烟气脱硫石膏对滩涂围垦土壤重金属解吸及残留形态的影响

滩涂围垦土壤是重金属等难降解污染物的主要最终归宿场所之一,其重金属的解吸将影响重金属的迁移性、生物有效性和潜在毒性,研究重金属的解吸对土壤污染评价、修复及环境容量预测至关重要.研究了烟气脱硫石膏对广州市南沙滩涂围垦土壤重金属的解吸效果,并分析了烟气脱硫石膏对重金属形态的影响.在离心管中称取20.0 g过0.25mm筛土样,加入20 mL水和不同量的烟气脱硫石膏,在室温下于恒温振荡器振荡,风干研碎后用原子吸收分光光度法测定重金属全量,并用Tessier连续提取法研究了处理前后重金属形态变化.研究结果表明,随着脱硫石膏施用量的增加,经过振荡离心后的滩涂围垦土壤中重金属质量分数先急剧下降,之后变化趋于平缓.与原土相比各重金属最大解吸率分别为:Cd 30.38%,Cu17.73%,Ni 15.00%,Zn 14.19%,Pb 9.46%,Cr 8.89%.比较处理前后重金属的形态变化,发现各重金属的可交换态解吸率均达50%以上,并且重金属碳酸盐结合态质量分数也有减少.说明烟气脱硫石膏能降低土壤对重金属的吸附,经振荡离心后能降低土壤中重金属的毒性和生物可利用性.     

衡阳市菜园使用的商品有机肥和有机废弃物中重金属含量状况调查

对衡阳市菜园使用的12个有机肥样品中的Zn、Cu、Cr、Pb、Cd、Ni、Hg和As的指标进行检测,样品中重金属总As、总Hg、总Pb、总Cd、总Cr等的含量按照中国NY525—2012有机肥料重金属限量指标,总Ni、总Cu、总Zn重金属参照德国腐熟堆肥中重金属限量标准进行分析,结果表明,除牛粪、菜籽饼肥外,有9个样品均发现有超限量值的重金属成分,超标样品数占总样品数的75%,超标的重金属成分以Cu和Zn较为普遍,分别占样品总数的75%和41.7%.而在超标程度方面,有两个样品的中的Cu和两个样品中的Cr均为严重超标.这些肥料使用不当,对菜园土和蔬菜品质产生不良影响,应给予关注.     

铜仁市土壤-玉米重金属含量及其健康风险

为了解铜仁市玉米地土壤和玉米籽粒重金属的含量分布特征,并评估当地居民通过玉米籽粒摄入重金属的健康风险.于2018年7月采集了铜仁市自然土壤样品65个、玉米地土壤样品122个和玉米样品100个,并分析其Cd、Pb、Cu、Zn、Ni、As、Hg含量,通过重金属摄入量评价居民膳食暴露的健康风险.结果表明,自然土壤Cd、Pb、Cu、Zn、Ni、As和Hg的含量均值分别为0.148、23.09、29.60、103.6、37.73、16.43、0.144 mg·kg^-1;玉米地土壤Cd、Pb、Cu、Zn、Ni、As和Hg的含量均值分别为0.273、30.00、27.79、103.4、29.89、13.58、1.037 mg·kg^-1.以《土壤环境质量农用地土壤污染风险管控标准》(GB 15618—2018)中的风险筛选值作为限量标准,玉米地土壤Cd、As和Hg超标率分别为18.9%、19.7%和17.2%;以风险管制值为限量标准,玉米地土壤Hg超标率为10.7%.依据GB 2762—2017《食品中污染物限量》,玉米籽粒Cd和Pb超标率分别为7.0%和44%.人体健康风险评价表明,居民通过食用玉米籽粒的重金属健康风险THQ值均小于1,表明食用当地玉米对居民的健康不会造成明显影响.     

