一个新的土壤重金属竞争吸附等温模型

A new competitive adsorption isothermal model (CAIM) was developed for the coexistent and competitive binding of heavy metals to the soil surface. This model extended the earlier adsorption isothermal models by considering more than one kind of ion adsorption on the soil surface. It was compared with the Langmuir model using different conditions, and it was found that CAIM, which was suitable for competitive ion adsorption at the soil solid-liquid surface, had more advantages than the Langmuir model. The new competitive adsorption isothermal model was used to fit the data of heavy metal (Zn and Cd) competitive adsorption by a yellow soil at two temperatures. The results showed that CAIM was appropriate for the competitive adsorption of heavy metals on the soil surface at different temperatures. The fitted parameters of CAIM had explicit physical meaning. The model allowed for the calculation of the standard molar Gibbs free energy change, the standard molar enthalpy change, and the standard molar entropy change of the competitive adsorption of the heavy metals, Zn and Cd, by the yellow soil at two temperatures using the thermodynamic equilibrium constants.     

土壤电动修复中电极切换对土壤微生物群落的影响

通过细菌计数和Biolog方法,研究了在3.0V·cm^-1的电压梯度下,不同电场切换周期（24h、5h、10min和1min）对土壤微生物群落的影响。结果表明,电压梯度为3.0V·cm^-1的电场作用能够促进土壤微生物的活性,但会轻微地降低土壤微生物功能多样性,电场切换不能改变这种电场对微生物群落的影响;长时间的电场处理下,电极反应对微生物数量和功能多样性损害严重,切换电场电极能有效消除电极效应,电场电极切换周期≤5h时,可保护电极附近土壤微生物多样性,当切换周期≤10min时,不仅可保护土壤微生物多样性,而且可以保护微生物数量。研究结果说明了电场电极切换能有效降低电极反应对微生物群落的影响,揭示了电场电极切换对土壤微生物群落影响的规律,为电场电极切换方法在污染土壤电动强化生物修复技术中的深化和应用提供理论依据。     

Microbial remediation of a pentachloronitrobenzene-contaminated soil under Panax notoginseng: A field experiment

Pentachloronitrobenzene (PCNB) is an organochlorine fungicide that is mainly used in the prevention and control of diseases in crop seedlings. Microbial removal is used as a promising method for in-situ removal of many organic pesticides and pesticide residues. A short-term field experiment (1 year) was conducted to explore the potential role of a PCNB-degrading bacterial isolate, Cupriavidus sp. YNS-85, in the remediation of a PCNB-contaminated soil on which Panax notoginseng was grown. The following three treatments were used:i) control soil amended with wheat bran but without YNS-85, ii) soil with 0.15 kg m^-2 of solid bacterial inoculum (A), and iii) soil with 0.30 kg m^-2 of solid bacterial inoculum (B). The removal of soil PCNB during the microbial remediation was monitored using gas chromatography. Soil catalase and fluorescein diacetate (FDA) esterase activities were determined using spectrophotometry. In addition, cultivable bacteria, fungi, and actinomycetes were counted by plating serial dilutions, and the microbial biodiversity of the soil was analyzed using BIOLOG. After 1 year of in-situ remediation, the soil PCNB concentrations decreased significantly by 50.3% and 74.2% in treatments A and B, respectively, when compared with the uninoculated control. The soil catalase activity decreased in the presence of the bacterial isolate, the FDA esterase activity decreased in treatment A, but increased in treatment B. No significant changes in plant biomass, diversity of the soil microbial community, or physicochemical properties of the soil were observed between the control and inoculated groups (P<0.05). The results indicate that Cupriavidus sp. YNS-85 is a potential candidate for the remediation of PCNB-contaminated soils under P. notoginseng.     

生物化学复合防腐剂在橙汁防腐保鲜中的协同增效作用

该文以天然生物防腐剂乳酸链球菌素(Nisin)、化学防腐剂山梨酸钾、乙二胺四乙酸(EDTA)以及食品抗氧化剂异Vc钠为原料,对通过复配后得到的各组复合型防腐剂在橙汁保鲜中的协同增效作用进行研究,并且与单一的防腐剂保鲜效果进行比较,得出一组适合在橙汁中使用的高效复合型防腐剂。结果表明,上述各种抑菌剂单独使用时均不能完全抑制橙汁中微生物的生长;正交试验结果表明,当选择0.05 g/kg Nisin、0.1 g/kg山梨酸钾、0.01 g/kg异Vc钠、0.03 g/kg EDTA作为复配型抑菌剂的最佳添加配比时,能显著地抑制橙汁中微生物的生长,第14、17、21 d对菌落总数的抑制率分别达到99.9%、99.9%和99.6%,其抑菌效果显著优于单一防腐剂的抑菌效果。因此,Nisin与三者复合使用时具有协同增效性,该复合防腐剂添加至橙汁中可起到良好的防腐保鲜效果。     

利用生物活性污染物剥离技术修复Hg污染的工业土壤

The method to remove bioavailable amounts of heavy metals from a contaminated soil by using plants is defined as bioavailable contaminant stripping (BCS) and could safely be applied if the soil’s long-term ability to replenish the bioavailable pool is known. The aim of this study was to evaluate the ability of three common plant species selected, Brassica juncea, Poa annua, and Helianthus annus, to remove bioavailable amounts of mercury (Hg) from a contaminated industrial soil containing 15.1 mg kg-1 Hg. Trials were carried out under greenhouse conditions using pots (mesocosms). According to the precautionary principle, we modified the BCS remediation approach by adding a new step, in which mercury bioavailability was increased by the addition of a strong mobilizing agent, ammonium thiosulphate, (NH 4 ) 2 S 2 O 3 , to obtain an estimate of the likely long-term bioavailable Hg pool. The modified BCS remediation approach was called enhanced bioavailable contaminant stripping (EBCS). After one growth cycle, nearly all the bioavailable mercury (95.7%) was removed and the metal remaining in the soil was considered inert since it was neither extractable by (NH 4 ) 2 S 2 O 3 nor taken up by plants during a second growth cycle. The results demonstrated that EBCS appeared promising since it removed the most dangerous metal forms while substantially shortening the cleanup time.     

