Overwhelming evidence reveals that concentrations of dissolved organic carbon （DOC） have increased in streams which brings negative environmental impacts. DOC in stream flow is mainly originated from soil-water solu...Overwhelming evidence reveals that concentrations of dissolved organic carbon （DOC） have increased in streams which brings negative environmental impacts. DOC in stream flow is mainly originated from soil-water solutions of watershed. Wetlands prove to be the most sensitive areas as an important DOC reserve between terrestrial and fluvial biogeosystems. This reported study was focused on the distribution characteristics and the controlling factors of DOC in soil-water solutions of annular wetland, i.e., a dishing wetland and a forest wetland together, in the Sanjiang Plain, Northeast China. The results indicate that DOC concentrations in soilwater solutions decreased and then increased with increasing soil depth in the annular wetland. In the upper soil layers of 0-10 cm and 10-20 cm, DOC concentrations in soil-water solutions linearly increased from edge to center of the annular wetland （R^2 = 0.3122 and R^2 = 0.443）. The distribution variations were intimately linked to DOC production and utilization and DOC transport processes in annular wetland soil-water solutions. The concentrations of total organic carbon （TOC）, total carbon （TC） and Fe（II）, DOC mobility and continuous vertical and lateral flow affectext the distribution variations of DOC in soil-water solutions. The correlation coefficients between DOC concentrations and TOC, TC and Fe（II） were 0.974, 0.813 and 0.753 respectively. These distribution characteristics suggested a systematic response of the distribution variations of DOC in annular wetland soil-water solutions to the geometry of closed depressions on a scale of small catchments. However, the DOC in soil pore water of the annular wetland may be the potential source of DOC to stream flow on watershed scale. These observations also implied the fragmentation of wetland landscape could bring the spatial-temporal variations of DOC distribution and exports, which would bring negative environmental impacts in watersheds of the Sanjiang Plain.展开更多
The carbon （C）, nitrogen （N） and phosphorus （P） variations of a temperate wetland soil under continuous cultivation for 40 yr were determined and evaluated in the Sanjiang Plain, Northeast China. The results sho...The carbon （C）, nitrogen （N） and phosphorus （P） variations of a temperate wetland soil under continuous cultivation for 40 yr were determined and evaluated in the Sanjiang Plain, Northeast China. The results showed that the soil organic carbon （SOC） and total nitrogen （TN） contents in each soil layer decreased sharply after cultivation for 2-3 yr, and exhibited minor differences after cultivation for 11 yr, which showed an exponential decline curve with the increase of cultivation years. The reduction rates of carbon and nitrogen reserves were 14.79% and 28.53% yr^-1 at the initial reclamation stages of 2-3 yr and then decreased to 2.02-3.08% yr^-1 and 1.98-2.93% yr^-1 after cultivation for 20 yr, respectively. Soil total phosphorus （TP） reserves decreased within cultivation for 5 yr, and then gradually restored to the initial level after cultivation for 17 yr. Both SOC and TN could be restored slightly when the farmland was left fallow for 8 yr after reclamation for 11 yr, whereas TP had no significant difference. These results demonstrated that wetland cultivation was one of the most important factors influencing on the nutrient fate and reserves in soil, which could lead to the rapid nutrient release and slow restoration through abandon cultivation, therefore protective cultivation techniques preventing nutrients from loss should be immediately established after wetland reclamation.展开更多
The sulfur cycle and its compartmental distribution within an atmosphere-plant-soil system was studied using a compartment model in the typical meadow Calamagrostis angustifolia wetland in the Sanjiang Plain Northeast...The sulfur cycle and its compartmental distribution within an atmosphere-plant-soil system was studied using a compartment model in the typical meadow Calamagrostis angustifolia wetland in the Sanjiang Plain Northeast China. The results showed that in the typical meadow C. angustifolia wetland ecosystem, soil was the main storage compartment and current hinge of sulfur in which 98.4% sulfur was accumulated, while only 1.6% sulfur was accumulated in the plant compartment. In the plant