污泥与施污土壤重金属生物活性及生态风险评价

将城市污泥以不同质量比施于土壤中构成污泥混合土壤,研究各污泥配比土壤中重金属的生物活性,并采用三种重金属评价方法(地累积指数法、潜在生态风险指数法、综合毒性指数模型)和黑麦草对重金属的吸收富集效果来对施污土壤中重金属具有的生态风险性进行评价。结果表明:污泥的添加使土壤中生物活性态Cd、Cu和Zn含量显著增加,对三种重金属具有活化作用,但对Pb却起到钝化作用。生态风险评价结果表明:污泥的添加使土壤中Pb呈现无污染和低生态风险;Cu和Zn呈现中度污染和低生态风险;Cd达到强度污染和重度生态风险,重金属潜在生态风险(RI)总体处于强度生态风险水平。当污泥添加比例大于6:10(污泥S3处理)时,施污土壤中重金属的综合毒性指数高于土壤对照。黑麦草对Cd、Pb、Cu和Zn的富集浓度与施污土壤中对应重金属的生物活性态含量存在显著正幂指数关系,同时黑麦草对施污土壤中Cd、Cu和Pb的富集能力大小与地累积指数法和潜在生态风险指数法对三种重金属具有的生态风险性的评价结果具有一致性。     

Enzyme Activities in a Sandy Soil Amended with Sewage Sludge and Coal Fly Ash

Previous studies showed that coal fly ash could stabilize sewage sludge by reducing metal availability, but fly ash may cause an adverse effect on soil microbial activities. Therefore, an experiment was performed to evaluate the effects of amendment of soil with anaerobically digested dewatered sewage sludge, stabilised with alkaline coal fly ash, on soil enzyme activity and the implications for soil nutrient cycling. Sewage sludge was amended with 0, 5, 10, 35 and 50% w/w of fly ash, and then the ash-sludge mixtures were incubated with a sandy soil at 1:1 (v/v). Dehydrogenase activity decreased with an increase in fly ash amendment level and the time of incubation. Soil receiving 5% ash-sludge amendment had a higher dehydrogenase activity than other treatments. Soil receiving 10% ash-sludge mixture had the highest urease activity and in general, urease activity decreased with increasing incubation time. Phosphatase activity was the highest at 5% ash-sludge mixture amended soil and no general trend was observed with time. Water-soluble Zn, Mn and Cu contents were suppressed by the addition of fly ash. The present experiment indicated that addition of 10% ash-sludge mixture should have a positive benefit on the activity of soil microorganisms, N and P nutrient cycling, and reduce the availability of heavy metals.     

城市污泥改良沙地土壤过程中氮磷的淋溶特征与风险分析

针对城市污泥组成成分的特点,以科尔沁沙地土壤为研究对象,分析其应用于沙地土壤改良的可行性及对地下水的潜在风险.室内土柱淋溶模拟试验研究结果表明,不同的污泥施入量可明显增加沙化土壤表层中氮磷养分含量,提高沙化土壤质量,同时污泥施用量对淋出液中氮磷养分含量存在显著影响,且氮素的淋溶风险大于磷素.当污泥施用量为30 t/hm2时,淋出液中总氮(TN)、总磷(TP)含量与不施用污泥的对照处理间未存在显著差异,且随淋洗次数的增加,TN含量呈现先下降后趋于稳定的变化趋势,TP含量呈现逐渐下降,而硝态氮(NO3--N)含量较不施用污泥的对照处理增加11％～33％,但与其差异不显著(P＞0.05).当污泥施用量为60,90 t/hm2时,淋洗液中TN和TP含量显著增加(P＜0.01),随淋洗次数的增加,TN和NO3--N含量呈现先上升后趋于稳定的变化趋势,而NO3--N含量在第3次淋洗后均超出地表水环境质量标准中Ⅲ类水质标准限值(20 mg/L),对地下水体污染风险增加.合理控制污泥施用量不仅可以实现城市污泥的资源化利用,同时也可控制其对地下水的影响.     

