菲在黑麦草种植土壤中的降解及其对土壤酶的影响

研究了种植黑麦草对土壤中3环多环芳烃菲的动态降解作用。结果表明,黑麦草可以促进土壤中菲的降解,在75 d的盆栽试验里,种植黑麦草土壤中菲的可提取浓度明显低于不种植土壤（p<0.05）。在菲浓度为5 mg kg^-1、50 mg kg^-1、200 mg kg^-1的3种处理中,种植黑麦草壤中菲的降解率分别为81.07%、90.35%、84.94%,而不种植土壤中菲的降解率分别为75.34%、86.62%、67.60%。种植黑麦草增强了土壤中多酚氧化酶、脱氢酶和过氧化氢酶的活性以及增加土壤中微生物生物量碳的含量,即提高了土壤中生物活性,从而促进了土壤中菲的降解率。不同浓度菲处理,土壤中生物活性存在明显差异,高浓度菲(200 mg kg^-1)对土壤中生物活性产生较强的抑制作用,影响土壤中生物对菲的降解作用,从而揭示了植物促进菲降解的生物学及酶学机理。黑麦草对土壤中多环芳烃有较强的忍耐性,但过高的菲浓度对黑麦草的生长有影响。     

铅和苯并[a]芘混合污染酸性土壤上黑麦草生长及对污染物的吸取作用

设置铅(Pb)处理浓度为0、5001、0002、000 mg kg-1(烘干土计),苯并[a]芘(B[a]P)处理浓度为0、12.5、255、0 mg kg-1(烘干土计),完全组合设计,对每一处理通过种植和不种植黑麦草盆栽试验,研究了B[a]P和Pb混合污染酸性红砂土上黑麦草(Lolium perenneL.)的生长及对污染物积累的吸取作用。试验表明,铅是抑制黑麦草株高和产量的主要因素,在低Pb处理浓度下,B[a]P对黑麦草生长有一定的促进作用。在试验61 d内,黑麦草吸收的铅占土壤铅添加量的4.7%,黑麦草吸收的B[a]P占土壤B[a]P添加量的0.023%;种植黑麦草的土壤B[a]P残留率平均为42.6%;而未种植黑麦草的土壤B[a]P平均残留率为50.9%。该研究结果表明,当Pb-B[a]P混合污染土壤时,在一定的浓度范围内黑麦草能吸收土壤中的Pb和B[a]P,黑麦草对Pb-B[a]P混合污染土壤有一定的吸取修复作用。     

污染土壤中六六六和DDT在温室中的分布特征及动态变化研究

应用PUF材料空气被动采样技术,研究了密闭温室条件下污染土壤中有机氯农药[DDT和六六六（HCH）]含量的动态变化及其向空气中扩散的规律。结果表明：土壤中∑HCHs和∑DDTs总量随着培养时间的延长而降低;空气中HCH和DDT浓度在20d时达到峰值,20d以后浓度逐渐降低。培养60d后,土壤中∑HCHs的浓度随土层深度增加而增加,0~2cm土层中∑HCHs的浓度（9.4±0.69）mg·kg-1显著低于6~8cm土层中的浓度（12.11±0.83）mg·kg-1;∑DDTs在土壤中浓度随土壤层次呈现先升高后降低的变化趋势。在温室条件下有机氯农药的异构体和降解产物的组成也发生一定变化,土壤中HCHs和DDTs在一定程度上被激活,温室条件也可能促进HCHs和DDTs的土-气交换过程;温室环境促进了p,p′-DDT和o,p′-DDT向p,p′-DDD和p,p′-DDE转化,从而增大DDT和HCH的环境风险。     

