Total mercury concentration of typical wetland plants was analyzed in thispaper. There were great differences of total mercury concentration among different plants:moss>hydrophyte>sedge>herbage>shrub. Tota...Total mercury concentration of typical wetland plants was analyzed in thispaper. There were great differences of total mercury concentration among different plants:moss>hydrophyte>sedge>herbage>shrub. Total mercury concentrations show an increasing trend fromvascular plants to bryophytes, and from dry to wet lands. The mercury concentration of wetlandplants was higher than that of crops. The wetland soil was the source of mercury in the air close tothe ground, so it affected the concentration of mercury in the plant. In different parts of aplant, mercury concentration was in the order of: dead stand>root>leaf>stem. Mercury concentrationincreased at the initial stage and decreased in the end of the growing season. According to themercury content and biomass, mercury stock of plants was 39.4μg/m^2 above ground in Calamagrostisangustifolia wetland and 35.8μg /m^2 in Carex lasiocarpa wetland.展开更多
The Sanjiang Plain is the largest and most concentrated wetland region in China, the total area is about 1.088×107ha with rich marsh resources and biodiversity. Before 1949, the Sanjiang Plain was a large untrave...The Sanjiang Plain is the largest and most concentrated wetland region in China, the total area is about 1.088×107ha with rich marsh resources and biodiversity. Before 1949, the Sanjiang Plain was a large untravelled wild plant and waterfowl habitat, and there were some rare swans, red-crowned cranes and thousands of hydrophytes. From 1950, the local government began to reclaim the marsh in the Sanjiang Plain, built the commodity grain base of Northeast China, and developed the industry of grain processing, animal husbandry, etc. Up to now, there are 54 farms which control 3.5087×106ha agriculture field. The marsh areas are reduced by 1/2; many rare animals and plants are near extinction. The human activities and agriculture reclamation made a great change on the environment, especially made water balance change and regional climate change. So to study and protect the wetland ecosystem and marsh resource are extremely urgent. This paper focus on the hydrology change and climate change before and after marsh reclamation, including evapotranspiration, run off, soil character, micro-climate on both marsh and agriculture field, and the reason that cause seasonal drought, waterlogging and degeneration of marsh.展开更多
Northeast China is the region with the largest area of wetlands in China. The Sanjiang Plain and the Songnen Plain are large freshwater marsh distribution regions that are affected by climate warming and by the increa...Northeast China is the region with the largest area of wetlands in China. The Sanjiang Plain and the Songnen Plain are large freshwater marsh distribution regions that are affected by climate warming and by the increasing frequency and density of extreme weather and are the regions most subject to disturbances by human activities in Northeast China. The wetlands of the Sanjiang Plain and the Songnen Plain have shrunk severely in the past 60 years, and wetland functions have been reduced substantially because of climate change, unreasonable land use, fire episodes, engineering and construction works and urbanization. Large-scale agricultural development started in the 1950 s has been the most important driving factor for wetland loss and degradation in the Sanjiang Plain. Water shortage has been the most important factor for degradation and fragmentation of wetlands in the Songnen Plain. To mitigate wetland degradation and better protect wetlands, special regulations, long-term mechanisms and technical support of wetland protection should be established. A wetland compensation program should be implemented, and technologies for increasing the adaptive capacity of wetlands should be developed. Moreover, it is most important to find the balanced threshold between agricultural development and wetland protection.展开更多
In this paper, the environment characteristics, micro-environment division and evolution of the mangrove tidal flats, peats and their genetic markers are discussed. It proves that the mangrove tidal flat is a kind of ...In this paper, the environment characteristics, micro-environment division and evolution of the mangrove tidal flats, peats and their genetic markers are discussed. It proves that the mangrove tidal flat is a kind of tidal flats and the peat flats are developed in a specific evolution stage of mangrove tidal flats; the mangrove peats are the products of a specific evolution stage of the mangrove tidal flats.展开更多
Over the past five decades, the natural wetlands in Sanjiang Plain, Northeast China, have been extensively reclaimed for agriculture with a total loss of nearly 80% of the surface area and the undrained marshes have r...Over the past five decades, the natural wetlands in Sanjiang Plain, Northeast China, have been extensively reclaimed for agriculture with a total loss of nearly 80% of the surface area and the undrained marshes have received a large amount of exogenous nitrogen (N) input from the adjacent agricultural land because of fertilization. In the present study, the effects of nitrogen additions on seed germination and seedling biomass of Calamagrostis angustifolia in freshwater marsh were tested in a greenhouse study. Seed bank soil was exposed to different N additions (0, 5, 10, 20 and 40 g/m^2) under non-flooded water regime. Results revealed that, low level of N additions (less than 10 g/m^2) did not significantly affect the species richness and seedling density, while the seedling biomass at 5 g/m^2 of N addition was higher than other nutrient conditions. But species richness, seedling emergence and biomass decreased significantly at high level of N additions (20-40 g/m^2). The responses were species-specific. High level of N additions had negative impacts on seed germination, seedling growth and biomass of dominant species Eleocharis ovata, Calamagrostis angustifolia, duncus effusus in the seed bank. To protect and restore the wetland vegetation community in the Sanjiang plain, fertilization, irrigation and land management strategies will need to be implemented to reduce the nutrient input from the agricultural land to the wetlands.展开更多
