Retention of Cd, Cu, Pb and Zn by Wood Ash, Lime and Fume Dust

Heavy metals are of interest due to their deleterious impacts on both human and ecosystem health. This study investigated the effectiveness of wood ash in immobilizing the heavy metals Pb, Cd, Cu and Zn from aqueous solutions. The effects of initial metal concentrations, solution pH, ash dose and reaction time on metal sorption, as well as the metal sorption mechanisms were studied. To investigate the effect of initial metal concentrations, solutions containing Cd, Zn (25, 50, 75, 100 or 125 mg L^?1), Cu (25, 50, 75, 100, 125, 150 or 175 mg L^?1) or Pb (250, 500, 750, 1000, 1250, or 1500 mg L^?1) were reacted with 10 g L^?1 ash for two hours. For the effect of pH, solutions containing 100 mg L^?1 of Cd, Cu or Zn or 1500 mg L^?1 of Pb were reacted with 15 g L^?1 ash over a pH range of 4 to 7. The wood ash was effective in immobilizing the four metals with a sorption range of 41–100 %. The amounts of metals retained by the ash followed the order of Pb > Cu > Cd > Zn. As expected, absolute metal retention increased with increasing initial metal concentrations, solution pH and ash dose. Metal retention by the ash exhibited a two-phase step: an initial rapid uptake of the metal followed by a period of relatively slow removal of metal from solution. Metal retention by the ash could be described by the Langmuir and Freundlich isotherms, with the latter providing a better fit for the data. Dissolution of calcite /gypsum minerals and precipitation of metal carbonate/sulfate like minerals were probably responsible for metal immobilization by the ash in addition to adsorption.     

洞庭湖区典型蔬菜土壤镉、铜、锌、铅含量状况及评价

采用单项污染指数和综合污染指数法对湖南洞庭湖区典型蔬菜土壤Cd,Cu,Zn,Pb含量状况进行了评价。结果表明,与湖南省潮土土壤背景值相比,土壤Cd,Cu和Zn含量明显富集,Pb含量总体不高。与国家土壤质量二级标准(GB15618-1995)相比,洞庭湖区蔬菜土壤以Cd污染为主,其次是Zn和Cu。Pb含量没有超标,其中湘阴县、沅江市、资阳区和赫山区蔬菜土壤环境质量为轻度污染,华容县处于警戒水平,需要修复治理或者改变土地利用方式。君山区和南县蔬菜土壤为清洁水平,适宜发展无公害蔬菜。污染风险高的区域土壤Cd,Cu和Zn之间存在极显著或显著正相关关系,但相关性弱。     

Changes in Concentrations of Cd,Zn, Mn,Cu and Pb in Spruce (Picea abies) Needle Litter During Decomposition

Spruce (Picea abies (L.) Karst) needle litter was placedin litterbags and incubated (≥6 yr) at five spruce standsin southern Sweden. The litterbags were collected twice a yearduring year 1–2 and thereafter once a year, for total analyses(conc. HNO₃) of Cd, Zn, Mn, Cu and Pb. The main objectiveswere to document changes in concentrations and amounts of theseelements during litter decomposition and to investigate factorscontrolling the changes.Concentrations of Cd, Zn, Cu and Pb increased to at least 0.5, 1.5, 3 and 13 times the initial concentration. During the latterpart of the incubations, concentrations became more stable ordecreased. Concentrations at which the metals are considered to be toxic to micro-organisms in the mor layer were not reached during the experiment. Generally, concentrations of Mn decreased.Total amounts of Cd, Zn and Mn had decreased by at least15, 24 and 43%, from the initial amount at the end of theexperiment. The total amount of Cu increased (>40%) before itstarted to decrease. The total amount of Pb increased by over230%. Thereafter it became more constant or decreased.According to a PCA, the dynamics of total amounts of Cd,Zn and Mn in the litter were similar, as were those of Pb and Cu.Furthermore, in most cases the heavy metal amounts on anysampling occasion differed more between than within sites. Thedynamics of total amounts of elements were more similar betweenadjacent sites than between more distant sites.     

