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A review of rapid transport of pesticides from sloping farmland to surface waters: Processes and mitigation strategies

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Journal of Environmental Sciences 2012年第3期24卷 351-361页

作者： Xiangyu Tang Bo Zhu Hidetaka Katou Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China National Institute for Agro-Environmental Sciences Kannondai 3-1-3Tsukuba 305-8604Japan

Pesticides applied to sloping farmland may lead to surface water contamination through rapid transport processes as influenced by the complex topography and high spatial variability of soil properties and land use in hilly or mountainous regions. However, the fate of pesticides applied to sloping farmland has not been sufficiently elucidated. This article reviews the current understanding of pesticide transport from sloping farmland to surface water. It examines overland flow and subsurface lateral flow in areas where surface soil is underlain by impervious subsoil or rocks and tile drains. It stresses the importance of quantifying and modeling the contributions of various pathways to rapid pesticide loss at catchment and regional scales. Such models could be used in scenario studies for evaluating the effectiveness of possible mitigation strategies such as constructing vegetated strips, depressions, wetlands and drainage ditches, and implementing good agricultural practices. Field monitoring studies should also be conducted to calibrate and validate the transport models as well as biophysical-economic models, to optimize mitigation measures in areas dominated by sloping farmland.

关键词： pesticide rapid transport sloping farmland overland flow subsurface flow

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Flame Spread over Aviation Kerosene with an Obstacle in Liquid Phase

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Journal of Thermal Science 2011年第6期20卷 543-547页

作者： Jin GUO Shouxiang LU Manhou LI Changjian WANG State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China School of Chemical Engineering Anhui University of Science and Technology Huainan 232001 Anhui China

The phenomena of flame spread over aviation kerosene with an obstacle in liquid phase are investigated experimentally through surface temperature measurement by using infrared camera,schlieren images of subsurface flow in front of and behind obstacle and residence time of flame obtained from video *** results reveal that obstacle has no effect on gas phase controlled flame *** for liquid phase controlled flame spread,flame can be stopped by an obstacle with its top edge flush with oil surface,and the residence time decreases with the increase of initial temperature of *** conduction and radiation only play a subsidiary role in flame spread over liquid fuel was proved by schlieren images and surface temperature profiles.

关键词： flame spread temperature profile infrared subsurface flow obstacle

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NATURAL AND ANTHROPOGENIC FACTORS CONTROLLING GULLY EROSION IN THEBASALTIC UPLAND OF SOUTHERN BRAZIL

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International Journal of Sediment Research 2005年第3期20卷 57-69页

作者： Ana C. VIERO,Nilza M. dos Reis CASTRO ,Joel A. GOLDENFUM ,Alfonso RISSO CPRM-Geological Survey of Brazil Rua Banco da Provincia 105 Porto Alegre RS 840-030 Brazil

This paper describes an analysis of natural and anthropogenic factors controlling the evolution of gullies in a rural basin in the basaltic upland in the State of Rio Grande do Sul, Southern Brazil. In this region of deep ferrallitic soils with more than 60% clay, runoff and erosion are of increasing concern. In the Tabo?o drainage basin (100 km2), gully erosion was studied in a field survey that measured rills and gullies. Eighty-four gullies were identified. They had an average length of 136 m, were 10 m wide, and 3 m deep and had a volume of 15.458 m3. Each gully was characterised in terms of factors that included slope, geological structure, presence of piping, drainage, soil use, and the presence of surface and subsurface flow. On average, the main channels had knickpoints varying from 2 m to 7 m, and their evolution in the vertical plane increased until bed-rock basalt material was reached, after which gullies increase in width and length. Gully development was also monitored from 1991 to 2003. subsurface flow appears to be the principal agent controlling their development. Results show that both natural (slope, surface curvature, geological structure and rainfall) and anthropogenic (soil use, road construction) factors are important in gully development. The change in cultural practices throughout the drainage basin from conventional to direct seeding has led to increased subsurface flow, which was more important than surface runoff in causing erosion. However, the higher rainfall during El Ni?o Southern Oscillation (ENSO) events and the consequently higher subsurface flow were the dominant factors. From 1991 to 2003 a total land loss of 1,013 m3 was observed in one gully, with 236 m3 lost during the 1992 ENSO and 702 m3 during the 1997 ENSO; 95% of the total volume lost occurred during ENSO periods.

关键词： Gully Geological structure subsurface flow No-tillage ENSO

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