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。     

镉胁迫下钝化剂对菠菜镉吸收累积及土壤微生物群落结构的影响

为了探究镉（Cd）胁迫下不同钝化剂对菠菜Cd吸收转运及根际微生物群落结构的影响,设置不施钝化剂（CK）、单施纳米羟基磷灰石（nHAP）、单施巯基生物炭（TMB）、配施纳米羟基磷灰石+巯基生物炭（HPTB）4个处理,比较各处理的土壤微生物群落结构、土壤化学性质与菠菜生物量及Cd含量。结果表明,各钝化剂处理下菠菜生物量均增加,Cd含量均降低;不同钝化剂对土壤主要优势菌群的组成没有显著影响,但会改变细菌和真菌的相对丰度。主成分分析表明,nHAP对细菌群落结构影响较大,对真菌群落结构影响较小。冗余分析发现,pH是影响细菌群落结构的主要因子,全磷含量是影响真菌群落结构的主要因子。综上所述,单施nHAP能够促进菠菜生长,降低Cd含量,且对微生物群落结构的影响较小。     

2种含铁材料对水稻土中砷和重金属生物有效性的影响

通过盆栽试验研究添加2种含铁材料(Fe(OH)3、FeCl3)对污染水稻土壤中As、Pb、Cd、Cu、Zn生物有效性的影响。结果表明,添加Fe(OH)3对土壤As交换态含量没有显著的影响,添加FeCl3显著降低了土壤As交换态含量,添加量为0.50g/kg时,土壤As交换态含量比对照下降46%。添加Fe(OH)3使土壤Pb、Cu交换态含量显著降低,2.00g/kg的添加量使Pb、Cu交换态含量分别下降63%,74%。添加FeCl3使土壤Pb、Cd、Zn交换态含量显著升高,2.00g/kg的添加量使Pb、Cd、Zn交换态含量分别升高3 834%,247%,1 744%。添加Fe(OH)3对糙米中无机As和重金属Pb、Cd、Cu、Zn含量没有显著的影响,添加FeCl3显著降低了糙米中无机As含量,但显著提高了糙米中Pb、Cu含量,1.00g/kg的添加量使糙米中无机As含量降低33%,Pb、Cu含量分别升高147%,50%。表明添加FeCl3能有效降低土壤As的生物有效性,但提高了土壤重金属的生物有效性。添加Fe(OH)3对土壤pH无显著影响,而添加FeCl3能显著降低土壤pH值,这是FeCl3能有效固定土壤As,提高土壤重金属交换态含量的重要原因之一。     

添加紫云英和水稻秸秆对稻田污染土壤Cd形态的影响

为给紫云英、水稻秸秆还田综合治理重金属污染土壤提供理论支撑,采用室内培养的方法,设置不添加任何有机物料(CK)、单独添加水稻秸秆0.2 g(R2G0)、添加水稻秸秆0.15 g+紫云英0.05 g(R3G1)、添加水稻秸秆0.1 g+紫云英0.1 g(R1G1)、单独添加紫云英0.2 g(R0G2)共5个处理,研究了紫云英、水稻秸秆对重金属污染稻田土壤中有效态Cd和Cd形态分级的影响。结果表明,随着紫云英添加比例的增加,有效态Cd含量呈降低的趋势;R0G2处理土壤有效态Cd含量比R2G0处理下降34.41%,且差异显著。R0G2和R2G0的残渣态Cd含量显著高于R3G1和R1G1处理,其中R0G2的残渣态Cd比其他处理提高20.00%～51.90%。通过冗余分析(RAD)认为,土壤可溶性氮(DON)和pH均与有效态Cd和弱酸提取态Cd呈负相关关系,有机质与有效态Cd和弱酸提取态Cd呈正相关关系,且DON、有机质和pH对有效态Cd与Cd形态分级的解释量分别为64.6%、17.2%和4.1%,达到显著性相关关系。单独添加紫云英对Cd的稳定具有较好的效果,其主要通过改变土壤DON、有机质和pH影响Cd有效性和形态特征。     

