Effects of salinity on soil bacterial and archaeal community in estuarine wetlands and its implications for carbon sequestration: verification in the Yellow River Delta

Soils from two typical tidal salt marshes with varied salinity in the Yellow River Delta wetland were analysed to determine possible effects of salinity on soil carbon sequestration through changes in soil microbiology. The mean soil respiration (SR) of the salt water–fresh water mixing zone (MZ) was 2.89 times higher than that of the coastal zone (CZ) (4.73 and 1.63?μmol?m^?2?s^?1, respectively, p?Pseudomonas sp. and Limnobacter sp. that might have led to its higher dehydrogenase activity and respiratory rates. Additionally, the CZ possessed more Halobacteria and Thaumarchaeota with the ability to fix CO₂ than the MZ. Significantly lower soil salinity in MZ (4.25?g?kg^?1) was suitable for β-Proteobacteria, but detrimental for Halobacteria compared with CZ (7.09?g?kg^?1, p?相似文献   

气相抽提去除红壤中挥发性有机污染物的去污机理探讨

通过探讨土壤气相抽提去除红壤中挥发性有机污染物的去污机理,建立了一维稳态条件下污染物在土壤多孔介质中传质的总微分方程,分别求出了平衡模型和动力学模型的解析解和数值解,并用实验结果对平衡模型和动力学模型进行了模拟和验证.实验结果和模型模拟结果表明理论模型与实验结果吻合良好,平衡模型和动力学模型在描述污染物在土柱通风过程中的传质时,分别适用于不同的阶段.在通风初期平衡模型能够很好地描述实验结果,而随着时间的推移,平衡模型的预测曲线逐渐偏离数据点,到了通风中后期,只有动力学模型才能够较好地描述和预测实验结果.     

生活垃圾填埋场封场后种植植物中重金属迁移研究

在上海老港生活垃圾填埋场填埋单元封场的覆盖土中掺混了矿化垃圾种植植物,分析Cd、Pb、Cu、Zn 4种重金属在土壤和植物中的迁移变化,研究表明:(1)覆盖土土质从一般耕作土变成肥沃土壤;覆盖土和种植混合土重金属Cd、Pb、Cu、Zn中Cd、Pb含量相近,但种植土的Cu含量略大于覆盖原土,Zn含量远大于覆盖原土;(2)植物能富集土壤和垃圾中的重金属,木本植物的根部富集重金属的能力强于草本植物,但重金属在草本植物根、茎、叶中的迁移速度大于木本植物;(3)植物根、茎、叶的Cu、Zn含量均远大于未受污染土壤种植植物相应部位的Cu、Zn含量,种植的植物不能供家养动物食用,以免通过食物链作用危及人体安全.     

冻融循环及有机肥配施对黑土中镉形态的影响

以黑龙江黑土为对象,研究了冻融循环及有机肥配施量对黑土中镉形态分布的影响。对配施不同有机肥的土壤样品进行5次冻融循环,采用电感耦合等离子质谱仪(ICP-MS)分析土壤样品中镉的赋存形态。结果表明,冻融循环数及有机肥的配施有助于降低黑土中的总镉量;冻融循环会促使黑土中的镉由交换态、碳酸盐结合态、有机结合态向铁锰氧化物结合态和残渣态转化,而增加有机肥配施量会使黑土中的镉由交换态向其他形态转化。因此,冻融循环及有机肥配施有助于降低土壤中镉的生物有效性,进而降低其环境风险。     

土壤-纳滤系统处理再生水补充地下水的研究

为充分保障再生水回灌地下时的水质安全、提供高质量地下水资源,在土壤处理系统中嵌入纳滤技术强化对再生水的处理效果,并初步探讨土壤系统作为前处理对纳滤膜污染的控制机理.结果表明,未采用臭氧氧化预处理前,土壤处理对再生水DOC和UV254的平均去除率分别为22%和20%.臭氧氧化对UV254的平均去除率为51%,并将土壤对D...     

重金属污染土壤中提高植物提取修复功效的探讨

随着对重金属超积累植物研究的加深 ,用植物提取修复技术来改良重金属污染的土壤已逐步进入实用阶段。本文所探讨的提高此技术功效的方法基于两个方面 :提高土壤溶液中重金属的浓度 ,促进植物对重金属的吸收 ;根据已了解的超积累的生理机制可能采取的一些措施     

土壤中水动力弥散系数的研究进展

从溶质运移的基本方程出发 ,系统论述了国内外对土壤中水动力弥散系数测定方法的研究进展 ,并指出了上述各种方法的适用条件及存在的问题     

Effects of sewage sludge amendments on pesticide sorption and leaching through undisturbed Mediterranean soils

The Gharb region in Morocco is an important agricultural zone where soils receive pesticide treatments and organic amendments to increase yields. The groundwater aquifer in the Gharb region is relatively shallow and thus vulnerable. The objective of this work was to study the influence of organic amendments on diuron, cyhalofop-butyl and procymidone leaching through undisturbed soil columns. Two soils were sampled from the Gharb region, a Dehs (sandy soil) and a R’mel (loamy clay soil). Following elution (124.5 mm), the amount of pesticide residues in the leachates of the sandy soil (0.06–0.21 %) was lower than in those of the loamy clay soil (0.20–0.36 %), which was probably due to preferential flow through the loamy clay soil. The amount of procymidone leached through the amended soil columns was greater than the control for the sandy soil only. The organic amendments did not significantly influence diuron and cyhalofop-butyl leaching in either of the soils. The application of organic amendments affected the amounts of dissolved organic matter (DOM) eluted and thus pesticide leaching as a function of soil-type. Nevertheless, in some case, the formation of pesticide-DOM complexes appeared to promote pesticide leaching, thus increasing groundwater contamination risks.     

pH和温度对2,2’,4,4’-四溴联苯醚在土壤中吸附和解吸行为的影响研究

研究了pH和温度对2,2’,4,4’-四溴联苯醚(BDE-47)在土壤中的吸附和解吸行为的影响。结果表明,pH和温度都可以影响BDE-47在受试土壤中的吸附和解吸行为。pH升高或降低均会使土壤对BDE-47的吸附能力提高,且在碱性环境中提高的程度更大;酸性或碱性条件下BDE-47在土壤中的解吸滞后性显著增强。温度降低后,土壤对BDE-47的吸附能力提高,5℃时的单点分配系数(Kd,表征土壤对BDE-47的吸附能力)是25℃时的1.03~1.67倍;温度由25℃降低到5℃后,BDE-47在土壤中的解吸滞后性增强。     

土壤重金属的植物污染化学研究进展

针对中国土壤重金属污染加剧的趋势,为改善土壤环境质量和保障农产品安全,提出了土壤重金属的植物污染化学研究领域.结合多年的研究工作,从土壤重金属的植物根际化学行为、土壤重金属的植物吸收与解毒机制和重金属污染土壤的植物-微生物交互作用等方面简要阐述了土壤-植物系统中重金属的分布、存在形态、迁移转化、累积及生物学效应和控制规律的研究进展,并对将来的植物污染化学理论研究提出了展望.