重金属污染土壤几种生物修复方式比较

土壤重金属污染是全球普遍存在的问题,生物修复因其环境友好且成本效益高而得到广泛关注。但不同生物修复技术有其优势和局限性,充分了解每种修复技术的特点,才能更经济、有效地对污染土壤进行修复。本研究阐述对比了目前的土壤重金属生物修复方法,包括植物修复（植物挥发、植物固定和植物提取）、转基因植物提取、螯合辅助植物修复、微生物辅助植物修复等技术的机制、优势、局限性和适用性等方面的差异。综述提出有效的生物修复技术需要土壤化学、植物生物学、遗传学、微生物学和环境工程等多学科的有机结合。根据污染土壤的特点,结合具有相应改良特性的转基因植物,是实现污染土壤大面积修复的有效方法。同时,农艺措施对天然超级积累植物的生物量和重金属提取能力的刺激作用还需要进一步挖掘。植物修复可以与其他几种传统修复技术有效结合,利用转基因技术建立土壤+植物+微生物的组合是未来修复技术发展的最佳途径。     

Use of saline–sodic waters through phytoremediation of calcareous saline–sodic soils

Use of poor-quality groundwater has become inevitable for irrigation to compensate rapidly increasing water demands in many arid and semiarid regions. Salinity and sodicity are the principal soil and water quality concerns in such areas. Many saline–sodic and sodic soils have saline or saline–sodic subsurface drainage waters. Amelioration of these soils needs a source of calcium (Ca²⁺) that can replace the excess exchangeable sodium (Na⁺). Most of these soils, however, contain calcite (CaCO₃) of extremely low solubility. The native calcite does not supply adequate levels of Ca²⁺ for soil amelioration as do other chemical amendments. Phytoremediation may help ameliorate such soils through cultivation of certain crops tolerant to ambient soil salinity and sodicity. This amelioration strategy works through plant root action to help dissolve CaCO₃ to supply adequate Ca²⁺ without the application of an amendment. During a 3-year field experiment conducted under irrigated conditions, we evaluated phytoremediation against soil application of gypsum and farm manure, and water treatment with sulphuric acid on a calcareous saline–sodic soil (pH_s=8.0–8.4, EC_e=24–32 dS m⁻¹, SAR=57–78, CaCO₃=45–50 g kg⁻¹ for the top 0.15 m depth; Calcic Haplosalids). A saline–sodic water (EC=2.9–3.4 dS m⁻¹, SAR=12.0–19.4, RSC=4.6–10.0 mmol_c l⁻¹, SAR_adj=15.6–18.4) was used to irrigate the rice (Oryza sativa L.) and wheat (Triticum aestivum L.) crops grown in rotation. Active desalinisation and desodication processes were observed in all the treatments. After the final wheat crop, the 1.2 m soil profile EC_e was 7±0.5 dS m⁻¹ and SAR was 15±2 with non-significant treatment differences, indicating comparable soil amelioration effect of phytoremediation with other treatments. Better crop yields were obtained from the manure-treated plots, owing to its annual addition to the soil that possibly improved soil fertility. Phytoremediation needed minimum capital input because no initial investment was made to purchase the amendments.     

Induction and Transfer of Enhanced Biodegradation of the Herbicide Napropamide in Soils

In laboratory incubations, the times to 50% loss (DT₅₀) of a first application of napropamide were approximately 25, 45 and 75 days in soil incubated at 25, 15 and 5°C respectively. When treated for a second time, the DT₅₀ values were 4, 7 and 15 days at the same temperatures, irrespective of the temperature of the first incubation. This indicates that enhanced degradation of napropamide in soil can be both induced and expressed at low temperature. A mixed microbial culture able to degrade the herbicide to a single degradation product, identified by HPLC retention time as naphthoxypropionic acid, was obtained from a soil capable of rapid degradation. Addition of a sub-sample of this mixed culture to a previously untreated soil introduced rapid degrading ability. When small amounts of soil capable of rapid degradation were added to previously untreated soil, in both the laboratory and the field, the degradation rate of napropamide increased compared with that in unamended soils.     

