A pot experiment was conducted with multi-metal （Pb, Cd, Cu, and Zn） contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes （fly ash and steel ...A pot experiment was conducted with multi-metal （Pb, Cd, Cu, and Zn） contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes （fly ash and steel slag）. The efficiency of amendments- induced metal stabilization was evaluated by diffusive gradients in thin films （DGT）, sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash （20 g kg-1） and steel slag （3 g kg-1） resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT （CDGT） and the metal uptake by Oryza sativa L. Significant correlations were found between CDGT and the concentration of a combination of metal fractions （exchangeable, bound to carbonates, and bound to Fe/Mn oxides）, unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R （ratio of CDGT to pore water metal concentration） values, significantly decreased in the amended soils. The CDGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, A1 and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake.展开更多
沉积物中磷(P)、铁(Fe)、硫(S)之间存在密切的耦合关系,但大部分研究并未提供直接的原位证据,需要借助高分辨的获取技术才能表征.为了探索三者之间的耦合关系,本文利用Zr O-Ag I DGT和Chelex DGT对东莞市黑臭河流沉积物中有效态P、Fe、...沉积物中磷(P)、铁(Fe)、硫(S)之间存在密切的耦合关系,但大部分研究并未提供直接的原位证据,需要借助高分辨的获取技术才能表征.为了探索三者之间的耦合关系,本文利用Zr O-Ag I DGT和Chelex DGT对东莞市黑臭河流沉积物中有效态P、Fe、S进行了高分辨分析.结果表明:应用DGT技术能够获得黑臭河流沉积物中有效态P、Fe、S的高分辨率浓度分布,并且实验结果可靠,有效地避免了主动采样方法和沉积物空间异质性对P、Fe、S同步分析的影响.各采样点沉积物中有效态P、S在垂向上的空间分布趋势基本相似,部分采样点出现有效态P、Fe、S同步变化的现象,同步获得的微界面浓度分布较好地反映了三者的耦合关系.对P、Fe、S在水-沉积物界面附近的含量分布进行相关性分析,结果表明三者之间具有显著正相关(p<0.05),进一步证实了黑臭河流沉积物中也存在P、Fe、S同步释放的现象.大部分样点沉积物-水界面有效态P、Fe、S的扩散通量为正值,表现为由沉积物向上覆水释放P、Fe、S.沉积物中P、Fe、S的耦合释放表明其对黑臭的形成和内源磷释放至关重要.展开更多
Pot experiments were conducted to evaluate the effect of water management,namely continuous flooding(CF),intermittent flooding(IF)and non-flooding(NF),on Cd phytoavailaility in three paddy soils that differed in p H a...Pot experiments were conducted to evaluate the effect of water management,namely continuous flooding(CF),intermittent flooding(IF)and non-flooding(NF),on Cd phytoavailaility in three paddy soils that differed in p H and in Cd concentrations.Diffusive gradients in thin films(DGT)technique was employed to monitor soil labile Cd and Fe concentrations simultaneously at three growth stages(tillering,heading and mature stage)of rice.The Cd phytoavailability were generally in the order of NF>IF>CF,and higher rice Cd(over permitted level,0.2 mg/kg)were only found in neutral and acidic soils under NF conditions.DGT measured soil labile Cd rather than total Cd was the most reliable predictor for Cd accumulation in rice.CF enhanced the formation of root plaques,which related to oxidation of large quantities of available Fe on root surfaces due to the O2 secretion of rice root.The Cd concentration in root plaques shared the same trend with DGT-Cd.Generally,root plaques would inhibit Cd uptake by rice under CF conditions,while under IF and NF conditions,root plaques act as a temporarily store of Cd,and soil labile Cd is the key factor that controls the transfer of Cd from soil to rice.The results of principle component analysis revealed that water management had the greatest effect on soil Cd lability and rice Cd in acidic soil.Thus,it is important to consider the availability of Cd and soil p H when assessing current agricultural practices of contaminated soil in China.展开更多