黑麦草对菲污染土壤修复的初步研究

本文研究了黑麦草(Lolium multiflorum Lam)对多环芳烃菲污染土壤的修复作用。通过60天的温室盆栽试验,观察到土壤中菲的可提取浓度随着时间逐渐减少,黑麦草加快了土壤中可提取态菲浓度的下降。在5、50、500mg/kg菲处理浓度下黑麦草生长的土壤中菲的降解率分别达93.1%、95.6%和94.7%。黑麦草增强土壤中多酚氧化酶活性而提高植物对菲的降解率。土壤自身具有修复多环芳烃菲的自然本能,种植黑麦草具有强化土壤修复菲污染的作用。增加黑麦草产量,增强土壤多酚氧化酶活性,可能提高黑麦草植物修复菲污染土壤的能力。     

兽药磺胺二甲嘧啶在土壤中的生态行为

通过室内培养和土壤薄层层析等实验方法，研究了磺胺二甲嘧啶对土壤微生物的毒性及其在土壤中的降解、迁移特性。结果显示：在土壤磺胺二甲嘧啶浓度为1mg kg^-1时，土壤中细菌和真菌数量明显减少（p〈0．05），但随时间延长，该抑制作用变缓；磺胺二甲嘧啶在土壤中降解缓慢，持留时间久，在灭菌土和未灭菌土中的半衰期分别为223．9d和102．4d，并容易在土壤中迁移和渗漏，迁移系数R大于0．7，迁移和渗漏速度受介质pH的影响，在非中性环境下，移动和渗漏能力增强。表明磺胺二甲嘧啶是一种在土壤中不易被降解、容易迁移和渗漏到水体、对土壤微生物和水体产生危害的新型污染源。     

杂交苏丹草(Sorghum bicolor×S.sudanense)修复DDT污染土壤效果研究

采用盆栽试验,研究了杂交苏丹草吸收和富集DDT的规律及其对DDT污染土壤的修复效果。结果表明:①土壤中添加高浓度的DDT,对杂交苏丹草的生物量没有显著影响,说明杂交苏丹草对DDT有耐受能力;②杂交苏丹草对DDT及其主要降解产物都有吸收,在旺盛生长期,植株中DDT的累积速率也较快;③杂交苏丹草根系中DDT及其主要降解产物的浓度是茎叶中相应组分浓度的4.81~10.32倍,质量比在0.57~1.55倍之间;④杂交苏丹草从土壤中吸收DDT占添加量的11.3%,而在其生长期间,土壤中DDT消失量为56.0%。     

纳米TiO2催化下表层土壤中BaP的紫外光降解

采用光解试验,研究了紫外照射与纳米TiO2联合作用下,土壤表层中苯并[a]芘（BaP）的降解动力学;同时考察了催化剂的浓度、土壤pH、腐植酸和光质对BaP的光催化降解的影响。结果表明,土壤中BaP的光催化降解表现为准一级动力学。催化剂TiO2可以明显地促进土壤中BaP的光降解,较少量的催化剂（0．5％）使光解的半衰期从363．22h减少到103．26h。H^＋和OH^-离子对BaP的催化光解起促进作用,在酸性和碱性土壤中BaP光催化降解高于中性土壤,酸性土壤中的降解速率最快。腐殖质吸收紫外光照射时,产生的活性氧中间产物能够攻击BaP,添加腐植酸能增加土壤表层中BaP的光催化降解。BaP的光解半衰期从无外加腐植酸的89．34h,减少到添加浓度分别为5、10、20和40mg·kg^-1的29．37、32．69、35．73和38．51h。BaP的催化降解随波长的增加而降低,在波长254、310和365nm下,BaP降解的一级动力学常数分别为0．0078h^-1、0．0061h。和0．005h^-1。     