不同工业大麻品种对田间5种重金属吸收积累特性的比较

为了分析不同工业大麻品种对不同重金属富集与转移的差异,以云南5个工业大麻主栽品种（ym1~ym5）为试验材料,修复云南矿区重金属污染严重的农田。结果表明： 5个工业大麻品种中,成熟期的根系对Pb和Cd吸收量最大的为ym1,对As、Cu和Zn吸收量最大的为ym3,而ym5对Pb、Cu、Cd和Zn吸收量皆最小;茎叶对As、Cu和Cd吸收量最大的为ym3,对Pb和Zn吸收量最大的分别为ym1和ym2;种子对Pb和Cd吸收量最大的为ym2,对As和Cu吸收量最大的为ym5,对Zn吸收量最大则为ym3,ym1种子对Pb、As和Cu吸收量皆最小,对Cd、Zn吸收最小的品种分别为ym4和ym2;5个品种表现为除Cu外,茎叶富集系数皆大于根,根系向茎叶的转运系数均大于1。研究表明,ym1可作为Pb污染修复植物,ym3可作为As、Zn、Cu和Cd污染修复的适推品种。     

耐镉阿氏芽孢杆菌缓解水稻受镉胁迫的研究

为了探究阿氏芽孢杆菌T61缓解水稻受镉胁迫的效应,运用96孔板法、电感耦合等离子体质谱法、比色法测定菌株T61的镉耐受性、镉去除率和植物促生性;利用绿色荧光蛋白标记的T61,观察菌株在水稻上的定殖;利用蘸根法施加T61菌剂,观察其降低水稻籽粒镉积累的效应。结果表明：菌株T61对Cd²⁺的最大耐受浓度达到500 μmol·L^-1;在含镉液体培养基中培养24 h后,菌株T61对Cd²⁺的去除率超过50%。菌株T61可以合成植物促生性物质吲哚乙酸（6.2 μg·mL^-1）和铁载体（46.6 μmol·L^-1）,并具有溶磷能力（37.1 μg·mL^-1）。菌株T61可以在水稻根和茎上定殖。大田条件下,T61菌剂可以降低营养期水稻茎叶丙二醛含量和抗氧化酶活性,并使水稻728B和NX1B籽粒中的镉含量分别降低13.5%和11.2%。研究表明,阿氏芽孢杆菌T61是一株具有植物促生性的耐镉细菌,可以缓解某些水稻品种遭受的镉胁迫,在镉污染稻田的微生物修复方面具有一定的应用前景。     

Survival and growth of the sea cucumber Holothuria leucospilota Brandt: a comparison between suspended and bottom cultures in a subtropical fish farm during summer

The feasibility of co‐culturing the sea cucumber Holothuria leucospilota Brandt in a subtropical fish farm was investigated in a field study. Sea cucumbers were cultured in the fish farm in cages suspended at 4 m deep (suspended culture) and directly on the seafloor (bottom culture). The survival and growth of the sea cucumbers were monitored twice during the 3‐month, summer experimental period (May 26–August 14, 2010). Results showed that the suspension‐cultured sea cucumbers exhibited excellent survival rate (100%) during the whole study period. There also occurred no mortality in the bottom‐cultured sea cucumbers during the first culture period (May 26–July 13); but all these died from anoxia caused by water column stratification during the second culture period (July 14–August 14). The specific growth rate of the bottom‐cultured sea cucumbers (1.05 ± 0.21 % day^?1) was nearly double that of the suspended culture animals (0.57 ± 0.21 % day^?1) during the first culture period, and the growth rates of the suspended culture sea cucumbers in the second culture periods (0.46 ± 0.24 % day^?1) was only a little lower than that of the first period. The sea cucumbers H. leucospilota could ingest and assimilate sediment with high organic matter content with an average assimilation efficiency of 14.9 ± 3.9%. This study indicated that fish farm detritus can be effectively used as a food source for the sea cucumber and that it can be turned into a valuable secondary crop in the form of the sea cucumber biomass.     

