氯酸钾对花生生长的毒害效应

氯酸盐是一类毒性强的氧化剂,曾被作为非选择性除草剂和脱叶剂大量施用,近年来,氯酸钾作为产期调控剂也在龙眼(Dimocarpus longan)反季节生产中大量应用。然而,氯酸根离子强氧化性对生物体有明显的毒害效应,其残留及次生污染物对水体和土壤环境也存在较强的污染效应。龙眼园通常间种花生(Arachis hypogaea),该文实验研究了氯酸钾和氯化钠对花生生长的毒害效应。结果表明,当浸种溶液的KClO₃浓度高于50 mg·L^-1时,花生种子的发芽率和胚根长度大大降低,幼芽的电解质渗漏率和过氧化氢酶活性显著升高;当土壤中KClO₃浓度高于50 mg·kg^-1时,会使花生幼苗叶片质膜透性增大,而硝酸还原酶活性、叶绿素含量和根系活力显著降低,氯酸钾的毒害效应远远超过氯化钠的盐害效应,高于50 mg·kg^-1的KClO₃还能使花生荚果期植株的光合速率、蒸腾速率、叶绿素含量、根系活力、生物量合成和根瘤菌的数量显著降低。结论是,土壤中的KClO₃浓度高于50 mg·kg^-1时,即会显著影响花生植株的正常生长。     

菱镁矿粉尘污染土壤机理及其植物修复

综述了菱镁矿粉尘对土壤的污染和植物的毒害作用机理,分析了镁粉尘污染土壤的改良途径,探讨了植物修复的可行性和关键技术.菱镁矿在开采、生产加工过程中产生的大量粉尘,主要成分为MgCO3和MgO,镁粉尘对土壤的污染和植物的毒害作用主要是通过碱化、板结土壤,以及使土壤中的水溶性钙、镁离子比例失调而造成的.虽然菱镁矿粉尘污染土壤的植物修复研究鲜见报道,但通过植物吸收、植物代谢和植物积累等作用去除土壤中的过量镁具有较强的可行性.     

四环素在土壤和水环境中的分布及其生态毒性与降解

四环素是新兴污染物PPCPs中的一种,因其在畜禽及水产养殖中的大量使用在环境中造成一定的残留,成为一个较突出的环境风险问题。概述了环境中四环素的来源,对微生物、动物及植物的生态毒性,在土壤及水体中的残留及降解等环境行为。认为,环境中四环素的含量既使在很高的情况下,其对动物和植物的直接毒害作用也是有限的,四环素在环境中长期残留产生的抗性基因问题,可能是一个重要的研究方向。     

龙眼对镉的吸收分布特性及耐性研究

以三年生可开花结果的盆栽松风本龙眼为试材,研究镉处理后龙眼体内镉含量变化及植株生长效应。结果表明,龙眼吸收的镉,大部分停留在根内,少量向地上的叶和果转移,各器官镉的含量依次为根> 叶> 果。龙眼对镉具有较强的耐性,即使土壤外加镉量达400 mg/kg,其植株外观也未出现明显的毒害症状,但果的镉含量已严重超标。     

铜胁迫对轮叶黑藻无菌苗生理代谢的影响

正随着工农业生产的发展,向环境中排放的重金属日趋增加,土壤、地表水、地下水受到的污染日趋严重。所谓重金属是指原子量大于铁或密度大于5.0 g/cm~3的金属,如汞、镉、铅、铜、镍、锌等,采矿、冶金、化工、石油、电镀等多种工业行业的生产废水均含有重金属元素。而重金属废水是对环境危害最严重和对人类危害最大的工业废水[1]。铜作为一种重要的高毒性重金属污染物,关于其对自然水体或模拟的人工水体毒害的研究国内已有一些报道[2-4]。沉水植物作为水体生态系统中行     

植物对锑的吸收和代谢及其毒性的研究进展

锑(Sb)是一种有毒致癌元素, 一些自然和人为因素已造成我国部分地区土壤、水体及农产品受到严重的锑污染。环境中高含量的锑不仅影响农作物生长、降低其产量, 如果通过食物链被人体大量吸收, 还会引起严重的健康问题。研究锑在植物体内的富集特征, 对于保护环境与人体健康具有重要的现实意义。该文对当前锑在环境中的含量、污染状况、植物对锑的吸收、代谢以及锑对植物的毒害作用等方面的研究现状进行了综述。同时建议今后应加强以下3方面的研究: (1) 锑在生物圈迁移与转化特征; (2) 植物对锑的吸收、转运和代谢机制及锑的毒害作用机理; (3) 锑污染土壤及水体的植物修复技术。     

微生物对砷的作用机理及利用真菌修复砷污染土壤的可行性

利用真菌修复砷污染土壤和水体具有很大的发展潜力,是环境科学领域研究的热点.环境中存在的砷虽然不能像有机污染物那样被微生物降解,但可以通过微生物对砷的氧化/还原、吸附/解吸、甲基化/去甲基化、沉淀/溶解等作用影响其生物有效性,从而达到降低环境中的砷毒害、修复砷污染环境的目的.本文阐述了微生物对砷的作用机理,综述了真菌对砷累积与挥发研究的最新进展,探讨了其在修复砷污染土壤方面的可行性,旨在为利用真菌来修复砷污染土壤提供理论依据.     