The flux of Cd,Cu, Pb and Zn in mining polluted soils

The monitoring of heavy metal deposition onto soils surrounding old Pb-Zn mines in two locations in the UK has shown that relatively large amounts of Cd, Pb, Zn and, in one case, Cu are entering the soil annually. Small particles of ore minerals in windblown mine tailings were found to be contributing up to 1.46 g m^?2 yr^?1 of Pb, 1.41 g m^?2 yr^?1 of Zn and 0.027 g m^?2 yr^?1 of Cd. However, when these inputs from bulk deposition are compared with the concentrations of the same metals within the soil profiles it is apparent that relatively little long-term accumulation is occurring. Metals are being lost from the soil profiles, probably through leaching. A calculated relative retention parameter gave values that ranged from 0.01 to 0.17 for Cd, 0.11 to 0.19 for Zn, 0.32 to 0.63 for Cu and over 1 for Pb. These relative retention values were found to follow the order of electronegativity of the elements concerned: Pb>Cu>Zn>Cd. Distribution coefficient (Kd) values quantifying the adsorptive capacity of the mine soils for Cd and Pb showed marked differences for the two metals (12 to 69 cm³ g^?1 for Cd and 14 to 126 cm³ g^?1 for Pb) and may, in part, account for the two to one hundred-fold variation in the relative retention parameter for the different metals within these soils.     

Solubility control of Cu, Zn, Cd and Pb in contaminated soils

We developed a semiempirical equation from metal complextion theory which relates the metal activity of soil solutions to the soil's pH, organic matter content (OM) and total metal content (MT). The equation has the general form: where pM is the negative logarithm (to base 10) of the metal activity, and a, b and c are constants. The equation successfully predicted free Cu²⁺ activity in soils with a wide range of properties, including soils previously treated with sewage sludge. The significant correlation of pCu to these measured soil properties in long-contaminated soils suggests that copper activity is controlled by adsorption on organic matter under steady state conditions. An attempt was made from separate published data to correlate total soluble Cu, Zn, Cd and Pb in soils to soil pH, organic matter content and total metal content. For Cu, the total Cu content of the soil was most highly correlated with total soluble Cu. Similarly, total soluble Zn and Cd were correlated with total metal content, but were more strongly related to soil pH than was soluble Cu. Smaller metal solubility in response to higher soil pH was most marked for Zn and Cd, metals that tend not to complex strongly with soluble organics. The organic matter content was often, but not always, a statistically significant variable in predicting metal solubility from soil properties. The solubility of Pb was less satisfactorily predicted from measured soil properties than solubility of the other metals. It seems that for Cu at least, solid organic matter limits free metal activity, whilst dissolved organic matter promotes metal solubility, in soils well-aged with respect to the metal pollutant. Although total metal content alone is not generally a good predictor of metal solubility or activity, it assumes great importance when comparing metal solubility in soils having similar pH and organic matter content.     

Short-Term Influence of Clinker Dust and Wood Ash on Macronutrients and Growth in Norway Spruce (Picea abies) and Scots Pine (Pinus sylvestris) Seedlings

The effects of clinker dust and wood ash on Norway spruce and Scots pine seedlings were compared in buried pots. Clinker dust (0.5 kg m^?2) and wood ash (0.5 kg m^?2) were applied to the surface of a nutrient-poor mineral soil. In the second year, the increase in soil pH by the dust and ash were larger than in the first year. Both alkaline treatments caused a large increase in the needle potassium (K) concentration. An excess of soil K relative to magnesium (Mg) was observed by decreased Mg concentration in needles shortly after treatment. However, Mg concentration in needles stayed in the sufficiency range. Current results confirmed earlier findings that despite a positive effect on base cation nutrition, wood ash has a low potential for increasing the biomass of forest stands on mineral soils due to the N limitation in these soils.     