淮南市城区地表灰尘重金属分布特征及生态风险评价

城市地表灰尘中重金属会对人体健康和生态环境产生危害,为研究城市中不同功能区地表灰尘重金属的含量和潜在生态危害水平,以典型煤炭资源型城市淮南市的地表灰尘为研究对象,采集工业区、商业区、交通区、文教区、居住区和公园绿地等6种功能用地共40个点位的地表灰尘。采用电感耦合等离子体发射光谱（ICP-OES）和DMA-80直接测汞仪测定Zn、Pb、Cu、Cr、Cd、Ni、Co、V、Hg的含量,分析其在不同功能区地表灰尘中的分布特征、相关性及可能的来源;并应用潜在生态危害指数法对重金属在不同功能区的潜在生态危害进行评价。结果表明：1）淮南市地表灰尘中 Zn、Pb、Cu、Cr、Cd、Ni、Co、V、Hg的平均质量分数分别是202.59、74.63、62.74、110.69、0.57、35.82、12.18、50.95和0.105 mg·kg-1,其中Zn、Pb、Cu、Cr、Cd、Ni、Hg的平均含量分别是淮南市土壤背景值的3.47、3.17、2.04、1.21、9.50、1.12、2.56倍,是中国土壤背景值的2.73、2.87、2.78、1.81、5.88、1.33、1.62倍。2）9种重金属中,Zn和V的含量在不同功能区分布相对均匀,其他重金属在不同功能区含量均表现出较明显的空间异质性。3）不同功能区中,Zn、Pb、Cu、Ni、Co、V、Hg的平均含量在工业区最高,Cr 和 Cd 的平均含量在交通区最高。4）不同重金属的相关性表明,Zn、Pb、Cu、Cd、Ni 等5种元素有同一来源,Co 和 V 有同一来源。5）单项潜在生态危害系数大小为 Cd〉Hg〉〉Pb〉Cu〉Ni〉Co〉Zn〉Cr〉V。不同功能区9种重金属复合生态危害均处于强生态危害水平（300≤RI〈600）,其中工业区和交通区潜在生态危害水平最高。     

珠江三角洲养殖鱼塘水体中重金属污染特征和评估

为了解珠江三角洲主要养殖环境中重金属含量及潜在生态危害程度,用电感藕合等离子质谱法和原子荧光法测定了肇庆、广州、惠州和茂名4市14个样点沉积物中7种元素的水体及底泥总量,并对底泥中主要重金属污染状况及潜在生态风险进行了评价。结果表明：养殖鱼塘水体中Cr质量浓度范围是nd-0.1011 mg·L-1,超标率为7.1%,Cu质量浓度范围为nd-0.1438 mg·L-1,超标率为64.3%,As质量浓度范围是0.0112-0.0812 mg·L-1,超标率为24.1%,Hg质量浓度范围是0.00004-0.00458 mg·L^-1,超标率为35.7%,Pb质量浓度范围为nd-0.0973 mg·L^-1,超标率为6.8%,其余Ni、Zn和Cd质量浓度范围分别为nd-0.0218、nd-0.0232和nd-0.00319 mg·L^-1,均未超渔业水质标准;底泥中重金属元素Cr、Cu、Zn、As、Hg、Cd和Pb的平均值分别为83.86、46.19、242.16、32.38、0.64、1.00和60.06 mg·kg^-1,地积累指数评价结果显示,表层沉积物重金属污染程度顺序为Cd＞Hg＞Zn＞Pb＞As＞Cu＞Cr,其中,Cd污染程度为中-强,是底泥污染最严重的元素。潜在生态风险指数分析,单项潜在生态风险指数生态风险均值排列顺序为 Hg＞As＞Cd＞Pb＞Cu＞Zn＞Cr。对区域综合潜在生态风险指数RI的贡献率最大的元素为Hg、As和Cd。4个市底泥潜在生态风险综合指数（RI）比较,惠州（290.13）＞广州（240.54）＞茂名（193.23）＞肇庆（116.40）。Hg和Cd是该水域污染和潜在生态风险最大的元素。     

