干湿交替下生物炭对复合污染土壤中镉砷有效性的影响

为了明确活性炭工业的副产品——杏壳生物炭和水分管理模式对石灰性土壤重金属有效性的钝化效果,采用重度Cd、As复合污染的农田土壤,通过土壤培养方法探索了干湿交替水分管理模式下,添加不同用量生物炭对土壤中Cd、As有效性的影响。结果表明:从土壤溶液中Cd、As浓度的变化来看,干湿交替培养条件下,添加2%~10%生物炭处理的土壤溶液中Cd浓度均显著低于对照(P<0.05),降幅为33.1%~62.2%,说明干湿交替模式下添加生物炭显著促进了Cd由土壤液相向土壤固相的转移,而添加生物炭对土壤溶液中砷浓度的影响不稳定,其主要受土壤水分管理模式的影响;从土壤固相Cd、As提取态的变化来看,添加生物炭(6%,8%,10%)处理与CK相比,可显著降低土壤中DTPA提取态Cd和NH4H2PO4提取态As的含量(P<0.05),降幅分别为8.7%~16.8%,5.1%~7.9%,表明干湿交替下添加生物炭显著降低了土壤Cd、As有效性;土壤连续分级提取的结果显示,施用生物炭促进了土壤Cd由酸可提取态和可氧化态向残渣态转化,土壤As由专性吸附态和无定形—弱结晶铁铝或铁锰水化氧化物结合态向残渣态转化,显著降低了污染土壤Cd、As活性。因此,在重度Cd、As复合污染的石灰性土壤区,施用6%生物炭并保持干湿交替的水分管理模式能显著降低土壤镉砷的有效性。     

有机质对红壤和黑土中外源铅镉稳定化过程的影响

采用室内培养方法研究了中国典型红壤和黑土中外源铅（Pb）、镉（Cd）在单一和复合污染下的稳定化过程,探讨了土壤有机质含量对Pb、Cd稳定化过程的影响。结果表明,加入500mg·kg-1Pb、1.0mg·kg-1Cd或1.0mg·kg-1Cd＋500mg·kg-1Pb条件下,各种土壤有效态Pb、Cd含量在培养前期迅速下降,随后变化减缓,培养30d后基本达到平衡。利用二级动力学方程对Pb、Cd稳定化过程进行拟合,在红壤和黑土上,有机质含量高的土样有效态Cd的平衡浓度比有机质含量低的土样中降低12.7%～37.3%;有效态Pb的平衡浓度比有机质含量低的土样中降低78.3%～96.2%,相关分析表明,土壤有机质含量的增加显著抑制了外源Pb、Cd的有效性（P〈0.05）。在铅镉复合污染中,Pb的存在提高了土壤中Cd的有效性,而Cd对Pb的影响较小。与黑土相比,红壤上外源Pb、Cd稳定化速率较小,达到平衡所需的时间较长,且有效态Pb、Cd的平衡浓度较高。因此,在农业生产实践中,通过提高红壤和黑土上有机质的含量能够显著降低外源重金属Pb、Cd的有效性,减少环境污染风险。     

生物炭对复合污染土壤—作物中镉砷累积和转运的影响

针对镉砷复合污染土壤中小麦籽粒重金属积累问题,采用生物模拟方法,以镉砷复合污染区土壤为研究对象,探究杏核生物炭(C1和C2分别表示3%和6%生物炭添加量)对复合污染土壤—小麦/玉米系统中镉砷累积和转运的影响。结果表明:添加生物炭(C1、C2)显著降低了小麦季根际/非根际土壤Cd、As有效性,并且小麦籽粒中Cd、As含量分别比CK平均降低19.25%和50.70%,但前者差异不显著。对玉米而言,生物炭C1、C2处理显著降低穗中Cd和As含量,降幅分别为85.67%,61.28%和98.36%,96.48%;此外,施用生物炭显著降低了小麦—玉米体系中镉砷的转运和累积,但对小麦镉由秸秆向籽粒转运及籽粒中镉累积的影响未达显著水平。总之,添加3%生物炭可降低小麦籽粒和玉米穗中镉、砷含量,且对玉米穗中重金属镉、砷降低效果更明显,综合分析生物炭对镉、砷在复合污染石灰性土壤—小麦/玉米体系中迁移和累积的阻控效应,推荐施用3%生物炭为宜。     

