Comprehensive and high-resolution emission inventory of atmospheric pollutants for the northernmost cities agglomeration of Harbin-Changchun, China: Implications for local atmospheric environment management.

Using a bottom-up estimation method, a comprehensive, high-resolution emission inventory of gaseous and particulate atmospheric pollutants for multiple anthropogenic sectors with typical local sources has been developed for the Harbin-Changchun city agglomeration (HCA). The annual emissions for CO, NOx, SO2, NH3, VOCS, PM2.5, PM10, BC and OC during 2017 in the HCA were estimated to be 5.82 Tg, 0.70 Tg, 0.34 Tg, 0.75 Tg, 0.81Tg, 0.67 Tg, 1.59 Tg, 0.12 Tg and 0.26 Tg, respectively. For PM10 and SO2, the emissions from industry processes were the dominant contributors representing 54.7% and 49.5%, respectively, of the total emissions, while 95.3% and 44.5% of the total NH3 and NOx emissions, respectively, were from or associated with agricultural activities and transportation. Spatiotemporal distributions showed that most emissions (except NH3) occurred in November to March and were concentrated in the central cities of Changchun and Harbin and the surrounding cities. Open burning of straw made an important contribution to PM2.5 in the central regions of the northeastern plain during autumn and spring, while domestic coal combustion for heating purposes was significant with respect to SO2 and PM2.5 emissions during autumn and winter. Furthermore, based on Principal Component Analysis and Multivariable Linear Regression model, air temperature, relative humidity, electricity and energy consumption, and the urban and rural population were optimized to be representative indicators for rapidly assessing the magnitude of regional atmospheric pollutants in the HCA. Such indicators and equations were demonstrated to be useful for local atmospheric environment management.

Atmospheric pollution of agriculture-oriented cities in Northeast China: A case in Suihua.

Agriculture-oriented cities in Northeastern China have experienced frequent atmospheric pollution events. Deeper understandings of the pollution characteristics, haze causes and effects of management on local air quality are crucial for conducting integrated management approaches for the sustainable development of agriculture-oriented cities. Taking a typical agriculture-dominant city (i.e., Suihua) in Northeast China, we analyzed in detail the characteristics and causes of atmospheric pollution and evaluated the straw-burning prohibition using multisource data. The results showed a clear temporal pattern of air quality index (AQI) on an annual scale (i.e., 2015-April 2019), with two typical pollution periods occurring in late autumn and early spring. The large areas of concentrated straw burning at local and regional scales accounted for the first period (i.e., October and November), while dust emissions and farming disturbances comprised the second period. The interannual variation in pollution periods among these years was large, showing similar trends from 2015 to 2017 and the postponed late-autumn pollution period in 2018. Our evaluation has shown that the prohibition effect of straw burning significantly improved air quality in 2018, with a reduction of 59% ± 88% in the PM2.5 concentrations in October and November compared to 2015-2017. However, From October to April of the following year, the improvement effect was not significant due to postponement of straw burning to February or March. Our analysis also highlighted the roles of meteorological conditions, Therefore, combined with the promotion of straw utilization, scientifically prescribed burning considering the burning amount and location, meteorological conditions and regional transportation should be implemented.

Ecological risk assessment of wetland vegetation under projected climate scenarios in the Sanjiang Plain, China.

Wetland ecosystems have comprehensive ecological functions and are sensitive to climate change. Under climate change, wetlands plant community productivity and diversity may be affected. In previous studies of wetlands, the effects of climate change have been primarily investigated using field observations, factor-controlled experiments, and mechanism analyses. However, the ecological risks to wetland communities under potential long-term climate change on a regional scale remain uncertain. The Sanjiang Plain is the largest area of natural marsh wetlands and the national ecological functions in China. In this study, the changes in plant productivity and diversity of wetland ecosystems in the Sanjiang Plain were simulated under different climate change scenarios (i.e., Representative Concentration Pathways, RCP 2.6, RCP4.5, RCP6.0, and RCP8.5), and the rank of spatiotemporal risk on a regional scale was estimated using a pressure-state-response model. Temperature and precipitation had average rates of increase of 0.44 °C/10a and 12.13 mm/10a, respectively, under different climate change scenarios to 2050. The fluctuation range in climatic factors was largest under the RCP8.5 scenario. On a long-term scale, compared with the base year of 2010, vegetation productivity increased significantly under the RCP2.6 scenario, remained almost constant under RCP4.5 and RCP6.0 scenarios, and decreased under the RCP8.5 scenario. In contrast to productivity, plant diversity increased under all four scenarios, but the range of increase gradually decreased with the increase in scenarios. Spatially, a fluctuation range change in precipitation was one of the important factors that caused high risks to regional wetlands. In the northwest of the Sanjiang Plain, most wetlands were assessed as high risk at level-3. In the other regions, the risks were lower with the values below level-2, and only a few places were assessed at risk level-3. In national wetland nature reserves, the northeast of the Qixing River, Xingkai Lake, and the Dongfanghong Marsh wetland area were ranked as high risk at level-3. These findings suggest that wetland protection and management should be focus on hydrological allocation and the potential ecological risks to national wetland nature reserves. However, a joint risk assessment of climate change and human activity should be conducted to provide a comprehensive reference for the protection and development of natural marsh wetlands.