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1.
Glyphosate is a commonly used herbicide in grassland soils and microorganisms control its degradation. We introduce the concept of using the degradation rate as an indicator for ecosystem health. Testing this concept, we used soils with a long history of heavy metal pollution (Cu, Pb, and Zn). We hypothesized lower degradation rates in metal-polluted compared to less polluted soils. The degradation rates were measured by repeated measurements of the parent compound in spiked soil-water slurries incubated at 20 °C over 21 days. Average rates showed no differences comparing among soils. We observed a positive correlation between glyphosate degradation rates and soil metal pollution. Therefore, we concluded that the expected impact of the metals on the bacteria responsible for the herbicide degradation was not established. We discuss the potential influence on biological degradation rates of soil pH and adsorption and implications using the concept of the soil health indicator.  相似文献   

2.
丛枝菌根真菌在植物修复重金属污染土壤中的作用   总被引:4,自引:1,他引:3  
菌根是真菌与植物根系所建立的互惠共生体,其中以丛枝菌根(AM)真菌在自然界中分布最广。在重金属污染条件下,AM真菌可以减轻重金属对植物的毒害,影响植物对重金属的吸收和转运,在重金属污染土壤的植物修复中显示出极大的应用潜力。文章通过讨论菌根植物对重金属修复的作用机制,提出菌根技术在重金属植物修复中应在通过广泛调查、筛选超积累植物的基础上,不断探索植物-菌根体系修复问题,以促进重金属污染土壤的生物修复。  相似文献   

3.
1 The Problem  One of the major problems facing risk assessment at polluted industrial sites and military bases is subsurface contamination by non-aqueous phase-liquids (NAPLs), since tracing the extent of a NAPL plume using conventional methods (drive point profiling) is usually associated with difficulties. In an effort to trace subsurface contamination as precisely as possible, monitoring points are placed in the area that might be affected by contaminants, and groundwater and soil samples are taken to the laboratory for analysis. However, the final number of monitoring points is hardly ever sufficient for distinctive contamination mapping, and this may ultimately result in an unsuitable remediation action being taken. 2 Objectives  To obtain a more detailed image of a subsurface NAPL plume and, hence, to facilitate remediation measures that are best suited for the site in question, a denser network of monitoring points is desirable. The aim of the investigation described in this paper was therefore to develop a new detection method for subsurface NAPL contamination, which is based on an easily accessibleindicator for NAPLs rather than on the analysis of soil and groundwater samples taken at the site. Based on the good solubility of radon in NAPLs, the idea was put forward that subsurface NAPL contamination should have an influence on the natural radon concentration of the soil gas. Provided this effect is significant, it would be possible to carry out a straightforward radon survey on an appropriate sampling grid covering the suspected site and thus enabling the NAPL contamination to be detected by the localization of anomalous low radon concentrations in the soil. The overall aim of the investigation was to assess the general suitability of the soil-gas radon concentration as an indirect tracer for NAPL contamination in the ground. 3 Methods  The partitioning coefficient KNAPL/air is one of the most influential parameters governing the decrease of the radon concentration in the soil gas in the presence of a subsurface NAPL contamination. Since NAPL mixtures such as gasoline, diesel fuel and paraffin are among the most important NAPLs regarding remediation activities, laboratory experiments were performed to determine the radon-partitioning coefficient for these three NAPL mixtures. Field experiments were carried out as well. The aim of the field experiments was to test the use of the soil-gas radon concentration as a tracer for NAPL contamination on-site. For the field experiments, each site was covered with a suitable grid of soil gas sampling points. Finally, the lateral radon distribution pattern achieved on each of the sites was compared to the respective findings of the earlier research performed by conventional means. 4 Results and Discussion  The results of the laboratory experiments clearly show a very strong affinity of radon to the NAPL mixtures examined. The partitioning coefficients achieved correspond to those published for pure NAPLs (Clever 1979) and are thus in the expected range. The results of the field experiments showed that the minimum radon concentrations detected match the respective NAPL plumes traced previously. 5 Conclusions  Both the results of the lab experiments and the on-site findings demonstrate that the soil-gas radon concentration can be used as an indicator for subsurface NAPL contamination. The investigation showed that NAPL-contaminated soil volumes give rise to anomalous low soil-gas radon concentrations in the close vicinity of the contamination. The reason for this decrease in the soil-gas radon concentration is the good solubility of radon in NAPLs, which enables the NAPLs to accumulate and ‘trap’ part of the radon available in the soil pores. 6 Recommendations and Outlook  Further research is required into contamination with rather volatile NAPLs such as BTEX. Further research is also needed to examine whether it is possible to not only localize a NAPL plume, but also to obtain some quantitative information about the subsurface NAPL contamination. The authors also believe that additional investigations should be carried out to study the ability of the method to not just localize a NAPL contamination, but also to monitor on-site, clean-up measures.  相似文献   