生物炭与沸石复配对碱性土壤铅镉有效性的影响

【目的】以生物炭单施及其与沸石复配为钝化剂,研究其对铅镉复合污染碱性土壤理化性质及铅镉有效性的影响,以期用钝化技术为碱性土壤重金属污染原位修复提供理论和实践支持。【方法】以河南某金属冶炼厂附近铅(Pb)镉(Cd)污染的碱性菜地土壤(Pb 227.75 mg kg^-1、Cd 3.38 mg kg^-1)为研究对象,采用盆栽试验,研究生物炭单施及其与沸石复配(生物炭∶沸石=1∶1)不同施入量(0、1%、2.5%、5%)对土壤理化性质、土壤Pb、Cd有效态含量、青菜根和叶中Pb、Cd含量以及青菜富集转运Pb、Cd的影响。【结果】与对照相比,生物炭单施及其与沸石复配处理,使土壤pH提高了0.03～0.17个单位,与对照无显著差异,但显著提高了土壤有机质、碱解氮、有效磷和速效钾含量(P <0.05)。土壤有效态Pb、Cd含量随钝化剂施用量增加呈下降趋势,分别下降了10.69%～32.75%和7.63%～26.72%,相同施用量下复配处理效果优于单施处理。生物炭及其复配沸石促进了青菜生长,降低了青菜Pb的含量,根部和茎叶中Pb的含量比对照分别下降了2...     

钝化剂种类和粒径对复合污染土壤镉铅有效态的影响

为探讨钝化剂种类和粒径对重金属污染土壤的钝化效果,采用室内培养的方法,通过添加三个粒径(60～100、100～200、200目)下的四种不同钝化剂(自制无机型钝化剂、石灰+生物质炭、硅藻土、磷矿粉),研究钝化剂种类和粒径对重金属复合污染土壤中有效态Cd、Pb的影响。钝化60 d之后的结果表明,自制无机型钝化剂、生物质炭+熟石灰和磷矿粉均在200目粒径下对土壤有效态Cd的钝化效果最好,较对照分别减少了9.54%、13.93%和11.08%;其中,硅藻土在100～200目的粒径下效果最佳,有效态Cd含量与对照相比降低了22.35%。自制无机型钝化剂、石灰+生物质炭、硅藻土和磷矿粉对土壤有效态Pb的钝化效果都在200目的粒径下最好,有效态Pb含量与对照相比分别减少了17.81%、18.70%、11.54%和22.19%,其中磷矿粉的钝化效果最佳。研究表明,自制无机型钝化剂、石灰+生物质炭和磷矿粉都是粒径越小钝化土壤重金属Cd、Pb效果越好,可能是由于较小粒径更有利于Cd和Pb由活性态向非活性态转化,硅藻土对Cd、Pb的钝化效果在三个粒径处理间差异不显著。     

铅镉高污染土壤的钝化材料筛选及其修复效果初探

本研究以重金属高污染农田土壤(全Pb含量为1 277 mg/kg,全Cd含量为39.0 mg/kg)为研究对象,通过土培试验和玉米苗期盆栽试验,探讨海泡石、石灰、腐植酸、钙镁磷肥、磷矿粉、生物质炭等常用稳定材料不同剂量及复配组合对高污染土壤重金属的钝化修复效应。土培试验结果表明,石灰对Pb和Cd钝化效果最好,其次是海泡石,但两者表现为较高添加量处理间没有显著差异;而低剂量生物质炭和腐植酸显著增加土壤有效态Pb和Cd含量,高剂量生物质炭具有较好的钝化效果。盆栽试验表明,海泡石与石灰配施钝化效果较好,与对照相比,土壤氯化钙提取态Pb、Cd含量分别降低了97.5%、81.4%;玉米根和地上部Cd含量分别降低48.5%、34.0%,Pb含量分别降低35.6%、29.6%;但海泡石与磷材料配施显著增加玉米根Pb含量,对玉米Cd吸收没有显著影响。以上结果表明,重金属高污染农田土壤添加合适的改良剂,可较大幅度降低土壤重金属有效性和植物重金属吸收性。     