硅藻土有机肥对Cd-Zn复合污染土壤重金属形态和有效性的影响

通过室内土壤培养试验研究硅藻土有机肥对Cd、Zn复合污染土壤重金属形态和有效性的影响。结果表明,添加硅藻土有机肥可提高Cd、Zn复合污染土壤的pH值,降低土壤有效态Cd、Zn的含量。硅藻土有机肥对Cd、Zn复合污染土壤Cd、Zn形态有明显的影响,表现为明显降低土壤交换态、松结有机态Cd、Zn含量,提高紧结有机态和残渣态Cd、Zn含量。相关分析表明,土壤交换态、松结有机态Cd、Zn的含量与土壤有效态Cd、Zn的含量均呈极显著相关,氧化锰结合态Cd与土壤有效态Cd含量显著相关。硅藻土有机肥用量(土壤重量的5%和10%)对土壤有效态Cd、Zn和不同形态Cd、Zn含量无显著差异。     

淹水条件下生物炭对污染土壤重金属有效性及养分含量的影响

以生物炭为改良剂,采用淹水培养方法研究不同添加量生物炭(BC)处理(1%,3%和5%)对污染土壤Zn、Cd、Pb、Cu有效性及养分含量的影响,并用毒性淋出试验(TCLP)法对其生态风险进行评价。结果表明:与对照相比,添加生物炭土壤中交换态Zn、Cd、Pb、Cu分别降低0.15%～24.11%,1.22%～16.09%,0.47%～21.51%,3.05%～77.30%,且表现为随生物炭施用量的增加其降低程度增大。TCLP态Zn、Cd、Pb、Cu含量分别降低0.74%～21.47%,6.67%～47.62%,2.02%～16.74%,0.29%～21.20%,且表现为随生物炭施用量的增加其降低程度增大。与对照相比,添加生物炭后土壤pH上升(-0.01)～0.35个单位,有机质、铵态氮和硝态氮分别增加0.09%～20.02%,1.59%～38.28%和2.74%～90.14%。土壤pH值与土壤交换态Cu含量呈显著负相关,有机质含量与交换态Zn含量呈显著负相关。淹水条件下污染土壤中施用生物炭可降低重金属Zn、Cd、Pb和Cu的有效性和生态风险,提高土壤养分含量,起到改良土壤作用。     

生物质炭添加对重金属污染稻田土壤理化性状及微生物量的影响

分析了生物质炭添加对红壤性水稻土理化性状、重金属含量及微生物生物量的影响。通过田间小区长期定位试验,一次性施入不同量生物质炭(0,10,20,30,40t/hm2),于2017年9月采集各处理表层土样(0—15cm),研究土壤理化性状、重金属含量及微生物生物量的变化。结果表明:生物质炭添加对土壤理化性状、重金属含量及微生物生物量均有显著影响。与对照相比,供试土壤的pH、EC和有机质含量随生物质炭添加量的增加而增大,增幅分别为5.11%~18.43%,37.62%~104.31%和1.72%~22.41%,而有效磷和铵态氮含量随生物质炭添加量的增加呈先增大后减小趋势,分别在生物质炭添加量为10t/hm2和30t/hm2时达到最大值。随生物质炭添加量的增加,土壤有效态Cd和有效态Pb含量均呈降低趋势,而土壤有效态As含量呈先增加后减少的趋势,三者均在生物质炭添加量为40t/hm2时达到最小值。土壤微生物生物量碳、氮和微生物商随生物质炭添加量的增加均呈先升高后降低的趋势,均在生物质炭添加量为20t/hm2时达到最大值。相关分析表明,生物质炭添加量分别与土壤有效态Cd和Pb含量之间呈极显著负相关(P0.01);通径分析表明,生物质炭主要是通过直接作用影响土壤有效态Cd含量,而土壤pH、EC、有机质、微生物生物量碳、氮和有效磷主要是通过间接作用影响土壤有效态Cd含量。因此,添加适量生物质炭不仅可以改善土壤重金属污染现状和土壤理化性状,提高土壤养分含量,还可以改良土壤生物学性质,增加土壤微生物量。研究结果可为提高稻田土壤肥力和改善土壤重金属污染状况提供科学依据。     