可控湿法氧化聚沉工艺对城市污泥中重金属的稳定化影响

采集了长沙市污水厂的剩余污泥（S1）和湿法氧化聚沉工艺处理的深度脱水污泥（S2）,对比分析了处理前后污泥的形貌变化及重金属Zn、Cu、Pb、Cd、Hg和As的形态分布,初步探讨了重金属稳定化机理,对脱水污泥中重金属Zn、Cu、Pb、Cd、Hg和As进行了稳定性评估.结果表明,脱水污泥中重金属的总量均低于我国污泥农用标准中的酸性限值,符合B级污泥泥质要求.处理后,污泥中Zn、Cu、Pb、Cd、Hg和As主要以硫化物有机结合态和残渣态（稳定态）存在,不稳定态在不同程度上向稳定态发生了转变,Cu、Hg的增幅最大,达21.1%.S2中重金属的生物可利用性较S1都有显著的降低,平均降幅达73.1%,S2中重金属的生物可利用性顺序为：Zn〉Pb〉Cu〉Cd〉As〉Hg.污泥经过湿法氧化聚沉工艺处理后,污泥中重金属Zn、Cu、Pb、Cd、Hg和As得到了明显的稳定化,为污泥后续资源化、安全化提供了科学依据.     

Assessing heavy-metal contamination and sources by GIS-based approach and multivariate analysis of urban–rural topsoils in Wuhan,central China

Nine potentially harmful heavy metals (Cd, Co, Cr, Cu, Hg, Mn, Pb, Ni, and Zn) were measured in 477 topsoil samples collected from urban–rural areas in the city of Wuhan in order to identify their concentrations and possible sources, and characterize their spatial variability for risk assessment. Results showed that in most rural areas heavy-metal concentrations in soil were similar to their natural background values, but Cd, Cu, Hg, Pb, and Zn concentrations were relatively higher in densely populated districts and around industrial facilities. Multivariate analyses (correlation matrix, principal component analysis, and cluster analysis) indicated that Cd, Cu, Hg, Pb, and Zn were mainly derived from anthropogenic inputs, and Co, Cr, and Mn were controlled by natural source, whereas Ni appeared to be affected by both anthropogenic and natural sources. The result of risk assessment indicated that nearly 48% of the study area suffered from moderate to severe contamination.     

Relationship between total concentration and dilute HCl extraction of heavy metals in sediments of harbors and coastal areas in Korea

Total concentrations of Cr, Ni, Cu, Zn, Cd and Pb in surface sediments were determined to investigate the regional trends of heavy metal contamination in 11 coastal areas in Korea. Enrichment factor (EF) of heavy metals was calculated by comparing the level of their regional background. The averages of EF values in study areas were 0.99 for Cr, 1.05 for Ni, 4.23 for Cu, 1.80 for Zn, 3.92 for Cd and 1.54 for Pb, respectively. Dilute HCl extractions were useful to deduce the anthropogenic sources of heavy metals and the 1 M HCl extractable fractions of each metal varied from 0.3 to 37.3% for Cr, 1.9 to 66.3% for Ni, 4.2 to 92.9% for Cu, 7.1 to 99.7% for Zn, 10.9 to 98.9% for Cd and 15.0 to 99.1% for Pb. Comparing 1 M HCl extractable fraction to total concentration, large portions of Cu, Zn, Cd and Pb were present as potentially bioavailable fractions from anthropogenic input and were significantly correlated with their EF values showing r > 0.68.     

