贵州省典型矿区土壤重金属污染对蚯蚓的毒性效应评估

选取我国贵州省某矿区典型的重金属复合污染土壤开展28 d慢性毒性暴露试验,以蚯蚓体内2种抗氧化酶活性——过氧化氢酶(CAT)和超氧化物歧化酶(SOD)、8-羟基脱氧鸟苷(8-ODHG)和金属硫蛋白(MT)含量为生物指标,评估了以上生物指标与土壤重金属含量的相关性,探讨该研究方法用于矿区土壤重金属生态风险评估的可行性。结果表明,CAT和SOD在暴露周期内均出现先诱导后抑制的动态响应过程,表明蚯蚓通过提高CAT和SOD的活性来清除机体因污染胁迫而产生的自由基,以适应环境变化,在毒性缓解后,蚯蚓体内代谢产物的积累抑制了抗氧化氢酶活性,CAT和SOD活性下降并趋于稳定。暴露于重金属污染亚致死浓度时,蚯蚓体内的8-OHDG含量随着暴露时间的延长显著降低,随着暴露浓度的增加,损伤存在由低到高的转变。在28 d暴露周期内,蚯蚓体内MT在重金属胁迫下发挥了解毒作用,MT含量在蚯蚓暴露后第7天增加,随后逐渐降低。本文基于生物毒性试验综合评估了矿区典型重金属污染土壤的生态风险,研究结果对指导重金属复合污染土壤的修复与再利用具有重要意义。     

丛枝菌根真菌(AMF)对铯胁迫宿根高粱生长及根际土壤酶的影响

通过盆栽试验研究了接种透光球囊霉(Glomus diaphanum)、摩西球囊霉(Glomus mosseae)、地表球囊霉(Glomus versiforme)及幼套球囊霉(Glomus etunicatum)等4种丛枝菌根真菌(AMF)对铯污染下宿根高粱生长及根际土壤酶活性的影响.结果表明,与未接种对照相比,接种AMF处理均显著增加了宿根高粱的株高和根长,同时增强了过氧化氢酶、蔗糖酶活性及根系活力(P0.05),且以接种G.etunicatum增强效果最好,上述酶活性和根系活力分别相当于对照的1.11、2.25和4.04倍,而接种Glomus diaphanum最显著增强了酸性磷酸酶活性,使其提高了24.53 mg·g-1·d-1·FW(P0.05),宿根高粱对铯的耐性指数均高于对照,说明AMF在一定程度上能缓解铯污染胁迫对根际土壤酶的抑制作用,进而减轻核素铯对植物的毒害;接种AMF处理显著抑制了脲酶活性,表明脲酶可作为反应土壤核素铯污染的一个有效指标.同时也表明AMF有效地增强了宿根高粱对核素铯的耐性能力.     

Evaluation of various tests for the diagnosis of soil contamination by 2,4,5-trichlorophenol (2,4,5-TCP)

Soil response to contamination with 2,4,5-triclorophenol was studied to test the validity of the concept of Generic Reference Levels (GRL), the main criterion used to define soil contamination. Soil samples were artificially contaminated with doses between 0 and 5000 mg kg⁻¹ of 2,4,5-triclorophenol, and analysed by various tests. Where possible, the response of soils to the contaminant was modelled by a sigmoidal dose-response curve in order to estimate the ED₅₀ values. The tests provided different responses, but only microbial biomass-C and dehydrogenase and urease activities demonstrated soil deterioration in response to contamination. The results suggest that the diagnosis of soil contamination has been greatly simplified in the legislation by the provision of a single figure for each compound, and that the GRL concept could perhaps be substituted by measurement of ED₅₀ values, which better reflect the alteration of a soil due to the presence of a xenobiotic substance.     

Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl2 ranging from 0 to 500microM. High accumulation of cadmium was observed (12,320+/-2155microgg(-1) at 500microM CdCl2), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1microM CdCl2 (137+/-13.2% of the control) and its reduction to only 47.4+/-4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed.     

黑藻对十二烷基苯磺酸钠和多聚磷酸钠胁迫的响应

研究了在十二烷基苯磺酸钠(SDBS)和多聚磷酸钠(STPP)及其复合胁迫下,黑藻过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)活性变化及其耐受浓度.结果表明,POD活性随着处理浓度的增加而逐渐增大;CAT在低浓度胁迫时活性逐渐增加,在较高浓度胁迫时活性降低;实验初期(6h时),SOD活性逐渐升高,随着SDBS处理浓度的提高及时间延长,SOD活性下降,并且在8mg/L浓度处理72h,SOD失活.SDBS对黑藻SOD的抑制作用大于STPP.黑藻对SDBS的耐受浓度(8mg/L)明显小于STPP的耐受浓度(256mg/L).黑藻对SDBS和STPP复合胁迫的耐受浓度值为(32+64)mg/L.     