Fractionation of Cu, Pb, Cr, and Zn in a Soil Column Amended with an Anaerobic Municipal Sewage Sludge

The objective of this study was to investigate the changes in the chemical partitioning of Cu, Pb, Cr and Zn within a column of soil incubated with an anaerobic sewage sludge (ANSS) for 2.5 months. The soil was irrigated during the incubation period. A sequential extraction method was used to fractionate these metals into exchangeable, weakly adsorbed, organic, Al oxide, Fe–Mn oxide, and residual, respectively. ANSS was applied at a loading rate of 69 Mg ha^?1. The soil is a Dystric Cambisol with low pH (<3.8), low CEC [<10 cmol(+) kg^?1 below the first 4 cm depth], and low base saturation (<7%). The addition of the ANSS caused a decrease in concentrations of Cu, Pb, and Cr in the A1 horizon, and an increase in the concentrations with depth. Below the A1 horizon, concentrations of Cu increased uniformly (~1 mg cm^?1), and the greatest increases were observed in the residual, Fe–Mn oxides, and weakly adsorbed fractions. Maximum increases in Pb occurred at 4–9 cm of depth (1.6 mg cm^?1), and mainly affected the weakly adsorbed fraction. Chromium essentially accumulated at the limit between the A2 and the Bw horizons (1.1–1.5 mg cm^?1) as residual and organic bound forms, probably through particulate transport. Zinc mainly accumulated in the A1 horizon (2.9 mg cm^?1) as exchangeable Zn. At depth, Zn increments were predominantly observed in the residual fraction. The results of this study thus demonstrate the redistribution of contaminants into different chemical pools and soil layers after sludge amendment.     

Environmental Implication of Soils Amended with Anaerobically Digested Sewage Sludge in Hong Kong

Rainfall leaching soil column trials wereused to characterize the downward movement ofpotential contaminants through a sandy loam and sandysoil following the application of an anaerobicallydigested sewage sludge at the rates of 10 and 25%(v/v). Leachate pH did not vary significantly withsludge application except for sandy loam with 25%sludge, while initial electrical conductivity (EC) anddissolved organic carbon (DOC) increased linearly withsludge application and declined shortly to levelsfound in soils without sludge. A higher initialleaching loss of ammonium (NH₄ ⁺) was found in sandy soilthan loamy sand due to its lower cation exchangecapacity. Nitrate (NO₃ ^-) was the dominant anion inleachates with an average in excess of 10 mg L^-1 NO₃ ^- at all loading rates after 12 weeks. The highestconcentration of NO₃ ^- occurred with the highest sludgeapplication rate. Leachate zinc (Zn) content increasedin loamy sand columns at the high sludge loading rateat the end of the experiment owing to the reduced pHfollowing nitrification. No significant difference inleachate copper (Cu) and phosphate (PO₄ ^3-) contents werenoted for both soils receiving various sludgeapplication rates. Evaluation of the soluble nutrientspresent in the soil profiles at the end of theleaching experiment showed that EC, NH₄ ⁺ and PO₄ ^3- increased according to sludge application rate up toa depth of 20 cm. Significant accumulation of NO₃ ^- wasfound in sandy loam with sludge application to thedepth of 50 cm. Analyses of leachates and soils forthe selected contaminants revealed that NO₃ ^- leaching islikely to occur without plant growth at the currentapplication rate. Therefore, the application rate forsludge should not exceed 10% (v/v), and the provisionof vegetation on the amended soil would reduce theleaching loss of NO₃ ^-.     

Availability of Heavy Metals for Brassica Chinensis Grown in an Acidic Loamy Soil Amended with a Domestic and an Industrial Sewage Sludge