4.
本文综述了土壤重金属污染的植物修复、金属超富集植物及其遗传工程的最新研究进展及存在问题,并提出加紧筛选和发现野生高生物量的金属超富集植物,在现有高生物量作物种质资源中筛选金属超富集作物,应用遗传工程技术把野生植物的超富集基因转移到现有高生物量植物(作物)中,寻找综合、可持续的植物修复手段等对策。  相似文献   

5.
利用高光谱遥感技术监测小麦土壤重金属污染   总被引:1,自引:1,他引:1  
为了探讨基于小麦叶片高光谱间接估测土壤重金属含量的潜力,该研究以江苏省宜兴市徐舍镇为研究区域,于2019-2020年采集农田土壤样品和小麦叶片光谱,经7种不同的光谱变换预处理后,以遗传算法(genetic algorithm,GA)优化的偏最小二乘回归算法(partial least squares regression,PLSR)对预处理后的光谱建立土壤重金属镉(Cd)和砷(As)含量的估测模型,并对模型结果进行精度评价。研究结果表明:1)光谱预处理技术能够突出光谱中的一些隐藏信息,对小麦叶片光谱进行微分变换、多元散射校正、标准正态变换等数学变换后更加有利于提取光谱敏感信息。2)GA-PLSR相较于一般的PLSR方法提高了模型精度,将GA用于光谱波段选择可以优化模型精度和提高稳定性。3)土壤Cd含量的最佳估测模型为标准正态变换预处理光谱与GA-PLSR结合,其外部验证的决定系数为0.87、均方根误差为0.04 mg/kg、相对分析误差为2.72;土壤As含量的最佳估测模型为多元散射校正预处理光谱与GA-PLSR结合,其外部验证的决定系数为0.91、均方根误差为0.32 mg/kg,相对分析误差为3.25。因此,能够利用小麦叶片高光谱间接估测土壤重金属Cd和As含量,该研究为将来实现定量、动态、无损遥感监测大面积农田土壤重金属污染状况提供参考依据。  相似文献   

6.
Analysis of vegetation and soils of the Rhondda Fawr, South Wales, shows that there is contamination by the heavy metals Pb, Cd, Cu and Ni throughout the valley, in particular within the urban development area. It is suggested that this contamination occurs mainly by aerial deposition, and that in the case of Pb, Cd and Ni the motor vehicle is the primary source. A correlation between the average heavy metal load of the soil of the urban strip, the urban strip width, and traffic frequency is established. Levels of heavy metals in soils and grasses within rural areas of the valley could be high enough to affect N mineralization in the soil, and could also have adverse effects upon grazing animals.  相似文献   

7.
采用单项与综合污染指数法,以海南省农产品为研究对象,开展了农产品中重金属Cu、Zn、Pb、Cd、Ni、As、Cr和Hg含量的抽样调查分析与评价。结果表明,全省农产品中重金属的平均含量均低于食品中规定的限值,各重金属的单项与综合污染指数均≤1,综合污染指数为0.57;全省农产品未受重金属污染,属于安全水平,适宜发展无公害农产品。同时发现,个别监测点的农产品中重金属含量有超标现象,新鲜水果中个别样品Pb、Cd、Hg超标,超标率在2.17%~10.87%之间;豆类蔬菜中个别样品Ni超标,超标率为9.09%;瓜果类蔬菜中个别样品Pb、Cd超标,超标率为12.24%~24.49%;叶菜蔬菜中个别样品Pb超标,超标率为6.67%;谷物中个别样品Pb、Cd、As超标,超标率在2.11%~7.37%之间。农产品中重金属含量间多呈正相关,其中Zn与Ni、As与Hg之间差异达到极显著水平,Cu与Zn、Cu与As、Cu与Hg、Zn与As、Zn与Hg、Cd与As、Cd与Cr、Cd与Hg、Ni与As、Ni与Hg、As与Cr之间差异达到显著水平。结合主成分分析结果,推测Cu、Zn、Ni、As、Hg含量主要受农业生产和人类活动的影响,而Cr、Pb和Cd含量受土壤母质的影响比较大。  相似文献   