规模化猪场废水灌溉农田土壤Pb, Cd和As空间变异及影响因子分析

为了了解长期灌溉猪场废水对农田土壤Pb、Cd和As（简称重金属）的影响,采集了河北省京安猪场周边农田的清洁区和灌溉8年猪场废水的污灌区耕层（0～20 cm）共52个土壤样品,并测定了样品中重金属的全量和有效态含量,应用GIS结合地统计学方法对重金属进行了空间结构和分布特征分析,探讨规模化猪场周边农田土壤重金属积累的影响因子及其贡献。结果表明,重金属全量和有效态含量的变异函数均很好地符合球状模型,其中全铅、有效铅、全砷、全镉和有效砷受随机性因素和结构性因素共同影响,有效镉主要受结构性因素影响。根据背景调查、重金属与pH值和土壤养分的相关性分析以及重金属变异函数分析,土壤中Cd和As污染来源为猪场废水和化肥,Pb的污染来源为化肥。富集因子分析表明,污灌猪场废水对土壤Cd和As富集效应很小,施用化肥对Pb富集有较大贡献。灌溉猪场废水会降低土壤pH值而增加重金属有效态含量,因此,需注意施用猪场废水带来重金属污染风险。     

生物炭和菌肥对土壤镉形态和棉花镉吸收的影响

  目的  为了明确生物炭和菌肥修复石灰性土壤镉（Cd）污染的效果,探寻适宜石灰性土壤重金属Cd修复技术。  方法  采用盆栽的试验方法,研究施用3%的生物炭（B3）和1.5%的菌肥（M1.5）对不同外源Cd浓度（0、1、2、4 mg kg?1）石灰性土壤的pH值、Cd形态分布、酶活性以及棉花各器官Cd含量的影响。  结果  结果表明,生物炭和菌肥均能显著提高土壤的pH,但随着培养时间的延续添加改良剂处理的土壤的pH值呈现出下降的趋势:生物炭和菌肥的施用均能降低土壤可交换态Cd比例,提高土壤残渣态Cd比例,与对照相比,生物炭和菌肥处理下可交换态Cd的含量分别下降了18.42% ~ 48.46%和15.21% ~ 50.19%。生物炭和菌肥的添加显著提高土壤酶活性,其中蔗糖酶、过氧化氢酶、脲酶和碱性磷酸酶的最大增幅分别为89.1%、140.1%、39.7%和38.1%,菌肥处理总体优于生物炭处理。生物炭和菌肥的施用降低了植株各器官Cd含量,其中生物炭处理各器官中Cd含量最大降幅为34.0%,菌肥处理下最大降幅为39.5%。相关性和主成分结果表明,可交换态Cd与土壤酶活性呈显著负相关（P < 0.05）,与植株根、茎和叶Cd含量呈现出显著的正相关（P < 0.05）。  结论  生物炭和菌肥作为土壤重金属钝化剂能够通过影响Cd的形态分布,从而缓解Cd对土壤酶活性的影响,降低棉花对Cd的吸收。总体来看,施加1.5%菌肥较3%生物炭在石灰性土壤Cd污染修复的效果更优。     

微生物和生物炭联用对猪粪堆肥后重金属Pb和Cd的钝化效果

为探讨微生物和生物炭联用对畜禽粪便堆肥过程中重金属钝化效果的影响,该文研究生物炭(花生壳炭、木屑炭、玉米秸秆炭)与复合微生物菌剂联用对重金属Pb、Cd形态转化及钝化效果的影响。试验结果表明:9个处理高温期维持天数均达无害化卫生要求,生物炭添加比例对堆肥过程中温度变化影响显著。对Pb的钝化效果最优处理是24%花生壳生物炭和1%的菌剂(T9),可交换态分配率较堆前下降16.32%,钝化效率为74.60%。对Cd的钝化效果最优的处理是24%木屑炭和1.5%的菌剂(T3),交换态Cd与堆前相比下降7.96%,钝化效率为58.13%。统计分析结果表明,重金属Pb、Cd的钝化效果与堆肥过程中平均pH值呈显著正相关,重金属Pb的钝化效果与堆肥过程中温度平均值呈显著正相关,重金属Cd的钝化效果与有机质降解率呈显著正相关。     