The use of sewage sludge on agriculture provides an alternativefor sewage sludge disposal. Therefore, it was the aim of thepresent study to evaluate the feasibility of using a domestic(Tai Po sludge) and an industrial (Yuen Long sludge) sewagesludge produced in Hong Kong for the growth of vegetable crops.The acidic loamy soil with or without lime treatment was amendedseparately with each sludge at application rates of 0, 5, 10, 25and 50% (v/v) for the growth of a common local vegetable crop,Brassica chinensis. The plant available metal contents, asindicated by the DTPA extraction, increased with an increase insludge amendment, but decreased with lime amendment at eachsludge application rate due to the reduced metal availabilityat a higher pH. Sludge amendment enhanced the dry weight yieldof B. chinensis and the increase was more obvious for thesoil with lime treatment. The industrial sludge caused a loweryield than that of the domestic sludge amendment and asignificant reduction in yield at high application rates of YuenLong sludge was also noted. Tissue heavy metal contents, exceptfor Fe, increased as the sludge amendment rate increased whileplant grown in Yuen Long sludge amended soil contained higher Crand Zn contents at each sludge application rate. Liming the soilreduced the heavy metal contents in the plant tissues, exceptfor Fe, which were all below the allowable levels for vegetablecrops. The present experiment demonstrates that liming wasimportant in facilitating the growth of B. chinensis in sludge amended soil. The optimal sludge amendment rate for thesoil with lime amendment was 25% Tai Po sludge and 10% YuenLong sludge, while for the soil without lime amendment was 10% and5%, respectively.     

Use of a Rhizosphere-Based Method for the Assessment of Heavy-Metal Bioavailability in Soils Amended with Polluted Sewage Sludge

A rhizosphere-based method (a low-molecular-weight organic acid solution) was evaluated for the assessment of cadmium (Cd), chromium (Cr), and lead (Pb) bioavailability to barley (Hordeum vulgare) roots from rhizosphere soils (n = 36) following a 15.71 g dry weight kg^?1 application of a metal-spiked sewage sludge under greenhouse conditions. Statistically significant correlation coefficients were found: r = 0.758, P < 0.001 for Cd, r = 0.762, P < 0.001 for Cr, and r = 0.723, P < 0.001 for Pb. The correlations were greater in acidic soils (n = 6; r = 0.983, P < 0.001 for Cd, r = 0.888, P < 0.01 for Cr, and r = 0.898, P < 0.01 for Pb). This extraction failed to assess heavy-metal bioavailability in basic soils (n = 30; r = 0.111, P > 0.05 for Cd, r = 0.002, P > 0.05 for Cr, and r = 0.037, P > 0.05 for Pb). The overall predictability was greatly improved when soil properties were considered (n = 36; r² = 0.730, P < 0.001 for Cd, r² = 0.800, P < 0.001 for Cr, and r² = 0.719, P < 0.001 for Pb), and texture was observed in all the prediction models.     

不同施用方式下酸性土坡地污泥氮素随径流迁移的研究

研究了以撒施和穴施方式施用于酸性赤红壤坡地上的污泥氮素在人工降雨条件下随径流的迁移情况。试验结果表明,污泥撒施后24 h径流中TN、TDN、TPN和NH4 -N的浓度和流失量最高,其中TN浓度为57.0 mg/L,TN流失量为1 086.5 mg/m2,占撒施TN累积流失量的70.6%,分别是穴施对应峰值的6.0倍和2.4倍,此后浓度和流失量均逐渐降低。穴施径流中氮素及撒施NO3--N浓度与流失量则呈先上升后逐渐下降趋势。撒施和穴施TDN/TN累积流失量分别为38.7%和65.0%,NH4 -N是TDN流失的主要形式(≥55.7%)。控制颗粒物流失是防止氮流失的重要内容,此外,污泥氮素在土壤中的转化及污泥对坡地土壤理化性状的改变均影响着径流中氮的迁移。     

砂质红壤污泥农用后P垂直迁移规律研究

为了解污泥施肥于红壤中,P在剖面中的淋溶和迁移状况,通过田间试验分别对污泥不同类型、施用量和施肥方式在典型红壤坡地P垂直迁移状况进行研究。结果表明:（1）不同处理的污泥施用均可引起Kcl-P和Olsen-P在红砂壤上的垂直迁移,含量随剖面深度而降低,养分积累主要集中在0—50 cm土层;（2）污泥类型、施肥量、施用方式都对P素迁移具有影响,随着施肥量的增加,剖面各层Kcl-P和Olsen-P含量增加,撒施处理比穴施更易造成Kcl-P和Olsen-P剖面深层迁移,干污泥养分含量随剖面深度变化更剧烈,更易造成Kcl-P深层迁移;（3）污泥撒施0—30 cm土层Olsen-P累计量占0—80 cm总累计量60%以上,基本可以反映剖面Olsen-P含量水平和迁移潜力。     