The determination of Zn,Cd, Pb and Cu in soil extracts by anodic stripping voltammetry

This work describes simultaneous determination of Zn, Cd, Pb and Cu in soil extract by d. c. anodic stripping voltammetry at the hanging mercury drop electrode. Soil samples were taken from six different areas characterized by different degrees of heavy metal pollution. The metals were extracted from the soil samples using 0.5 M HCI. The base electrolyte for ASV was 0.2 M acetic buffer at pH 5.0. These results are compared with those obtained by using atomic absorption spectrophotometric method. The accuracy and precision of the presented method are satisfactory (relative standard deviation is 3.5 to 11%). Iron, Al and Ti contained in the extract in the concentration of 1120, 5400, and 480 µg g^?1, respectively, do not present measurement difficulties.[/p]     

几种土壤在单一Zn及Cd Cu共存条件下对Zn的吸附

研究了Zn2+在单一及与Cd2+、Cu2+共存条件下在塿土、黄绵土、黑垆土、黄褐土、砂土5种土壤中的吸附特征,并探讨了其吸附机制。结果表明,在20℃、30℃下,Zn2+在各供试土样中吸附等温线总体上均呈I或III型等温线形式,总体上黑垆土、塿土对Zn2+吸附最强,而砂土的吸附总是最差;塿土、黄绵土和黄褐土中Zn2+吸附的温度效应呈现升温正效应特征,砂土中则总体上表现出随温度上升呈下降趋势,黑垆土中Zn2+吸附的温度效应则与重金属处理有关。Freundlich模型是描述Zn2+吸附等温线最佳模型。Cd2+、Cu2+的共存对Zn2+的吸附均具有显著的拮抗作用,但对Zn2+吸附规律的影响不同。机理分析表明,Zn2+在土壤中的吸附主要以化学吸附为主,Cu2+由于其与Zn2+相似的化学吸附特点而竞争Zn2+化学吸附点位,但Cd2+吸附主要竞争以电性引力形式吸附的Zn2+,因而Cu2+对Zn2+吸附的影响较大,而Cd2+影响较小。     

重金属复合处理对小麦锌铜镍镉积累和分布的影响

为增加粮食可食用部分有益元素的浓度,同时减少有毒重金属元素的含量,需要更好地了解元素在植株和籽粒内的运输和分布。在温室盆栽条件下,以春小麦为供试材料,设置对照（不添加重金属）和重金属复合处理（同时添加铜、锌、镍、镉,以不影响小麦生长为前提）,研究锌（Zn）、铜（Cu）、镍（Ni）、镉（Cd）在成熟植株和籽粒不同部位的分布特点。结果表明,重金属复合处理对小麦成熟期籽粒和秸秆产量、收获指数以及粒重均无显著影响,但使小麦各器官重金属浓度均显著增加,增幅因不同器官和不同元素而异,籽粒中Zn、Cu、Ni和Cd浓度分别增加1.8、0.5、48.1倍和45.3倍。重金属复合处理还显著改变了Zn和Ni在地上部各器官中的分配模式：对照小麦吸收的Zn更易向生殖器官中转运,处理植株则更多地滞留在营养器官中,而Ni呈相反的趋势。激光剥蚀电感耦合等离子体质谱仪（LA-ICP-MS）对籽粒糊粉层和胚乳的定量分析表明,重金属复合处理使糊粉层Zn和Cu浓度仅增加了78%和86%,而糊粉层Ni和Cd浓度分别增加了30倍和121倍。重金属复合处理使胚乳Zn和Cu浓度分别增加了49%和48%,使Ni和Cd浓度均超出小麦标准中Ni和Cd的最大允许浓度（对照籽粒胚乳中没有检验到Ni和Cd）。以上结果表明,在小麦生物强化实践中,在增加有益营养元素（如Cu和Zn）的同时亦存在有毒重金属（如Ni和Cd）超标的巨大风险。     

The effect of pH on the retention of Cu,Pb, Cd,and Zn by clay-fulvic acid mixtures

The addition of fulvic acid to clay suspensions (kaolinite, illite or montmorrillonite) resulted in increased uptake of Cu, Pb, Cd, and Zn ions over the pH range 3 to 6, due to the limited solubility of one of the metal-fulvate species formed. At higher pH values, residual metal ion was retained in solution, instead of precipitating as hydroxy species. The amount of total metal ion found in solution at equilibrium was determined by the quantity and type of clay added; the amount of organic acid present; and to a lesser extent, pH. The behavior of the clay-fulvic acid systems differed from that observed using other organic materials such as gelatine, tannic acid or a humic acid.     

