Samples of roadside dust were collected from 30 sites in Hong Kong.The total concentrations of 10 metals in the samples were analyzed,and the correlation coefficients among the metal contents and the annual average da...Samples of roadside dust were collected from 30 sites in Hong Kong.The total concentrations of 10 metals in the samples were analyzed,and the correlation coefficients among the metal contents and the annual average daily traffic(AADT)in 1986 were determined.Pb was found to have a significant correlation(P<0.01)with AADT.No correlation was found between Al, Ba,Cd,Cr,Cu,Fe,Mn,Ni,and Zn with respect to AADT.A general decrease in the level of Pb in roadside dust in the past few years has been observed since the reduction in the level of lead in petrol.1989 Academic Press,Inc.展开更多
In this paper,we construct a power type functional which is the approximation functional of the Singular Trudinger-Moser functional.Moreover,we obtain the concentration level of the functional and show it converges to...In this paper,we construct a power type functional which is the approximation functional of the Singular Trudinger-Moser functional.Moreover,we obtain the concentration level of the functional and show it converges to the concentration level of singular Trudinger-Moser functional on the unit ball.展开更多
Per-and polyfluoroalkyl compounds,also known as"forever chemicals",are ubiquitous in the environment and harm human health.Developing safer,eco-friendly alternatives is vital,but new compounds may cause new ...Per-and polyfluoroalkyl compounds,also known as"forever chemicals",are ubiquitous in the environment and harm human health.Developing safer,eco-friendly alternatives is vital,but new compounds may cause new issues.Enhanced monitoring and risk assessment are essential.In this study,the detection of PFASs in environmental media,including lake surface water,bottom sediment,soil,and bryophytes,was accomplished by instrumentation in the Caohai region.Subsequently,their distribution characteristics and ecological risks were scientifically analyzed and evaluated.The results showed that new and traditional PFASs were widely found in Caohai,a non-industrial area,and showed obvious short-chain and new PFAS substitution effects.The total concentrations of PFASs(ΣPFASs)in surface water and sediment were measured at 39.55–67.64 ng/L and 2.36–11.55 ng/g dry weight(dw),respectively.The concentrations ofΣPFASs in soil and moss ranged from 0.39 to 1.31 ng/g dw and from 8.90 to 18.07 ng/g dw,respectively.Notably,PFBA and F-53B emerged as the most prevalent PFAS compounds in this region.The calculated risk quotients(RQs)for PFASs are less than 0.01,indicating no significant environmental risk.However,the long-term cumulative risk cannot be ignored,and the ecological protection of Caohai still needs to be paid attention to.The results of this study can help understand the pollution level of PFASs in the wetland water system in plateau areas and provide data references for environmental control such as PFASs pollution protection and ecological management in Caohai.展开更多
Objective:To demonstrate the versatility of the natural soil gas harvesting technique,coupled with a semi-dynamic injection algorithm,as an efficient and reliable source for continuous ^(222)Rn delivery to a large-vol...Objective:To demonstrate the versatility of the natural soil gas harvesting technique,coupled with a semi-dynamic injection algorithm,as an efficient and reliable source for continuous ^(222)Rn delivery to a large-volume calibration chamber across different soil conditions and climatic conditions.Methods:Long-term experiments were performed during three seasons of a year in a tropical monsoonal climatic region with high rainfall on the Southwest Coast of India.Soil gas extraction was performed using soil-gas probes,inserted to 1 m deep into the ground.Soil gas was harvested at a flow rate of 60 L/min,passed through a moisture trap,a ^(222)Rn progeny filter,and a delay volume and pumped into a ^(222)Rn calibration chamber of volume 22.7 m^(3).Continuous monitoring of ^(222)Rn concentration in the chamber was performed using ionization chamber-based reference monitors.To achieve and maintain the desired ^(222)Rn concentration values in the calibration chamber,the semi-dynamic injection method was adopted,in which the ^(222)Rn concentration in the soil gas was monitored periodically,and injection into the chamber was controlled using a well-defined pumping algorithm.Three ranges of ^(222)Rn concentration values were chosen as the target values to be maintained in the calibration chamber for long-term experiments(15 d):low concentration(500-1,000 Bq/m3),medium concentration(1,000-10,000 Bq/m^(3)),and high concentration(10,000-25,000 Bq/m^(3)).Results:The achieved ^(222)Rn concentration values were in good agreement with the target values,with deviations of 12%,8% and 5% for the low,medium and high concentration exposures,respectively,during the summer season.During the monsoon season,the deviations between the target and the achieved concentration values were 12%,10% and 5% for low,medium and high concentration exposures,respectively,and the corresponding deviations were 12%,4%,and 5% for the winter season.These deviations are well within the cumulative uncertainty associated with the measurements.Conclusions:The results of this study conclusively demonstrate that the soil gas harvesting method,when coupled with the semi-dynamic injection approach,is a reliable method for generating and maintaining the desired ^(222)Rn concentration in the large volume calibration chamber during different seasons and environmental conditions.展开更多
文摘Samples of roadside dust were collected from 30 sites in Hong Kong.The total concentrations of 10 metals in the samples were analyzed,and the correlation coefficients among the metal contents and the annual average daily traffic(AADT)in 1986 were determined.Pb was found to have a significant correlation(P<0.01)with AADT.No correlation was found between Al, Ba,Cd,Cr,Cu,Fe,Mn,Ni,and Zn with respect to AADT.A general decrease in the level of Pb in roadside dust in the past few years has been observed since the reduction in the level of lead in petrol.1989 Academic Press,Inc.