施污土壤与污泥中Cu、Pb、Cd、Zn的形态分布

污泥中的重金属元素是限制其大规模农田利用的重要因素。施污土壤和污泥中重金属的形态研究可以用来评价土壤中重金属的生物有效性以及它们在土壤中的移动性。用修正BCR三步连续提取法进行分步提取研究了污水污泥和施污后的西红柿地土壤中Cu、Pb、Cd、Zn的形态分布状况。施用污泥堆肥10t hm-2后的土壤中Cu、Pb、Cd、Zn的全量与各种形态含量无明显增加,Cu、Pb、Zn含量远低于国家土壤环境质量标准。土壤中Cu的各种形态分布关系是:残渣态>可还原态=可氧化态>可交换态和弱酸溶解态,Cu在土壤中的存在是以最稳定的残渣态为主。堆肥污泥与干化污泥相比,残渣态Cu的比例明显增加。土壤中Pb的各种形态分布关系是以残渣态和可还原态为主,但可氧化态的分布比例最小。土壤中Cd的可交换态、可还原态和残渣态各占据相等的含量,但可氧化态Cd的含量几乎为零。Zn在土壤中的各种形态分布关系是:可交换态和弱酸溶解态>可氧化态>可还原态>残渣态,Zn在土壤中的存在是以最易迁移的可交换态和弱酸溶解态为主。这些金属元素在土壤中的相对稳定性顺序为:Cu>Pb>Cd>Zn。Zn在土壤中的移动性要远高于Cu。     

Visualization of Long-Term Quantitative Changes of Microelements in Soils Amended with Sewage Sludge Compost Evaluated with Two Extraction Solutions

This research deals with the effects of soil amendment with sewage sludge compost (SSC) on long–term quantitative changes of available microelements [iron (Fe), zinc (Zn), manganese (Mn), copper (Cu)] in two types of soils using various extraction solutions [diethylenetriaminepentaacetic acid (DTPA) and hydrochloric acid (HCl)]. These changes were visualized using principal component analysis (PCA) and hierarchical cluster analysis. A 3-year pot experiment was conducted in a randomized, factorial design with two soils (light vs. medium) and a treatment with SSC at the rate of 6 Mg ha^?1. The application of SSC to the light soil increased the HCl-extractable Cu, Zn, Mn, and Fe. The effect of SSC application on the microelement quantitative changes was lower in the medium soil, as shown primarily by DTPA extraction. The results of the PCA highlighted that one can correctly conclude on the basis of the limited collection of data without loss of information, which is incorporated by individual microelements.     

污泥中重金属的环境活性及生态风险评估

研究了湖南省长沙市、株洲市和常德市10个污水处理厂剩余污泥中As,Cd,Cu,Ni,Pb,Zn的含量和形态特征,并利用潜在生态危害指数法对污泥农用过程中重金属的生态风险进行了综合评价。结果表明,城市污泥中富含有机质及N,P,K等养分,然而,污泥表现为以Cd为主的多金属污染,不能直接农用。污泥中Cd含量为1.43～260mg/kg,以可还原态为主,占全量比例高于28.9%;As,Pb的可还原态,Ni,Zn的酸可溶态和可还原态,Cu可还原态和氧化态所占比例较高,表明污泥中重金属的潜在环境活性较高。风险指数评价结果表明,污泥中Cd和As是潜在的强生态风险元素;以工业废水处理为主的污水处理厂污泥重金属单因子生态风险相对较高,且综合潜在生态风险严重。     

