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Chemodynamics of heavy metals in long-term contaminated soils:Metal speciation in soil solution

Journal of Environmental Sciences 2009年第11期21卷 1532-1540页

作者： Kwon-Rae Kim Gary Owens Centre for Environmental Risk Assessment and Remediation University of South Australia climate change & agroecology division Department of Agricultural Environment National Academy of Agricultural Science

The concentration and speciation of heavy metals in soil solution isolated from long-term contaminated soils were investigated. The soil solution was extracted at 70% maximum water holding capacity （MWHC） after equilibration for 24 h. The free metal concentrations （Cd^2＋, Cu^2＋, Pb^2＋, and Zn^2＋） in soil solution were determined using the Donnan membrane technique （DMT）. Initially the DMT was validated using artificial solutions where the percentage of free metal ions were significantly correlated with the percentages predicted using MINTEQA2. However, there was a significant difference between the absolute free ion concentrations predicted by MINTEQA2 and the values determined by the DMT. This was due to the significant metal adsorption onto the cation exchange membrane used in the DMT with 20%, 28%, 44%, and 8% mass loss of the initial total concentration of Cd, Cu, Pb, and Zn in solution, respectively. This could result in a significant error in the determination of free metal ions when using DMT if no allowance for membrane cation adsorption was made. Relative to the total soluble metal concentrations the amounts of free Cd^2＋（3%-52%） and Zn^2＋（11%-72%） in soil solutions were generally higher than those of Cu^2＋（0.2%-30%） and Pb^2＋（0.6%-10%）. Among the key soil solution properties, dissolved heavy metal concentrations were the most significant factor governing free metal ion concentrations. Soil solution pH showed only a weak relationship with free metal ion partitioning coefficients （Kp） and dissolved organic carbon did not show any significant influence on Kp.

关键词： Donnan membrane technique free metal ion heavy metals partitioning coefficient solubility speciation

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Influence of Indian mustard (Brassica juncea) on rhizosphere soil solution chemistry in long-term contaminated soils:A rhizobox study

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Journal of Environmental Sciences 2010年第1期22卷 98-105页

作者： Kwon-Rae Kim Gary Owens Soon-lK Kwon climate change & agroecology division Department of Agricultural EnvironmentNational Academy of Agricultural ScienceRDARepublic of Korea Centre for Environmental Risk Assessment and Remediation University of South Australia

This study investigated the influence of Indian mustard （Brassicajuncea） root exudation on soil solution properties （pH, dissolved organic carbon （DOC）, metal solubility） in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation of Indian mustard in the rhizobox filled four different types of heavy metal contaminated soils （two alkaline soils and two acidic soils）. The growth of Indian mustard resulted in a significant increase （by 0.6 pH units） in rhizosphere soil solution pH of acidic soils and only a slight increase （〈 0.1 pH units） in alkaline soils. Furthermore, the DOC concentration increased by 17-156 mg/L in the rhizosphere regardless of soil type and the extent of contamination, demonstrating the exudation of DOC from root. Ion chromatographic determination showed a marked increase in the total dissolved organic acids （OAs） in rhizosphere. While root exudates were observed in all soils, the amount of DOC and OAs in soil solution varied considerably amongst different soils, resulting in significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb, and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and Zn from solid phase to liquid phase.

关键词： dissolved organic carbon heavy metals root exudates solubility rhizosphere chemistry

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Effect of Root-Induced Chemical changes on Dynamics and Plant Uptake of Heavy Metals in Rhizosphere Soils

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Pedosphere 2010年第4期20卷 494-504页

作者： K.R.KIM G.OWENS R.NAIDU climate change & agroecology division Department of Agricultural EnvironmentNational Academy of Agricultural Science Centre for Environmental Risk Assessment and Remediation University of South Australia Cooperative Research Centre for Contamination Assessment and Remediation of the Environment

