Examining the competing effects of contemporary land management vs. land cover changes on global air quality
Examining the competing effects of contemporary land management vs. land cover changes on global air quality
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DOI：
10.5194/acp-21-16479-2021
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发表时间：
2021-11
影响因子：
6.3
通讯作者：
A. Y. H. Wong;J. Geddes
中科院分区：
文献类型：
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作者：
A. Y. H. Wong;J. Geddes
抽象的。我们的工作探讨了土地系统变化的两个重要方面，土地利用和土地覆被变化（LULCC）以及土壤直接农业活性氮（Nr）排放对臭氧（O3）和细颗粒物（PM2.5）在当代（1992年至2014年）时间尺度上空气质量的影响。我们考虑LULCC和农业氮排放变化与一致的遥感产品和新的全球排放清单，分别估计其对全球表面O3和PM2.5浓度以及氮沉降的影响，使用GEOS-Chem全球化学传输模型。在这段时间内，我们的模型结果表明，农业氮排放量的变化导致欧洲和北方亚洲的年平均PM2.5水平下降（高达-2.1 µg m−3），而印度，中国和美国东部的PM2.5水平上升（高达+3.5 µg m−3）。土地覆被变化导致亚马逊河流域、中国和印度PM2.5的小幅减少（最多-0.7 µg m−3），这是由于生物挥发性有机化合物（BVOC）排放减少和气溶胶前体气体（例如，NO2、SO2）。农业氮排放变化仅导致年平均地表O3水平的微小变化（最多±0.6 ppbv），主要是在中国、印度和缅甸。与此同时，我们的模型结果表明，在整个南美洲的时间段内，LULCC对地表O3的影响更大;干沉降和异戊二烯排放的变化导致地表臭氧变化为-0.8至+1.2 ppbv。干沉降的增加降低了中国南部、美国东部和非洲中部的地面臭氧水平（高达-1 ppbv）。由于作物扩张而导致的土壤NO排放的增加也有助于撒哈拉以南非洲的地表臭氧变化（高达+0.6 ppbv）。在某些地区，土地利用、土地利用变化和农业氮排放变化对O3和PM2.5空气质量的综合影响与同期人为排放变化相当（> 20%）。最后，我们计算出，全球农业氮排放量的增加导致全球土地面积净增加（+3.67 106 km 2），可能面临临界氮负荷（>5 kg N ha−1 yr−1）的增加。我们的研究结果表明，当代LULCC和农业氮排放变化对PM2.5和O3的空气质量的影响，以及土地系统的变化对空气质量在几十年的时间尺度的重要性。
Abstract. Our work explores the impact of two important dimensions of land system changes, land use and land cover change (LULCC) as well as direct agricultural reactive nitrogen (Nr) emissions from soils, on ozone (O3) and fine particulate matter (PM2.5) in terms of air quality over contemporary (1992 to 2014) timescales. We account for LULCC and agricultural Nr emissions changes with consistent remote sensing products and new global emission inventories respectively estimating their impacts on global surface O3 and PM2.5 concentrations as well as Nr deposition using the GEOS-Chem global chemical transport model. Over this time period, our model results show that agricultural Nr emission changes cause a reduction of annual mean PM2.5 levels over Europe and northern Asia (up to −2.1 µg m−3) while increasing PM2.5 levels in India, China and the eastern US (up to +3.5 µg m−3). Land cover changes induce small reductions in PM2.5 (up to −0.7 µg m−3) over Amazonia, China and India due to reduced biogenic volatile organic compound (BVOC) emissions and enhanced deposition of aerosol precursor gases (e.g., NO2, SO2). Agricultural Nr emission changes only lead to minor changes (up to ±0.6 ppbv) in annual mean surface O3 levels, mainly over China, India and Myanmar. Meanwhile, our model result suggests a stronger impact of LULCC on surface O3 over the time period across South America; the combination of changes in dry deposition and isoprene emissions results in −0.8 to +1.2 ppbv surface ozone changes. The enhancement of dry deposition reduces the surface ozone level (up to −1 ppbv) over southern China, the eastern US and central Africa. The enhancement of soil NO emission due to crop expansion also contributes to surface ozone changes (up to +0.6 ppbv) over sub-Saharan Africa. In certain regions, the combined effects of LULCC and agricultural Nr emission changes on O3 and PM2.5 air quality can be comparable (>20 %) to anthropogenic emission changes over the same time period. Finally, we calculate that the increase in global agricultural Nr emissions leads to a net increase in global land area (+3.67×106km2) that potentially faces exceedance of the critical Nr load (>5 kg N ha−1 yr−1). Our result demonstrates the impacts of contemporary LULCC and agricultural Nr emission changes on PM2.5 and O3 in terms of air quality, as well as the importance of land system changes for air quality over multidecadal timescales.