传统的沉积物孔隙水磷酸盐含量测定方法通常是采用离心法获取沉积物柱芯孔隙水,然后再进行磷酸盐含量测定。这种常规测定方法不仅破坏了沉积物的原本物理化学结构,而且分样间距多为厘米级,无法满足沉积物-水界面磷酸盐的高分辨率分布特...传统的沉积物孔隙水磷酸盐含量测定方法通常是采用离心法获取沉积物柱芯孔隙水,然后再进行磷酸盐含量测定。这种常规测定方法不仅破坏了沉积物的原本物理化学结构,而且分样间距多为厘米级,无法满足沉积物-水界面磷酸盐的高分辨率分布特征研究和释放通量的高精度估算要求。为克服传统监测技术破坏系统原始状态和分辨率低的弊端,近年来沉积物孔隙水磷酸盐原位监测技术迅猛发展,较为成熟的有透析装置技术(Dialysis peepers)、薄膜扩散平衡技术(Diffusive equilibrium in thin-films technique,DET)和薄膜扩散梯度技术(Diffusive gradients in thin-films technique,DGT)等。本文综述了透析装置技术、薄膜扩散平衡技术和薄膜扩散梯度技术的基本原理和应用实例,对比分析了他们各自的优缺点和发展应用前景。DGT作为一种新型、廉价的原位被动采样技术,具有原位和高分辨率监测的优点,被广泛应用于水体、沉积物和土壤等研究,在获取沉积物孔隙水磷酸盐含量及时空分布特征等方面优势突出。如何延长DGT胶体的使用寿命、提高监测的空间分辨率和实现多元素同步监测是其主要发展方向。大量研究表明,沉积物内源磷释放与沉积物中Fe-S的耦合循环存在密切联系,深入了解湖泊沉积物P-Fe-S的耦合生物地球化学循环过程是揭示湖泊内源磷释放机制的一把钥匙。快速发展的薄膜扩散梯度(DGT)技术及其与DET技术联用无疑为P-Fe-S耦合循环研究提供了有效手段,亟待在不同类型湖泊中应用和完善,为深刻揭示P-Fe-S耦合循环过程与机制提供独特信息。展开更多
A diffusive gradients in thin films （DGT） technique based on hydrous zirconium oxide （Zr-oxide） has been recently developed for the measurement of dissolved reactive phosphate （DRP）. In this study, the detailed ...A diffusive gradients in thin films （DGT） technique based on hydrous zirconium oxide （Zr-oxide） has been recently developed for the measurement of dissolved reactive phosphate （DRP）. In this study, the detailed performance of the DGT technique is reported. Spiking experiments revealed that several orthophosphate monoester compounds contributed to the Zr-oxide DGT measurements of DRP. However, such a phenomenon is unlikely to occur during field conditions due to the low concentration of organic P in typical natural waters. The presence of Cl- （up to 106 g/L）, SO42- （up to 16 g/L）, HCO3- （up to 817 g/L）, and AsO2- and AsO 3 4 （both up to 1 mg As/L） in solutions had negligible effects on the measurement of DRP. The threshold concentrations of Cl-, SO42- and HCO3- have been increased from previous reports for the measurements of DRP using other adsorbent-based DGT techniques. The capacity for DGT measurements of DRP decreased with increasing solution pH （4.2-9.2）. The lowest capacity （95 μg P/m2 at pH 9.2） was still greater than that of other DGT techniques that are usually used for the measurement of DRP （2-12 μg P/cm2 ）. The Zr-oxide binding gel could be stored for up to 2 years without any aging effect. This period of validity was considerably longer than the ferrihydrite binding gel that is commonly used in present DGT devices （6 months）. The field application revealed that the concentrations of DRP measured in three fresh water samples using the Zr-oxide DGT technique were in agreement with those of the traditional colorimetric method.展开更多
基金Supported by the NSFC-Guangdong Joint Foundation of China(No.U0833004)the National Natural Science Foundation of China(No.41101483)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2011),China
文摘A pot experiment was conducted with multi-metal （Pb, Cd, Cu, and Zn） contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes （fly ash and steel slag）. The efficiency of amendments- induced metal stabilization was evaluated by diffusive gradients in thin films （DGT）, sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash （20 g kg-1） and steel slag （3 g kg-1） resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT （CDGT） and the metal uptake by Oryza sativa L. Significant correlations were found between CDGT and the concentration of a combination of metal fractions （exchangeable, bound to carbonates, and bound to Fe/Mn oxides）, unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R （ratio of CDGT to pore water metal concentration） values, significantly decreased in the amended soils. The CDGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, A1 and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake.
文摘沉积物中磷(P)、铁(Fe)、硫(S)之间存在密切的耦合关系,但大部分研究并未提供直接的原位证据,需要借助高分辨的获取技术才能表征.为了探索三者之间的耦合关系,本文利用Zr O-Ag I DGT和Chelex DGT对东莞市黑臭河流沉积物中有效态P、Fe、S进行了高分辨分析.结果表明:应用DGT技术能够获得黑臭河流沉积物中有效态P、Fe、S的高分辨率浓度分布,并且实验结果可靠,有效地避免了主动采样方法和沉积物空间异质性对P、Fe、S同步分析的影响.各采样点沉积物中有效态P、S在垂向上的空间分布趋势基本相似,部分采样点出现有效态P、Fe、S同步变化的现象,同步获得的微界面浓度分布较好地反映了三者的耦合关系.对P、Fe、S在水-沉积物界面附近的含量分布进行相关性分析,结果表明三者之间具有显著正相关(p<0.05),进一步证实了黑臭河流沉积物中也存在P、Fe、S同步释放的现象.大部分样点沉积物-水界面有效态P、Fe、S的扩散通量为正值,表现为由沉积物向上覆水释放P、Fe、S.沉积物中P、Fe、S的耦合释放表明其对黑臭的形成和内源磷释放至关重要.
