Đăng nhập
 
Tìm kiếm nâng cao
 
Tên bài báo
Tác giả
Năm xuất bản
Tóm tắt
Lĩnh vực
Phân loại
Số tạp chí
 

Bản tin định kỳ
Báo cáo thường niên
Tạp chí khoa học ĐHCT
Tạp chí tiếng anh ĐHCT
Tạp chí trong nước
Tạp chí quốc tế
Kỷ yếu HN trong nước
Kỷ yếu HN quốc tế
Book chapter
Tạp chí quốc tế 2018
Số tạp chí 15(2018) Trang: 3049–3069
Tạp chí: Biogeosciences

Human activities are drastically altering water and material flows in river systems across Asia. These anthropogenic perturbations have rarely been linked to the carbon (C) fluxes of Asian rivers that may account for up to 40–50 % of the global fluxes. This review aims to provide a conceptual framework for assessing the human impacts on Asian river C fluxes, along with an update on anthropogenic alterations of riverine C fluxes. Drawing on case studies conducted in three selected rivers (the Ganges, Mekong, andYellow River) and other major Asian rivers, the review focuses on the impacts of river impoundment and pollution on CO2 outgassing from the rivers draining South, South-east, and East Asian regions that account for the largest fraction of river discharge and C exports from Asia and Oceania. A critical examination of major conceptual models of  riverine processes against observed trends suggests that to better understand altered metabolisms and C fluxes in “anthropogenic land water-scapes”, or riverine landscapes modified by human activities, the traditional view of the river continuum should be complemented with concepts addressing spatial and temporal discontinuities created by human activities, such as river impoundment and pollution. Recent booms in dam construction on many large Asian rivers pose a host of environmental problems, including increased retention of sediment and associated C. A small number of studies that measured greenhouse gas (GHG) emissions in dammed Asian rivers have reported contrasting impoundment effects: decreased GHG emissions from eutrophic reservoirs with enhanced primary production vs. increased emissions from the flooded vegetation and soils in the early years following dam construction or from the impounded reaches and downstream estuaries during the monsoon period. These contrasting results suggest that the rates of metabolic processes in the impounded and downstream reaches can vary greatly longitudinally over time as a combined result of diel shifts in the balance between autotrophy and heterotrophy, seasonal fluctuations between dry and monsoon periods, and a long-term change from a leaky post-construction phase to a gradual C sink. The rapid pace of urbanization across southern and eastern Asian regions has dramatically increased municipal water withdrawal, generating annually 120 km3 of wastewater in 24 countries, which comprises 39 % of the global municipal wastewater production. Although municipal wastewater constitutes only 1 % of the renewable surface water, it can disproportionately affect the receiving river water, particularly downstream of rapidly expanding metropolitan areas, resulting in eutrophication, increases in the amount and lability of organic C, and pulse emissions of CO2 and other GHGs. In rivers draining highly populated metropolitan areas, lower reaches and tributaries, which are often plagued by frequent algal blooms and pulsatile CO2 emissions from urban tributaries delivering high loads of wastewater, tended to exhibit higher levels of organic C and the partial pressure of CO2 (pCO2) than less impacted upstream reaches and eutrophic impounded reaches. More field measurements of pCO2, together with accurate flux calculations based on river-specific model parameters, are required to provide more accurate estimates of GHG emissions from the Asian rivers that are now underrepresented in the global C budgets. The new conceptual framework incorporating discontinuities created by impoundment and pollution into the river continuum needs to be tested with more field measurements of riverine metabolisms and CO2 dynamics across variously affected reaches to better constrain altered fluxes of organic C and CO2 resulting from changes in the balance between autotrophy and heterotrophy in increasingly human-modified river systems across Asia and other continents.

Các bài báo khác
Số tạp chí Volume 50, Issue 4, 391-399(2018) Trang: 391-399
Tạp chí: Korean Journal of Food Science and Technology
Số tạp chí 30(2018) Trang:
Tạp chí: Asia Pacific Journal of Marketing and Logistics
Số tạp chí 4th AADGC(2018) Trang: 237-242
Tạp chí: The 4th International Asian-Australasian Dairy Goat Conference 17-19 October, 2018, Tra Vinh Univ. Vietnam
Số tạp chí 37(2018) Trang: 5935-5950
Tạp chí: Computational and Applied Mathematics
Số tạp chí 17(2018) Trang: 180
Tạp chí: Biomedical Engineering Online
Số tạp chí 16(2018) Trang: 302-316
Tạp chí: Thai Journal of Mathematics
Số tạp chí 4(4)(2018) Trang: 306-319
Tạp chí: European Journal of Education Studies
Số tạp chí Vol 6, Issue 1(2018) Trang: 47-55
Tạp chí: Asian Journal of Economic Modelling
Số tạp chí 4th(2018) Trang: 429-434
Tạp chí: The 4th International Asian-Australasian Dairy Goat Conference 17-19 October, 2018, Tra Vinh Univ. Vietnam
Số tạp chí 4th AADGC(2018) Trang: 457-464
Tạp chí: The 4th International Asian-Australasian Dairy Goat Conference 17-19 October, 2018, Tra Vinh Univ. Vietnam
Số tạp chí 4th AADGC(2018) Trang: 278-282
Tạp chí: The 4th International Asian-Australasian Dairy Goat Conference 17-19 October, 2018, Tra Vinh Univ. Vietnam
Số tạp chí 7(2018) Trang: 45-51
Tạp chí: International Journal of Business and Management Invention (IJBMI)
Số tạp chí Volume 8, Issue 12(2018) Trang: 452-461
Tạp chí: International Journal of Scientific and Research Publications


Vietnamese | English






 
 
Vui lòng chờ...