土壤生物与土壤污染研究前沿与展望

随着社会经济发展,人类生产活动对自然环境产生越来越广泛深刻的影响,土壤污染已成为危及生态系统稳定、农产品质量安全和人体健康的突出环境问题之一。重金属、有机污染化合物、病原菌及抗性基因等各类污染物大量进入土壤后,对土壤生物系统造成毒害作用,影响到土壤生态功能;另一方面,土壤生物如细菌、真菌、土壤动物等在一定程度上能够适应土壤污染,深刻影响着污染物在土壤中的迁移转化过程,在土壤污染修复中具有潜在重要作用。从土壤污染的生态毒理效应、土壤生物对土壤污染的响应与适应机制、污染土壤修复原理与技术等三方面综述了土壤生物与土壤污染相关研究前沿,展望了重点研究方向。     

农业土壤中邻苯二甲酸酯污染研究进展

由邻苯二甲酸酯(PAEs)引起的环境污染和食品安全问题已经引起全球性关注.我国既是邻苯二甲酸酯生产大国,又是消费大国,其环境污染问题不容忽视.本文综述了美国国家环保署所列出的6种优先控制PAEs污染物在我国农田土壤中的污染现状,分析了其来源,重点阐述了不同类型农作物对PAEs化合物的吸收累积特征及PAEs类污染物的生物毒害效应.我国多数地区农业土壤中PAEs的含量显著高于美国和欧洲等国家.大气沉降、农用薄膜、施用污泥和污水灌溉是我国农业土壤中PAEs的主要来源.不同作物对PAEs的吸收、累积和分配特征具有显著的差异性.PAEs不但影响土壤质量、作物生长和生理生化性质,而且具有生物累积效应.最后指出了当前研究中的不足及对今后研究的展望,建议扩大PAEs污染调查范围,深入揭示PAEs对农作物的毒害机理,重点研发PAEs污染土壤的原位修复技术.     

生物脱氮中工程纳米颗粒的毒害作用及减毒措施的研究进展

氮化合物在生命代谢过程中扮演着重要的角色,但过多的无机氮会导致水体恶化进而影响人类健康,生物脱氮技术可高效去除环境中的无机氮且不引起二次污染。随着工程纳米颗粒在生活中的广泛应用,导致其大量释放到土壤及水体中,极大地阻碍了废水处理中的生物脱氮过程,因此,微生物脱氮过程中工程纳米颗粒的毒害作用及减毒措施成了近年来的研究热点。阐述了工程纳米颗粒进入水环境的方式,系统分析了工程纳米颗粒对废水处理系统和生物脱氮过程的影响,详细说明了工程纳米颗粒对脱氮微生物的毒害作用、脱氮微生物的抵御机制及减毒措施,并对未来的研究趋势进行了展望。旨为提高工程纳米颗粒存在条件下的脱氮效率具有重要的理论指导意义,同时,可促进工程纳米颗粒对耐冷异养硝化和好氧反硝化菌的毒害及应激机制研究。     

SOME ORGANIC SUBSTANCES AND THE NITRIFYING BACTERIA

SUMMARY: The rate of nitrification in mixed cultures was not affected by the simultaneous decomposition of cellulose. No stimultion of the rate of nitrification was observed in cultures containing: culture filtrates, soil extract, thiamin, yeast extract, urine, or β-indolylacetic acid. These substances either had no effect or, in larger doses, delayed or stopped nitrification.
Peptone was toxic to the nitrifying bacteria. Potassium chlorate did not affect the oxidation of ammonia to nitrite, but stopped the oxidation of nitrite to nitrate in cultures, as it does in soil. M/25 sodium fluorides stopped the oxidation of ammonia to nitrite.     