陕西省泾惠渠灌区土壤重金属污染累积趋势预测

在对泾惠渠灌区农业生态环境污染现状调查的基础上,以灌区土壤中Cd、Hg、Pb、Cr、As、Cu、Zn为评价因子,通过建立模型,预测和分析了施肥、灌溉等农事活动对土壤中重金属环境容量及累积趋势的影响。结果表明,从2007年到2050年,泾惠渠灌区耕层土壤中Cr增加了4.87%,As7.61%,Pb11.7%,Hg26.4%,Zn30.3%,Cd68.1%,Cu83.2%;各重金属元素的总静环境容量由大到小依次为Zn〉Pb〉Cu〉Cr〉As〉Hg〉Cd,其中Zn的环境容量高出Cd的270倍;灌区土壤用完现存容量所需要的时间Zn最短,只有52a,其次是Cu,为54a,Hg最长,可达572a,但就现存容量所占的比例来看,灌区土壤中As和Zn的现存容量所占比例最小。     

会泽某铅锌矿周边农田土壤重金属生态风险评价

为了了解云南会泽某铅锌矿废周边农田土壤中重金属含量及潜在的生态危害程度,利用野外采样与实验室分析相结合的方法,以会泽某铅锌矿周边农田土壤（0-20 cm）为研究对象,分析其中7种的重金属（Cd、As、Pb、Cr、Cu、Zn和Hg）含量,并采用风险评价代码法和Hankanson潜在生态风险指数法评价对重金属污染程度与潜在生态风险进行评价。结果表明：7种重金属都存在超标或污染,其中Pb、As、Cd等的污染较为严重。统计学分析结果表明,Pb、As、Hg、Zn、Cd来源相同,铅锌矿冶炼污染物的排放可能是导致研究区域农田土壤重金属含量升高的主要原因。7种重金属化学形态也不尽相同：在重金属有效态中,Cd的水溶态和可提取态较高（平均值达到31.2%）;Pb、Cu和Zn可还原态、可氧化态这两部分含量较高,两部分之和的平均值分别可达到27.9%、30%和27.2%;Hg、As和Cr的残渣态含量较高,平均值分别为90.4%、72.9%和76.8%。风险评价代码评价结果表明,54.4%的样点Cd为高生态风险,45.6%的样点Cd为中度生态风险;100%的样点Zn为中度生态风险;Cu有41.2%的点位属于低生态风险,58.8%的点位属于中度生态风险;As和Pb主要以低生态风险为主（所占比例分别为92.6%和91.8%）;Hg主要以无生态风险为主（所占97.1%）。Hakanson潜在生态风险指数法结果表明,7种重金属潜在生态危害大小顺序为：Cd（331）〉Hg（127.5）〉Pb（43.6）〉As（14.9）〉Cu（9.3）〉Zn（2.3）〉Cr（2.1）。7种重金属的综合潜在生态风险指数（RI）的范围为58.2-1839.3。11%的采样点处于轻微生态风险程度,27.1%的采样点处于中等生态风险程度,46.3%的的采样点处于强生态风险程度,15.6%的采样点处于很强的生态风险程度。综上所述,该矿区周边农田土壤受到了严重的重金属污染,由此引起的重金属生态风险不容忽视?     

Heavy metals from soil and domestic sewage sludge and their transfer to Sorghum plants

We studied the mobility and transport of heavy metals such as Cu, Zn, As, Cd, Cr, Ni, and Pb, from soil and soil amended with sewage sludge to sorghum plants. The total and ethylenediaminetetraacetic acid (EDTA) extractable heavy metals in agricultural soil and untreated domestic sewage sludge (DWS) samples were determined. The correlation between the total and extractable metals in soil and sewage sludge was investigated. The total and extractable heavy metals in soil, sewage sludge and sorghum grain were analysed by flame and electro thermal atomic absorption spectrometer (FAAS/ETAAS), after digestion in microwave oven. Statistically good correlations were obtained between the total contents of all heavy metals and their respective extractable fractions in soil and domestic wastewater sludge. Transfer factors of all heavy metals from domestic sewage sludge to sorghum grains were determined.     