subsystem, roots and litters were the main storage compartment of sulfur and they remained 83.5% of the total plant sulfur. The calculations of sulfur turnover through the compartments of the typical meadow C. angustifolia wetland ecosystem demonstrated that the above-ground component took up 0.99 gS/m^2 from the root, of which 0.16 gS/m^2 was translocated to the roots and 0.83 gS/m^2 to the litter. The roots took in 1.05 gS/m^2 from the soil, subsequent translocation back to the soil accounted for 1.31 gS/m^2, while there was 1.84 gS/m^2 in the litter and the net transfer of sulfur to the soil was more than 0.44 gS/（m^2·a）. The emission of H2S from the typical meadow C. angustifolia wetland ecosystem to the atmosphere was 1.83 mgS/（m^2·a）, while carbonyl sulfide （COS） was absorbed by the typical meadow C. angustifolia wetland ecosystem from the atmosphere at the rate of 1.76 mgS/（m^2·a）. The input of sulfur by the rainfall to the ecosystem was 4.85 mgS/m^2 during the growing season. The difference between input and output was 4.78 mgS/m^2, which indicated that sulfur was accumulated in the ecosystem and may cause wetland acidify in the future.展开更多
Different types of vegetation occupy different geomorphology and water gradient environments in the San- jiang Plain, indicating that the soil moisture dynamics and water balance patterns of the different vegetation c...Different types of vegetation occupy different geomorphology and water gradient environments in the San- jiang Plain, indicating that the soil moisture dynamics and water balance patterns of the different vegetation communi- ties might differ from each other. In this paper, a lowland system, perpendicular to the Nongjiang River in the Honghe National Nature Reserve （HNNR）, was selected as the study area. The area was occupied by the non-wetland plant forest and the typical wetland plant meadow. The Microsoft Windows-based finite element analysis software package for simulating water, heat, and solute transport in variably saturated porous media （HYDRUS）, which can quantita- tively simulate water, heat, and/or solute movement in variably-saturated porous media, was used to simulate soil moisture dynamics in the root zone （20-40 cm） of those two plant communities during the growing season in 2005. The simulation results for soil moisture were in a good agreement with measured data, with the coefficient of determi- nation （R2） of 0.44-0.69 and root mean square error （RMSE） ranging between 0.0291 cm3/cm3 and 0.0457 cm3/cm3, and index of agreement （d） being from I）.612 to 0.968. During the study period, the volumetric soil moisture content of meadow increased with the depth and its coefficient of variation decreased with the depth （from 20 cm to 40 cm）, while under the forest the soil moisture content at different depths varied irregularly. The calculated result of water budget showed that the water budget deficit of the meadow was higher than that of the forest, suggesting that the meadow is more likely to suffer from water stress than the forest. The quantitative simulation by HYDRUS in this study did not take surface runoff and plant growth processes into account. Improved root water uptake and surface runoff models will be needed for higher accuracy in further researches.展开更多
The iron concentrations of snows,semi-melting snows,snowmelts,and ditch waters were observed in four typical microhabitats,Carex lasiocarpa marsh(Ⅰ), Calamagrostis angustifolia wet meadow(Ⅱ),dry land (Ⅲ)and paddy f...The iron concentrations of snows,semi-melting snows,snowmelts,and ditch waters were observed in four typical microhabitats,Carex lasiocarpa marsh(Ⅰ), Calamagrostis angustifolia wet meadow(Ⅱ),dry land (Ⅲ)and paddy field(Ⅳ),of Sanjiang Plain Wetland, Northeast China.Each sample was collected from three sites of one microhabitat,mixed together, filtrated with 0.45μm membrane,and tested using atomic absorption spectrometry(AAS)for iron measurement.The iron concentrations of soil solutions were investigated as well.Each soil solution was in-situ extracted by negative pressure,filtrated with 0.45μm membrane,and tested using AAS,too. The results showed that the wet precipitation of iron from snow were little to detect.The loss of iron was attributed to the interaction of water and soil surface. The iron concentrations of snowmelts were 7.4,15,展开更多
基金Project supported by the Knowledge Innovation Engineering Project of the Chinese Academy of Sciences(No. KSCX2-YW-N-46-06)the National Natural Science Foundation of China(No. 40501030).
