RESUMO
Affected by both future anthropogenic emissions and climate change, future prediction of PM2.5 and its Oxidative Potential (OP) distribution is a significant challenge, especially in developing countries like China. To overcome this challenge, we estimated historical and future PM2.5 concentrations and associated OP using the Danish Eulerian Hemispheric Model (DEHM) system with meteorological input from WRF weather forecast model. Considering different future socio-economic pathways and emission scenario assumptions, we quantified how the contribution from various anthropogenic emission sectors will change under these scenarios. Results show that compared to the CESM_SSP2-4.5_CLE scenario (based on moderate radiative forcing and Current Legislation Emission), the CESM_SSP1-2.6_MFR scenario (based on sustainability development and Maximum Feasible Reductions) is projected to yield greater environmental and health benefits in the future. Under the CESM_SSP1-2.6_MFR scenario, annual average PM2.5 concentrations (OP) are expected to decrease to 30 (0.8 nmolmin-1m-3) in almost all regions by 2030, which will be 65 % (67 %) lower than that in 2010. From a long-term perspective, it is anticipated that OP in the Fen-Wei Plain region will experience the maximum reduction (82.6 %) from 2010 to 2049. Largely benefiting from the effective control of PM2.5 in the region, it has decreased by 82.1 %. Crucially, once emission reduction measures reach a certain level (in 2040), further reductions become less significant. This study also emphasized the significant role of secondary aerosol formation and biomass-burning sources in influencing OP during both historical and future periods. In different scenarios, the reduction range of OP from 2010 to 2049 is estimated to be between 71 % and 85 % by controlling precursor emissions involved in secondary aerosol formation and emissions from biomass burning. Results indicate that strengthening the control of anthropogenic emissions in various regions are key to achieving air quality targets and safeguarding human health in the future.
RESUMO
Atmospheric deposition is a major input of mercury (Hg) to aquatic and terrestrial ecosystems. To evaluate Hg pollution mitigation strategies for inland lakes, the two Great Lakes (Ontario and Erie) adjacent to New York State (NYS), and rural land areas of Upstate New York, the relative contributions to atmospheric Hg deposition from anthropogenic emission reductions and meteorological variations were investigated using a regional three-dimensional chemical transport model with detailed Hg and bromine chemistry (CMAQ-newHg-Br). Our simulations suggested that NYS in-state emissions and the Northeastern US emission reductions from 2005 to 2011 did not significantly alter Hg wet and dry deposition in all study areas when averaged over time and space. However, such emission changes significantly altered intensive emission sources (>10 lb/year) with subsequent effects on deposition to nearby water bodies. For the Great Lakes, Hg dry deposition was enhanced by a factor of 2-5 in the adjacent model grids (within distances of ~12 km downwind), and the enhancements decreased to negligible values over ~50 km distances. Over land, anthropogenic emissions contributed 30% of the spatial variation in Hg dry deposition and 46% in ambient concentrations of gaseous oxidized Hg (GOM). Spatial and temporal variations in meteorology and foliar characteristics were found to affect both Hg wet and dry deposition. Convective precipitation significantly contributed to spatial and seasonal variations (~65%) in Hg wet deposition over both lake and land surfaces, whereas wind speed and surface heat flux were the main factors contributing to the spatial variation in Hg dry deposition over the lake surfaces through their impacts on dry deposition velocities of GOM and PBM. Leaf area index, which regulates deposition velocity, contributed 14% of the spatial variation in dry deposition flux over land. Variation in solar radiation, which influences photochemical formation of GOM and PBM, explained ~10% of the spatial variation over lake and land surfaces alike. Findings from our highly focused study suggested broad implications. Future climate change will likely serve to enhance Hg concentrations in biota via increases in Hg dry and wet deposition to varying degrees contingent on land surface type. Hence, liminating the health risks of Hg requires mitigation of both anthropogenic Hg emission hotspots and human-induced climate change.
