Anthropogenic dust emissions due to livestock trampling in a Mongolian temperate grassland

Erdenebayar Munkhtsetseg,George Nikolich,Reiji Kimura,Masato Shinoda,Masahide Ishizuka,Masao Mikami

doi:10.5194/acp-17-11389-2017

Abstract

Abstract. Mongolian grasslands are a natural dust source region and they contribute to anthropogenic dust due to the long tradition of raising livestock there. Past decades of abrupt changes in a nomadic society necessitate a study on the effects of livestock trampling on dust emissions, so that research studies may help maintain a sustainable ecosystem and well-conditioned atmospheric environment. In this study, we conducted a mini wind tunnel experiment (using a PI-SWERL® device) to measure dust emissions fluxes from trampling (at three disturbance levels of livestock density, N) and zero trampling (natural as the background level) at test areas in a Mongolian temperate grassland. Moreover, we scaled anthropogenic dust emissions to natural dust emissions as a relative consequence of livestock trampling. We found a substantial increase in dust emissions due to livestock trampling. This effect of trampling on dust emissions was persistent throughout all wind friction velocities, u* (varying from 0.44 to 0.82 m s−1). Significantly higher dust loading occurs after a certain disturbance level has been reached by the livestock trampling. Our results suggest that both friction velocity (u*) and disturbance level of livestock density (N) have an enormous combinational effect on dust emissions from the trampling test surface. This means that the effect of livestock trampling on dust emissions can be seen or revealed when wind is strong. Our results also emphasize that better management for livestock allocation coupled with strategies to prevent anthropogenic dust loads are needed. However, there are many uncertainties and assumptions to be improved on in this study.

Highlights

Mongolian grasslands are a natural dust source region and they contribute to anthropogenic dust due to the long tradition of raising livestock there
The mean rate of PM10 emissions from the test surface areas for each friction velocity of the PI-SWERL® experiment reveals greater detail concerning the behavior of dust emissions and the effect of trampling (Fig. 4) (Supplement 1)
We studied the effects of livestock trampling on dust emissions strength by conducting PI-SWERL® experiments in temperate grassland of Mongolia

Summary

Introduction

Mongolian grasslands are a natural dust source region and they contribute to anthropogenic dust due to the long tradition of raising livestock there. The Mongolian ecosystem is generally sensitive to any external disturbance of the environment, natural or human, such as climate change or human activity (Peters, 2002; Pogue and Schnell, 2001). The projected increasing aridity warns that enhanced warming (climate change) coupled with rapidly increasing human activities will further exacerbate the risk of land degradation and desertification in the dry lands in the near future (Huang et al, 2016). Natural grassland exposures to livestock trampling, overgrazing, and road vehicle traffic are some of the most prevalent modifiable risk factors for dust emissions in Mongolia. Animal husbandry will contribute to atmospheric dust loading through degraded and disturbed land by (i) graz-

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Discussion

Conclusion