文摘Overwhelming evidence reveals that concentrations of dissolved organic carbon （DOC） have increased in streams which brings negative environmental impacts. DOC in stream flow is mainly originated from soil-water solutions of watershed. Wetlands prove to be the most sensitive areas as an important DOC reserve between terrestrial and fluvial biogeosystems. This reported study was focused on the distribution characteristics and the controlling factors of DOC in soil-water solutions of annular wetland, i.e., a dishing wetland and a forest wetland together, in the Sanjiang Plain, Northeast China. The results indicate that DOC concentrations in soilwater solutions decreased and then increased with increasing soil depth in the annular wetland. In the upper soil layers of 0-10 cm and 10-20 cm, DOC concentrations in soil-water solutions linearly increased from edge to center of the annular wetland （R^2 = 0.3122 and R^2 = 0.443）. The distribution variations were intimately linked to DOC production and utilization and DOC transport processes in annular wetland soil-water solutions. The concentrations of total organic carbon （TOC）, total carbon （TC） and Fe（II）, DOC mobility and continuous vertical and lateral flow affectext the distribution variations of DOC in soil-water solutions. The correlation coefficients between DOC concentrations and TOC, TC and Fe（II） were 0.974, 0.813 and 0.753 respectively. These distribution characteristics suggested a systematic response of the distribution variations of DOC in annular wetland soil-water solutions to the geometry of closed depressions on a scale of small catchments. However, the DOC in soil pore water of the annular wetland may be the potential source of DOC to stream flow on watershed scale. These observations also implied the fragmentation of wetland landscape could bring the spatial-temporal variations of DOC distribution and exports, which would bring negative environmental impacts in watersheds of the Sanjiang Plain.
基金supported by the National Natural Science Foundation of China(41071056)the Discovery Research Project of Chinese Academy of Sciences(KZCX2-YW-309)
文摘The carbon （C）, nitrogen （N） and phosphorus （P） variations of a temperate wetland soil under continuous cultivation for 40 yr were determined and evaluated in the Sanjiang Plain, Northeast China. The results showed that the soil organic carbon （SOC） and total nitrogen （TN） contents in each soil layer decreased sharply after cultivation for 2-3 yr, and exhibited minor differences after cultivation for 11 yr, which showed an exponential decline curve with the increase of cultivation years. The reduction rates of carbon and nitrogen reserves were 14.79% and 28.53% yr^-1 at the initial reclamation stages of 2-3 yr and then decreased to 2.02-3.08% yr^-1 and 1.98-2.93% yr^-1 after cultivation for 20 yr, respectively. Soil total phosphorus （TP） reserves decreased within cultivation for 5 yr, and then gradually restored to the initial level after cultivation for 17 yr. Both SOC and TN could be restored slightly when the farmland was left fallow for 8 yr after reclamation for 11 yr, whereas TP had no significant difference. These results demonstrated that wetland cultivation was one of the most important factors influencing on the nutrient fate and reserves in soil, which could lead to the rapid nutrient release and slow restoration through abandon cultivation, therefore protective cultivation techniques preventing nutrients from loss should be immediately established after wetland reclamation.
