-plena had high capacity in absorbing Pb;Populus xiahei, P. nigra var.Italica, P. alba x P. berolinensis andSalix matsudana had had high capacity in absorbing Cd;Phellodendron amurense, Syringa oblata, Salix matsudana, Pinus tabulaeformis var.mukdensis, Picea koraiensis, Prunus persica f.rubro-plena, P. triloba andAcer negundo, etc. had high capacity in absorption of Cr;Prunus triloba, Quercus mongolica, Salix matsudana, Sambucus williamsii, Pyrus ussuuriensis andSpiraea fritschiana were good at absorption of Hg. This study might offer scientific foundation for selection of urban afforestation species in different polluted conditions caused by heavy metals. Keywords Greening tree species - Heavy metal - Pollutants - Plumbum - Cadmium - Chromium - Mercury - Absorptivity CLC number S731.2 - X501 Document code A Foundation item: This study is financially supported by the Special Programme for Agriculture under Ministry of Chinese Science and Technology (No. 2002BA516A15-01).Biography: MU Li-qiang (1966-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China.Responsible editor: Zhu Hong

Characteristics of Lead Sorption on Clay Minerals in Relation to Metal Oxides

Difference of montmorillonite (Mt), illite (It) and kaolinite (Kt) in lead sorption characteristics and the effects of amorphous Fe and Al oxide coatings on the characteristics were experimentally studied with logistic model. The sorption curves had sigmoid feature due to use of acetate-type buffer solution. With the model the sorption process could be divided into four stages and the sorption characteristics at the stages were discussed. The results showed that, after Mt, It and Kt were coated by amorphous Fe oxide, their maximum sorption capacity (MSC) and percentage of high-SSC concentration scope (HCS) of Pb2+ increased markedly, but the specific sorption capacity (SSC) decreased. With regard to effects of amorphous Al oxide coating, except for It+AI, the SSC of other samples showed a downtrend, despite that their MSC remained unchanged. Eventually, the gray correlation degrees to Pb2+ sorption for different physicochemical characteristics of the clay minerals were indicated to be higher for hydronium, zero point of surface charge and hydroxy, but lower for specific surface area, density of surface charge and amount of surface charges.

Assessment of heavy metal pollution in sediments from Xiangjiang River(China) using sequential extraction and lead isotope analysis

The heavy metal(such as Cr,Ni,Cu,Cd,Pb,and Zn)concentration,speciation,and pollution source in 43 sediment samples from the Xiangjiang River were investigated using sequential extraction combined with Pb isotope analysis.Cu,Cd,Pb,and Zn concentrations are higher than their background values,while Cr and Ni concentrations are close to those.Sequential extraction demonstrates that heavy metals have different fractions,showing different bioavailabilities.The w(206Pb)/w(207Pb)ratio increases with decreasing bioavailability in the order of exchangeable<carbonate≈Fe-Mn oxides≈organic<residual(p<0.05).Wastewater,dust,and slag from mining and smelting areas,and the residual Pb are assumed to be the primary anthropogenic and natural sources of Pb,respectively.The percentages of anthropogenic Pb in the exchangeable,carbonate,Fe-Mn oxides,and organic fractions are(91.5±16.7)%,(61.1±13.9)%,(57.4±11.1)%,and(55.5±11.2)%,respectively,suggesting a significant input of anthropogenic Pb in these four fractions.

Magnetic field assisted electrocatalytic oxidation of organic pollutants in electroplating wastewater

To degrade the organic compounds in the electroplating wastewater,magnetic field was tentatively introduced into electrocatalytic oxidation on Ti-PbO2 anode.The magnetic field assisted electrocatalytic oxidation can promote anion movement and the generation of active species,resulting more organic compounds to be oxidized and degraded.Oxidation parameters such as treatment time,current density and initial pH of the wastewater were systematically discussed and optimized.The mineralization of organic compounds is improved by over 15% under a magnetic density of 22 mT while the current density is 50 A/m2,pH is 1.8 and the reaction time is 1.5 h.The results indicate that the magnetic field assisted electrocatalytic oxidation has considerable potential in electroplating wastewater treatment.

