PRESENTATION 1595 Presented during Coastal peatlands in a changing world II, 5/31/2019 1:00 PM-2:50 PM
REGIONAL DISTRIBUTION AND ECOLOGICAL RISK EVALUATION OF HEAVY METALS IN SURFACE SEDIMENTS FROM DAFENG COASTAL WETLANDS IN YANCHENG, JIANGSU, CHINA. Yuan, Hongming, QIMG, CGS Guangming, Zhao, Xue, Li, Ye, Siyuan, QIMG, CGS Known as the Oriental Wetland City, Yancheng City has the largest coastal wetlands in the Asia covering an area of more than 45,000 km2, accounting for one seventh of the total area of the whole coastal China. It is also an important overwintering site for the endangered species redcrowned crane in China and has been listed in the world key wetland list in 2002.Dafeng coastal wetlands is one of important parts of Yancheng wetlands. The regional distribution characteristics of seven heavy metals contents in the surface sediments of Dafeng coastal wetlands are seriously studied. The results show that the mean values of Hg, Cd, As, Cu, Pb, Cr and Zn in the surface sediments were 0.05, 0.25, 7.21, 25.5, 20.3, 67.79 and 68.09 mg/kg respectively, and the mean values of the tidal flat wetlands were higher than those in man-made wetlands. The site JST-02 of the tidal flat wetland near the Dafeng Port has the highest content of heavy metals, showing a pollution pattern by a single point source. The regional distribution of heavy metals is positively correlated with particle size, suggesting that the clay content plays a controlling role on the enrichment and distribution of heavy metals. The average values of single factor pollution indices show an ordered pattern from high to low in the surface sediments of the study area as Cd > Cr > Cu > Zn > Pb > As > Hg, and the maximum value of Cd, the main pollution element of the study area is as high as 1.57. The comprehensive potential ecological risk index(RI) varies between 15.70 and 184.91, with a mean of 27.41, in an order of Hg > Cd > as > Cu > Pb > Cr > Zn, which is higher than that of man-made wetland. Hg and Cd are the main potential ecological risk factors. Our data further suggests that though the whole region has lower potential ecological risk indices and remains under the level of environmental pollution, the concentration of single pollutant maybe too high already in some the local areas. Comparing with the similar research of 2005, the contents of Hg, Cd, As, and Cr are much lower than those of 2005, Pb and Cu keep same level with 2005, while the content of Zn raise a little higher than that of 2005. Furthermore the RI reduced from 297.7 to 184.9. It shows that
although more and more human activities affect the coastal wetlands through these years, the pollution level of heavy metals in Dafeng coastal wetland is getting better by local government’s policy and treatments. ■
PRESENTATION 1596 Presented during Poster Session & Silent Auction Reception, 5/30/2019 6:30 PM-8:30 PM
WARMING EFFECT OF AN OPEN TOP CHAMBER AND ITS SHORT-TERM INFLUENCE ON A PHRAGMITES WETLAND ECOSYSTEM Yu, Xueyang, Qingdao Institute of Marine Geology Ye, Siyuan, QIMG, CGS Lei, Guo, Yuan, Hongming, QIMG, CGS Kauss, Ken, Brix, Hans, Open-top chamber (OTC) is a widely applied passive warming method in the research of field in-situ experiment, considering the study of global climate change. A model of OTC warming instance was conducted in a Phragmites wetland located at the Yellow River delta of Dongying city, China. With continuous climate data collection, the attributes and patterns of the chamber’s warming effects are demonstrated. Combined with in-situ plant observation, we also quantified the influence of chamber warming to plant properties, which could provide clues on future study of how wetland ecosystem responds to future climate change. According to our results, our design of OTC averagely increases air temperature by 0.8°C during the growing season of 2018, surface soil temperature is increased by 0.54°C. The soil was warmed by 0.46°C. The warming effects highly depends on heat sources of incoming radiation in daytime and outcoming soil heat in nighttime. The instant warming effects of air temperature ranges from -2.5 to 8.3 °C due to various meteorological conditions. Nighttime temperature depression events are regulaly observed, and the environmental factors indicates that the cooling effects was due to the low turbulence inside warming chambers and the surface soil-atmosphere heat transfer. Besides, warming resulted in soil dehydration. Significant short-term response of plant were detected including the shoot density change, height change, stem diameter change. Due to the experimental warming, plant shoot density decreased by 23%, plant height increased by 4.5%, and plant stem diameter increased by 6.2%. Plant biomass was estimated to be decreased by 31.6%, which was related to the changes in individual plant traits and community changes such as pests damage and reed lodging within the warming chambers. ■ Wetland Science & Practice July Special Issue 2019 227