黑麦草对土壤中苯并[a]芘动态变化的影响

本文通过盆栽试验初步研究了黑麦草 (LoliummultiflorumLam)对污染土壤中多环芳烃苯并 [a]芘动态变化的影响。盆栽试验设计 3种苯并 [a]芘处理浓度 ,分别为 1、10、10 0mgkg-1。将苗龄为 1周的黑麦草移植于受苯并 [a]芘污染的土壤中 ,同时设置有相同的苯并 [a]芘处理浓度但不种植物的对照试验。试验在2 0m3 的控温、控光的生长室内进行 ,土壤湿度维持在田间持水量的 6 0 %。通过 12 0d的温室盆栽试验 ,观察到土壤中苯并 [a]芘的可提取浓度随着时间逐渐减少 ,种植黑麦草加快了土壤中可提取态苯并 [a]芘浓度的下降。在 1、10、10 0mgkg-1苯并 [a]芘处理浓度下 ,黑麦草生长的土壤中苯并 [a]芘的减少率分别达 82 3%、74 0 %和 5 5 9%。结果还显示 ,随盆栽时间的延长 ,黑麦草根圈土壤中多酚氧化酶含量提高 ,这可能根圈土壤中可提取态苯并 [a]芘含量降低有关。黑麦草的地上部可以积累苯并 [a]芘 ,变幅在 0 0 6～ 3 6 0mgkg-1。初步认为 ,土壤具有缓解苯并 [a]芘污染的自然本能 ,促进黑麦草生长 ,增强土壤多酚氧化酶活性 ,可提高黑麦草对苯并 [a]芘污染土壤的修复能力。     

苏丹草对土壤中菲芘的修复作用

采用盆栽试验法,研究了苏丹草对土壤中菲、芘的去除效果,及植物和微生物在去除土壤菲、芘中的交互效应。结果显示,在试验浓度范围（0-322．06mg·kg^-1内,土壤～苏丹草系统（TR,）对菲、芘的去除效果明显。种植苏丹草60d后,土壤菲、芘去除率分别为73．07％-83．92％、63％～77．62％;平均去除率分别比对照1（无植物,不加0．1％NaN3）高55．58％、50．71％,比对照2（无植物,加0．1％NaN3）高72．71％、66．57％,说明种植苏丹草可以促进微生物对土壤中芘、菲降解。土壤酶活性测定结果也显示,酶活性越高,污染物降解率越高,反之亦然。因此,植物一微生物间的交互效应是土壤中多环芳烃降解的主要途径。     

丛枝菌根对菲芘污染土壤中几种酶活性的影响

采用温室盆栽试验方法,研究了丛枝菌根真菌（AMF）Glomus mosseae和Glomus etunicatum对菲芘复合污染土壤中3种酶活性的影响。宿主植物为三叶草（Trifolium repens L.）和黑麦草（Lolium multiflorum Lam）。土样中菲和芘起始浓度分别为203.4mg·kg^-1和107.5mg·kg^-1。结果表明,植物增加了土壤多酚氧化酶、酸性磷酸酶和过氧化氢酶活性。接种Glomus mosseae和Glomus etunicatum使三叶草根际土壤多酚氧化酶活性20-60d分别增加19.6%-72.0%和29.7%-90.6%,过氧化氢酶活性分别增加3.3%-12.2%和7.8%-34.7%,酸性磷酸酶活性总体呈增加趋势;接种Glomus mosseae使黑麦草根际多酚氧化酶活性增加18.0%-43.1%,过氧化氢酶活性总体上呈降低趋势,酸性磷酸酶活性先升高后降低。供试的两种AMF对三叶草根际酸性磷酸酶和过氧化氢酶活性的影响30d前有显著差异。AM真菌作用的性质与宿主植物特性有关。     

