The contribution of phytoliths to total biogenic silica(BSi) volumes in rivers worldwide,and the associated implications for the biogeochemical cycle,require in-depth study.Based on samples from rivers in Peninsular M...The contribution of phytoliths to total biogenic silica(BSi) volumes in rivers worldwide,and the associated implications for the biogeochemical cycle,require in-depth study.Based on samples from rivers in Peninsular Malaysia,this project investigated the source and characteristics of B Si found in Asian tropical rivers,as well as the process of reverse weathering taking place in these fluvial systems.Results indicated that BSi samples collected in sediments consisted of phytolith,diatom and sponge spicules.Phytoliths,predominantly of the elongate form,comprised 92.8%-98.3% of BSi in the Pahang River.Diatom BSi in this river consisted mainly of pennatae diatoms,but represented a relatively small proportion of the total BSi volume.However,diatom BSi(predominantly of the Centricae form) was more prevalent in the Pontian and Endau Rivers with shares of 68.8% and 79.3% of the total BSi volumes,respectively,than Pahang River.Carbon contents of the BSi particulates ranged from 1.85% to 10.8% with an average of 4.79%.These values are higher than those recorded in other studies to date,and indicate that BSi plays a major role in controlling permanent carbon burial.This study suggests that phytoliths from terrestrial plants are the primary constituents of BSi in the rivers of Peninsular Malaysia,and therefore represent a significant proportion of the coastal silica budget.展开更多
The new gravity field models of gravity field and steady-state ocean circulation explorer(GOCE),TIM_R6 and DIR_R6,were released by the European Space Agency(ESA)in June 2019.The sixth generation of gravity models have...The new gravity field models of gravity field and steady-state ocean circulation explorer(GOCE),TIM_R6 and DIR_R6,were released by the European Space Agency(ESA)in June 2019.The sixth generation of gravity models have the highest possible signal and lowest error levels compared with other GOCE-only gravity models,and the accuracy is significantly improved.This is an opportunity to build high precision geostrophic currents.The mean dynamic topography and geostrophic currents have been calculated by the 5th(TIM_R5 and DIR_R5),6th(TIM_R6 and DIR_R6)release of GOCE gravity field models and ITSG-Grace2018 of GRACE gravity field model in this study.By comparison with the drifter results,the optimal filtering lengths of them have been obtained(for DIR_R5,DIR_R6,TIM_R5 and TIM_R6 models are 1°and for ITSG-Grace2018 model is 1.1°).The filtered results show that the geostrophic currents obtained by the GOCE gravity field models can better reflect detailed characteristics of ocean currents.The total geostrophic speed based on the TIM_R6 model is similar to the result of the DIR_R6 model with standard deviation(STD)of 0.320 m/s and 0.321 m/s,respectively.The STD of the total velocities are 0.333 m/s and 0.325 m/s for DIR_R5 and TIM_R5.When compared with ITSG-Grace2018 results,the STD(0.344 m/s)of total geostrophic speeds is larger than GOCE results,and the accuracy of geostrophic currents obtained by ITSG-Grace2018 is lower.And the absolute errors are mainly distributed in the areas with faster speeds,such as the Antarctic circumpolar circulation,equatorial region,Kuroshio and Gulf Stream areas.After the remove-restore technique was applied to TIM_R6 MDT,the STD of total geostrophic speeds dropped to 0.162 m/s.展开更多
PM2.5 samples for 24h were collected during winter in Tianjin, China. The ambient mass concentration and chemical composition of the PM2.5 were determined. Ionic species were analyzed by ion chromatography, while carb...PM2.5 samples for 24h were collected during winter in Tianjin, China. The ambient mass concentration and chemical composition of the PM2.5 were determined. Ionic species were analyzed by ion chromatography, while carbonaceous species were determined with the IMPROVE thermal optical reflectance (TOR) method, and inorganic elements were measured by inductively coupled plasma-atomic emission spectrometer. The daily PM2.5 mass concentrations ranged from 48.2 to 319.2 μg/m^3 with an arithmetic average of 144.6 μg/m^3. The elevated PM2.5 in winter was mostly attributed to combustion sources such as vehicle exhaust, heating, cooking and industrial emissions, low wind speeds and high relative humidity (RH), which were favorable for pollutant accumulation and formation of secondary pollutants. By chemical mass balance, it was estimated that about 89.1% of the PM2.5 mass concentrations were explained by carbonaceous species, secondary particles, crustal matters, sea salt and trace elements. Organic material was the largest contributor, accounting for about 32.7% of the total PM2.5 mass concentrations. SO4^2-, NO3^-, Cl^- and NH4^+ were four major ions, accounting for 16.6%, 11.5%, 4.7% and 6,0%, respectively, of the total mass of PM2.5.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.41106072,41376093)the International Collaboration Science Plan(No.GASI-01-02-01-04)
文摘The contribution of phytoliths to total biogenic silica(BSi) volumes in rivers worldwide,and the associated implications for the biogeochemical cycle,require in-depth study.Based on samples from rivers in Peninsular Malaysia,this project investigated the source and characteristics of B Si found in Asian tropical rivers,as well as the process of reverse weathering taking place in these fluvial systems.Results indicated that BSi samples collected in sediments consisted of phytolith,diatom and sponge spicules.Phytoliths,predominantly of the elongate form,comprised 92.8%-98.3% of BSi in the Pahang River.Diatom BSi in this river consisted mainly of pennatae diatoms,but represented a relatively small proportion of the total BSi volume.However,diatom BSi(predominantly of the Centricae form) was more prevalent in the Pontian and Endau Rivers with shares of 68.8% and 79.3% of the total BSi volumes,respectively,than Pahang River.Carbon contents of the BSi particulates ranged from 1.85% to 10.8% with an average of 4.79%.These values are higher than those recorded in other studies to date,and indicate that BSi plays a major role in controlling permanent carbon burial.This study suggests that phytoliths from terrestrial plants are the primary constituents of BSi in the rivers of Peninsular Malaysia,and therefore represent a significant proportion of the coastal silica budget.