It is increasingly recognized that metal bioavailability is a better indicator of the potential for phytoremediation than the total metal concentration in soils; therefore, an understanding of the influence of phytoremediation plants on metal dynamics at the soil-root interface is increasingly vital for the successful implementation of this remediation technique. In this study, we investigated the heavy metal and soil solution chemical changes at field moisture, after growth of either Indian mustard （Brassica juncea） or sunflower （Helianthus annuus L.）, in long-term contaminated soils and the subsequent metal uptake by the selected plants. In addition, the fractions of free metal ions in soil solution were determined using the Donnan membrane technique. After plant growth soil solution pH increased by 0.2-1.4 units and dissolved organic carbon （DOC） increased by 1-99 mg L^-1 in all soils examined. Soluble Cd and Zn decreased after Indian mustard growth in all soils examined, and this was attributed to increases in soil solution pH （by 0.9 units） after plant growth. Concentrations of soluble Cu and Pb decreased in acidic soils but increased in alkaline soils. This discrepancy was likely due to a competitive effect between plant-induced pH and DOC changes on the magnitude of metal solubility. The fractions of free Cd and Zn ranged from 7.2% to 32% and 6.4% to 73%, respectively, and they generally decreased as pH and DOC increased after plant growth. Metal uptake by plants was dependant on the soil solution metal concentration, which was governed by changes in pH and DOC induced by plant exudates, rather than on the total metal concentrations. Although plant uptake also varied with metal and soil types, overall soluble metal concentrations in the rhizosphere were mainly influenced by root-induced changes in pH and DOC which subsequently affected the metal uptake by plants.

关键词： bioavailability phytoremediation speciation

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EFFECTS OF AEROSOLS ON AUTUMN PRECIPITATION OVER MID-EASTERN CHINA

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Journal of Tropical Meteorology 2014年第3期20卷 242-250页

作者：陈思宇黄建平钱云葛觐铭苏婧 Key Laboratory for Semi-Arid climate change of the Ministry of Education Lanzhou University Atmospheric Science and Global change division Pacific Northwest National Laboratory Richland WA USA

Long-term observational data indicated a decreasing trend for the amount of autumn precipitation(i.e. 54.3 mm per decade) over Mid-Eastern China, especially after the 1980s(~ 5.6% per decade). To examine the cause of the decreasing trend, the mechanisms associated with the change of autumn precipitation were investigated from the perspective of water vapor transportation, atmospheric stability and cloud microphysics. Results show that the decrease of convective available potential energy(i.e. 12.81 J kg-1/ decade) and change of cloud microphysics, which were closely related to the increase of aerosol loading during the past twenty years, were the two primary factors responsible for the decrease of autumn precipitation. Our results showed that increased aerosol could enhance the atmospheric stability thus weaken the convection. Meanwhile, more aerosols also led to a significant decline of raindrop concentration and to a delay of raindrop formation because of smaller size of cloud droplets. Thus, increased aerosols produced by air pollution could be one of the major reasons for the decrease of autumn precipitation. Furthermore, we found that the aerosol effects on precipitation in autumn was more significant than in other seasons, partly due to relatively more stable synoptic systems in autumn. The impact of large-scale circulation dominant in autumn and the dynamic influence on precipitation was more important than the thermodynamic activity.

关键词： aerosol autumn precipitation atmospheric stability cloud microphysical properties

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Increasing chloride concentration causes retention of mercury in melted Arctic snow due to changes in photoreduction kinetics

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Journal of Environmental Sciences 2018年第6期30卷 122-129页

作者： E.A.Mann S.E.Ziegler A.Steffen N.J.O'Driscoll Department of Environmental Science Acadia University Environmental Science Programme Memorial University of Newfoundland Environment and climate change Canada Science and Technology Branch Air Quality Research Division

Mercury（Hg） in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with high chloride（Cl-） concentrations. We hypothesised that Cl- would increase Hg retention by decreasing Hg photoreduction to Hg（0） in melted Arctic snow. To test this, changes in Hg photoreduction kinetics in melted Alert, NU snow were quantified with changing Cl- concentration and UV intensity. Snow was collected and melted in Teflon bottles in May 2014, spiked with 0–10 μg/g Cl-, and irradiated with 3.52–5.78 W·m-2 UV（280–400 nm）radiation in a Luz Chem photoreactor. Photoreduction rate constants（k）（0.14–0.59 hr-1） had positive linear relationships with [Cl-], while photoreduced Hg amounts（Hg（Ⅱ）red） had negative linear relationships with [Cl-]（1287–64 pg in 200 g melted snow）. Varying UV and[Cl-] both altered Hg（Ⅱ）red amounts, with more efficient Hg stabilisation by Cl- at higher UV intensity, while k can be predicted by Cl- concentration and/or UV intensity, depending on experimental parameters. Overall, with future projections for greater snowpack Cl- loading,our experimental results suggest that more Hg could be delivered to Arctic aquatic ecosystems by melted snow（smaller Hg（Ⅱ）red expected）, but the Hg in the melted snow that is photoreduced may do so more quickly（larger k expected）.