生物炭对不同酸化水平稻田土壤性质和重金属Cu、Cd有效性影响

针对南方稻田土壤酸化严重,导致养分流失有毒重金属活化,严重影响稻米质量安全的重大现实问题。以水稻秸秆和谷壳等农业废弃物为原料制备生物炭(分别记为RSC和RHC),研究不同原料生物炭对酸化土壤改良及其对重金属有效性的影响。设置3个生物炭用量(0,20,50 g/kg,分别记为CK、C1、C2),4种土壤酸化水平(pH 4.01,4.25,4.33,4.58,分别记为L1、L2、L3、L4),生物炭与重金属污染土壤共同培养60天后测定土壤pH、全氮、有机质、有效磷、速效钾和有效态Cu、Cd含量。结果表明:RSC对酸化土壤pH的改良效果明显优于RHC,且施炭量越高提高幅度越大,RSC的C2处理使4种酸度水平的土壤pH分别提高了0.68,0.97,1.29,1.71个单位。2种生物炭均能提高土壤的全氮、有效磷、速效钾和有机质含量,其中各施炭处理有机质显著提高,尤以速效钾的增幅最为显著,RSC对4种养分的提高均优于RHC。RHC对土壤有效态Cu含量无显著影响;RSC的C2较C1处理更能降低土壤中有效态Cu含量,使4种酸度水平的土壤分别降低了13.62%,6.57%,4.36%,7.88%。RHC处理的L3、L4土壤中有效态Cd含量显著降低,最大分别降低了13.79%,19.23%。RSC使4种酸度土壤有效态Cd含量最大分别降低了20.00%,25.81%,20.69%,19.23%。相关分析表明,土壤pH与有效态重金属含量呈显著负相关关系。水稻秸秆炭用于改良酸化土壤、降低重金属Cu和Cd有效性的效果更佳,且降低污染土壤中Cd的有效性较Cu好;生物炭对酸化程度越低的土壤pH和有效磷含量的提高以及有效态Cd含量的降低效果较好,而有效态Cu含量的降低效果则在酸化程度越高的土壤中表现更佳;土壤pH是生物炭调控重金属Cu、Cd有效性的主要影响因素。     

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。     

油枯对镉污染土壤的钝化研究

为了研究油枯对镉(Cd)污染土壤的钝化效果,以油枯为外源添加物(质量比:1%、2%、3%、4%、5%),模拟田间条件在塑料桶中进行为期45 d的培养,对镉污染土壤中Cd形态分布特征、DTPA提取态Cd(DTPA-Cd)含量、pH、有机质含量进行分析。结果表明,添加油枯可显著降低镉污染土壤中可交换态镉(Ex-Cd)的比例,提高碳酸盐结合态镉(Cb-Cd)、铁锰氧化物结合态镉(Fe-Mnb-Cd)以及有机质及硫化物晶格态镉(OMb-Cd)的比例,而残渣晶格结合态镉(RLb-Cd)变化不明显。添加油枯显著降低镉污染土壤中DTPA-Cd含量,降幅最高可达49%。镉污染土壤p H值维持在6.0左右,1%~4%添加处理中土壤pH波动幅度较大;而5%添加处理的土壤pH波动幅度小。添加油枯均能显著提高镉污染土壤中有机质含量。由此可见,油枯对镉污染土壤有较好的钝化效果,这为重金属污染土壤的修复和农业废弃物的循环利用提供了参考。     

棉秆生物质炭添加对棉田土壤理化性质及根际微生物群落结构的影响

以新疆滴灌棉田为研究对象,研究生物质炭施用对棉田土壤理化性质和棉花根际土壤微生物群落特征的影响。试验采集了不施生物质炭(CK)、施生物质炭3 t/hm²(BC1)、施生物质炭6 t/hm²(BC2)和施生物质炭9 t/hm²(BC3)4种处理棉花根际土壤,分析土壤理化性质和根际土壤微生物群落结构和组成的变化。结果表明,生物质炭施用后土壤pH和电导率分别下降了5.58% ~ 9.18%和5.38% ~ 18.04%;与CK相比,生物质炭施用使土壤有机质、全氮、全磷、碱解氮和有效磷含量均显著增加,且BC3增加效果最好,但生物质炭施用导致土壤钾含量显著降低。生物质炭施用显著降低了浮霉菌门(Planctomycetota)、芽单胞菌门(Gemmatimonadota)、厚壁菌门(Firmicutes)和被孢霉门(Mortierellomycota)相对丰度,但增加了子囊菌门(Ascomycota)、斯克尔曼氏菌属(Skermanella)、苔藓杆菌属(Bryobacter)、毛壳菌属(Chaetomium)、头束霉菌属(Cephalotrichum)、金孢属(Chrysosporium)和拟棘壳孢属(Pyrenochaetopsis)的相对丰度。另外,生物质炭施用降低了根际土壤微生物多样性和细菌丰富度,但根际土壤真菌的丰富度提高。生物质炭施用显著影响根际土壤微生物特别是真菌的群落结构,电导率、速效钾和pH是根际土壤微生物群落的主要影响因子。研究表明,生物质炭施用可以改善棉田土壤理化性质进而影响根际土壤微生物群落组成和结构,9 t/hm²为本试验的推荐施用量。     