不同钝化剂对猪粪堆肥中重金属形态转化的影响

采用三级四步连续提取法(BCR)研究了磷矿粉、硅藻土和膨润土3种重金属钝化剂对猪粪堆肥过程中重金属As、Pb、Cd含量和形态的影响.结果表明:(1)堆肥处理后,重金属总量会表现出“相对浓缩效应”,使其浓度升高.(2)堆肥处理能促进重金属As、Pb、Cd的形态向活性降低的方向转化,从而降低其生物有效性.(3)不同钝化剂对不同重金属钝化效果不同,膨润土和磷矿粉对交换态铅的钝化效果较好;膨润土对交换态砷的钝化效果较好;硅藻土对交换态镉的钝化效果较好.因此,磷矿粉、硅藻土和膨润土处理有利于降低猪粪堆肥施用中的重金属污染风险.     

石灰与生物炭配施对不同浓度镉污染土壤修复

通过室内培养试验,研究生物炭与石灰不同用量配施对镉污染土壤pH和镉赋存形态的影响。结果表明,生物炭与石灰配施能够明显提高污染土壤pH,且随着施入量的增加pH提升效果显著。随着石灰和生物炭配施用量的增加,土壤交换态镉降低比例逐渐增大。培养60天后,镉污染浓度为5mg/kg的土壤交换态镉含量同对照处理相比依次减少36.80%,49.12%和57.38%;而土壤镉污染浓度为20mg/kg的土壤交换态镉含量较对照相比分别降低29.27%,31.68%和39.03%。2个浓度中土壤碳酸盐结合态镉、铁锰氧化物结合态镉和有机结合态镉均有所增加,残渣态镉虽有所增加,但在不同浓度之间存在差异。总体来看,本试验用量条件下,石灰和生物炭配施对污染浓度为5mg/kg的土壤镉钝化效果优于污染浓度为20mg/kg的土壤。     

利用土壤改良剂固定污染土壤中铅、镉的研究进展

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.     

Simultaneous immobilization of lead,cadmium, and arsenic in combined contaminated soil with iron hydroxyl phosphate

Purpose

Combined contamination of lead (Pb), cadmium (Cd), and arsenic (As) in soils especially wastewater-irrigated soil causes environmental concern. The aim of this study is to develop a soil amendment for simultaneous immobilization of Pb, Cd, and As in combinative contaminated soil.

Materials and methods

A soil amendment of iron hydroxyl phosphate (FeHP) was prepared and characterized, and its potential application in simultaneous immobilization of Pb, Cd, and As in combined contaminated soil from wastewater-irrigated area was evaluated. The effects of FeHP dosage, reaction time, and soil moisture on Pb, Cd, and As immobilization in the soil were examined.

Results and discussion

The immobilization efficiencies of Pb, Cd, and As generally increased with the increasing of FeHP dosage. With FeHP dosage of 10 %, the immobilization percentages of NaHCO₃-extractable As and DTPA-extractable Pb and Cd reached 69, 59, and 44 %, respectively. The equilibrium time required for immobilization of these contaminants was in the following order: NaHCO₃-extractable As (0.25 days) < DTPA-extractable Cd(3 days) < DTPA-extractable Pb (7 days). However, the immobilization efficiencies of Pb, Cd, and As have not changed much under soil moisture varied from 20 to 100 %. According to the results of the sequential extraction, the percentages of Pb, Cd, and As in residual fractions increased after the application of FeHP amendment, while their percentages in exchangeable fractions decreased, illustrating that FeHP can effectively decrease the mobilities and bioavailabilities of Pb, Cd, and As in the soil. Moreover, the application of FeHP will not have soil acidification and soil structure problem based on the soil pH measurements and soil morphology.