蚯蚓与黑麦草相互作用对土壤中荧蒽去除的影响

Earthworms can promote the bioremediation of contaminated soils through enhancing plant growth and microorganism development. The individual and combined effects of earthworms and ryegrass (Lolium multiflorum Lam.) on the removal of fluoranthene from a sandy-loam alluvial soil were investigated in a 70-d microcosm experiment. The experiment was set up in a complete factorial design with treatments in four replicates: without earthworms or ryegrass (control, CK), with earthworms only (E), with ryegrass only (P), and with both earthworms and ryegrass (EP). The residual fluoranthene, microbial biomass C, and polyphenol oxidase activity in the soil changed significantly (P<0.01) with time. In general, the residual concentration of fluoranthene in the soil decreased sharply from 71.8-88.7 to 31.7-37.4 mg kg 1 in 14 d, and then decreased gradually to 19.7-30.5 mg kg 1 on the 70th d. The fluoranthene concentration left in the soil was the least with both earthworms and ryegrass, compared to the other treatments at the end of the experiment. Half-life times of fluoranthene in the E, P, and EP treatments were 17.8%-36.3% smaller than that of CK. More fluoranthene was absorbed by earthworms than ryegrass. However, the total amounts of fluoranthene accumulated in both the ryegrass and earthworms were small, only accounting for 0.01%-1.20% of the lost fluoranthene. Therefore, we assumed that microbial degradation would play a dominant functional role in fluoranthene removal from soil. We found that earthworms significantly increased microbial biomass C and polyphenol oxidase activity (P<0.01) in the presence of ryegrass at the end of the experiment. Furthermore, microbial biomass C and polyphenol oxidase activity were significantly (P<0.05) and negatively related to the residual fluoranthene concentration. This implied that earthworms might promote the removal of fluoranthene from soil via stimulating microbial biomass C and polyphenol oxidase activity.     

蚓粪对黑麦草吸收污染土壤重金属铜的影响

在长江冲积物形成的高沙土中加入CuSO4.5H2O模拟土壤污染,使Cu污染浓度分别为200、400、600 mg kg-1,并设置加蚓粪(15%)和加原土(15%)处理,二处理各设种植黑麦草(Lolium multiflorum)和不种黑麦草培养试验,研究蚓粪对黑麦草生长及对Cu吸收的影响,以揭示蚓粪在Cu污染土壤植物修复中的作用。结果表明:蚓粪显著增加了黑麦草的地上部和地下部的生物量(p<0.001**)以及根系的长度、表面积、体积和根尖数(p<0.05*),在Cu浓度为200 mg kg-1时促进作用最大;蚓粪还显著提高了黑麦草地上部Cu的浓度及累积量,但显著降低了地下部的Cu浓度(p<0.05*),而对地下部的铜累积量没有影响,显示蚓粪能促进Cu从根系向地上部的运移及在地上部的富集。通过对土壤的pH和Cu的形态特征分析,发现种植黑麦草处理降低了土壤的pH并增加了可交换态铜的含量,而且这种作用在加入蚓粪后更加明显。推测蚓粪主要通过促进黑麦草根系的生长和活性而影响根系周围环境,提高重金属铜的生物有效性进而增加植物对铜的吸收。     

Earthworm-mycorrhiza interaction on Cd uptake and growth of ryegrass

The effects of inoculation of earthworms and arbuscular mycorrhiza separately, and in combination, on Cd uptake and growth of ryegrass were studied in soils contaminated with 0, 5, 10, 20 mg of Cd kg⁻¹ soil. Both earthworms and mycorrhiza were able to survive in all the treatments with added Cd. Earthworm activity significantly increased mycorrhizal infection rate of root and ryegrass shoot biomass. Earthworm activity decreased soil pH by about 0.2 units, and enhanced root Cd concentration and ryegrass Cd uptake. Mycorrhiza inoculation increased shoot and root Cd concentration substantially, and at the highest dosage of 20 mg Cd kg⁻¹ decreased biomass of ryegrass. Inoculation of both earthworms and mycorrhiza increased ryegrass shoot Cd uptake at low Cd concentrations (5 and 10 mg Cd kg⁻¹ soil), when compared with inoculation of earthworms or mycorrhiza alone. In conclusion, earthworm, mycorrhiza and their interaction may have a potential role in elevating phytoextraction efficiency in low to medium level metal contaminated soil.     