关键词： Mercury Photoreduction Arctic Melted snow

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Spatiotemporal trends of PM_(2.5) and its major chemical components at urban sites in Canada

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Journal of Environmental Sciences 2021年第5期33卷 1-11页

作者： Huanbo Wang Leiming Zhang Irene Cheng Xiaohong Yao Ewa Dabek-Zlotorzynska School of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China Air Quality Research division Science and Technology BranchEnvironment and Climate Change CanadaTorontoCanada Lab of Marine Environmental Science and Ecology Ministry of EducationOcean University of ChinaQingdao 266100China Air Quality Research division Science and Technology BranchEnvironment and Climate Change CanadaOttawaCanada

To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM_(2.5) data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM_(2.5) collected at seven urban and two rural sites during 2010-2016 were analyzed to characterize geographical and seasonal patterns and associated potential causes. Site-specific seven-year mean gravimetric PM_(2.5) mass concentrations ranged from 5.7 to 9.6 μg/m^(3). Seven-year mean concentrations of SO_(4)^(2-), NO_(3)^(-), NH_(4)^(+), organic carbon(OC), and elemental carbon(EC) were in the range of 0.68 to 1.6, 0.21 to 1.5, 0.27 to 0.71, 1.1 to 1.9, and 0.37 to 0.71 μg/m^(3), accounting for 10.8%-18.1%, 3.7%-16.7%, 4.7%-7.4%, 18.4%-21.0%, and 6.4%-10.6%, respectively, of gravimetric PM_(2.5) mass. PM_(2.5) and its five major chemical components showed higher concentrations in southeastern Canada and lower values in Atlantic Canada, with the seven-year mean ratios between the two regions being on the order of 1.7 for PM_(2.5) and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO_(4)^(2-) and NH_(4)^(+) were comparable, while those of NO_(3)^(-), OC, and EC were around 20%, 40%-50%, and 70%-80%, respectively, higher at urban than rural sites, indicating the regional scale impacts of SO_(4)^(2-) and NH_(4)^(+) and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO_(4)^(2-) and wintertime peaks for NO_(3)^(-), but those of NH_(4)^(+), OC, and EC exhibited different seasonality at different locations.

关键词： Fine particulate matter Aerosol chemical composition Monitoring network

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Understanding human influence on climate change in China

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National Science Review 2022年第3期9卷 128-143页

作者： Ying Sun Xuebin Zhang Yihui Ding Deliang Chen Dahe Qin Panmao Zhai National climate Center Laboratory for Climate Studies Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science &Technology climate Research division Environment and Climate Change Canada Department of Earth Sciences University of Gothenburg China Meteorological Administration State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences

China’s climate has been warming since the 1950s, with surface air temperature increasing at a rate higher than the global average. changes in climate have exerted substantial impacts on water resources,agriculture, ecosystems and human health. Attributing past changes to causes provides a scientific foundation for national and international climate policies. Here, we review recent progress in attributing the observed climate changes over past decades in China. Anthropogenic forcings, dominated by greenhouse gas emissions, are the main drivers for observed increases in mean and extreme temperatures. Evidence of the effect of anthropogenic forcings on precipitation is emerging. Human influence has increased the probability of extreme heat events, and has likely changed the occurrence probabilities for some heavy precipitation events. The way a specific attribution question is posed and the conditions under which the question is addressed present persistent challenges for appropriately communicating attribution results to non-specialists.

关键词： human influence detection and attribution climate change climate extremes

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Carbon sequestration in a bamboo plantation:a case study in a Mediterranean area

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Journal of Forestry Research 2024年第3期35卷 231-238页

作者： Tommaso Chiti Emanuele Blasi Maria Vincenza Chiriaco Department for Innovation in Biological Agro-Food and Forest Systems(DIBAF)University of TusciaVia San C.De Lellis snc01100 ViterboItaly Foundation Euro-Mediterranean Center on climate change(CMCC) Division on Climate Change Impacts on AgricultureForests and Ecosystem Services(IAFES)Via Garbini5101100 ViterboItaly