Reduction of Pb,Zn and Cd Availability from Tailings and Contaminated Soils by the Application of Lignite Fly Ash

The effectiveness of lignite fly ash for stabilization of Pb,Zn and Cd in tailings and contaminated soils was examined. Flyash was mixed with the contaminated soil or oxidic tailingssamples at various doses and pot experiments were performed.The effectiveness of stabilization was mainly evaluated by thestandard US EPA TCLP toxicity test. The 5-stage sequentialextraction procedure was also applied to determine the form ofcontaminants in the fly ash amended soil or tailings samples.Complementary EDTA extraction tests were also carried out. Thefly ash treatment resulted in the reduction of TCLP solubilityof Pb, Zn and Cd to below the respective regulatory limits at5 and 10% w/w fly ash addition rates in tailings and soil,respectively. Speciation of lead, in the treated soil andtailings samples indicated that there was a significanttransition of the heavy metals form from the exchangeable andcarbonate fractions to reducible and residual, suggesting thatthe potential mechanisms of heavy metals retention are, apartfrom increase of pH, sorption on the oxides and hydroxidessurfaces and binding with the hydrated fly ash compounds.     

Chemical speciation and bioavailability of Cd,Cu, Pb and Zn in Western Balkan soils

Abstract

Three thermal power plants in Serbia, Croatia and Bosnia of the Western Balkan region were expected to be metal polluting sources, and this study was performed to investigate the bioavailability and chemical speciation of trace metals in soils and soil water extracts, respectively. Surface (0–15 cm) soil samples along with maize and grass samples were collected at a gradient from the pollution source. The chemical speciation of metals was conducted using the Windereme Humic Aqueous Model (WHAM)/Model VI for water, whereas the Diffusion Gradient in Thin Films (DGT) technique was used to estimate plant availability. The chemical speciation indicated that more than 99% of all four metals in soil water extracts were complexed to fulvic acid. This is connected to relatively high soil pH (> 6.5) and high contents of soil organic matter in these soils. The accumulation of trace metals by DGT was not correlated to plant uptake. This is connected to the very low partitioning of free ions in solution, but also to the low variation in metal solubility and metal concentration in plant tissue between sites. In spite of active thermal power plants located in the areas, hardly any differences in concentration of soil metals between sites were seen and the partition of metals in soil waters was insignificant. The latter indicates that these soils have a large metal-retaining capacity. The only significant soil chemical variable affecting the variation in metal solubility was the soil pH. In a time with large infrastructure and industrial expansion in these areas, this investigation indicates the importance of protecting these high-quality soils from industrial use and degradation. High industrial activity has so far had insignificant effect on soil quality with respect to bioavailability of trace metals in these soils.     

Hg, Cu, Pb, Cd, and Zn Accumulation in Macrophytes Growing in Tropical Wetlands

The concentrations of Hg, Cu, Pb, Cd, and Zn accumulated by regional macrophytes were investigated in three tropical wetlands in Colombia. The studied wetlands presented different degrees of metal contamination. Cu and Zn presented the highest concentrations in sediment. Metal accumulation by plants differed among species, sites, and tissues. Metals accumulated in macrophytes were mostly accumulated in root tissues, suggesting an exclusion strategy for metal tolerance. An exception was Hg, which was accumulated mainly in leaves. The ranges of mean metal concentrations were 0.035?C0.953 mg g^?1 Hg, 6.5?C250.3 mg g^?1 Cu, 0.059?C0.245 mg g^?1 Pb, 0.004?C0.066 mg g^?1 Cd, and 31.8?363.1 mg g^?1 Zn in roots and 0.033?C0.888 mg g^?1 Hg, 2.2?C70.7 mg g^?1 Cu, 0.005?C0.086 mg g^?1 Pb, 0.001?C0.03 mg g^?1 Cd, and 12.6?C140.4 mg g^?1 Zn in leaves. The scarce correlations registered between metal concentration in sediment and plant tissues indicate that metal concentrations in plants depend on several factors rather than on sediment concentration only. However, when Cu and Zn sediment concentrations increased, these metal concentrations in tissues also increased in Eichhornia crassipes, Ludwigia helminthorriza, and Polygonum punctatum. These species could be proposed as Cu and Zn phytoremediators. Even though macrophytes are important metal accumulators in wetlands, sediment is the main metal compartment due to the fact that its total mass is greater than the corresponding plant biomass in a given area.     