8.
Current U.S. Food and Drug Administration regulations prohibit feeding of protein derived from mammalian tissue, excluding blood and blood products and any product that consists entirely of porcine or equine protein. A novel lateral flow immunoassay device has been developed that can quickly and qualitatively determine the presence of bovine immunoglobulin G (IgG), a major component in blood products, at very low levels (0.01% v/v). The device can be used to test for bovine IgG commingling in spray-dried porcine plasma used in the feed industry. Producers and consumers alike could use this device to verify product content at threshold levels.  相似文献   

9.
建立基于土壤磁化率的重金属污染等级标准可为土壤重金属污染评价提供更为简便的磁学方法。采集开封市城市土壤表层样品99个,测定As、Cd、Cr、Cu、Ni、Pb和Zn含量以及低频磁化率(χLF)和高频磁化率(χHF)。采用普通Kriging插值法探讨χLF的空间分布,污染负荷指数(PLI)评价土壤重金属污染程度,并在PLI与χLF相关分析的基础上建立了基于χLF的土壤重金属污染等级标准。结果表明,开封市城市土壤各样点7种重金属的平均PLI为2.53,呈中度污染,Cd是最主要的污染因子。土壤χLF平均值为125.7×10-8m3kg-1,总体上由东南向西北递减,高值区出现在东南部、老城区北部和陇海铁路沿线附近。各样点土壤重金属PLI与其χLF的回归方程为PLI=0.011χLF+0.320(r=0.663),呈极显著正相关(p0.01)。用土壤χLF可以评价开封市城市土壤重金属污染程度:当土壤χLF≤62×10-8m3kg-1时,为无污染;当62×10-8χLF≤153×10-8m3kg-1时,为轻度污染;当153×10-8χLF≤244×10-8m3kg-1时,为中度污染;当χLF244×10-8m3kg-1时,为强度污染。  相似文献   

10.

Purpose

Human exposure to particulate matter emitted from on-road motor vehicles includes complex mixtures of heavy metals from tyres, brakes, part wear, and resuspended road sediment. The purpose of this study was to determine the concentrations of 14 platinum-group and other traffic-related heavy metals in road sediment within the metropolitan area of Guangzhou, China, with a view to identifying their sources and assessing the extent of anthropogenic influence on heavy metal contamination of road sediment.

Materials and methods

Thirty-five samples of road sediment were collected. The concentrations of Cr, Mn, Ni, Cu, Zn, La, Ce, Mo, Cd, Pb, Ba, and Rh were measured by inductively coupled plasma?Cmass spectrometry. Pt and Pd were analyzed by isotopic dilution?Cinductively coupled plasma?Cmass spectrometry. Multivariate statistical analysis and enrichment factor methods were employed to identify the sources of these heavy metals and to assess anthropogenic influences on their occurrence.

Results and discussion

The mean concentrations of Pt, Pd, Rh, Cr, Mn, Ni, Cu, Zn, La, Ce, Mo, Cd, Pb, and Ba in the road sediment samples were 68.24, 93.15, 23.85, 147.5, 712.3, 47.24, 177.5, 1254, 47.50, 96.62, 4.91, 3.00, 198.1, and 641.3?ng?g?1, respectively. Very weak to significant linear positive correlations were found among the various heavy metals. The elemental composition of road sediment was dominated by five principal components. Three clusters were identified through cluster analysis, and enrichment factors were calculated relative to soils in China. The sources and degree of contamination of the heavy metals are discussed based on the results.

