In order to understand the water pollution characteristics in Huailai section of the Yongding River,the monitoring from November of 2016 to October of 2017 was conducted. 6 sampling points were selected for monitoring...In order to understand the water pollution characteristics in Huailai section of the Yongding River,the monitoring from November of 2016 to October of 2017 was conducted. 6 sampling points were selected for monitoring 6 indicators,and the temporal-spatial variation characteristics of nitrogen and phosphorus in the river were explored. Moreover,the ratio of nitrogen to phosphorus and an exponential universal formula of power function in logarithmic form were used to analyze temporal-spatial variation rules of nitrogen and phosphorus in water,assess the degree of eutrophication,and analyze eutrophication risk. The results showed that water pollution in Huailai section of the Yongding River was more serious. TN was13. 25 times of concentration limit of class III water in the dividing of surface water environment function area in the " 13 thFive-year" Development Planning" of National Environmental Protection Standard. ON and NO-3-N were the main forms of TN,while mean value of TP was 0. 64 mg/L,and each index had the characteristics of agricultural non-point source pollution. The temporal-spatial distribution characteristics of nitrogen and phosphorus in the water body was obvious. At the time scale,the concentrations of nitrogen and phosphorus in the water body showed seasonal variation; at the space scale,the distribution of nitrogen and phosphorus in the water body was similar. The annual average ratio of nitrogen and phosphorus in Huailai section of the Yongding River was 32. 78,and the phytoplankton was in the overall state of phosphorus limitation. During the flat water period,phosphorus was the limiting nutrient element,and the ratio of nitrogen and phosphorus in the dry period and the abundant water period was suitable for the growth and reproduction of algae. The temporal-spatial variation of water body in Huailai section of the Yongding River was mostly in the " eutrophication" stage. The maximum EI value was 228. 11 in dry season,and the lowest was 213. 06 in flood season,while it was218. 30 in flat water period. The fluvial dynamics process in Huailai section of the Yongding River was good,and the flow pattern of the river was continuous. The flow velocity of the main stream was 0. 43-1. 45 m/s,which was much larger than that of the algal bloom. The risk of cyanobacteria blooms in the main stream was low.展开更多
This experiment studies the influence of main climatic factors on the structure of grassland plant community under different grazing intensities, determines the influence of climatic factors on the quantitative charac...This experiment studies the influence of main climatic factors on the structure of grassland plant community under different grazing intensities, determines the influence of climatic factors on the quantitative characteristics of meadow steppe community structure changes, and explores the response and adaptation of meadow steppe biodiversity and ecosystem functions to climate changes, so as to provide a reference and basis for rational utilization and management of natural grassland and prediction of development trend of meadow steppe under global climate changes. The results showed that the correlations between grassland community characteristic index and different climatic factors were significantly different under different grazing intensities. The average temperature and annual precipitation in the critical period were the main climatic factors affecting the changes in meadow steppe community characteristics, and the sensitivity of community indexes to the changes in average temperature of the critical period was greater than that to the changes in annual precipitation. The aboveground biomass of zero grazing and moderate grading was positively correlated with the average temperature and annual precipitation during the critical period, and the correlations between aboveground biomass and environmental factors were no significant under heavy grazing.展开更多
基金Supported by the National Water Pollution Control and Treatment Science and Technology Major Project(2015ZX07203-005-06)
文摘In order to understand the water pollution characteristics in Huailai section of the Yongding River,the monitoring from November of 2016 to October of 2017 was conducted. 6 sampling points were selected for monitoring 6 indicators,and the temporal-spatial variation characteristics of nitrogen and phosphorus in the river were explored. Moreover,the ratio of nitrogen to phosphorus and an exponential universal formula of power function in logarithmic form were used to analyze temporal-spatial variation rules of nitrogen and phosphorus in water,assess the degree of eutrophication,and analyze eutrophication risk. The results showed that water pollution in Huailai section of the Yongding River was more serious. TN was13. 25 times of concentration limit of class III water in the dividing of surface water environment function area in the " 13 thFive-year" Development Planning" of National Environmental Protection Standard. ON and NO-3-N were the main forms of TN,while mean value of TP was 0. 64 mg/L,and each index had the characteristics of agricultural non-point source pollution. The temporal-spatial distribution characteristics of nitrogen and phosphorus in the water body was obvious. At the time scale,the concentrations of nitrogen and phosphorus in the water body showed seasonal variation; at the space scale,the distribution of nitrogen and phosphorus in the water body was similar. The annual average ratio of nitrogen and phosphorus in Huailai section of the Yongding River was 32. 78,and the phytoplankton was in the overall state of phosphorus limitation. During the flat water period,phosphorus was the limiting nutrient element,and the ratio of nitrogen and phosphorus in the dry period and the abundant water period was suitable for the growth and reproduction of algae. The temporal-spatial variation of water body in Huailai section of the Yongding River was mostly in the " eutrophication" stage. The maximum EI value was 228. 11 in dry season,and the lowest was 213. 06 in flood season,while it was218. 30 in flat water period. The fluvial dynamics process in Huailai section of the Yongding River was good,and the flow pattern of the river was continuous. The flow velocity of the main stream was 0. 43-1. 45 m/s,which was much larger than that of the algal bloom. The risk of cyanobacteria blooms in the main stream was low.
文摘This experiment studies the influence of main climatic factors on the structure of grassland plant community under different grazing intensities, determines the influence of climatic factors on the quantitative characteristics of meadow steppe community structure changes, and explores the response and adaptation of meadow steppe biodiversity and ecosystem functions to climate changes, so as to provide a reference and basis for rational utilization and management of natural grassland and prediction of development trend of meadow steppe under global climate changes. The results showed that the correlations between grassland community characteristic index and different climatic factors were significantly different under different grazing intensities. The average temperature and annual precipitation in the critical period were the main climatic factors affecting the changes in meadow steppe community characteristics, and the sensitivity of community indexes to the changes in average temperature of the critical period was greater than that to the changes in annual precipitation. The aboveground biomass of zero grazing and moderate grading was positively correlated with the average temperature and annual precipitation during the critical period, and the correlations between aboveground biomass and environmental factors were no significant under heavy grazing.