Contrasting Effects of Four Plant Residues on Phosphorus Sorption-Desorption in Some Phosphorus Fertilized Calcareous Soils

Four types of plant residues (fruit waste, potato, sunflower, and wheat) with wide ranges of carbon to nitrogen (C/N) and carbon to phosphorus (C/P) ratios were added to the soil at the rate of 20 g kg^?1 (dry weight basis) and incubated for two months. In soils treated with plant residues, the P sorption ranged from 62.0% (potato) to 96.6% (wheat) and from 12.6% (fruit waste) to 50.6% (wheat) when 20 and 1500 mg P kg^?1 were added to the soils, respectively. In general, incorporation of plant residues decreased maximum P sorption capacity but increased bonding energy. The maximum P sorption capacity was reduced from 586 mg kg^?1to 500, 542, and 548 by wheat, fruit, and potato residues, respectively, but increased to 665 mg kg^?1 by sunflower residue. At higher P addition, the highest percentage of desorbed P was observed in soils treated with wheat residue (49.9%); followed by fruit waste (46.5%), potato (43.5%), sunflower (38.8%) and control soils (37.0%). It indicated that the P content of the organic residues had an important role in the sorption and desorption of P in calcareous soils. Among organic residues, sunflower residue showed high sorption and low desorption of P in soils, indicating a higher potential of this organic residue for P retention and reducing surface and groundwater contamination in calcareous soils.     

黑麦草生长及根系形态对土壤Cd，Pb与石油污染的响应

[目的] 研究不同污染条件下黑麦草生理指标的动态变化,为植物修复污染土壤提供初步理论基础。[方法] 通过室内试验模拟不同类型的土壤污染。设置4个处理,未污染土壤+黑麦草（SH）、重金属污染土壤（500 mg/kg Pb²⁺和50 mg/kg Cd²⁺）+黑麦草（SGH）、石油污染土壤（1 000 mg/kg石油）+黑麦草（SPH）、石油和重金属复合污染土壤（500 mg/kg Pb²⁺,50 mg/kg Cd²⁺和1 000 mg/kg石油）+黑麦草（SPGH）,采用WINRHIZO根系分析系统测量根系形态指标,用分光光度计测量叶片色素指标,研究不同类型土壤污染对黑麦草生长的影响。[结果] 3种不同类型的污染土壤均不同程度地刺激了黑麦草根系的生长。与未污染处理相比,在20 d时,石油重金属复合处理下的黑麦草根系的根长、根表面积、根体积、根直径分别增加了88.10%,148.60%,221.90%,32.20%。与未污染相比,随着培养时间的增加各污染处理的地下生物量呈现出先增加后减少的趋势,地上生物量均低于未污染处理,且在第10,40,80 d时,复合污染处理的地上生物量最小,较未污染处理分别降低了34.68%,45.42%,58.05%。80 d时,重金属污染处理、石油污染处理和石油重金属复合污染处理的黑麦草叶绿素含量显著低于未污染处理,分别降低了26.84%,44.82%和47.02%。[结论] 不同污染物都可以促进黑麦草根系形态发育,降低黑麦草的生物量及色素含量;石油重金属复合处理对黑麦草的生长影响最大,石油污染处理次之。基于不同污染物对黑麦草根系形态及生长影响的差异,在今后植物修复土壤污染过程中,可添加一些生长调节物质来缓解污染对植物的毒害作用,提高植物生物量及增强相关生理功能,提升污染土壤修复效果。     

Effect of different forms and sources of arsenic on crop yield and arsenic concentration