Cu Cd Pb Zn对酸性耕作土壤3种酶活性的影响

采用添加外源重金属和室内培养的方法,研究了Cu、Cd、Pb、Zn对1个酸性耕作土壤中脲酶、蛋白酶和过氧化物酶活性的影响。Cu添加浓度为50、100、200、400、600mg·kg^-1,Cd添加浓度为1、5、10、15、20mg·kg^-1,Pb添加浓度为100、300、500、800、1200mg·kg^-1,Zn添加浓度为50、100、200、400、800mg·kg^-1。结果表明,Cu、Cd、Pb、Zn对脲酶以抑制作用为主,4种重金属对酶毒性大小依次为Cu〉Cd〉Zn≥Pb,但在培养末期抑制作用都趋于减弱。Ph、Cu、Cd、Zn在前17d的培养中使蛋白酶酶活性急剧降低,以后蛋白酶活性维持在此较低水平上。短时间内（3d）Zn对过氧化物酶具有强烈的抑制作用,但总体看来4种重金属对过氧化物酶活性的影响均较小。上述结果表明,脲酶对农田土壤Cu污染具有指示作用,蛋白酶对农田土壤4种重金属污染都具有指示作用,过氧化物酶仅对土壤Zn的短期污染具有指示作用。     

绿化植物废弃物对重金属迁移的影响

采用土柱模拟实验,比较研究了覆盖绿化植物废弃物与土壤之上和绿化植物废弃物与土壤混合处理对城市绿地土壤中重金属淋溶的影响。结果表明,Zn、Pb和Cd均在80天后淋溶完全,而Cu有所不同,在80天后又有增加的趋势,原因可能跟重金属与有机质的结合能力有关。此外,绿化植物废弃物与土壤相混合能抑制Cu、Zn、Pb和Cd向下淋溶,而绿化植物废弃物覆盖于土壤之上则有促进Cu、Zn、Pb和Cd淋溶的趋势,且不论是混合处理还是覆盖处理,20cm厚绿化植物废弃物的处理均比10cm厚绿化植物废弃物处理对Cu、Zn、Pb和Cd的促进或抑制作用大。研究还得知,Cu、Zn、Pb和Cd的迁移还与土壤pH有关,低pH土壤有利于重金属的淋溶。     

太原市污灌区土壤有效态铜锌和锰含量评价

为了研究太原市污水灌溉对土壤有效态元素铜、锌和锰含量的影响,对太原市污水灌溉区（小店区、尖草坪区、晋源区和清徐县）150个土壤样品有效态微量元素铜、锌和锰的含量和分布进行了测定和分析。结果表明,长期污水灌溉导致该区土壤铜、锌和锰的含量均高于文献测定值。有效铜含量晋源区〉小店区〉清徐县〉尖草坪区,分级评价结果均以中等级含量为主;有效锌含量小店区〉晋源区〉清徐县〉尖草坪区,除小店区以低、中级含量为主外,其他3个污灌区均以低等级含量为主;有效锰含量晋源区〉清徐县〉尖草坪区〉小店区,其分级分布情况变异最大,除小店区以低等级含量为主外,其他研究区域有效态锰均以高等级和极高等级含量为主。整体来看,研究区整体缺锌,有效铜含量适中,有效锰含量较高。     

