[Temporal and Spatial Dynamics of Greenhouse Gas Emissions and Its Controlling Factors in a Coastal Saline Wetland in North Jiangsu].

Although coastal wetlands play an important role in governing the atmospheric concentrations of CO2, CH4, and N2O, thus control the global warming, research of the greenhouse gas emissions conducted in the coastal wetlands were not well-documented because of the difficulty in fieldwork in these harsh environments, and the complicated controlling factors affecting the greenhouse gas emissions. The temporal and spatial variations of CO2, CH4, and N2O were investigated simultaneously in the coastal saline wetland in North Jiangsu during the period from April, 2014 to March, 2014, using the closed static dark chamber method. And the results showed that seasonal variations of CO2, CH4, and N2O were higher in summer, and lower CO2 and N2O fluxes were observed in winter, while for CH4 in spring, it presented the sink in the coastal wetland. The annual average CO2 emission derived from the Spartina alterniflora flat (SAF) was the highest, with the value of (766.3±496.9) mg·(m2·h)-1, and for CH4 and N2O, the highest values were found in Phragmites australis flat (PAF), with the values of (0.420±0.900) mg·(m2·h)-1 and (17.4±5.0) µg·(m2·h)-1, respectively. The bare mud flat (BF) presented the sink of CH4, and the source of CO2 and N2O, with the lowest emission rates across all the tidal flats. The global warming potential (GWP) from the coastal wetlands in north Jiangsu was observed higher in SAF[68841.280 kg·(hm2·a)-1], which was 1.41 and 3.02 times higher compared with those of PAF and SGF, the GWP of BF was the lowest, with the value of 5002.100 kg·(hm2·a)-1. Furthermore, significant correlations were found between CO2 fluxes and temperature, including air temperature (AT), soil temperature (ST), and temperature inside the chamber (CT), however, for CH4 and N2O, the correlations were not so obvious. Above all, the temporal variations of CO2, CH4, and N2O were mainly controlled by the temperature and characteristics of vegetation, the spatial variations of CO2, CH4, and N2O were determined by the characteristics of vegetation. Furthermore, we may safely draw the conclusion that the invasive S. alterniflora increased the global warming potential dominantly through increasing the CO2 emission rates, compared with the native plant.

[Connotation characterization and evaluation of ecological well-being based on ecosystem service theory.] / åŸºäºŽç”Ÿæ€ç³»ç»ŸæœåŠ¡ç†è®ºçš„ç”Ÿæ€ç¦ç¥‰å† æ¶µè¡¨å¾ä¸Žè¯„ä»·.

China is advocating ecological civilization construction nowadays. Further researches on the relation between ecosystem service and humanity well-being are full of theoretical and practical significance. Combining related researches, this paper defined the concept and connotation of ecological well-being based on ecosystem service theory. Referencing theory of national economic accounting and relative researches, the evaluation indicators of ecological well-being supply and consumption were established. The quantitative characterization and evaluation method of red line of regional ecological well-being was proposed on the basis of location quotient. Then the evaluation of ecological well-being in mainland China in 2012 was set as an example for empirical research. The results showed that the net product values of 6 ecosystems, includingcultivated land, forest land, grassland, wetland, water area and unused land, were respectively 1481.925, 8194.806, 4176.277, 4245.760, 3177.084 and 133.762 billion CNY. Spatial heterogeneity of ecosystem net product in different provinces was distinct. Ecological well-being per capita of forest land, grassland, wetland, cultivated land and unused land in eastern and middle provinces were under the red line and less than the national average. The spatial distribution of 9 kinds of ecological well-being per capita split at Hu's line with high value in northwest and low value in southeast, and was aggravated by differences in density of population and land resources gift.

[Source Apportionment and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Water from Yangtze River, China: Based on PMF Model].

To study the features and ecological risk of PAHs in surface water from Yangtze River, 19 water samples were collected from the main stream and branch of Yangtze River in August 2015. Solid phase extraction method was used to extract PAHs, and the concentrations of the 16 priority PAHs were determined using GC-MS. The results indicated that the concentration of total PAHs (∑PAHs) in the surface water ranged from 17.7-110 ng·L-1 with an average value of 42.6 ng·L-1. The predominant PAHs in the water were PAHs with 2-3 rings, accounting for 67.7% of ∑PAHs. The results of molecular diagnostic ratios indicated that the origin of PAHs was mostly combustion sources, including fossil fuel and biomass combustion. PMF model was used to quantitatively acquire the source contribution of PAHs, which indicated that four sources were identified and their contribution rates were respectively biomass and coal combustion (40.1%), petroleum source (19.6%), traffic source (17.5%) and coke oven source (22.8%). The results of ecological risk assessment indicated that PAHs with 2-3 rings had a relatively high risk level, and Wujiang station and lower reach had a relatively high risk level based on risk quotient. Overall, the ecological risk of PAHs in the Yangtze River was at a relatively low level.

Changes in water and sediment exchange between the Changjiang River and Poyang Lake under natural and anthropogenic conditions, China.

To study the fluvial interaction between Changjiang River and Poyang Lake, we analyze the observed changes of riverine flux of the mid-upstream of Changjiang River catchment, the five river systems of Poyang Lake and Poyang Lake basin. Inter-annual and seasonal variations of the water discharge and sediment exchange processes between Changjiang River and Poyang Lake are systematically explored to determine the influence of climate change as well as human impact (especially the Three Gorges Dam (TGD)). Results indicate that climate variation for the Changjiang catchment and Poyang Lake watershed is the main factor determining the changes of water exchanges between Changjiang River and Poyang Lake. However, human activities (including the emplacement of the TGD) accelerated this rate of change. Relative to previous years (1956-1989), the water discharge outflow from Poyang Lake during the dry season towards the Changjiang catchment increased by 8.98 km(3)y(-1) during 2003-2010. Evidently, the water discharge flowing into Poyang Lake during late April-late May decreased. As a consequence, water storage of Poyang Lake significantly reduced during late April-late May, resulting in frequent spring droughts after 2003. The freshwater flux of Changjiang River towards Poyang Lake is less during the flood season as well, significantly lowering the magnitude and frequency of the backflow of the Changjiang River during 2003-2010. Human activities, especially the emplacement and operation of the TGD and sand mining at Poyang Lake impose a major impact on the variation of sediment exchange between Changjiang main river and Poyang Lake. On average, sediments from Changjiang River deposited in Poyang Lake before 2000. After 2000, Changjiang River no longer supplied sediment to Poyang Lake. As a consequence, the sediment load of Changjiang River entering the sea increasingly exists of sediments from Lake Poyang during 2003-2010. As a result, Poyang Lake converted from a depositional to an erosional system, with a gross sediment loss of 120.19 Mty(-1) during 2001-2010, including sand mining.