硫酸根自由基高级氧化技术对污染场地多环芳烃的修复效果研究

硫酸根自由基高级氧化技术(sulfate radical(SO₄^·–)based advanced oxidation processes,SR-AOPs)是一种被广泛应用于降解土壤有机污染物的原位氧化修复技术。然而,关于SR-AOPs降解土壤多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的报道相对较少。本研究以南京某炼钢厂附近土壤作为试验样本,通过设置不同比例混合体系的过硫酸钠(Na₂S₂O₈)和亚铁离子(Fe²⁺)以及反应不同时间,探究SR-AOPs对土壤中16种PAHs的修复效果以及最佳技术方案。结果表明:Na₂S₂O₈和Fe²⁺的配比会显著影响土壤PAHs的降解效果,当两者比例达到10︰1时,即Na₂S₂O₈用量为5 mmol/g,Fe²⁺     

Microbial dynamics and natural remediation patterns of Fusarium‐infested watermelon soil under 3‐yr of continuous fallow condition

Long‐term monoculture of watermelon results in inhibited growth and decreased crop yields, possibly because of imbalance in microbial ecology caused by accumulation of the pathogen in soil. This results in serious problems in the economics of watermelon production. We investigated the build‐up of Fusarium in soil under watermelon cultivation and changes over 3 yr of fallow in a microcosm. We focused on changes in the microbial community of Fusarium‐infected soil, including the diversity of the microfloral species composition, and species abundance. Long‐term monoculture of watermelon leads to changes in microbial diversity and community structure. The microbes most readily cultured from infested soil were suppressed by watermelon wilt pathogen Fusarium oxysporum f. sp. niveum (FON). Of 52 isolated and identified culturable microbes, 83.3% of bacteria, 85.7% of actinomycetes, 31.6% of fungi and 20.0% of Fusarium sp. were inhibited by FON on bioassay plates. Prior to fallowing, infested soil was a transformed ‘fungus‐type’ soil. After 3 yr of fallow, the infested soil had remediated naturally, and soil microbial diversity recovered considerably. Abundance of dominant bacterial populations was increased by 118–177%, actinomycetes, fungi and FON were decreased by 23–32, 33–37 and 50%, respectively. The ratio of bacteria: actnomycetes: fungus: Fusarium sp. in infested soil changed from 24 000:100:4:1 prior to fallow to 57 000:100:3.5:1 after fallowing, nearer to the 560 000:400:8:1 ratio of healthy soil not used for watermelon cultivation. This suggests the ‘fungus‐type’ soil was converting to ‘bacteria‐type’ soil and that disrupted microbial communities in infested soil were restored during fallow.     

Evaluation of immobilizing agents as soil quality conditioners in addition to their metal(loid) immobilizing effect

In trace metal (TM)-contaminated agricultural soils, management of TM availability is important for safe crop production. In addition, maintenance or improvement of soil quality is vital for sustainable crop cultivation. Decreased TM phytoavailability and increased soil quality can be achieved by the application of various immobilizing agents to soil, which can supply both macronutrients and organic matter. This study investigated the long-term influences of four common immobilizing agents on so...     

Growth,Cadmium and Zinc Accumulation of Ornamental Sunflower(Helianthus annuus L.)in Contaminated Soil with Different Amendments

Use of ornamental plants for phytoremediation of metal-contaminated soil is a new option. A pot experiment was carried out to assess the effect of application of amendments, i.e., swine manure, salicylic acid (SA) and potassium chloride (KCl), on the growth, uptake and translocation of cadmium (Cd) and zinc (Zn) of ornamental sunflower (Helianthus annuus L.) grown on a contaminated soil. The three amendments increased sunflower height, flower diameter, and biomass. Manure significantly decreased Cd and Zn concentrations in sunflower, and thus decreased the bioaccumulation coeffcient (BCF) of Cd and Zn. However, using of KCl markedly increased Cd concentrations in sunflower and the BCF of Cd. Additionally, both swine manure and KCl application increased Cd and Zn translocation from root to aboveground part. Swine manure and salicylic acid reduced the Cd/Zn ratios in flower of sunflower, while KCl significantly increased the Cd/Zn ratios. Correlation analysis demonstrated that the Cd/Zn ratio in the root of sunflower was affected by K/Na ratio in root and soil available potassium (K) concentration. Ornamental sunflower could be grown as an alternative plant in the Cd- and Zn-contaminated soil with KCl application to get the balance between environmental and economic interests.     

有机肥和化肥配施对黑土有机氮形态组成及分布的影响

研究了长期定位施用有机肥和化肥对黑土中有机氮各组分含量及其在土壤各层次中分布的影响。结果表明,在耕层土壤中,常量氮磷钾和倍量有机肥配施,有机氮中铵态氮、氨基酸态氮和氨基糖态氮含量最高,各组分含量在不同肥料处理中的顺序是酸不溶氮>氨基酸态氮>铵态氮>酸解未知氮>氨基糖态氮。不同施肥处理有机氮各组分含量随着土层的加深而下降,与有机质的变化规律一致;不同土层的C/N比值在9.03～12.49之间变动。