药剂输液滴干对龙眼成花的影响

虹吸输液滴干技术作为一种新型的输液技术,能显著提高龙眼对调节剂的利用率。该研究利用虹吸输液滴干技术来研究氯酸钾与多效唑对龙眼成花的影响,同时探索从花芽生理分化期开始控制龙眼冲梢的方法。结果表明：氯酸钾输液滴干不但能够促使龙眼提早开花,而且能够提高其成花率、抽穗率、雌雄花比例与坐果率。不同品种龙眼对氯酸钾的敏感度不同,‘石硖’对氯酸钾最为敏感,但稳定性低;‘储良’对氯酸钾的敏感性低,但稳定度高;‘桂香’对氯酸钾的敏感性与稳定度居中。从整体上看,‘石硖’的处理效果最好,最佳处理次数为3次,每次施用7.5 L浓度为1 g·L-1的氯酸钾,处理后枝梢成花率、枝梢抽穗率、雌雄花比例、坐果率分别为53.67％、59.38％、16.01和19.58％。多效唑输液滴干对‘桂龙1号’的控梢效果显著,有效促进了龙眼成花,并以160 mg·L-1的多效唑溶液处理效果最佳,抽梢率为15.16％,抽穗率、雌花率、花穗长、花穗宽和坐果率分别为96.53％、10.36％、21.95 cm、12.96 cm和38.37％。药剂输液滴干技术施用氯酸钾和多效唑对于龙眼成花坐果有积极作用,该研究结果为实现高效、省工、环保的果园管理模式提供了借鉴。     

Comparative toxicity of nanoparticulate CuO and ZnO to soil bacterial communities

The increasing industrial application of metal oxide Engineered Nano-Particles (ENPs) is likely to increase their environmental release to soils. While the potential of metal oxide ENPs as environmental toxicants has been shown, lack of suitable control treatments have compromised the power of many previous assessments. We evaluated the ecotoxicity of ENP (nano) forms of Zn and Cu oxides in two different soils by measuring their ability to inhibit bacterial growth. We could show a direct acute toxicity of nano-CuO acting on soil bacteria while the macroparticulate (bulk) form of CuO was not toxic. In comparison, CuSO(4) was more toxic than either oxide form. Unlike Cu, all forms of Zn were toxic to soil bacteria, and the bulk-ZnO was more toxic than the nano-ZnO. The ZnSO(4) addition was not consistently more toxic than the oxide forms. Consistently, we found a tight link between the dissolved concentration of metal in solution and the inhibition of bacterial growth. The inconsistent toxicological response between soils could be explained by different resulting concentrations of metals in soil solution. Our findings suggested that the principal mechanism of toxicity was dissolution of metal oxides and sulphates into a metal ion form known to be highly toxic to bacteria, and not a direct effect of nano-sized particles acting on bacteria. We propose that integrated efforts toward directly assessing bioavailable metal concentrations are more valuable than spending resources to reassess ecotoxicology of ENPs separately from general metal toxicity.     

Enhanced Toluene Degradation Under Chlorate-Reducing Conditions by Bioaugmentation of Sand Columns with Chlorate- and Toluene-Degrading Enrichments

Chlorate was examined as a potential electron acceptor for enhancing toluene degradation. Most chlorate respiring bacteria (CRB) use nitrate as an electron acceptor, and toluene is known to be degraded under denitrifying conditions. Therefore, it was hypothesized that there would be bacteria that could degrade toluene using chlorate as an electron acceptor, and that chlorate could be used to stimulate toluene degradation. Repeated tests and different approaches in batch tests failed to produce an enrichment capable of toluene degradation supported by chlorate reduction. However, the addition of chlorate increased the overall rate of toluene degradation in bioaugmented columns that were fed chlorate vs. a control column. Toluene removal at an influent toluene concentration of 11 mg/L was 93±5%, which was larger by a factor of 1.95 than toluene removal in a nonbioaugmented control column. Following the discontinued feed of chlorate, toluene removal decreased to 69±4%, demonstrating that chlorate could be used to produce a 1.36-fold increase in toluene removal.     

Chlorate toxicity in Aspergillus nidulans. Studies of mutants altered in nitrate assimilation.

Summary It had previously been held that chlorate is not itself toxic, but is rendered toxic as a result of nitrate reductase-catalysed conversion to chlorite. This however cannot be the explanation of chlorate toxicity in Aspergillus nidulans, even though nitrate reductase is known to have chlorate reductase activity. Among other evidence against the classical theory for the mechanism of chlorate toxicity, is the finding that not all mutants lacking nitrate reductase are clorate resistant. Both chlorate-sensitive and resistant mutants lacking nitrate reductase, also lack chlorate reductase. Data is presented which implicates not only nitrate reductase but also the product of the nirA gene, a positive regulator gene for nitrate assimilation, in the mediation of chlorate toxicity. Alternative mechanisms for chlorate toxicity are considered. It is unlikely that chlorate toxicity results from the involvement of nitrate reductase and the nirA gene product in the regulation either of nitrite reductase, or of the pentose phosphate pathway. Although low pH has an effect similar to chlorate, chlorate is not likely to be toxic because it lowers the pH; low pH and chlorate may instead have similar effects. A possible explanation for chlorate toxicity is that it mimics nitrate in mediating, via nitrate reductase and the nirA gene product, a shut-down of nitrogen catabolism. As chlorate cannot act as a nitrogen source, nitrogen starvation ensures.     