干污泥和堆肥污泥施用于红壤中N素的释放特性

在红壤自然状况下,模拟了施肥沟,对红壤不同污泥施肥处理的N素释放特性进行了研究。试验结果表明,干污泥配比在10%~20%时,碱解氮、铵态氮和硝态氮累计释放量分别为:25.71%~33.48%,9.57%~14.85%和4.08%~7.65%。堆肥污泥配比在20%~33%时,其累计释放量分别为13.55%~15.65%,2.03%~4.23%和3.11%~5.37%。干污泥处理的释放量大于堆肥污泥处理的释放量,释放过程变化较堆肥污泥剧烈,铵态氮和硝态氮均有明显峰值,铵态氮最大含量532.98±10 mg/kg,释放量最大达10.95%;硝态氮含量最大为149.2±14 mg/kg,释放量最大时为3.32%。无论是从氮的肥效角度,还是氮释放的环境风险角度考虑,污泥堆肥处理后施肥方式均优于干污泥处理施肥方式。     

关于水土保持生态修复相关问题的商榷

生态修复是从整个生态结构与功能整体上的恢复与改善为目标的综合防治水土流失的全新观念。本提出生态修复关键措施是封山育林育草，核心是预防保护；充分发挥生态的自我修复能力，是社会性的系统工程，需要行政、法律、政策、经济和技术等各个方面的有力支撑；生态修复工作要着重发展农村经济，解决群众生产生活问题，加快水土流失防治步伐。     

城市污水处理厂污泥对沙漠化土壤的改良效果

为探究城市生活污水处理厂脱水污泥作为土地改良剂对沙漠化土壤的改良效果,确定合适的污泥掺混量,试验以离心脱水污泥与沙漠表层土壤按污泥掺混量为5%,10%,15%,20%,25%,30%,35%充分掺混,以土壤物理指标、营养指标为考察指标,研究不同污泥掺混量对沙土的改良效果,并与3种适于耕作土壤平行对比。试验表明沙土经污泥掺混后,随着污泥掺混量的增大,其土粒密度、土壤容重降低;污泥掺混量与土粒密度和土壤容重呈负相关,相关系数可达-0.99,-0.89,而土壤孔隙度增加,呈正相关(r=0.79),当污泥掺混量大于10%后,污泥掺混量对土壤容重、孔隙度的改良效果减缓;改良沙土中有机物含量、含水率随污泥掺混量增加呈线性增加(r0.99),持水能力与污泥掺混量呈显著正相关(r=0.99)。改良沙土较对比土壤有更强的保水能力;氮、磷元素含量和污泥投加量呈显著正相关(r0.95),污泥掺混量为15%~25%时,改良沙土氮磷含量均接近对比土壤含量,污泥掺混对土壤全钾含量改善不大,但能有效提高土壤有效钾含量。污泥掺混量为10%~25%时,改良沙漠化土壤的理化性质接近对比适宜耕作土壤。     

Toxicity of Light Soil Fertilized by Sewage Sludge or Compost in Relation to PAHs Content

The aim of the present study was to determine the influence of light soil fertilization using sewage sludges or composts on soil toxicity for three plant species (Lepidium sativum, Sorgo saccharatum, and Sinapis alba) and crustaceans (Heterocypris incongruens). The results obtained were compared to the polycyclic aromatic hydrocarbon (PAHs) content as a potential toxicity factor. The PAH content in soils fertilized with sludges was proportional to the dose applied. Soil fertilization with the studied materials negatively influenced plant growth and development. The negative influence was clearer in the case of sewage sludges than composts. Both sludges and composts significantly influenced H. incongruens mortality. However, the influence of sludges and composts on H. incongruens growth did not exceed 20%. The EC50 and LC50 values calculated on the basis of toxicity parameters showed that H. incongruens was characterized by a higher sensitivity to sludges and composts than most of the plants. L. sativum was characterized by the lowest EC50 values among all plants. No significant relationships between sewage sludge or compost toxicity and their PAHs content were observed.     

