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Abstract: Acid rain is a major regional-scale environmental problem in China. To control acid rain pollution and to protect the ecological environment, it is urgent to document acid rain patterns in various regions of China. Taking Liaoning Province as the study area, the present work focused on the spatial and temporal variations of acid rains in northeastern China. It presents a means for predicting the occurrence of acid rain using geographic position, terrain characteristics, routinely monitored meteorological factors and column concentrations of atmospheric SO2 and NO2. The analysis applies a decision tree approach to the foregoing observation data. Results showed that: (1) acid rain occurred at 17 stations among the 81 monitoring stations in Liaoning Province, with the frequency of acid rain from 0 to 84.38%; (2) summer had the most acid rain occurrences followed by spring and autumn, and the winter had the least; (3) the total accuracy for the simulation of precipitation pH (pH ≤ 4.5, 4.5 < pH ≤ 5.6, and pH > 5.6) was 98.04% using the decision tree method known as C5. The simulation results also indicated that the distance to coastline, elevation, wind direction, wind speed, rainfall amount, atmospheric pressure, and the precursors of acid rain all have a strong influence on the occurrence of acid rains in northeastern China. [ABSTRACT FROM AUTHOR]

The rapid growth of the vehicle population was regarded as an important factor that contributed to the urban air pollution in China during the past decades. We used Tianjin, a typical megacity facing vehicle pollution problems, as the study domain to investigate a comprehensive estimation of vehicle emissions, including carbon monoxide (CO), volatile organic compounds (VOCs), nitrogen oxides (NO x), inhalable particles (PM 10), carbon dioxide (CO 2) and sulphur dioxide (SO 2), from 2000 to 2030. The Computer Programme to calculate Emissions from Road Transport (COPERT) model was used to simulate the vehicle emission factors. Historical simulations show that the total emissions of CO, VOCs, NO x , PM 10 , CO 2 , and SO 2 changed from 545.1 Gg, 70.04 Gg, 60.19 Gg, 6.57 Gg, 6.82 Tg and 12.88 Gg to 259.11 Gg, 34.01 Gg, 55.14 Gg, 3.42 Gg, 25.30 Tg and 0.16 Gg from 2000 to 2016, respectively. Passenger cars (PC) and light-duty vehicles (LDV) were the main contributors to the CO and VOCs emissions. Heavy-duty trucks (HDT) and buses (BUS) were the important contributors to NO x and PM 10. PC was the major contributor to CO 2 and SO 2. With respect to the future, four Single Control Policy Scenarios (SCPS), including Passenger car Population Regulation (PPR), Emission Standard Updating (ESU), Public Transportation Promotion (PTP) and Electric Vehicle Popularity (EVP), and Integrated Scenarios (IS), were assembled to describe the impact of future policies on vehicle pollution from 2017 to 2030. Among all SCPS, the results show that the ESU is the more effective policy to control emissions of CO, NO x and PM 10 , while PPR is the more effective way to reduce emissions of VOCs, CO 2 , and SO 2. • A comprehensive estimation of vehicle emissions was investigated in Tianjin from 2000 to 2030. • The estimation incorporated the impacts of vehicle emission control policies that were newly implemented. • The compositions of vehicular emission standards were considered to improve the accuracy of the estimation. • The reduction effects on six pollutants were evaluated under five vehicle emission reduction scenarios. [ABSTRACT FROM AUTHOR]