Conclusions

FeHP can immobilize Pb, Cd, and As in the combinative contaminated soil from wastewater irrigation area simultaneously and effectively. Thus, it can be used as a potential soil amendment for the remediation of Pb, Cd, and As-combined contaminated soil.

     

含磷材料及生物炭对复合重金属污染土壤修复效果与修复机理

选取含磷材料（胛）、牛粪生物炭（DM）和水稻秸秆生物炭（Rs）实施Pb、Zn、Cd复合污染土壤化学稳定修复,进而评价修复效果,并分析影响因素;借助BCR连续提取法和x射线衍射光谱（XRD）探讨可能存在的修复机理。经过56d的化学稳定修复,修复材料均能显著降低TCLP提取态Pb、zn、cd,修复效果均为：Pb〉Zn〉Cd。三种修复材料对Pb、cd的修复效果为Er〉DM〉RS,对zn的修复效果基本相同。胛处理使土壤TCLP提取态的Pb、zn、cd分别降低了77．6％、31．5％、27．9％;DM处理使TCLP提取态的Pb、zn、cd分别降低了56．0％、26．1％、10．O％;RS处理使TCLP提取态的Pb、zn、cd分别降低了35．8％,25．0％和4．4％。三种修复材料均可促进Pb、cd从不稳定态向稳定状态转化。胛对Ph的固定机理主要是溶解一沉淀,XRD证明有Ca2Pb8（PO4）6（OH）2和Pb10（PO4）6（OH）2沉淀生成;DM固定Pb包括沉淀、吸附、离子交换等,XRD证明有Ca2Pb8（PO4）6（OH）2生成;Rs固定Pb主要为吸附、离子交换。研究结果表明,含磷材料和牛粪生物炭可作为理想的土壤Pb、zn、cd的修复材料。     

镉砷复合污染土壤钝化材料研究进展

我国土壤重金属污染严重,尤以镉砷污染最为突出。镉砷复合污染土壤中各元素间表现为拮抗和协同等作用,其有效态含量受土壤pH变化和氧化还原电位等的影响,增加了镉砷复合污染土壤的修复难度,严重威胁我国粮食安全。综述了常见的镉砷复合污染土壤钝化修复材料的优缺点及其对镉砷复合污染土壤钝化修复效果和机理。常见的钝化材料有生物质炭类、磷酸盐类、金属及其氧化物类、含硅类材料、黏土矿物类、有机肥类和新型材料等。有大量研究表明生物质炭材料对镉有良好的吸附效果,为了同时钝化镉砷,通常使用改性生物质炭或与其他材料配合施用,常见的改性/配施材料有金属及其氧化物、黏土矿物、家禽粪便、复合肥等,其钝化反应机制包括离子交换、共沉淀和表面络合等;磷酸盐类主要与铁盐或铁粉配施,通过吸附和同晶替代钝化镉、点位竞争机制钝化砷;金属及其氧化物类多与生物质炭、石灰和黏土矿物等配施,通过专性吸附和共沉淀钝化镉、氧化还原和络合作用等钝化砷;铁硅肥、硅钙肥、硅钾肥等通过共沉淀钝化镉、专性吸附和点位竞争机制钝化砷;黏土矿物中多施用海泡石,主要与金属氧化物和钙镁磷肥等配施,通过离子交换、沉淀和络合反应钝化镉砷;污泥和动物粪便中含有腐殖化程度较高的有机质,主要通过吸附、氧化还原和有机络合以及微生物作用钝化镉砷;此外,富含巯基和氨基、谷聚多以及富含硫和硒的物质也可有效钝化镉砷。本文对镉砷复合污染土壤钝化修复材料进行总结,归纳了镉砷钝化材料特性,以期为镉砷复合污染土壤修复提供一定的指导。     

