Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of veg...Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.展开更多
利用红外气体箱式法(Infrared Gas Analyze,IRGA),于2008年8月晴天对福州市马尼拉草坪(Zoysia matrel-la)的生态系统CO2净交换(NEE)和环境因子进行观测,阐明NEE及其组分的昼夜动态变化特征和影响因子。马尼拉草坪NEE的昼夜变化呈现为单...利用红外气体箱式法(Infrared Gas Analyze,IRGA),于2008年8月晴天对福州市马尼拉草坪(Zoysia matrel-la)的生态系统CO2净交换(NEE)和环境因子进行观测,阐明NEE及其组分的昼夜动态变化特征和影响因子。马尼拉草坪NEE的昼夜变化呈现为单峰型曲线,昼间其变化规律较强,夜间呈波动状态。NEE(取绝对值)最大值出现在10:00,最小值出现在16:00左右。太阳辐射、腔室内空气相对湿度和气温与NEE的相关性均为极显著(p<0.01),太阳辐射、腔室内空气相对湿度和5cm土壤温度共同解释NEE速率昼夜变异的89.30%。太阳辐射和腔室内空气相对湿度是影响草坪生态系统CO2净交换量日动态的主导环境因子;其中,太阳辐射可以单独解释NEE速率昼夜变化的79.70%,腔室内空气相对湿度可以单独解释NEE速率昼夜变化的50.40%;夏季晴天草坪生态系统在日尺度上表现为净吸收,平均CO2净交换速率为-4.11μmol/(m2.s)(负值表示吸收),平均日总通量为-0.18 mol/(m2.d)。展开更多
The development of high-performance Ir-based catalyst for electrocatalysis of oxygen evolution reaction(OER)in acidic media plays a critical role in realizing the commercialization of polymer electrolyte membrane-base...The development of high-performance Ir-based catalyst for electrocatalysis of oxygen evolution reaction(OER)in acidic media plays a critical role in realizing the commercialization of polymer electrolyte membrane-based water electrolyzer technology.Here we report a low-Ir core–shell OER electrocatalyst consisting of an intermetallic IrGa(IrGa-IMC)core and a partially oxidized Ir(IrOx)shell.In acidic electrolytes,the IrGa-IMC@IrOx core–shell catalysts exhibit a low overpotential of 272 mV at 10 mA·cm^(−2) with Ir loading of~20µg·cm^(−2) and a mass activity of 841 A·gIr^(−1) at 1.52 V,which is 3.6 times greater than that of commercial Ir/C(232 A·gIr^(−1))catalyst.We understand by the density functional theory(DFT)calculations that the enhanced OER activity of the IrGa-IMC@IrO_(x) catalysts is ascribed to the lifted degeneracy of Ir 5d electron of surface IrO_(x) sites induced by the intermetallic IrGa core,which increases the adsorption capacity of IrO_(x) layer for O and OH binding and eventually lowers the energy barrier of the OER rate-determining steps.展开更多
基金the financial support received from the University Grants Commission (UGC) in the form of a Junior Research Fellowship (JRF)。
文摘Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.
文摘利用红外气体箱式法(Infrared Gas Analyze,IRGA),于2008年8月晴天对福州市马尼拉草坪(Zoysia matrel-la)的生态系统CO2净交换(NEE)和环境因子进行观测,阐明NEE及其组分的昼夜动态变化特征和影响因子。马尼拉草坪NEE的昼夜变化呈现为单峰型曲线,昼间其变化规律较强,夜间呈波动状态。NEE(取绝对值)最大值出现在10:00,最小值出现在16:00左右。太阳辐射、腔室内空气相对湿度和气温与NEE的相关性均为极显著(p<0.01),太阳辐射、腔室内空气相对湿度和5cm土壤温度共同解释NEE速率昼夜变异的89.30%。太阳辐射和腔室内空气相对湿度是影响草坪生态系统CO2净交换量日动态的主导环境因子;其中,太阳辐射可以单独解释NEE速率昼夜变化的79.70%,腔室内空气相对湿度可以单独解释NEE速率昼夜变化的50.40%;夏季晴天草坪生态系统在日尺度上表现为净吸收,平均CO2净交换速率为-4.11μmol/(m2.s)(负值表示吸收),平均日总通量为-0.18 mol/(m2.d)。
基金the National Key Research and Development Program of China(No.2018YFA0702001)the National Natural Science Foundation of China(Nos.22071225 and 11774327)+2 种基金the Fundamental Research Funds for the Central Universities(No.WK2060190103)the Joint Funds from Hefei National Synchrotron Radiation Laboratory(No.KY2060000175)the support by“the Recruitment Program of Thousand Youth Talents”.
文摘The development of high-performance Ir-based catalyst for electrocatalysis of oxygen evolution reaction(OER)in acidic media plays a critical role in realizing the commercialization of polymer electrolyte membrane-based water electrolyzer technology.Here we report a low-Ir core–shell OER electrocatalyst consisting of an intermetallic IrGa(IrGa-IMC)core and a partially oxidized Ir(IrOx)shell.In acidic electrolytes,the IrGa-IMC@IrOx core–shell catalysts exhibit a low overpotential of 272 mV at 10 mA·cm^(−2) with Ir loading of~20µg·cm^(−2) and a mass activity of 841 A·gIr^(−1) at 1.52 V,which is 3.6 times greater than that of commercial Ir/C(232 A·gIr^(−1))catalyst.We understand by the density functional theory(DFT)calculations that the enhanced OER activity of the IrGa-IMC@IrO_(x) catalysts is ascribed to the lifted degeneracy of Ir 5d electron of surface IrO_(x) sites induced by the intermetallic IrGa core,which increases the adsorption capacity of IrO_(x) layer for O and OH binding and eventually lowers the energy barrier of the OER rate-determining steps.