Effects of modified Pb-, Zn-, and Cd- availability on the microbial communities and on the degradation of isoproturon in a heavy metal contaminated soil

The effects of modified heavy metal (HM) availability on the microbial community structure and on the microbe-mediated degradation of herbicide isoproturon (IPU) were evaluated in soil with a long-term HM contamination. The fate of ¹⁴C-ring labelled IPU was investigated for over 60 days under controlled microcosm conditions. Phosphate mineral apatite and a water solution of Pb, Zn, and Cd salts were previously homogeneously mixed into the soil material to reduce and to increase the proportion of bioavailable HM, respectively. The availability of Pb, Zn, and Cd was determined by HM fractionation and plant uptake 110 days after the addition of amendments, shortly before IPU addition. Apatite treatment reduced the availability of HM, but did not affect the microbial biomass and the microbial community structure on the genotype level (total soil DNA-RAPD). However, it changed the microbial community structure on the phenotype level, based on the composition of phospholipid fatty acids (PLFA) at the end of the degradation experiment. The degradation of IPU did not change. In contrast to apatite treatment, HM supplementation increased the bioavailability of Pb, Zn and Cd, which resulted in biomass reduction and changes of microbial community structure on the genotypic (total soil DNA-RAPD) and phenotypic (PLFA) level. Increased bioavailability of HM also significantly reduced the rate of IPU degradation and mineralisation. The total mineralisation over a period of 60 days decreased from 12 to 5% of initial ¹⁴C. Increased HM bioavailability did not influence the degradation pathways and kinetics of IPU.     

Pig manure vermicompost (PMVC) can improve phytoremediation of Cd and PAHs co-contaminated soil by Sedum alfredii

Purpose

A major challenge to phytoremediation of co-contaminated soils is developing strategies for efficient and simultaneous removal of multiple pollutants. A pot experiment was conducted to investigate the potential for enhanced phytoextraction of cadmium (Cd) by Sedum alfredii and dissipation of polycyclic aromatic hydrocarbons (PAHs) in co-contaminated soil by application of pig manure vermicompost (PMVC).

Materials and methods

Soil contaminated by Cd (5.53?mg?kg^?1 DW) was spiked with phenanthrene, anthracene, and pyrene together (250?mg?kg^?1 DW for each PAH). A pot experiment was conducted in a greenhouse with four treatments: (1) soil without plants and PMVC (Control), (2) soil planted with S. alfredii (Plant), (3) soil amended with PMVC at 5?% (w/w) (PMVC), and (4) treatment 2?+?3 (Plant?+?PMVC). After 90?days, shoot and root biomass of plants, Cd concentrations in plant and soil, and PAH concentrations in soil were determined. Abundance of PAH degraders in soil, soil bacterial community structure and diversity, and soil enzyme activities and microbial biomass carbon were measured.

Results and discussion

Application of PMVC to co-contaminated soil increased the shoot and root dry biomass of S. alfredii by 2.27- and 3.93-fold, respectively, and simultaneously increased Cd phytoextraction without inhibiting soil microbial population and enzyme activities. The highest dissipation rate of PAHs was observed in Plant?+?PMVC treatment. However, neither S. alfredii nor PMVC enhanced PAH dissipation when applied separately. Abundance of PAH degraders in soil was not significantly related to PAH dissipation rate. Plant?+?PMVC treatment significantly influenced the bacterial community structure. Enhanced PAH dissipation in the Plant?+?PMVC treatment could be due to the improvement of plant root growth, which may result in increased root exudates, and subsequently change bacterial community structure to be favorable for PAH dissipation.

Conclusions

This study demonstrated that remediation of Cd and PAHs co-contaminated soil by S. alfredii can be enhanced by simultaneous application of PMVC. Long-term evaluation of this strategy in co-contaminated field sites is needed.     