Conclusions

The mean concentrations of heavy metals are higher than background values, especially for Pt, Pd, Rh, Cd, and Zn. Four main sources are identified: (1) Pt, Pd, and Rh were derived from traffic sources; (2) La, Ce, Mn, and Ba were derived mainly from natural sources; (3) Cr, Ni, Cu, Mo, Cd, and Pb showed mixed traffic-industry sources; and (4) Zn originated mainly from industrial sources. Enrichment factor analysis supported this source identification and further indicated that contamination of road sediment in Guangzhou is extremely high for Pt, Pd, and Rh; moderate to very high for Cd, Zn, Pb, Cu, and Mo; and minimal for Cr, Ni, La, Ce, and Ba.  相似文献   

11.
The utility of landfill temperature measurements both as a means of understanding landfill behavior and the interpretation of anomalous data points is explored by demonstration in a case study application. The availability of a pathway facilitating easy intrusion of atmospheric OZ into a landfill is shown to cause aerobic conditions and spontaneous combustion, during landfill pumping experiments. The landfill temperature measurements provide an effective means of isolating the extent of the problem.  相似文献   

12.
《Soil biology & biochemistry》2001,33(12-13):1811-1816
A high metal-containing soil and a low metal-containing soil were supplied with 14C-labelled glucose at two rates, one to provide a constant glucose-to-soil ratio and the other a constant glucose-to-biomass ratio. The aim was to assess the effects of these different ratios on the microbial substrate utilisation efficiency. Glucose was added with or without N to investigate the extraction efficiency of the fumigation-extraction method shortly after substrate addition. The addition of glucose without N resulted in a proportionally larger increase in microbial biomass C than in microbial ninhydrin-reactive N (ENIN) within the first few days after substrate addition, due to N deficiency. The biomass C-to-ENIN ratio remained constant in all soil treatments after glucose addition in combination with N, indicating that the extraction efficiency of the fumigation-extraction method is not affected by the addition of glucose. Lower percentages of glucose added were incorporated into the microbial biomass with an increasing ratio of glucose-to-biomass. The ratio of respired to biomass incorporated 14C increased in all high metal-containing soil treatments markedly above that of the low metal-containing soil from day two of the incubation, markedly overriding the effects on the glucose C-to-biomass C ratio. Our results clearly demonstrated that more substrate was diverted by microorganisms into catabolic at the expense of anabolic processes in a high metal-containing soil.  相似文献   

13.
Biomonitoring of the local population and environmental monitoring in eastern Croatia have revealed abnormalities in metal and metalloid distribution that could be related to war activities during the 1990s. The goal of this study was to determine whether there are differences in the concentrations of metals and metalloids by comparing locations of high and low-intensity combat activity; we also evaluated a possible connection between metal contamination in soil and in humans. We sampled 14 locations and measured the concentrations of 20 war related metals and metalloids (Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Ni, Pb, Sb, Si, Sr, U, V and Zn). The results of principal components analysis showed two main clusters: locations Dopsin and Dalj (both characterized by high-intensity combat activity), where the concentrations of most elements (except Hg) were increased. Although the concentrations of metals and metalloids in cabbage samples collected in eastern Croatia did not exceed the maximum allowed values, the results of our study confirmed existance of environmental ‘hotspot’ with higher concentrations of war metals and metalloids. Our findings indicate that there is a possible common source and mechanism of transferring metals from the environment to the population.  相似文献   

14.
The threat of heavy metal contamination to food and human health in south and east China has become a public concern as industrial development continues. The aims of this study were to investigate the influence of repeated phytoextraction over a two-year period by successive crops of the Zn and Cd hyperaccumulator Sedum plumbizincicola on multiple metal contaminated soils and to assess recovery of soil quality. Total and NH4OAc-extractable Zn and Cd concentrations were significantly reduced in planted soils compared to unplanted soils. Microbial biomass C (Cmic), basal respiration and microbial quotient (qM) were significantly and positively correlated and soil metabolic quotient (qCO2) was negatively correlated with heavy metal concentrations in unplanted soils (P < 0.05). However, Cmic, basal respiration and qM values increased significantly after phytoremediation by five crops over two years compared to unplanted soil. Urease, β-glucosidase, neutral phosphatase and arylsulfatase activities also increased significantly with decreasing heavy metal contents and hydrolase activity was enhanced in planted soil (P < 0.05) compared to the unplanted control. The data indicate the capacity of S. plumbizincicola to extract Zn and Cd from contaminated soil and also that phytoremediation had beneficial effects on soil microbial and hydrolase activities, with the metal phytoextraction procedure restoring soil quality.  相似文献   