铜对夏腊梅种子萌发及抗氧化酶活性的影响

采用室内水培试验,研究不同浓度的外源铜处理对夏腊梅(Sinocalycanthus chinensis)种子萌发、根伸长抑制率、呼吸强度、丙二醛及抗氧化酶系统的影响.结果表明,(1)铜浓度与夏腊梅根伸长抑制率呈显著正相关(P＜0.01),但与萌发率相关性不显著.(2)铜处理对夏腊梅种子的过氧化物酶(POD EC1.11.1.7)具有激活效应,且随着铜浓度的增加激活效应逐渐增强.丙二醛(MDA)含量随铜浓度的增大先略降而后逐渐升高.对超氧化物歧化酶(SOD EC 1.15.1.1)和过氧化氢酶(CAT EC 1.11.1.6)存在胁迫初期低浓度下的激活效应,随着铜浓度的增加及胁迫时间的延长,表现为抑制效应,且随着铜浓度的增加抑制效应逐渐增强.     

卤代酚复合污染对鲤科金鱼的生化毒性效应研究

为探讨卤代酚复合污染对水生生物的联合毒性效应,探究较为可靠的检测方法,根据所选6种卤代酚化学结构的相似程度和48 h LC₅₀值,将其分为3组二元混合物进行急性暴露实验, 毒性单位比为1∶1,每组分2个浓度级别观察金鱼生物学行为的变化,同时检测金鱼肝脏中3种抗氧化酶(SOD,CAT和GSH-Px)活性以及酶活性影响率的变化. 结果表明:3组卤代酚对金鱼肝脏中3种抗氧化酶的酶活性影响率变化均有显著性差异(P<0.01);3种抗氧化酶中仅SOD在1/2LC₅₀剂量暴露组中均表现为明显升高的酶活性激活率或酶活性抑制率,提示SOD较适合作为卤代酚低浓度复合水污染情况监测的生物化学检测指标.      

Enzyme activity and microorganisms diversity in soil contaminated with the Boreal 58 WG herbicide

Next-generation herbicides are relatively safe when used properly, but the recommended rates are relatively low, which can lead to overdosing. This study evaluated the responses of soil-dwelling microorganisms and soil enzymes to contamination with the Boreal 58 WG herbicide. The analyzed product contains active ingredients flufenacet and isoxaflutole. All tests were performed under laboratory conditions. The analyzed material was sandy clay. Boreal 58 WG was introduced to soil in four doses. Soil without the addition of the herbicide served as the control. The soil was mixed with the tested herbicide, and its moisture content was maintained at 50% of capillary water capacity. Biochemical and microbiological analyses were performed on experimental days 0, 20, 40, 80 and 160. Accidental contamination of soil with the Boreal 58 WG herbicide led to a relatively minor imbalance in the soil microbiological and biochemical profile. The herbicide dose influenced dehydrogenase activity in only 0.84%, urease activity in 2.04%, β-glucosidase activity in 8.26%, catalase activity in 12.40%, arylsulfatase activity in 12.54%, acid phosphatase activity in 42.11%, numbers of organotrophic bacteria in 18.29%, actinomyces counts in 1.31% and fungi counts in 6.86%.     

重金属镉胁迫下氮磷对江蓠体内主要抗氧化酶活性的影响

以大型海藻细基江篱繁枝变种(Gracilaria tunuistipitata Var Liui)为实验材料,研究重金属Cd2+胁迫下,无机氮磷作用对藻体各类抗氧化酶类活性的影响,为进一步探索重金属和营养盐复合污染下江蓠对水体的修复能力奠定一定的理论基础.实验结果显示:适当浓度N、P(560 μmol/L、56 μmol/L)的添加能提高藻体内各主要抗氧化酶的活性,降低Cd2+对藻体的毒害作用.不加入N、P或加入过量的N、P(2 160 μmol/L、216 μmol/L)均会抑制藻体内各主要抗氧化酶的活性.从总体上看,同时加入N、P要比加入单一的营养盐更有利于提高藻体内各主要抗氧化酶的活性,增强藻体的抗氧化能力.     

Evaluation of antioxidant enzymes activities and identification of intermediate products during phytoremediation of an anionic dye (C. I. Acid Blue 92) by pennywort (Hydrocotyle vulgaris)

The potential of pennywort(Hydrocotyle vulgaris)for phytoremediation of C.I.Acid Blue 92(AB92)was evaluated.The efects of various experimental parameters including pH,temperature,dye concentration and plant weight on dye removal efciency were investigated.The results showed that the optimal condition for dye removal were pH 3.5 and temperature 25°C.Moreover,the absolute dye removal enhanced with increase in the initial dye concentration and plant weight.Pennywort showed the same removal efciency in repeated experiments(four runs)as that obtained from the first run(a 6-day period).Therefore,the ability of the plant in consecutive removal of AB92 confirmed the biodegradation process.Accordingly,a number of produced intermediate compounds were identified.The efect of treatment on photosynthesis and antioxidant defense system including superoxide dismutase,peroxidase and catalase in plant roots and leaves were evaluated.The results revealed a reduction in photosynthetic pigments content under dye treatments.Antioxidant enzyme responses showed marked variations with respect to the plant organ and dye concentration in the liquid medium.Overall,the increase in antioxidant enzyme activity under AB92 stress in the roots was much higher than that in the leaves.Nevertheless,no significant increase in malondialdehyde content was detected in roots or leaves,implying that the high efciency of antioxidant system in the elimination of reactive oxygen species.Based on these results,pennywort was founded to be a capable species for phytoremediation of AB92-contaminated water,may be efective for phytoremediation dye-contaminated polluted aquatic ecosystems.