中国铅流改变原因分析

近年来,伴随一系列铅污染综合整治行动,我国铅流有所改变.探究产生这些变化的深层原因,可进一步为资源环境改善提供依据.根据铅流分析框架,辨识出引起铅流变化的因素,包括规模性和技术性两类因素.在此基础上,围绕铅产量、废铅回收量等规模性指标,铅循环率、环境释放率等技术性指标,分别从消费、贸易、技术、管理等方面分析了我国铅流改变的原因.结果表明,10年来铅制品国内消费量以年均24.7%的速度急剧增长,拉动了铅消费量增长;而铅消费增长又拉动了铅产量以年均14.2%的速度快速增长,进而最终拉动了国内铅矿石资源消耗量、铅矿石净进口量、废铅回收量的增长;铅制品国内消费率的增大方便了铅循环率的提高;国家宏观管理加强,通过关停规模小、技术落后的涉铅企业,并倡导先进技术的应用,为提高资源利用率,降低铅环境释放率提供了重要保障.

Immobilization of Lead and Cadmium in Contaminated Soil Using Amendments: A Review

Since the inception of industrial revolution, metal refining plants using pyrometallurgical processes have generated the prodigious emissions of lead(Pb) and cadmium(Cd). As the core target of such pollutants, a large number of soils are nowadays contaminated over widespread areas, posing a great threat to public health worldwide. Unlike organic pollutants, Pb and Cd do not undergo chemical or microbial breakdown and stay likely in site for longer duration after their release. Immobilization is an in-situ remediation technique that uses cost-effective soil amendments to reduce Pb and Cd availability in the contaminated soils. The Pb and Cd contamination in the soil environment is reviewed with focus on source enrichment, speciation and associated health risks, and immobilization options using various soil amendments. Commonly applied and emerging cost-effective soil amendments for Pb and Cd immobilization include phosphate compounds, liming, animal manure, biosolids, metal oxides, and biochar. These immobilizing agents could reduce the transfer of metal pollutants or residues to food web(plant uptake and leaching to subsurface water) and their long-term sustainability in heavy metal fixation needs further assessment.

Biochar and alternate partial root-zone irrigation greatly enhance the effectiveness of mulberry in remediating lead-contaminated soils

Aims Soil lead contamination has become increasingly serious and phytoremediation can provide an effective way to reclaim the contaminated soils.This study aims to examine the growth,lead resistance and lead accumulation of mulberry(Morus alba L.)seedlings at four levels of soil lead contamination with or without biochar addition under normal or alternative partial root-zone irrigation(APRI).Methods We conducted a three-factor greenhouse experiment with biochar(with vs.without biochar addition),irrigation method(APRI vs.normal irrigation)and four levels of soil lead(0,50,200 and 800 mg·kg^(-1)).The performance of the seedlings under different treatments was evaluated by measuring growth traits,osmotic substances,antioxidant enzymes and lead accumulation and translocation.Important Findings The results reveal that mulberry had a strong ability to acclimate to soil lead contamination,and that biochar and APRI synergistically increased the biomass and surface area of absorption root across all levels of soil lead.The seedlings were able to resist the severe soil lead contamination(800 mg·kg^(-1) Pb)by adjusting glutathione metabolism,and enhancing the osmotic and oxidative regulating capacity via increasing proline content and the peroxidase activity.Lead ions in the seedlings were primarily concentrated in roots and exhibited a dose–effect associated with the lead concentration in the soil.Pb,biochar and ARPI interactively affected Pb concentrations in leaves and roots,translocation factor and bioconcentration.Our results suggest that planting mulberry trees in combination with biochar addition and APRI can be used to effectively remediate lead-contaminated soils.

PbCrO_4 yellow-pigment nanorods: An efficient and stable visible-light-active photocatalyst for O_2 evolution and photodegradation

Here, PbCrO4 nanorods, a commonly used and low-cost yellow pigment, was synthesized via a simple pre-cipitation reaction and can serve as a highly efficient oxygen production and photodegradation photocatalyst. The obtained PbCrO4 nanorods exhibit excellent stability and pho-tocatalytic performance for O2 evolution from water. The production rate is approximately 314.0μmol h^-1 g^-1 under visible light, and the quantum efficiency is approximately 2.16% at 420±10 nm and 0.05% at 600±10 nm. In addition, the PhCrO4 shows good degradation performance for methylene blue, methyl blue, methyl orange and phenol under visible-light irradiation. These results indicate that it is potential to fabricate an effective, robust PbCrO4 photocatalyst by trans-forming heavy-metal pollutants Pb（II） and Cr（VI） into a highly efficient O2 evolution and photodegradation material. This strategy which uses pollutant to produce clean energy and degrade contaminants is completely green and environmentally benign, and thus could be a promising way for practical environmental applications. Keywords： 02 evolution, pollutant, PbCrO4 nanorods, visible-light-active, photocatalyst