15.
Traditionally, three threshold levels have been accepted for heavy metal concentrations in agricultural soils, depending on soil pH. The aim of this work was to ascertain how the three threshold values proposed for Cd (3, 6.5, and 12.5 mg kg?1) and Zn (300, 650, and 1300 mg kg?1) really affect soil microbial activity. Two soils, a scrubland soil and a forest soil, differing widely in their organic C content, were used in this study. Despite the different soil characteristics, the fractions of Cd and Zn extracted with a solution of diethylenetriaminepentaacetic acid (DTPA) showed little difference between soils. Parameters, such as microbial biomass C (Cmic), soil basal respiration (BR), adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), urease activity (UA), alkaline phosphatase activity (APA), and β-glucosidase (β-GA), were less affected by heavy metals in the forest soil than in the scrubland soil. In general, the simultaneous addition of both metals had a synergistic effect on microbial activity, and this treatment produced a significant decrease of microbial activity of both soils with respect to control. The highest level (L3) of Cd, Zn and Cd + Zn treatments produced significant decrease of microbial and biochemical parameters in both soils.  相似文献   

16.
重金属Cd、Zn、Cu和Pb复合污染对土壤生物活性的影响   总被引:6,自引:0,他引:6  
通过野外土样采集及室内培养试验(25℃),研究了云南东川铜矿区土壤酶和微生物特征,以及模拟重金属Cd、Zn、Cu、Pb复合污染对土壤微生物和酶活性的影响。结果表明,矿区土壤(距矿口0~800 m)重金属污染严重,Pb、Cd、Zn、Cu全量和有效含量是对照土壤(距矿口10 000 m)的3.7~141.0倍和2.2~773.2倍;距矿口越近,土壤有机质、有效氮、有效磷和速效钾含量及土壤pH亦越低,土壤酶活性和土壤微生物数量、微生物生物量碳和氮受到的抑制程度也显著增强。与对照土壤相比,距矿口0~800 m的土壤蔗糖酶、脲酶、酸性磷酸酶、过氧化氢酶和脱氢酶活性分别降低25.5%~47.3%、22.6%~74.2%、30.9%~83.1%、16.7%~69.1%和34.6%~92.3%;细菌、放线菌和真菌数量分别较对照下降30.5%~80.1%、8.1%~49.9%和3.3%~8.3%。土壤酶中的酸性磷酸酶和过氧化氢酶,土壤微生物中的细菌对重金属污染较为敏感。恒温(25℃)培养试验中,低量的Cd、Zn、Cu、Pb复合污染刺激了土壤酶活性和细菌、真菌、放线菌、微生物生物量碳和氮的数量,但高量的Cu、Zn、Pb、Cd复合污染使土壤酶活性、细菌、真菌、放线菌、微生物生物量碳和氮均显著下降。重金属Cd、Zn、Cu、Pb之间存在着一定的协同或拮抗作用,Cd、Zn、Cu和Pb之间在微生物生物量碳和氮上表现出明显的协同效应,Pb与Cd、Zn、Cu对细菌数量的复合效应机制为拮抗效应,Cd、Zn、Cu和Pb对真菌数量和放线菌数量的复合效应机制表现为协同效应和拮抗效应并存。  相似文献   

17.
长期集约化耕作导致中国设施土壤重金属累积和面源污染风险增加的状况已引起广泛关注。该研究总结了中国设施土壤重金属累积状况及其来源,发现长期盲目投入肥料及农药是引发设施菜田土壤重金属累积问题的主要原因。目前,设施土壤重金属累积呈现出广泛性和中轻度污染特征,其中镉是主要的污染元素。遵循面源污染治理中“源头预控-过程阻断-末端修复”原则,基于国内外文献综述,该文总结归纳出适用于设施土壤重金属累积特征与污染的联合阻控技术及作用机制。首先在灌溉和肥药投入等源头环节减少重金属输入;其次在作物种植过程中,通过选用重金属低积累特性的蔬菜种类或品种,结合水肥一体化施用大分子有机水溶性肥料或叶面喷施具有阻控重金属作用的营养型阻控剂,抑制作物吸收重金属;最后在末端修复环节,利用具有多元功能的土壤改良剂或微生物菌剂进行土壤钝化修复,或采用具有超重金属富集能力且能提高设施土壤生物多样性的植物作为填闲作物,实现生物修复的目标。该联合阻控技术的原则在于协同考虑污染防治、土壤改良、减肥增效等农学和环境目标,集成土壤修复与改良、水肥一体化、填闲作物栽培等技术,并兼顾设施土壤重金属污染修复工程所面临的投入品成本较高、经济效益不明显、缺失可持续改良导致效果不稳定等问题,优推能够钝化重金属并改良土壤的多功能土壤改良剂以及具有阻控重金属吸收、提高作物抗逆性的多功能有机水溶性肥料。上述措施能解决设施土壤普遍存在的重金属累积问题,提升土壤的安全生产能力,可为设施农业可持续发展提供更有效的技术支撑。  相似文献   

