Modelling of sand/dust emission in Northern China from 2001 to 2014

摘要

Wind erosion is a major contributing factor to soil degradation and environmental pollution. As a hot spot of wind erosion, Northern China suffers from severe wind erosion hazards. Besides, there is an ongoing controversy regarding the magnitudes of sand/dust emissions of anthropogenic sources. To understand the mechanism of soil degradation and environmental pollution caused by wind erosion, and to resolve the controversy whether sand/dust emissions is from natural or anthropogenic sources in Northern China, accurate spatio-temporal distributions of sand/dust emission should be obtained. Herein, a wind erosion model with a high spatio-temporal resolution was developed and employed to identify the sand and dust emissions of areas with different land cover types. The sand and dust emission hot spots from 2001 to 2014 were mainly distributed in the Gashun Gobi and Kumutage Deserts, those are all natural areas. In these regions, the average sand and dust emissions exceeded 10,000 kg/m/y (year) and 240 g/m(2)/y, respectively. The intensities of sand and dust emissions demonstrated significant decreasing trends during this time. According to Moderate Resolution Imaging Spectroradiometer (MODIS) land cover data, the average sand/dust emission rates in natural sources were much higher than that in anthropogenic areas, e.g. from 2001 to 2014, the average annual dust emission of Northern China was about 130 Tg/y, and only approximately 3.7% of dust emissions originated from anthropogenic areas. Dust deflation correspondingly caused the entrainment of soil nutrients into atmosphere and result in soil degradation. Our results also show that the Soil Organic Carbon (SOC) loss due to wind erosion in Northern China was about 0.9 Tg/y and that 32.5% and 7.5% of the SOC loss originated from grasslands (including woody savannas, savannas, and grasslands) and farmlands (including croplands and cropland/natural vegetation mosaics), respectively. With regard to such severe sand and dust emissions, we believe that the results of this study could provide valuable information for the creation of strategies to cope with wind erosion hazards and measures to control the extent of wind-blown sand. In addition, the proposed model could be of interest to ecological and environmental researchers.