Two greenhouse experiments were conducted to investigate the effects of different sources of As application on the yield of ryegrass (Lolium perenne L.) and barley (Hordeum vulgare L.) and the arsenic concentration in crop tissue. The soils used were a sand and a loam soil. In the first experiment (3 yr), As was applied either as sodium arsenite or as disodium hydrogen arsenate at the rate of 0, 2, 10, 50, and 250 mg As kg^?1 soil in year 1. In years 2 and 3, only the residual effect of As applied in year 1 was investigated. In the second experiment (5 yr), a NPK(16-7-12) fertilizer containing 10, 100 and 3000 mg As kg^?1 as sodium arsenite was applied at rates of 750 and 600 mg kg^?1 to ryegrass and barley, respectively, with lime and without lime. Arsenite had more inhibitory effect on crop yield than arsenate. Although the residual effect persisted up to year 3, it was found to be dependent on As application rate, soil type, and crop species. Only minor differences in As concentration in crops between arsenite and arsenate sources were observed. The yield reduction and the increase of As concentration in crops was highly related to As application rates. The As rates of 50 and 250 mg As kg^?1 resulted in significant yield reduction and marked increase of As concentration in both crops and these rates could be considered as critical for both crops. The application of As containing fertilizer had little or no effect on crop yield. The As concentration in both crops was little affected by the fertilizer containing up to 100 mg As kg^?1 but the concentration increased several folds when the fertilizer containing 3000 mg As kg^?1 was applied. The application of additional P to the treatment containing 3000 mg As kg^?1 fertilizer only slightly increased crop yields but it increased As concentration in ryegrass markedly. The repeated application of As containing fertilizer up to a period of 5 yr, even at 3000 mg As kg^?1 level, generally did not affect either the yields or the As concentration in both crops although a slight increase of As concentration in barley grain over the years was observed. In both experiments, the yield reduction and the increase in As concentration in crop tissue were lower in the loam soil than in the sand and barley straw cointained much higher As than barley grains, indicating that greater proportion of the As taken up by this crop was retained in the vegetative organs.     

水稻品种和砷污染对土壤溶解性有机碳氮的影响

选取有机质含量和pH不同的2种水稻土(黄泥田和红泥田),通过盆栽实验研究砷(As)污染条件下,种植9个水稻品种对土壤溶解性有机碳(DOC)和溶解性有机氮(DON)含量的影响,分析水稻品种、As污染和土壤类型的相对影响与交互作用.结果表明,水稻品种显著影响了土壤DOC和DON的变化,在水稻收获后,DOC平均含量的大小顺序为杂交稻(41.09±0.92 mg kg-1)＞籼稻(38.10±1.53 mg kg-1)＞粳稻(37.74± 1.37 mg kg-1);DON平均含量的大小顺序为粳稻(2.94± 0.40 mg kg-1)＞杂交稻(2.61±0.42 mg kg-1)＞籼稻(1.45± 0.17 mg kg-1).As污染降低了土壤DOC和DON的含量,但不同品种水稻的响应不同.与对照相比,As污染条件下,黄泥田和红泥田中DOC平均含量分别下降了14.4％和11.1％,DON平均含量分别下降了65.0％和44.7％;DOC在种植杂交稻后降幅最小,而DON在种植籼稻后降幅最小.在两种水稻土中,黄泥田的DOC和DON平均含量高于红泥田,在没有As污染条件下,分别高22.4％和45.8％,这与黄泥田有机质含量和pH高有关.水稻品种、As污染和土壤类型对DOC和DON变化的影响不同,3个因子对DOC变化的相对贡献率分别为7.7％、15.5％和27.6％,对DON变化的相对贡献率分别为14.7％、24.2％和2.0％.     

Residues of organochlorine pesticides in fish from the Arabian Gulf

High-resolution electron capture gas chromatography was used to determine residue levels of organochlorine pesticides in 13 commercially important fish species collected from the NW Arabian Gulf. While most of the residues were below the detection limit of 1 μg kg^?1 wet weight, relatively low concentrations of ΣDDT, endrin and dieldrin were detected in the edbile tissue of these fishes. The ΣDDT residue levels ranged from 2 to l 1μg kg^?1 wet weight, endrin ranged from none detected (nd) to 45 μg kg^?1 and dieldrin from nd to 5 μg kg^?1. A definite correlation was established between total organochlorine pesticide residues and lipid content (r = 0.6) for the NW Arabian Gulf fishes. Comparison with fish from Hor-al-Hammar Lake (an area that used to be sprayed with pesticides) has shown that the latter contained significantly higher residue levels. The ΣDDT residue levels ranged from 5 to 45 μg kg^?1 wet weight, endrin from 3 to 83 μg kg^?1 and dieldrin from nd to 4 μg kg^?1 Based upon the observation that the original DDT (p, p′-DDT) was identified in the NW Arabian Gulf fishes, it has been concluded that there was a recent input of DDT to this region. Since DDT application has been banned in Iraq, consequently it was assumed that DDT must originate from a more remote source.     