基金supported by the National Natural Science Foundation of China(Nos.41601533 and U1401234)the Guangdong Natural Science Foundation(No.2017A030313241)
文摘Pot experiments were conducted to evaluate the effect of water management,namely continuous flooding(CF),intermittent flooding(IF)and non-flooding(NF),on Cd phytoavailaility in three paddy soils that differed in p H and in Cd concentrations.Diffusive gradients in thin films(DGT)technique was employed to monitor soil labile Cd and Fe concentrations simultaneously at three growth stages(tillering,heading and mature stage)of rice.The Cd phytoavailability were generally in the order of NF>IF>CF,and higher rice Cd(over permitted level,0.2 mg/kg)were only found in neutral and acidic soils under NF conditions.DGT measured soil labile Cd rather than total Cd was the most reliable predictor for Cd accumulation in rice.CF enhanced the formation of root plaques,which related to oxidation of large quantities of available Fe on root surfaces due to the O2 secretion of rice root.The Cd concentration in root plaques shared the same trend with DGT-Cd.Generally,root plaques would inhibit Cd uptake by rice under CF conditions,while under IF and NF conditions,root plaques act as a temporarily store of Cd,and soil labile Cd is the key factor that controls the transfer of Cd from soil to rice.The results of principle component analysis revealed that water management had the greatest effect on soil Cd lability and rice Cd in acidic soil.Thus,it is important to consider the availability of Cd and soil p H when assessing current agricultural practices of contaminated soil in China.
文摘传统的沉积物孔隙水磷酸盐含量测定方法通常是采用离心法获取沉积物柱芯孔隙水,然后再进行磷酸盐含量测定。这种常规测定方法不仅破坏了沉积物的原本物理化学结构,而且分样间距多为厘米级,无法满足沉积物-水界面磷酸盐的高分辨率分布特征研究和释放通量的高精度估算要求。为克服传统监测技术破坏系统原始状态和分辨率低的弊端,近年来沉积物孔隙水磷酸盐原位监测技术迅猛发展,较为成熟的有透析装置技术(Dialysis peepers)、薄膜扩散平衡技术(Diffusive equilibrium in thin-films technique,DET)和薄膜扩散梯度技术(Diffusive gradients in thin-films technique,DGT)等。本文综述了透析装置技术、薄膜扩散平衡技术和薄膜扩散梯度技术的基本原理和应用实例,对比分析了他们各自的优缺点和发展应用前景。DGT作为一种新型、廉价的原位被动采样技术,具有原位和高分辨率监测的优点,被广泛应用于水体、沉积物和土壤等研究,在获取沉积物孔隙水磷酸盐含量及时空分布特征等方面优势突出。如何延长DGT胶体的使用寿命、提高监测的空间分辨率和实现多元素同步监测是其主要发展方向。大量研究表明,沉积物内源磷释放与沉积物中Fe-S的耦合循环存在密切联系,深入了解湖泊沉积物P-Fe-S的耦合生物地球化学循环过程是揭示湖泊内源磷释放机制的一把钥匙。快速发展的薄膜扩散梯度(DGT)技术及其与DET技术联用无疑为P-Fe-S耦合循环研究提供了有效手段,亟待在不同类型湖泊中应用和完善,为深刻揭示P-Fe-S耦合循环过程与机制提供独特信息。
基金sponsored by the National Natural Scientific Foundation of China (No. 41001334, 41001325)the Project of Knowledge Innovation for the 3rd period, the Chinese Academy of Sciences (No. KZCX2-YW-JS304)the Natural Scientific Foundation of Jiangsu Province, China (No. BK2010606)
文摘A diffusive gradients in thin films （DGT） technique based on hydrous zirconium oxide （Zr-oxide） has been recently developed for the measurement of dissolved reactive phosphate （DRP）. In this study, the detailed performance of the DGT technique is reported. Spiking experiments revealed that several orthophosphate monoester compounds contributed to the Zr-oxide DGT measurements of DRP. However, such a phenomenon is unlikely to occur during field conditions due to the low concentration of organic P in typical natural waters. The presence of Cl- （up to 106 g/L）, SO42- （up to 16 g/L）, HCO3- （up to 817 g/L）, and AsO2- and AsO 3 4 （both up to 1 mg As/L） in solutions had negligible effects on the measurement of DRP. The threshold concentrations of Cl-, SO42- and HCO3- have been increased from previous reports for the measurements of DRP using other adsorbent-based DGT techniques. The capacity for DGT measurements of DRP decreased with increasing solution pH （4.2-9.2）. The lowest capacity （95 μg P/m2 at pH 9.2） was still greater than that of other DGT techniques that are usually used for the measurement of DRP （2-12 μg P/cm2 ）. The Zr-oxide binding gel could be stored for up to 2 years without any aging effect. This period of validity was considerably longer than the ferrihydrite binding gel that is commonly used in present DGT devices （6 months）. The field application revealed that the concentrations of DRP measured in three fresh water samples using the Zr-oxide DGT technique were in agreement with those of the traditional colorimetric method.
