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Study on Seasonal Variation Characteristics and Transformation Process of Soil Nitrogen in Yellow River Estuary Wetland

Author: ZuoQin
Tutor: LuoXianXiang
School: Ocean University of China
Course: Environmental Science
Keywords: Wetlands in the Yellow River Mouth Soil nitrogen Spatial distribution Transformation process Reed decomposition
CLC: X144
Type: Master's thesis
Year: 2010
Downloads: 163
Quote: 3
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Abstract

Yellow River mouth wetlands located on the south bank of the Bohai Bay and Laizhou Bay Bank, is typical of estuaries and coastal wetland ecosystems. In this paper, the Yellow River Delta Wetlands study explores the seasonal variations of the wetlands in the Yellow River Mouth nitrogen spatial distribution pattern and nitrogen forms, estimates of wetlands in the Yellow River Mouth nitrogen reserves; laboratory experiment of wetlands nitrogen Mine process, nitrification and denitrification process, and estimate the amount of conversion of organic nitrogen mineralization process, the conversion of ammonium nitrogen nitrification process and denitrification process nitrate loss; wild reed litter decomposition test, The reed of litter restitution amount estimate. Systems research in the laboratory analysis and field observations on the basis of the nitrogen transformation process, explore Nitrogen biogeochemical processes in wetlands generation mechanism and the main factors, and analysis of the potential ecological effects of wetland nitrogen transformation process, provide a scientific basis for the sustainable use of the Yellow River mouth wetlands management and protection. Wetland nitrogen spatial distribution pattern of the Yellow River mouth showed that: agricultural growing areas of surface soil nitrogen content higher than that of natural wetlands, organic nitrogen is in the form of the main components of the nitrogen in the organic nitrogen content of more than 98% of the total nitrogen content of ammonium nitrogen accounted for inorganic nitrogen content of about 80%. The study area surface soil nitrogen content in the low nutrient levels, natural wetlands area ammonium nitrogen content of less than 10mg/kg, the nitrate content of less than 3mg/kg, total nitrogen content lower than 1000mg/kg. Vertical direction, HHK-14-HHK-62 the sampling points nitrogen content gradually decreased with soil depth deepened surface 0-20cm soil nitrogen content was significantly higher than the layers of soil below 20cm, 30cm below soil nitrogen content changes small. Temperature, moisture conditions, the different vegetation growth process, nitrogen seasonal change significantly, higher than the seasonal variation of inorganic nitrogen organic nitrogen. Vegetation distribution, differences in soil texture, soil organic carbon and nitrogen transformation process spatial distribution pattern of differences Different different season nitrogen content and the nitrogen reserves in the soil there are differences in the 0-60cm depth of soil total nitrogen reserves in May, August, October of 2047.77-3540.44g · m-3 ,1177.18-2682 .38 g · m -3,1540.09-2759.78 g · m-3 range change. Soil nitrogen transformation process: Tamarix dominant species the HHK-14 sampling points nitrogen conversion rate is higher than the dominant species reeds the HHK-21 sampling points. Conversion capacity of the two sampling sites showed the surface 0-20cm soil nitrogen transformation capacity higher than 20cm below the depth of soil nitrogen transformation processes denitrification capacity is strongest, weakest capacity mineralization, nitrification capacity between between. Nitrogen transformation process, the amount of the maximum conversion of organic nitrogen 0.91g · m-3 · d-1, the maximum conversion of ammonium nitrogen, 12.77 g · m-3 · d-1, the maximum loss of the nitrate 23.44 g · m-3 · d-1. Reed of litter decomposition tests showed: showed a gradually decreased the nitrogen absolute amount of litter decomposition process, intermittently flooded environments reed material ground litter section, the underground stems, underground capillary root of the absolute amount of nitrogen release reduced by 35.96% -53.49% 8.62% -76.77% 31.20% -72.43%. Non-flooded environment, the absolute amount of nitrogen release were reduced by 16.03% -50.34% 14.68% -69.33% 37.65% -73.77%, the decomposition process reed various parts of accumulation coefficients were less than 100%, reed decomposition process the net release of nitrogen. Summer reed of litter nitrogen restitution of the amount of the highest and lowest in winter, the reed the underground part of the nitrogen restitution above ground part. In short, the Yellow River Mouth wetland soil nitrogen content in the middle and lower nutrient levels, soil texture, organic carbon content and distribution of vegetation soil nitrogen spatial distribution of the most important influencing factors, general, clay is a high proportion of high organic carbon content and higher nitrogen content of vegetation-rich region. Soil nitrogen reserves of nitrogen transformation process is closely related to the weak capacity of the wetlands in the Yellow River Mouth soil organic nitrogen mineralization, denitrification of nitrogen in nitrate loss, this study area soil denitrification lower nitrogen content match. Litter decomposition process of nitrogen to the soil restitution affect soil nitrogen pool of reserves, and the reed litter decomposition process in nitrogen average daily return of the amount of up to 0.039g · m-2 d-1.

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