文摘The sulfur cycle and its compartmental distribution within an atmosphere-plant-soil system was studied using a compartment model in the typical meadow Calamagrostis angustifolia wetland in the Sanjiang Plain Northeast China. The results showed that in the typical meadow C. angustifolia wetland ecosystem, soil was the main storage compartment and current hinge of sulfur in which 98.4% sulfur was accumulated, while only 1.6% sulfur was accumulated in the plant compartment. In the plant subsystem, roots and litters were the main storage compartment of sulfur and they remained 83.5% of the total plant sulfur. The calculations of sulfur turnover through the compartments of the typical meadow C. angustifolia wetland ecosystem demonstrated that the above-ground component took up 0.99 gS/m^2 from the root, of which 0.16 gS/m^2 was translocated to the roots and 0.83 gS/m^2 to the litter. The roots took in 1.05 gS/m^2 from the soil, subsequent translocation back to the soil accounted for 1.31 gS/m^2, while there was 1.84 gS/m^2 in the litter and the net transfer of sulfur to the soil was more than 0.44 gS/（m^2·a）. The emission of H2S from the typical meadow C. angustifolia wetland ecosystem to the atmosphere was 1.83 mgS/（m^2·a）, while carbonyl sulfide （COS） was absorbed by the typical meadow C. angustifolia wetland ecosystem from the atmosphere at the rate of 1.76 mgS/（m^2·a）. The input of sulfur by the rainfall to the ecosystem was 4.85 mgS/m^2 during the growing season. The difference between input and output was 4.78 mgS/m^2, which indicated that sulfur was accumulated in the ecosystem and may cause wetland acidify in the future.
基金Under the auspices of National Natural Science Foundation of China (No. 40871241,41001050)Direction Project of Chinese Academy of Science (KZCX2-YW-Q06-03)
文摘Different types of vegetation occupy different geomorphology and water gradient environments in the San- jiang Plain, indicating that the soil moisture dynamics and water balance patterns of the different vegetation communi- ties might differ from each other. In this paper, a lowland system, perpendicular to the Nongjiang River in the Honghe National Nature Reserve （HNNR）, was selected as the study area. The area was occupied by the non-wetland plant forest and the typical wetland plant meadow. The Microsoft Windows-based finite element analysis software package for simulating water, heat, and solute transport in variably saturated porous media （HYDRUS）, which can quantita- tively simulate water, heat, and/or solute movement in variably-saturated porous media, was used to simulate soil moisture dynamics in the root zone （20-40 cm） of those two plant communities during the growing season in 2005. The simulation results for soil moisture were in a good agreement with measured data, with the coefficient of determi- nation （R2） of 0.44-0.69 and root mean square error （RMSE） ranging between 0.0291 cm3/cm3 and 0.0457 cm3/cm3, and index of agreement （d） being from I）.612 to 0.968. During the study period, the volumetric soil moisture content of meadow increased with the depth and its coefficient of variation decreased with the depth （from 20 cm to 40 cm）, while under the forest the soil moisture content at different depths varied irregularly. The calculated result of water budget showed that the water budget deficit of the meadow was higher than that of the forest, suggesting that the meadow is more likely to suffer from water stress than the forest. The quantitative simulation by HYDRUS in this study did not take surface runoff and plant growth processes into account. Improved root water uptake and surface runoff models will be needed for higher accuracy in further researches.
文摘The iron concentrations of snows,semi-melting snows,snowmelts,and ditch waters were observed in four typical microhabitats,Carex lasiocarpa marsh(Ⅰ), Calamagrostis angustifolia wet meadow(Ⅱ),dry land (Ⅲ)and paddy field(Ⅳ),of Sanjiang Plain Wetland, Northeast China.Each sample was collected from three sites of one microhabitat,mixed together, filtrated with 0.45μm membrane,and tested using atomic absorption spectrometry(AAS)for iron measurement.The iron concentrations of soil solutions were investigated as well.Each soil solution was in-situ extracted by negative pressure,filtrated with 0.45μm membrane,and tested using AAS,too. The results showed that the wet precipitation of iron from snow were little to detect.The loss of iron was attributed to the interaction of water and soil surface. The iron concentrations of snowmelts were 7.4,15,