文摘In this paper,we construct a power type functional which is the approximation functional of the Singular Trudinger-Moser functional.Moreover,we obtain the concentration level of the functional and show it converges to the concentration level of singular Trudinger-Moser functional on the unit ball.
基金supported by the National Natural Science Foundation of China(Grant No.21966011)the Guizhou Medical University Doctoral Initiation Fund(Project Contract No.:XBOHJZi[2020]No.044)the Guizhou Provincial Basic Research Program(Natural Science)(Grant No.QKHJC-ZK[2022]YB229).
文摘Per-and polyfluoroalkyl compounds,also known as"forever chemicals",are ubiquitous in the environment and harm human health.Developing safer,eco-friendly alternatives is vital,but new compounds may cause new issues.Enhanced monitoring and risk assessment are essential.In this study,the detection of PFASs in environmental media,including lake surface water,bottom sediment,soil,and bryophytes,was accomplished by instrumentation in the Caohai region.Subsequently,their distribution characteristics and ecological risks were scientifically analyzed and evaluated.The results showed that new and traditional PFASs were widely found in Caohai,a non-industrial area,and showed obvious short-chain and new PFAS substitution effects.The total concentrations of PFASs(ΣPFASs)in surface water and sediment were measured at 39.55–67.64 ng/L and 2.36–11.55 ng/g dry weight(dw),respectively.The concentrations ofΣPFASs in soil and moss ranged from 0.39 to 1.31 ng/g dw and from 8.90 to 18.07 ng/g dw,respectively.Notably,PFBA and F-53B emerged as the most prevalent PFAS compounds in this region.The calculated risk quotients(RQs)for PFASs are less than 0.01,indicating no significant environmental risk.However,the long-term cumulative risk cannot be ignored,and the ecological protection of Caohai still needs to be paid attention to.The results of this study can help understand the pollution level of PFASs in the wetland water system in plateau areas and provide data references for environmental control such as PFASs pollution protection and ecological management in Caohai.
文摘Objective:To demonstrate the versatility of the natural soil gas harvesting technique,coupled with a semi-dynamic injection algorithm,as an efficient and reliable source for continuous ^(222)Rn delivery to a large-volume calibration chamber across different soil conditions and climatic conditions.Methods:Long-term experiments were performed during three seasons of a year in a tropical monsoonal climatic region with high rainfall on the Southwest Coast of India.Soil gas extraction was performed using soil-gas probes,inserted to 1 m deep into the ground.Soil gas was harvested at a flow rate of 60 L/min,passed through a moisture trap,a ^(222)Rn progeny filter,and a delay volume and pumped into a ^(222)Rn calibration chamber of volume 22.7 m^(3).Continuous monitoring of ^(222)Rn concentration in the chamber was performed using ionization chamber-based reference monitors.To achieve and maintain the desired ^(222)Rn concentration values in the calibration chamber,the semi-dynamic injection method was adopted,in which the ^(222)Rn concentration in the soil gas was monitored periodically,and injection into the chamber was controlled using a well-defined pumping algorithm.Three ranges of ^(222)Rn concentration values were chosen as the target values to be maintained in the calibration chamber for long-term experiments(15 d):low concentration(500-1,000 Bq/m3),medium concentration(1,000-10,000 Bq/m^(3)),and high concentration(10,000-25,000 Bq/m^(3)).Results:The achieved ^(222)Rn concentration values were in good agreement with the target values,with deviations of 12%,8% and 5% for the low,medium and high concentration exposures,respectively,during the summer season.During the monsoon season,the deviations between the target and the achieved concentration values were 12%,10% and 5% for low,medium and high concentration exposures,respectively,and the corresponding deviations were 12%,4%,and 5% for the winter season.These deviations are well within the cumulative uncertainty associated with the measurements.Conclusions:The results of this study conclusively demonstrate that the soil gas harvesting method,when coupled with the semi-dynamic injection approach,is a reliable method for generating and maintaining the desired ^(222)Rn concentration in the large volume calibration chamber during different seasons and environmental conditions.