基金The Open Fund of Key Laboratory of Marine Environmental Information Technologythe Open Foundation of Technology Innovation Center for Marine Information,Ministry of Natural Resources+7 种基金the Liao Ning Revitalization Talents Program under contract No.XLYC1807161the Dalian High-level Talents Innovation Support Plan under contract No.2017RQ063the National Natural Science Foundation of China under contract Nos 41206013 and 41430963the Scientific Research Project of Liaoning Province Department of Education under contract No.QL201905the Projects of Institute of Marine Industry Technology of Liaoning Universitiesthe grant from Key R&D Program of Liaoning Province under contract No.2019JH2/10200015the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0402the Shandong Provincial Key Research and Development Program(SPKR&DP)under contract No.2019JZZY020713.
文摘The new gravity field models of gravity field and steady-state ocean circulation explorer(GOCE),TIM_R6 and DIR_R6,were released by the European Space Agency(ESA)in June 2019.The sixth generation of gravity models have the highest possible signal and lowest error levels compared with other GOCE-only gravity models,and the accuracy is significantly improved.This is an opportunity to build high precision geostrophic currents.The mean dynamic topography and geostrophic currents have been calculated by the 5th(TIM_R5 and DIR_R5),6th(TIM_R6 and DIR_R6)release of GOCE gravity field models and ITSG-Grace2018 of GRACE gravity field model in this study.By comparison with the drifter results,the optimal filtering lengths of them have been obtained(for DIR_R5,DIR_R6,TIM_R5 and TIM_R6 models are 1°and for ITSG-Grace2018 model is 1.1°).The filtered results show that the geostrophic currents obtained by the GOCE gravity field models can better reflect detailed characteristics of ocean currents.The total geostrophic speed based on the TIM_R6 model is similar to the result of the DIR_R6 model with standard deviation(STD)of 0.320 m/s and 0.321 m/s,respectively.The STD of the total velocities are 0.333 m/s and 0.325 m/s for DIR_R5 and TIM_R5.When compared with ITSG-Grace2018 results,the STD(0.344 m/s)of total geostrophic speeds is larger than GOCE results,and the accuracy of geostrophic currents obtained by ITSG-Grace2018 is lower.And the absolute errors are mainly distributed in the areas with faster speeds,such as the Antarctic circumpolar circulation,equatorial region,Kuroshio and Gulf Stream areas.After the remove-restore technique was applied to TIM_R6 MDT,the STD of total geostrophic speeds dropped to 0.162 m/s.
基金supported by National Natural Science Foundation of China (Grant No. 20677030)Tianjin Science and Technology Development Commission (Grant No. 06YFSYSF02900)
文摘PM2.5 samples for 24h were collected during winter in Tianjin, China. The ambient mass concentration and chemical composition of the PM2.5 were determined. Ionic species were analyzed by ion chromatography, while carbonaceous species were determined with the IMPROVE thermal optical reflectance (TOR) method, and inorganic elements were measured by inductively coupled plasma-atomic emission spectrometer. The daily PM2.5 mass concentrations ranged from 48.2 to 319.2 μg/m^3 with an arithmetic average of 144.6 μg/m^3. The elevated PM2.5 in winter was mostly attributed to combustion sources such as vehicle exhaust, heating, cooking and industrial emissions, low wind speeds and high relative humidity (RH), which were favorable for pollutant accumulation and formation of secondary pollutants. By chemical mass balance, it was estimated that about 89.1% of the PM2.5 mass concentrations were explained by carbonaceous species, secondary particles, crustal matters, sea salt and trace elements. Organic material was the largest contributor, accounting for about 32.7% of the total PM2.5 mass concentrations. SO4^2-, NO3^-, Cl^- and NH4^+ were four major ions, accounting for 16.6%, 11.5%, 4.7% and 6,0%, respectively, of the total mass of PM2.5.