The Formation Of The Xiaopo Lake Wetland And Its Environment Characteristics In The Qinghai Lake Watershed

The Xiaopo lake wetland is an important part of ecological environment of Qinghai lake, bordering the riyue mountain in the east and Qilian mountain in the north. It has some special ecological functions, such as adjusting the region climate,conserving the water resource and protecting the biodiversity. With the development of the region tourism industry and people’s lack of knowledge for the wetland, the ecological environment has been destroyed to some degree and the ecological functions has been weakened. So the research on Xiaopo lake wetland will help to improve our understanding of the wetlands environmental features, and also will contribute to recover the ecological environment. This paper measures the samples of the Xiaopo lake wetland by using AMS14 C dating method, and discusses the environment of the wetland combining with environmental proxies, such as the organic matter, color, magnetic susceptibility, particle size, etc., and draws the following conclusions:Measures the samples of the Xiaopo Lake Wetland by using the AMS14 C dating method, and corrects the dating results by using Calibration CALIB 7.0.2. As the organic carbon content in stratum 0~20 cm is higher than 100 pMC, and the exact strata age can’t be measured, the only exact age which can be measured is the sample deeper than 20 cm. Through Calibration CALIB 7.0.2 correction to the dating results,the sample age error is within 30 years, and as the sample reflects, the age of wetland may be less than 300 years.The organic matter content of the sample near the earth’s surface is high, and its overall content is lower. This may be closely related to clay’s occupation in this soil.The overall changing curve of organic matter content has two obvious peak values,which are near the surface and in the bottom layer. The fluctuation of the changing curve is very frequent, which may be due to the regional weather climate and the transfer system of matter.Overall, the brightness value is higher, the yellowness and the redness values are lower, but the fluctuation of the color curve is also very frequent, and shows obvious high or low value. The higher brightness value corresponds to the lower organic matter content. The lower redness value shows that the input of the red matter is less.The change of the redness value is mainly controlled by the sand strength, the vegetation coverage and the climate change. The better vegetation coverage can weaken the sand strength, and then the input of the red matter will be less, and vice versa.On the whole, the low frequency mass magnetic susceptibility is low, but the fluctuation of the changing curve of the magnetic susceptibility is frequent, and hasobvious peank value, which means that the overall magnetic mineral content is less.The high value of the magnetic susceptibility may be caused by the stronger sand, or because the warm humid climate makes the river runoff increase. The frequent fluctuation of the magnetic susceptibility reflects the instability of the sedimentary environment.The size composition is mainly composed of sand particles, and the clay is at a minimum percent, which is less than 1% on average. The average grain diameter is2.24, which means the particle diameter is larger. The average sorting coefficient value is 0.67, and it means good sorting. The average skewness value is 0.09, which means the particle size on the frequency summation curve shows symmetric distribution. The average kurtosis value is 1.09 and the overall kurtosis is high and narrow, which means the sorting is good, and the size composition mainly shows sand fraction. Considering the magnetic susceptibility and the change features of the particle size, we can speculate that the formation of the Xiaopo Lake wetland is mainly related to the control of geologic agent of the wind, which accords with the sand dunes widely distributed around the Xiaopo wetland. But there are also some low and wide kurtosises, which means the wetland deposit was affected by more than one geological force. According to the field reconnaissance, the wetland is still developing the river, so we can speculate that the Xiaopo Lake wetland is a result of wind deposition and river deposition.