Effective alleviation of Cd stress to microbial communities in mining reclamation soils by thiourea-modified biochar amendment

Reclaimed soils in mining area usually display low fertility and present Cd stress. The amendment of modified biochar effectively fixes Cd in soils,enhances soil fertility, and reduces Cd stress in soil microorganisms. However, the effect of thiourea-modified biochar(TBC) on microbial adaptability to Cd stress in mining reclamation soils is still unclear. The present work studied the Cd immobilization and microbial community changes in a mining reclamation soil displaying extreme Cd contaminatio...     

羟基磷灰石–植物联合修复对Cu/Cd污染植物根际 土壤微生物群落的影响

针对江西贵溪Cu、Cd重金属污染土壤,通过田间试验,比较无机生物材料羟基磷灰石及3种植物(海州香薷、巨菌草、伴矿景天)与羟基磷灰石联合修复对土壤总Cu、Cd的吸收及对活性Cu、Cd的钝化吸收能力差异。采用磷脂脂肪酸(PLFA)分析法,比较不同修复模式对土壤微生物群落结构的影响,以评估土壤微生态环境对不同修复措施的响应。研究结果表明:羟基磷灰石的施加可显著提高土壤pH,并有效钝化土壤活性Cu、Cd含量,但对土壤总Cu、Cd的含量影响较小。植物与羟基磷灰石的联合修复在显著降低土壤活性Cu、Cd(P0.05)的同时,减少了植物根际土壤总Cu、Cd的含量(P0.05)。不同修复措施对土壤微生物群落组成影响差异明显。单独施加羟基磷灰石与土壤真菌群落呈显著正相关,使土壤真菌生物量提高,从而引起真菌/细菌(F/B)的升高。植物与羟基磷灰石的联合修复可有效缓解土壤真菌化的趋势,其中巨菌草与羟基磷灰石的联合修复可有效提高土壤革兰氏阳性、革兰氏阴性细菌生物量及多样性,降低F/B值,从而降低土壤真菌病害的风险。不同植物根系活性代谢引起有机质的积累促进植物与羟基磷灰石处理中根际有机碳含量显著提高。聚类增强树(Aggregated boosted tree,ABT)分析结果表明:不同修复模式是影响土壤微生物群落的重要因素,其次土壤pH和Cu的含量及活性也是改变重金属污染区域微生物群落的因子。该研究从微生物群落结构角度解释了植物与羟基磷灰石联合修复对土壤微生态体系的作用,为开展Cu、Cd等重金属污染地植物与无机生物材料的联合修复方式的筛选及实施提供可靠的理论依据。     

有机无机肥配施对日光温室番茄连作土壤微生物的影响

  目的  为解决日光温室番茄连作障碍,必须弄清有机无机肥配施对番茄连作土壤微生物的影响。  方法  试验共设置6个处理,分别为不施肥（CK）、20%有机肥 + 80%化肥（M20C80）、40%有机肥 + 60%化肥（M40C60）、60%有机肥 + 40%化肥（M60C40）、80%有机肥 + 20%化肥（M80C20）、100%有机肥 + 0%化肥（M100）。测定了连作土壤理化性质、细菌和真菌的微生物群落结构、物种组成和丰度等相关指标。  结果  M40C60处理使连作土壤孔隙度在54.38% ~ 55.61%,pH维持在7.19 ~ 7.22,有机质和速效钾含量分别维持在49.70 ~ 59.21 g kg?1和536.1 ~ 605.5 mg kg?1的中等水平,速效磷含量则维持在680.4 ~ 783.0 mg kg?1的高水平。增施有机肥,可以改善土壤微生物群落组成,分别提高芽孢杆菌（Bacillus）、土胞杆菌（Terrisporbacter）、链霉菌（Streptomyces）以及头束霉菌（Cephalotrichum）等有益菌群落相对丰度0.86%、0.60%、0.12%和47.82%,降低变形菌（Proteobacteria）酸杆菌（Acidobacteriota）等有害菌群落相对丰度3.47%和1.74%。  结论  增施有机肥改善番茄连作土壤的基础理化性质,保持土壤中的养分含量。同时有益于微生物群落演替,维持或提高有益菌群的丰度,抑制或降低有害菌群的丰度,使连作土壤维持在一个较稳定的微生物群落结构。减少番茄连作土壤病害的发生,维持良好的土壤状态。     