Fluxes of Cu,Zn, Pb,Cd, Cr,and Ni in temperate forest ecosystems

The literature on the fluxes of six heavy metals in temperate forest ecosystems is reviewed. Special attention is given to wet and dry deposition and internal flux, to metal budgets for ecosystems and soils, to concentrations in aqueous compartments of the ecosystem and to speciation in soil solutions. Metal fluxes are discussed in relation to pollution load, soil type, tree species and land use. The mobility of Cu and Pb is strongly dependent on the solubility of organic matter. These metals are commonly accumulated in forest soils. Zinc, Cd and Ni are greatly influenced by soil acidity and are often lost in considerable amounts from acidified soils. Chromium is often at balance in forest ecosystems. Implications for metal solubility and budgets in forest soils are discussed in connection with an increase in soil acidification.     

绿化植物废弃物对土壤中Cu Zn Pb和Cd形态的影响

利用自制的Cu、Zn、Pb和Cd污染的灰潮土和黄泥土,通过室内培养实验研究了不同绿化植物废弃物添加量和不同培养时间对这两种污染土壤中这4种重金属形态的影响。结果表明,绿化植物废弃物的加入抑制了Cu的活化,且添加60%绿化植物废弃物时有机结合态Cu的含量最高;绿化植物废弃物与污染土培养2～3个月时,残余态Zn的含量最高,对植物的毒害最小;绿化植物废弃物添加量为60%时灰潮土中有效态Pb含量较低,而添加量为30%时黄泥土中有效态Pb含量最低;绿化植物废弃物添加量的多少对灰潮土Cd形态的影响较小,但黄泥土中的Cd则随绿化植物废弃物量的增加活性逐渐减弱,且两种土壤均在培养2～3个月时可交换态Cd的含量最低。     

污泥添加粉煤灰堆肥化对Cu、Zn、Pb形态的影响

污泥中重金属的危害是影响污泥土地利用的重要因素;污泥重金属危害不仅取决于总量,其形态分布更能反映重金属的迁移性以及生物有效性。实验以木屑为调节剂,粉煤灰作为钝化剂,研究污泥堆肥前后重金属Cu、Zn与Pb的形态分布变化。结果表明,堆肥对Cu有活化作用,而添加粉煤灰堆肥化能有效抑制这种活化,起到钝化作用,堆肥化使Pb向更稳定形态转化,添加粉煤灰堆肥化对Zn的钝化效果较好,当粉煤灰添加量为35%时,对Cu、Zn、Pb 3种重金属的易迁移态均具明显的钝化效果。     

Distribution of Zn, Cd, Pb and Cu Metals in Groundwater of the Guadiamar River Basin

Traditionally, the Guadiamar River Basin (Seville, SouthwestSpain) has received pollution from two different sources. Inits upper course, from a pyrite exploitation and, in itslower reaches, from untreated urban and industrial wastes aswell as wastes from intensive agricultural activity. In 1998,the accidental release in the river of about 6 million m³ of acid water and sludge from mine tailings contributedto worsen the pollution of an already contaminated area. Themain polluting agents of the spill were heavy metals. Itaffected a large number of wells either directly or as a consequence of infiltration from polluted soils. Assessment of the pollution by total metal determination does not revealthe true environmental impact of the spill and speciation studies showing the distribution of the main pollutants are required. There is a direct association between the physicochemical speciation of an element and its bioavailability, toxicity and mobility. This article describesa distribution study of the metals Zn, Cd, Pb and Cu by speciation analysis of groundwater in six wells of the GuadiamarRiver Basin; the samples were taken several weeks after the spill. The speciation analysis resulted in the definition ofthree species categories: a) labile metal (H⁺ exchangeable),b) metal strongly associated to dissolved organic matter and c) metal associated with suspended material. Analysis was carried out by anodic stripping voltammetry (ASV). Metal speciation ingroundwater of the Guadiamar River Basin allows a differentiationbetween: on the one hand, metals from the mining spill, andon the other hand a less recent pollution from accumulatedinfiltration of either mining or agricultural origin, the last one due to an abuse of phytosanitary products.