Biodegradation and ecotoxicity of soil contaminated by pentachlorophenol applying bioaugmentation and addition of sorbents

Biodegradation of pentachlorophenol (PCP) in soil by autochthonous microorganisms and in soil bioaugmented by the bacterial strain Comamonas testosteroni CCM 7530 was studied. Subsequent addition of organomineral complex (OMC) or lignite as possible sorbents for PCP immobilization has been investigated as well. The OMC was prepared from humic acids (HAs) isolated from lignite by binding them onto zeolite. Biodegradation of PCP and number of colony forming units (CFUs) were determined in the three types of soil, Chernozem, Fluvisol, and Regosol, freshly spiked with PCP and amended separately with tested sorbents. The enhancing effect of sorbent addition and bioaugmentation on PCP biodegradation depended mainly on the soil type and the initial PCP concentration. Microbial activity resulted in biotransformation of PCP into certain toxic substances, probably lower chlorinated phenols that are more soluble than PCP, and therefore more toxic to present biota. Therefore, it was necessary to monitor soil ecotoxicity during biodegradation. Addition of the OMC resulted in a more significant decrease of soil toxicity in comparison with addition of lignite. Lignite and OMC appear to be good traps for PCP with potential application in remediation technology.     

川西亚高山森林土壤动物对杨树和箭竹凋落物分解过程中微生物群落的影响

为了解凋落物分解过程中碎屑食物链土壤动物与微生物的相互联系,本研究以川西亚高山森林杨树和箭竹凋落叶为对象,通过原位控制试验,于2016年4月至2018年4月采用磷脂脂肪酸(PLFAs)生物标记法,研究了土壤动物对两种凋落叶分解过程中微生物丰度、群落结构和多样性的影响.结果表明: 土壤动物的参与显著影响两个树种凋落叶分解过程中微生物PLFAs含量,降低了分解前240天的PLFAs含量,增加了分解360~480 d的PLFAs含量;土壤动物的参与降低了杨树分解过程中的真菌/细菌比值,增加了革兰氏阳性菌(G⁺)/革兰氏阴性菌(G^-)比值,对箭竹分解过程中真菌/细菌和G⁺/G^-比值的影响作用相反;两个树种凋落叶的微生物多样性和均匀性在分解的120 d和480 d维持着较高水平,在分解的360 d和720 d急剧降低,土壤动物的参与显著影响杨树凋落叶的微生物多样性和均匀性,但对箭竹影响不显著;土壤动物对凋落叶微生物PLFAs变化的影响随分解持续时间和树种变化存在差异.亚高山森林凋落物分解过程中土壤动物与微生物群落的相互作用随季节和树种变化具有变异性.     

A life cycle assessment study of a Canadian post-combustion carbon dioxide capture process system

Purpose

While carbon dioxide capture and storage (CCS) has been widely recognized as a useful technology for mitigating greenhouse gas emissions, it is necessary to evaluate the environmental performance of CCS from a full life cycle perspective to comprehensively understand its environmental impacts. The primary research objective is to conduct a study on life cycle assessment of the post-combustion carbon dioxide capture process based on data from SaskPower’s electricity generation station at the Boundary Dam in Saskatchewan, Canada. A secondary objective of this study is to identify the life cycle impact assessment (LCIA) methodology which is most suitable for the assessment of carbon dioxide capture technology integrated with the power generation system in the Canadian context.

Methods

The study takes a comparative approach by including three scenarios of carbon dioxide capture at the electricity generation station: no carbon dioxide capture (“no capture”), partial capture (“retrofit”), and fully integrated carbon dioxide capture of the entire facility (“capture”). The four LCIA methods of EDIP 97, CML2001, IMPACT2002+, and TRACI are used to convert existing inventory data into environmental impacts. The LCIA results from the four methods are compared and interpreted based on midpoint categories.

Results and discussion

The LCA results showed an increase in the retrofit and capture scenarios compared to the no capture scenario in the impact categories of eutrophication air, ecotoxicity water, ecotoxicity ground surface soil, eutrophication water, human health cancer ground surface soil, human health cancer water, human health noncancer ground surface soil, ozone depletion air, human health noncancer water, and ionizing radiation. The reductions were observed in the retrofit and capture scenarios in the impact categories of acidification, human health criteria air-point source, human health noncancer air, ecotoxicity air, global warming, human health cancer air, and respiratory effects.

Conclusions

Although the four LCIA methodologies significantly differ in terms of reference substances used for individual impact categories, all (TRACI, IMPACT2002+, CML2001, and EDIP 97) showed similar results in all impact categories.