双季稻田土壤微生物群落对连续5年施有机肥和石灰的响应差异

  目的  土壤微生物是土壤健康的敏感“指示器”,但不同的土壤微生物类群对连续施用有机肥和石灰的响应规律及不同指标的敏感性仍不明确。  方法  本文选取中亚热带双季稻区的紫泥田作为研究对象,研究连续5年施用有机肥或石灰后,土壤微生物“黑箱指标”（微生物生物量碳氮、微生物熵和土壤呼吸速率）和土壤活体微生物（PLFAs）组成的响应规律与差异。  结果  与对照相比,连续施用有机肥后,土壤微生物生物量碳（MBC）、氮（MBN）含量和土壤呼吸速率分别提高37%、28%和44% ~ 59%,微生物多样性也显著提高,土壤细菌结构发生改变,尤其是革兰氏阴性菌（G?）的PLFAs绝对量提高了100%,但真菌类群的响应不敏感。相反,连续施用石灰5年后,土壤微生物生物量碳、氮含量均呈下降趋势,微生物熵和土壤呼吸速率分别降低11%和26% ~ 52%,微生物多样性显著降低,细菌、放线菌和绝大多数真菌类群PLFAs绝对量下降30% ~ 58%。相关性分析结果表明,土壤有机质含量与土壤微生物总PLFAs和细菌PLFAs含量呈显著正相关关系;而土壤pH仅与Simpson多样性指数呈显著正相关关系。施有机肥显著提高了土壤有机质含量进而导致细菌MBC、MBN、G?和土壤呼吸速率显著增加;而施石灰后土壤微生物群落结构及活性降低与土壤pH有关。  结论  连续5年施用有机肥、石灰后,土壤微生物指标分别表现为正面、负面响应。与“黑箱指标”相比,某些特定微生物类群（如G?）的敏感性指数值更高,在土壤健康评价中极具应用潜力。     

Bioremediation of cadmium-dichlorophen co-contaminated soil by spent <Emphasis Type="Italic">Lentinus edodes</Emphasis> substrate and its effects on microbial activity and biochemical properties of soil

Purpose

Soil contamination resulting from industrial and agricultural activities has caused high concerns in recent years. Compared with single pollutant, co-contaminants of heavy metal and organic pollutant in soil are quite complicated. The overall objective of this study was to evaluate the potential of spent Lentinus edodes substrate (SLS) as an organic amendment for bioremediation of cadmium (Cd) and dichlorophen (DCP) co-contaminated soil.

Materials and methods

Pot experiments were conducted to investigate the effect of SLS on the distribution of Cd and dissipation of DCP. The microbial counts and soil respiration rate were determined. The ligninolytic enzymes (manganese peroxidase and laccase) and soil enzymes (dehydrogenase, urease, and acid phosphatase) were analyzed. Variations of Cd fractions in soil were determined following the modified BCR sequential extraction procedure. DCP in soil was detected on a gas chromatography–mass spectrometry (Agilent 6890N GC–MS).

Results and discussion

Results showed that the addition of SLS or sterilized SLS (SSLS) could facilitate soil biological properties including microbial counts, respiration intensity, and soil enzyme activities compared to control soil. The HOAc extractable Cd decreased by 10.94–17.09 and 9.63–12.02 % in SLS and SSLS amended soil, respectively. As for the dissipation of DCP, the SSLS amended soil recorded 82.4–92.8 % while the SLS amended soil recorded 85.0–96.9 % compared to the non-amended soil (68.3–84.1 %). The presence of available residual nutrients in the substrate could promote the growth of indigenous microbes, which could contribute to the dissipation of DCP.

Conclusions

This study investigated the potential of SLS on the bioremediation of sites co-contaminated with Cd and DCP. The SLS-facilitated removal of soil DCP was due to SLS-promoted soil biological properties including the microbial numbers and soil respiration as well as the ligninolytic enzymes. The addition of SSLS and SLS resulted in a decrease of Cd extractability in soil, and significantly facilitated the activities of dehydrogenase, urease, and acid phosphatase. The results demonstrated the potential of SLS in ex situ bioremediation of soil co-contaminated with Cd and DCP, providing an attractive reusing option of this organic waste.