镉污染水稻秸秆生物炭对土壤中镉稳定性的影响

中国农田土壤镉等重金属污染问题突出,对其生产过程中产生的镉污染水稻秸秆进行无害化和资源化利用研究具有重要意义。该研究通过连续提取试验、风险评价指数法、吸附动力学/热力学、土柱试验,以及X射线衍射分析、傅里叶变换红外光谱分析等手段,探究了不同热解温度下制备的镉污染水稻秸秆生物炭对土壤中Cd的稳定特性。研究结果表明,镉污染水稻秸秆热解制备的生物炭可有效吸附土壤镉。热解温度显著影响生物炭对Cd的吸附能力（P<0.05）,高温生物炭对Cd吸附容量大,700 ℃下制备的生物炭对Cd的吸附容量可达72.57 mg/g。生物炭对Cd的吸附主要通过含氧官能团表面络合和碳酸盐共沉淀吸附,其吸附过程符合Langmuir方程和准二级动力学模型,吸附过程受化学速率控制。土柱试验表明,镉污染水稻秸秆生物炭能有效降低土壤Cd的下渗迁移能力,其作用机制主要是将土壤Cd从酸可提取态转化为残渣态,施入高温生物炭的土壤中Cd的残渣态比例最高。上述结果表明,热解可有效处理镉污染水稻秸秆,制备的生物炭可用于Cd等重金属污染土壤的稳定修复,有效解决镉污染水稻秸秆的潜在二次污染问题并实现其安全利用。     

Influence of organic and inorganic passivators on Cd and Pb stabilization and microbial biomass in a contaminated paddy soil

Purpose

Soil contamination with heavy metals, such as Cd and Pb, has caused severe health and environmental risks all over the world. Possible eco-friendly solutions for Cd and Pb immobilization were required to reduce its mobility through various cost-effective amendments.

Materials and methods

A laboratory incubation study was conducted to assess the efficiency of biochar (BC), zeolite (ZE), and rock phosphate (RP) as passivators for the stabilization of Cd and Pb in paddy soil as well as soil microbial biomass. Various extraction techniques were carried out: a sequential extraction procedure, the European Community Bureau of Reference (BCR), toxicity characteristic leaching procedure (TCLP) test, and single extraction with CaCl₂. The impact of passivators on soil pH, dissolved organic carbon (DOC), and microbial biomass (carbon, nitrogen, and phosphorus) was examined in the metal contaminated soil.

Results and discussion

The results showed that the exchangeable portion of Cd in soil was significantly reduced by 34.8, 21.6, and 18.8% with ZE, RP, and BC at a 3% application rate, respectively. A similar tendency of reduction in Pb soluble portion was observed by ZE (9.6%), RP (20%), and BC (21.4%) at a 3% application rate. Moreover, the TCLP leachate of Cd and Pb was apparently reduced by 17 and 30.3% with BC at a 3% application dose, respectively, when compared to the control. Soil pH, nutrients, and microbial biomass C, N, and P were significantly increased with the addition of BC, RP, and ZE passivators.

Conclusions

The results showed that the incorporation of BC, ZE, and RP significantly reduced the Cd and Pb mobility in paddy soil as well as enhanced soil nutrients and microbial biomass. Overall, among all the amendments, rice straw derived-BC performed better for Cd and Pb immobilization in paddy soil.

     

Influence of Organic Manure and Lime on Cadmium Mobility in Soil and Uptake by Spinach (Spinacia oleracea L.)

Spinach grown in cadmium (Cd)-contaminated soils accumulates Cd compounds in toxic concentration contaminating the food chain leading to the chronic toxic effects on human and animal health. A study was conducted in a Cd-contaminated soil to examine the ameliorative effect of lime and organic manure on the mobility of Cd and its uptake in spinach. Application of lime or organic manure or both decreased the Cd concentration in soil and shoots and increased chlorophyll content of leaves. As compared to the control treatment, combined application of lime and organic manure decreased the level of Cd in soil by 54.7%, in spinach shoot by 61.3%, and the transfer factor of Cd by 35.0% and increased in leaf chlorophyll content by 29.4%. Combined application of lime and organic manure emerged as a viable option in reducing the mobility of Cd in contaminated soil for growing spinach.