珠江磨刀门河口表层沉积物中重金属含量及其分布特征

分析了在珠江磨刀门河口采集的37个表层沉积物样品重金属(Cu、Pb、Zn、Cr、Cd、Hg、As、Ni)的含量及分布特征。采用原子吸收法分析了Cu、Pb、Zn、Cr、Cd、Ni的含量,采用冷原子吸收法分析了Hg、As含量。结果表明,口门处及其两侧和拦门沙内坡重金属的含量最高;外海区域重金属含量普遍较低;由口内河床至口门处,Cu、Cr、Hg、As的含量减小,Pb、Cd、Zn、Ni的含量逐渐增大;大部分重金属(Cu、Pb、Zn、Cd、As、Ni)的含量由口门处至拦门沙地区是先减小再增大的;由拦门沙至外海,Cu、Pb、Cd、As的含量减小,Zn和Ni的含量先减小后增大;由口门处至外海,Cr和Hg含量的总体趋势是增大的。磨刀门河口表层沉积物中重金属元素含量与CEC、小于0.001mm粘粒以及沉积物有机质含量的相关性均达到显著或极显著水平;重金属含量与沉积物pH值的相关性不显著;重金属元素的含量变化和分布规律还表明磨刀门表层沉积物的重金属主要受陆源污染物的影响。     

重金属积累对土壤酶活性的影响

研究了华北平原某铅冶炼厂附近农田33个土壤样品中重金属积累对土壤酶活性的影响。结果表明,样品中Pb和Cd全量的平均值分别为144和5.59mg·kg-1,DTPA态Pb和Cd含量平均值分别为54.1和0.964mg·kg-1,均超过了未污染农田潮土的正常范围,而Cu、Ni和Zn的有效性和全量与未污染土壤接近;土壤过氧化氢酶活性与DTPA态Pb和Cd含量、全Pb含量均呈显著的负线性关系(P<0.01);与磷酸酶和脲酶相比,土壤脱氢酶活性更易受到土壤中Pb和Cd积累的影响;随DTPA-Ni含量增加,土壤蛋白酶和碱性磷酸酶活性增加(P<0.1);土壤脲酶活性与重金属全量或有效态重金属含量无显著相关性(P>0.1)。以上结果说明,利用土壤过氧化氢酶和脱氢酶活性能够表征基本性质较为一致的土壤中重金属污染程度;与重金属全量相比,有效态重金属对土壤酶活性影响更大。     

宝鸡城市街尘、土壤及河流沉积物重金属形态迁移特征

在宝鸡城市街尘、土壤及河流沉积物基本理化性质和重金属元素含量分析的基础上,重点研究了重金属元素在街尘、土壤及河流沉积物中的赋存形态和迁移特征.结果表明:在街尘中Cu主要以可氧化态和残余态形式存在,Pb主要以可还原态和可氧化态形式存在,Zn和Cd主要以乙酸可提取态形式存在,Mn、Fe、Co、Ni和Cr主要以残余态形式存在...     

Accumulation of heavy metals in soil and paddy crop (Oryza sativa), irrigated with water of Ramgarh Lake,Gorakhpur, UP,India

Heavy metals, a highly polluting group of constituents known to exert adverse effects, tend to accumulate in living organisms. The objective of this study was to determine the accumulation and translocation of heavy metals in soil and in paddy crop irrigated with lake water compared to soil and paddy crop irrigated with bore-well water. The quantities of heavy metals (Cd, Cr, Cu, Pb, Zn, As, Mn, and Hg) were determined in different parts of rice plants (Oryza sativa). Results revealed that the mean levels of soil Cd, Cr, Pb, Zn, As, Mn, and Hg in experimental soil and in different parts of rice plant (root, straw, and grain) were higher than the control except for Cu. The content of eight toxic metals was significantly higher in root than in aerial parts of the rice (straw and grains). Rice roots were enriched in Cd, As, Hg, and Pb from the soil, while Cr, Cu, Zn, and Mn were hardly taken by the roots. Bioaccumulation factor for Hg was significantly higher than other heavy metals. Metal transfer factors from soil to rice plants were significant for Cd, Cr, Cu, Pb, Zn, As, Mn, and Hg. The concentrations of metals in lake water were found to be within the permissible limit of Indian standard prescribed by Central Pollution Control Board (2000), except for Hg and As, which were higher than the limit of Indian standard. However, the concentrations of heavy metals in soil and rice grains were still below the maximal levels, as stipulated by Indian Prevention of Food Adulteration Act (PFA, 1954) and World Health Organization (WHO, 1993) guidelines.     