In the Mediterranean region,despite bamboo being an alien species that can seriously alter plant and ani-mal biocoenosis,the area occupied by bamboo plantations continues to increase,especially for the purpose to seques-ter carbon(C).However,the C dynamics in the soil-plant system when bamboo is grown outside its native area are poorly *** we investigated the C mitigation potential of the fast-growing Moso bamboo(Phyllostachys edulis)introduced in Italy for climate-change *** analyzed aboveground(AGB)and belowground(as root/shoot ratio)biomass,litter and soil organic C(SOC)at O-15-and 15-30-cm depths in a 4-year-old bamboo plantation in comparison with the former annual cropland on which the bamboo was *** have an idea of the maximum C stored at an ecosystem level,a natural forest adjacent the two sites was also *** the plantation,C accumulation as AGB was stimulated,with 14.8±3.1 Mg C ha^(-1) stored in 3 years;because thinning was done to remove culms from the first year,the mean sequestration rate was 4.9 Mg C ha^(-1) a^(-1).The sequestration rates were high but comparable to other fast-growing tree species in Italy(e.g.,Pinus nigra).SOC was significantly higher in the bamboo plantation than in the cropland only at the 0-15 cm depth,but SOC stock did not *** 4 years were not enough time for a clear increase in SOC,or the high nutrient uptake by bamboos might have depleted the soil nutrients,thus inhibiting the soil organic matter formation by *** comparison,the natural forest had significantly higher C levels in all the *** C dynamics at an ecosystem level,the bamboo plantation on the former annual cropland led to substantial C removal from the atmosphere(about 12 Mg C ha^(-1) a^(-1)).However,despite the promising C sequestration rates by bamboo,its introduction should be carefully considered due to potential ecological problems caused by this species in overexploited environments such as the Med

关键词： Carbon sequestration climate change mitigation Mediterranean area Moso bamboo Soil organic carbon

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Erodibility study of sediment in a fast-flowing river

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International Journal of Sediment Research 2019年第2期34卷 144-154页

作者： Cheng He David Nguyen Watershed Hydrology and Ecology Research division National Water Research InstituteEnvironment and Climate Change Canada Department of Environmental Engineering University of Guelph

Determination of sediment stability in the field is challenging because bed shear stress(BSS),a determining factor of sediment erosion,can’t easily be directly *** tackle this challenge and reliably assess sediment erodibility in a fast flowing river,a standalone underwater camera system and a new insitu flume(ISF)were developed and applied in this *** camera system was used to record sediment movement and the new ISF was used for measuring critical bottom shear stress(CBSS).The camera can be deployed alone in water to record videos or take pictures with light emitting diode(LED)lighting and flexible schedule *** ISF is based on the concept that the amount of force needed to erode the same particle under different flow conditions should be *** high resolution Acoustic Doppler Current Profilers(ADCP)also were deployed in the field to collect velocity-depth profiles which are used by conventional methods to calculate BSS with the law of the *** sediment erodibility was then assessed based on the comparison between the obtained CBSS and BSS and then further verified with the recorded observations from the deployed *** results reveal that the widely used conventional method can produce large uncertainties and is not adequate to provide meaningful conclusion under these conditions.

关键词： Sediment erodibility Bed shear stress Critical bed shear stress Underwater camera

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An Overview of Mineral Dust Modeling over East Asia

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Journal of Meteorological Research 2017年第4期31卷 633-653页

作者： Siyu CHEN Jianping HUANG Yun QIAN Chun ZHAO Litai KANG Ben YANG Yong WANG Yuzhi LIU Tiangang YUAN Tianhe WANG Xiaojun MA Guolong ZHANG Key Laboratory for Semi-Arid climate change of the Ministry of Education Lanzhou University Atmospheric Science and Global change division Pacific Northwest National Laboratory School of Atmospheric Sciences Nanjing University Department of Earth System Science Tsinghua University

East Asian dust（EAD） exerts considerable impacts on the energy balance and climate/climate change of the earth system through its influence on solar and terrestrial radiation, cloud properties, and precipitation efficiency. Providing an accurate description of the life cycle and climate effects of EAD is therefore critical to better understanding of climate change and socioeconomic development in East Asia and even worldwide. Dust modeling has undergone substantial development since the late 1990 s, associated with improved understanding of the role of EAD in the earth system. Here, we review the achievements and progress made in recent decades in terms of dust modeling research,including dust emissions, long-range transport, radiative forcing（RF）, and climate effects of dust particles over East Asia. Numerous efforts in dust/EAD modeling have been directed towards furnishing more sophisticated physical and chemical processes into the models on higher spatial resolutions. Meanwhile, more systematic observations and more advanced retrieval methods for instruments that address EAD related science issues have made it possible to evaluate model results and quantify the role of EAD in the earth system, and to further reduce the uncertainties in EAD simulations. Though much progress has been made, large discrepancies and knowledge gaps still exist among EAD simulations. The deficiencies and limitations that pertain to the performance of the EAD simulations referred to in the present study are also discussed.

关键词： East Asia dust aerosol dust modeling dust emissions long-range dust transport dust radiative forcing

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