Effects of a New-Type Cleaning Agent and a Plant Growth Regulator on Phytoextraction of Cadmium from a Contaminated Soil

In China, great efforts are being made to remediate farmlands polluted by heavy metals. In this study, a soil pot experiment was conducted to examine the effects of a new-type cleaning agent, methylglycinediacetic acid(MGDA), and a plant growth regulator(PGR), diethl aminoethyl hexanoate(DA-6), on plant growth and extraction and detoxification of cadmium(Cd) by ryegrass. The results showed that foliar spray of DA-6 alone improved plant growth, with root length and shoot dry biomass increased by 38.5%–58.6% and 71.1%–89.3%, respectively, whereas addition of MGDA alone decreased root length and shoot dry biomass by 10.3%–18.6%and 9.1%–21.8%, respectively. Diethl aminoethyl hexanoate promoted the binding of Cd to cell walls and thus alleviated the toxicity of Cd and/or MGDA to plants. Applications of DA-6 and/or MGDA resulted in a significant increase in Cd extraction efficiency(P 0.05), and the efficiency decreased in the order of MGDA + DA-6 DA-6 MGDA. The treatment of MGDA + DA-6 achieved 2.2%, 1.7%, and 0.8% Cd extraction efficiency by ryegrass in soils spiked with 25, 50, 100 mg Cd kg~(-1), respectively. Therefore,treatment of MGDA + DA-6 could be an efficient method for enhancing phytoremediation of Cd-contaminated soil by ryegrass.     

Co-remediation of DDT-contaminated soil using white rot fungi and laccase extract from white rot fungi

Purpose

2,2-Bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT), one of the most widely used organochlorine pesticides in soil, was banned in the 1970s for agricultural use because of its detrimental impacts on wildlife and harmful effects on human health via the food chain. However, high levels of DDT are frequently detected in agricultural soils in China. Considering this situation, this study investigated the use of white rot fungi and laccase derived from white rot fungi to co-remediate DDT-contaminated soil.

Materials and methods

A culture of white rot fungi was used to inoculate soil samples and also to extract laccase from. Soil was contaminated with four components of DDT (p,p′-DDE, o,p′-DDT, p,p′-DDD, and p,p′-DDT). Individual DDT components and the sum of the DDT components (p,p′-DDE, o,p′-DDT, p,p′-DDD, and p,p′-DDT—collectively referred to as DDTs) were both analyzed by GC at various stages during the incubation period. The efficacy of co-remediating DDT-contaminated soil using white rot fungi and laccase was tested by investigating how degradation varied with varying amounts of white rot fungi, sterilizing soil, temperature, soil pH, concentrations of DDT, and concentration of the heavy metal ion Cd²⁺.

Results and discussion

“”It was concluded that the reduction of DDTs in soil using white rot fungi and laccase was higher than reduction using only white rot fungi or laccase by nearly 14 and 16 %, respectively. Five milliliters fungi per 15 g soil and 6 U laccase per gram soil were the optimal application rates for remediation, as shown by a reduction in DDTs of 66.82 %. The difference in the reduction of individual DDT components and DDTs between natural and sterilized soils was insignificant. The optimal temperature and pH in the study were 28 °C and 4.5, respectively. In addition, reduction of individual DDT components and DDTs increased with increasing concentrations of DDT and decreased with increasing concentrations of Cd²⁺.

Conclusions

Compared with the remediation of DDT using only white rot fungi or laccase, the co-remediation of DDT using white rot fungi and laccase degraded DDT in soil more rapidly and efficiently; the highest reduction of DDTs was 66.82 %.