合肥市城市土壤重金属元素含量及空间分布特征

研究了合肥市城市土壤中重金属的含量、空间分布特征及来源。结果表明,合肥市城市土壤中,Ni和As2种元素污染不明显,但受到Cu、Zn、Pb、Sr、Cd、Hg6种元素不同程度的污染,其中Hg污染最严重。Ni和As2种元素的分布主要受自然因素影响,Cu、Zn、Pb、Sr、Cd、Hg6种元素主要来源于人为输入。Zn,Cd,Pb3种元素的空间分布规律比较相似,表现为在东部工业区和老城区内明显出现富集。Cu和Hg2种元素在合肥市城市土壤中含量的分布规律比较相似,峰值出现在东部工业区、老城区、北部和南部交通干线交汇区。Zn、Cd、Pb、Cu、Hg5种元素可能主要来源于工业活动和交通污染。Sr元素峰值出现在老城区和工业区中间,主要交通干线沿线和交汇地区含量也较高,Sr元素可能主要来源于交通污染。     

The correlation of total and extractable heavy metals from soil and domestic sewage sludge and their transfer to maize ( Zea mays L.) plants

A study to understand the mobility and transport of heavy metals (HMs) from soil and soil amended with sewage sludge to maize plants was carried out. The total and ethylenediaminetetraaceticacid (EDTA)-extractable HMs in agricultural soil and untreated domestic sewage sludge samples, and the correlation between the total and extractable metals in soil and sewage sludge were carried out. Pot experiments were performed to study the transfer of HMs to maize grains, grown in soil (control) and in soil amended with sewage sludge (test samples). The total and extractable HMs in soil, sewage sludge, and maize grains were analysed by FAAS/ETAAS (flame atomic absorption spectrometer/electrothermal atomic absorption spectrometer) after digestion in microwave oven. Statistically significant correlations were obtained between the total contents of Cu, Cd, As and their respective extractable fractions in soil, while in domestic wastewater sludge (DWS) the better correlation was observed only for Ni and Cd. The edible part of maize plants (grains) from test samples presented high concentration of Zn, Pb, Ni, Cd, Cu, As, and Cr concentrations (80.7–85.6, 3.8–3.95, 2.35–2.5, 0.75–0.82, 3.21–3.29, 0.23–0.27, and 0.22–0.29?mg?kg^?1, respectively). Good correlations were found between metals in exchangeable fractions of both soil and DWS and total metals in control and test samples of maize grains. The transfer factor of all HMs from DWS to maize grains was also determined.     