18.
Several microbial parameters (microbial biomass, respiration, dehydrogenase, phosphatase, sulphatase, glucosidase, protease and urease activities) were measured in soils from five sites located in urban green areas close to roads differing in traffic density. Our aims were to evaluate the suitability of such parameters as field biomarkers of stress induced by heavy metal pollution, and to compare results obtained by single microbial parameters with results given by an index expressing the average microbial (AME) response of the microbial community. Data showed that all parameters were significantly reduced in the sites characterized by the highest load of metals in soil. Dehydrogenase, sulphatase, glucosidase activities and respiration, declined exponentially with increasing metal concentration, whereas phosphatase activity and AME decreased following a sigmoidal type relationship. In contrast, protease, urease and microbial biomass were not significantly correlated with soil metal concentration. Microbial parameters differed both in sensitivity to critical metal concentrations and in the rate of decline at increasing metal loads in soil. Due to the complex interplay of chemical, physical and biological factors which influence microbial activities and biomass, the proposed index (AME) appeared more suitable than single microbial parameters for a biomonitoring study of this type.  相似文献   

19.
Abstract. Finely ground limestone waste from lead mining is discarded as useless but could be a valuable alternative to agricultural limestone. A glasshouse pot experiment established that it is an effective liming material. Two kinds were used: one from north Wales (HMT) represented metal-rich waste produced by the older water-gravity separation of ores; the other (NLB) was a modern flotation tailings. A commercial lime (CLS) was used for comparison. The materials were applied to an acid soil in quantities sufficient to raise the pH to 7 (single liming) and at much greater rates equivalent to annual limings for 369 years. All treatments were replicated five times and the soil/lime mixtures were analysed for EDTA-extractable lead, zinc and cadmium. Radish was grown as the test plant and hypocotyl and leaf tissue were analysed for the same metals. The larger additions of HMT and NLB caused chlorosis and decreased yields. The cadmium and lead concentrations of leaves and hypocotyls suggested that the HMT material could be safely applied to soil annually for 79 years and NLB for 277 years. It is concluded that NLB can be used as agricultural limestone.  相似文献   

20.
We assessed the effects of chronic heavy metal (HM) contamination on soil microbial communities in a newly established forest ecosystem. We hypothesized that HM would affect community function and alter the microbial community structure over time and that the effects are more pronounced in combination with acid rain (AR). These hypotheses were tested in a model forest ecosystem consisting of several tree species (Norway spruce, birch, willow, and poplar) maintained in open top chambers. HMs were added to the topsoil as filter dust from a secondary metal smelter and two types of irrigation water acidity (ambient rain vs. acidified rain) were applied during four vegetation periods. HM contamination strongly impacted the microbial biomass (measured with both fumigation-extraction and quantitative lipid biomarker analyses) and community function (measured as basal respiration and soil hydrolase activities) of the soil microbial communities. The most drastic effect was found in the combined treatment of HM and AR, although soil pH and bioavailable HM contents were comparable to those of treatments with HM alone. Analyses of phospholipid fatty acids (PLFAs) and terminal restriction fragment length polymorphisms (T-RFLPs) of PCR-amplified 16S ribosomal DNA showed that HM treatment affected the structure of bacterial communities during the 4-year experimental period. Very likely, this is due to the still large bioavailable HM contents in the HM contaminated topsoils at the end of the experiment.  相似文献   

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