海水网箱养殖对近岸环境影响的研究进展

近年来,我国的海水网箱养殖业发展迅猛,已成为我国渔业新兴产业的生力军。海水网箱养殖系统作为一种高密度、高投饵的人工养殖生态系统,其输出的废物,残饵、代谢及排泄废物等是引发环境问题的主要污染源,再加上网箱养殖区布局不合理,通常设在水交换率较低的内湾,当养殖容量超出了海域的环境容量,就会引发一系列生态环境问题[1]。本文就海水网箱养殖对环境污染及防治的研究进展进行综述,并提出今后的重点研究方向。1养殖区水质污染网箱养殖对浅海生态系统的影响主要表现为养殖水域营养负荷增加[2]。一般来说,鲑鳟鱼类的网箱养殖,饲料中总氮的…     

大型藻类在综合海水养殖系统中的生物修复作用

减少水产养殖自身对环境的负面影响是维持水产业持续健康发展的关键所在。大型藻类生物滤器可以有效地吸收、利用养殖环境中多余的营养物质，从而减轻养殖废水对环境的影响，并提高养殖系统的经济输出，被广泛应用于鱼、虾和贝类等的综合养殖系统中，是控制水体富营养化、增进食品安全和对污染水体进行生物修复的有效措施之一。本研究概述了大型藻类生物滤器用于养殖废水生物修复和环境控制的原理、依据、研究现状、修复效果以及应用大型藻类生物滤器产生的效益和存在的问题。     

石油烃类污染物降解动力学和微生物群落多样性分析

为了探讨不同初始浓度石油污染土壤堆腐化修复机制,以石油降解菌剂和腐熟鸡粪为调理剂,研究了初始浓度分别为5 000(T1)、10 000(T2)和50 000 mg/kg(T3)的石油污染土壤堆腐化修复过程石油烃类污染物降解动力学特征和微生物群落多样性。结果表明:堆腐化修复过程石油烃类污染物降解符合一级反应动力学,反应常数分别为0.012、0.094和0.050 d-1,半衰期分别为6.79、7.37和13.86 d。整个堆腐过程石油烃类污染物平均降解速率分别为112.08、230.05和887.93 mg/(kg·d)。3个处理的孔平均颜色变化率(average well color development)和碳源利用率(除芳香烃类化合物外)随堆腐进程的推进逐渐升高,在堆腐中、后期达到最大,T3处理显著高于T1、T2处理。多聚物类和糖类代谢群是堆腐体系中的优势菌群。主成分分析表明3个处理的微生物群落差异显著(除第9天外),起分异作用的碳源主要是糖类和羧酸类。微生物群落的丰富度指数和均一度指数随堆腐进程的推进逐渐升高并在堆腐后期达到最大,与T1处理相比,T3处理分别高了0.21%和17.64%,差异达到显著水平(P0.05)。微生物群落优势度指数在中期达到最大,T1处理分别比T2、T3处理高2.12%和9.44%,3个处理间差异不显著(P0.05)。堆肥结束时3个处理的种子发芽指数(seed germination index,SGI)分别比堆腐初期提高了18.26%、20.42%和36.41%。该研究结果为黄土高原不同程度石油污染土壤堆腐化修复的应用提供参考依据和理论基础。     

反硝化技术对模拟养殖池塘修复的研究

浙江奉化市池塘的底泥经过反复培养、驯化,从中筛选、分离出反硝化细菌,在模拟实验条件下,研究其对不同浓度的硝酸盐氮和亚硝酸盐氮的去除情况,讨论反硝化菌种的生长情况。结果表明,在初始浓度为1、25、50mg·L^-1的硝酸盐氮和亚硝酸盐氮模拟池塘中,随着实验的进行,对污染物的去除效果逐渐提高。其中在1mg·L^-1的浓度组中,3d内硝酸盐氮和亚硝酸盐氮去除率就分别达到了95．8％和90．2％;在25mg·L^-1的浓度组中,第6d硝酸盐氮和亚硝酸盐的去除率分别为93．8％和87．8％;在50mg·L^-1的浓度组中,第6d硝酸盐氮和亚硝酸盐的去除率分别为89．7％和78．7％。此外,反硝化菌对硝酸盐氮的去除效果略优于亚硝酸盐氮,而且硝酸盐氮和亚硝酸盐氮的浓度越低,对其去除效果越好,达到稳定状态的时间越短。在模拟池塘中,菌种的生长情况与硝酸盐氮和亚硝酸盐氮的浓度呈负相关,即污染物的浓度越高反硝化菌的生长情况越差。对反硝化菌的生态影响因子研究表明,其反硝化最适宜的pH值为6～7,温度为25～35℃;而且在同一pH值和温度条件下,硝酸盐氮和亚硝酸盐氮浓度越低,反硝化菌对其去除效果越好。