拉萨巴嘎雪湿地土壤重金属分布及生态风险评价

巴嘎雪湿地是西藏拉萨河流域的代表性湿地之一.文章为了解巴嘎雪湿地的重金属分布特征,在2018年10月采集了巴嘎雪湿地的表层土壤样品,对土壤中的Cu、Zn、Cr、Ni、Pb、Cd、As、Hg重金属的含量进行了检测.巴嘎雪湿地表层土壤的重金属污染评价采用的方法主要包括内梅罗综合污染指数法、地积累指数法和潜在生态风险指数法.结果表明,重金属Cu、Zn、Cr、Ni、As、Hg含量的平均值低于国家土壤环境质量标准(一级),但Pb、Cd的含量略偏高;Ni、As、Cr、Hg的平均含量低于拉萨市环境背景值,但Cu、Zn、Pb、Cd平均含量高于环境背景值.该研究区域的内梅罗综合污染指数平均值P_N=1.50,说明湿地整体处于轻度污染;按照国家土壤环境质量标准(二级)作为背景值,得到的P_N=0.64,属于安全水平.地积累指数平均值在-2.587到-0.744范围内,I_geo<0区域整体上无污染;潜在生态风险指数的平均值RI=72.779,属于低风险.各元素组合之间总体相关性不足,说明重金属累积方式具有多源性特点.巴嘎雪湿地整体生态环境优于国内大部分湿地,其表层土壤中Hg、Pb、Cd元素为强度变异,在部分位点中存在明显富集,受到人类活动影响,应加强关注.     

典型野生食用菌重金属含量及其人体健康风险评价

土壤重金属污染是影响生态环境、食品安全和人体健康的重要因素.云南省土壤重金属背景值较高,且矿产资源丰富、采矿活动频繁,导致土壤重金属含量较高.野生食用菌是高效重金属储积器,云南是中国野生食用菌最大产区.因此,本文以云南省8种典型野生食用菌为研究对象,探究其重金属含量(汞、镉、铅、锌、铜、砷)与分配特征,采用单因子污染指数对其进行重金属污染评价,利用概率方法(THQ指数)评估其对不同年龄人群(成人、儿童)的人体健康风险.研究结果表明,不同种类野生食用菌重金属含量存在显著差异(P<0.05).Hg、Cd、Pb、Zn、Cu浓度范围分别为0.5—7.2、0.3—15、0—26.8、47.7—214、56.7—428 mg·kg^-1 dw;As未检出.此外,Hg、Cd、Pb、Zn、Cu均主要分布于菌盖.除虫草花、白森、干巴菌中Hg未检出,其余重金属污染评价中单因子污染指数均>1,且同一元素在同种野生食用菌不同部位污染程度不同,其中,老人头菌盖受Cd污染最为严重.基于国家食品安全标准,本研究中98%野生食用菌Hg、Cd、Pb含量超标.然而,THQ指数表明,部分野生食用菌中Zn无风险(THQ<1),老人头菌盖、鸡枞菌盖中Cd、Hg、Pb、Cu具有人体健康风险(THQ>1),且风险值儿童>成人.     

Effect of lime on speciation of heavy metals during composting of water hyacinth

Composting is attractive and inexpensive method for treatment and biomass disposal of water hyacinth. However, the major disadvantage of water hyacinth composting is the high content of heavy metals in the final compost. Addition of lime sludge significantly reduced most bioavailable fractions (exchangeable and carbonate) of heavy metals. Studies were carried on composting of water hyacinth (Eichhornia crassipes) with cattle manure and sawdust (6:3:1 ratio) and effects of addition of lime (1%, 2% and 3%) on heavy metal speciation were evaluated during 30 days of composting period. The Tessier sequential extraction method was employed to investigate the changes in speciation of heavy metals such as Zinc (Zn), Copper (Cu), Manganese (Mn), Iron (Fe), Lead (Pb), Nickel (Ni), Cadmium (Cd) and Chromium (Cr) during water hyacinth composting. Effects of physicochemical parameters such as temperature, pH and organic matter on speciation of heavy metals were also studied during the process. Results showed that, the total metal content was increased during the composting process. The higher reduction in bioavailability factor (BF) of Cu, Fe, Ni, Cd and Cr was observed in lime 2 treatment about 62.1%, 64.4%, 71.9%, 62.1% and 58.9% respectively; however higher reduction in BF of Zn and Pb was observed in lime 1 treatment during the composting process. Reducible and oxidizable fractions of Ni, Pb and Cd were not observed during the process. Addition of lime was very effective for reduction of bioavailability of heavy metals during composting of water hyacinth with cattle manure and sawdust.