污泥改良锰矿尾渣对4种花卉植物生长及其富集重金属的影响

采用盆栽试验方法,研究了污泥改良锰矿尾渣对紫茉莉（Mirabills jdapa）、青葙（Celosia argentea）、一串红（Salviasplendens）和鸡冠花（Celosia cristata）4种花卉植物生长及其富集铅、镉、锌和锰的影响。结果表明,添加污泥增加基质的EC值、总氮、总磷、总钾和有机质含量,而降低铅、镉、锌和锰含量。紫茉莉与青葙生物量、株高和根长大于一串红和鸡冠花。紫茉莉根部铅、镉和锰含量分别为3110．93～4189．16、300．28～399．16和31100．93～36809．77mg·kg-1,都远高于其地上部分含量。青葙根部铅含量超过1000mg·kg-1,而其地上部分含量少;其地上部分镉和锰含量分别为322．13～441．88和21888．54～26511．31mg·kg-1,都大于其根部含量,青葙具有镉和锰超富集植物的特性。污泥改良锰矿尾渣促进这4种花卉植物生物量、株高和根长增加。除紫茉莉锌含量外,添加污泥改良锰矿尾渣增加这4种花卉植物的铅、镉、锌和锰含量。在锰矿尾渣污染区进行植物修复时,采用紫茉莉、青葙和添加污泥强化植物修复效率可行。     

污泥有机肥改良铅锌尾矿对4种草本植物生长和重金属积累的影响

[目的]研究添加不同量的污泥有机肥对生长在铅锌尾矿中的黑麦草、白三叶、草木樨、沙打旺4种植物生长状况和对Pb,Zn,Cu,Cr,Cd累积的影响,以期为合理利用污泥有机肥改良、修复尾矿库提供理论依据。[方法]采用盆栽试验的方法。[结果]20g/kg处理水平下,4种植物株高、根长、地上鲜重、根鲜重均达到最大。施肥处理下,供试的4种植物叶绿素a+b含量均比对照高。随着改良剂含量的增加,黑麦草、白三叶丙二醛含量呈下降趋势。黑麦草、白三叶、草木樨体内Pb,Zn,Cd含量在10g/kg处理水平下达到最大,在20g/kg水平下降低。[结论]随着有机肥添加量的增加,重金属量向植物体内转移减少,有利于缓解重金属的毒害作用。     

污泥堆肥对盐碱土土壤环境和作物生长的影响

以城市污水处理厂污泥堆肥为研究对象,采用盆栽试验方法研究不同用量(0%,5%,10%,20%)污泥堆肥施入盐碱土后,对玉米、大豆生长情况及土壤环境的影响。结果表明,施用污泥堆肥可降低盐碱土pH值和总盐含量,提高土壤养分及酶活,增加土壤微生物量碳、微生物量氮,同时施用污泥堆肥土壤重金属Zn、Cu含量增加,当施用量为20%时,土壤Zn含量超标。另外,玉米和大豆在污泥堆肥施用比例分别为10%和5%时长势最佳,且作物籽粒中重金属含量在国家食品卫生标准范围内。     

Heavy Metals in Soil, Plants and Groundwater Following High-Rate Sewage Sludge Application to Land

The concentrations, solubility and mobility of Cr, Cu, Ni, Pb and Zn were measured over a four year period in soil from a site that had received over 1000 t ha^-1 wet, undigested, sewage sludge (on average, 15% dry solids). The pH of this light-textured sandy soil was markedly reduced after sludge application (to ≤4 in some samples), presumably as a result of breakdown of the unstable organic matter, nitrification of the NH₄ ⁺-N and sulphide oxidation. As a consequence, soil solution concentrations of Cu, Ni, and especially, Zn were initially elevated, and this was reflected in high plant uptake of Zn and elevated levels of all three metals in some groundwater wells. An extensive liming programme resulted in soil pH values generally between 5 and 6, more normal for this soil, in the following years. Soil solution metal concentrations were substantially lower, e.g., Zn from a high of 27 mg kg^-1 in 1995 to 0.04 mg kg^-1 in the equivalent sample in 1999. Herbage Zn concentrations declined accordingly and overall there was a strong relationship between plant metal uptake and soil solution concentration of this element (R² = 0.84), although not for any of the other metals. Our results suggested that, for this soil, pH was by far the greatest determinant of metal solubility and that the metal source, whether sewage sludge or geochemical, had little influence. Results from extractants that solubilise other metal phases, i.e., NaNO₃, EDTA and HNO₃, are also presented and discussed.