Elements (vanadium and zinc) were determined in the two most abundant species of shell mollusks (Unio tigridis and Fiviparous bengalensis) and the water where they live in five stations in the Iraqi marshes. The s...Elements (vanadium and zinc) were determined in the two most abundant species of shell mollusks (Unio tigridis and Fiviparous bengalensis) and the water where they live in five stations in the Iraqi marshes. The study of concentrations elements was a target organ for aquatic environmental. Comparison between the mean concentrations of the elements in the water concentration levels of all studied elements was the highest with the mollusks. The results show that the station 5 is where the highest concentrations are found in water and in the two species. There is a significant correlation (P = 0.224) for concentrations of vanadium and P = 0.735 for zinc in two species of mollusks relative to their concentrations in surface water. All significant differences were accepted at a level of P 〈 0.05. The potential uptake of elements including V and Zn, as Viviparous bengalensi 〉 Unio tigridis, The mechanism for elements uptake determined by water for organisms confined to the contaminated areas seemed to be largely independent of species, mollusks demonstrated a significant positive relationship with water. These results have important implications for the utility of marshes biota as subjects for elements monitoring program.展开更多
There is a variety of nice results about strongly Gorenstein flat modules over coherent rings. These results are done by Ding, Lie and Mao. The aim of this paper is to generalize some of these results, and to give hom...There is a variety of nice results about strongly Gorenstein flat modules over coherent rings. These results are done by Ding, Lie and Mao. The aim of this paper is to generalize some of these results, and to give homological descriptions of the strongly Gorenstein flat dimension (of modules and rings) over arbitrary associative rings.展开更多
Let B^Hi,Ki ={ Bt^Hi,Ki, t ≥ 0}, i= 1, 2 be two independent bifractional Brownian motions with respective indices Hi ∈ (0, 1) and K∈ E (0, 1]. One of the main motivations of this paper is to investigate f0^Tδ...Let B^Hi,Ki ={ Bt^Hi,Ki, t ≥ 0}, i= 1, 2 be two independent bifractional Brownian motions with respective indices Hi ∈ (0, 1) and K∈ E (0, 1]. One of the main motivations of this paper is to investigate f0^Tδ(Bs^H1 ,K1 - the smoothness of the collision local time, introduced by Jiang and Wang in 2009, IT = f0^T δ(Bs^H1,K1)ds, T 〉 0, where 6 denotes the Dirac delta function. By an elementary method, we show that iT is smooth in the sense of the Meyer-Watanabe if and only if min{H-1K1, H2K2} 〈-1/3.展开更多
文摘Total mercury concentration of typical wetland plants was analyzed in thispaper. There were great differences of total mercury concentration among different plants:moss>hydrophyte>sedge>herbage>shrub. Total mercury concentrations show an increasing trend fromvascular plants to bryophytes, and from dry to wet lands. The mercury concentration of wetlandplants was higher than that of crops. The wetland soil was the source of mercury in the air close tothe ground, so it affected the concentration of mercury in the plant. In different parts of aplant, mercury concentration was in the order of: dead stand>root>leaf>stem. Mercury concentrationincreased at the initial stage and decreased in the end of the growing season. According to themercury content and biomass, mercury stock of plants was 39.4μg/m^2 above ground in Calamagrostisangustifolia wetland and 35.8μg /m^2 in Carex lasiocarpa wetland.
基金Supported by the National Natural Science Foundation of China (No. 49771002) and the Foundation of the Labo-ratory of Wetland Pr
文摘The Sanjiang Plain is the largest and most concentrated wetland region in China, the total area is about 1.088×107ha with rich marsh resources and biodiversity. Before 1949, the Sanjiang Plain was a large untravelled wild plant and waterfowl habitat, and there were some rare swans, red-crowned cranes and thousands of hydrophytes. From 1950, the local government began to reclaim the marsh in the Sanjiang Plain, built the commodity grain base of Northeast China, and developed the industry of grain processing, animal husbandry, etc. Up to now, there are 54 farms which control 3.5087×106ha agriculture field. The marsh areas are reduced by 1/2; many rare animals and plants are near extinction. The human activities and agriculture reclamation made a great change on the environment, especially made water balance change and regional climate change. So to study and protect the wetland ecosystem and marsh resource are extremely urgent. This paper focus on the hydrology change and climate change before and after marsh reclamation, including evapotranspiration, run off, soil character, micro-climate on both marsh and agriculture field, and the reason that cause seasonal drought, waterlogging and degeneration of marsh.
基金Under the auspices of National Key Research and Development Program of China(No.2016YFC0500403)National Natural Science Foundation of China(No.41471079,41571191,41671087)Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(No.IGA-135-05)
文摘Northeast China is the region with the largest area of wetlands in China. The Sanjiang Plain and the Songnen Plain are large freshwater marsh distribution regions that are affected by climate warming and by the increasing frequency and density of extreme weather and are the regions most subject to disturbances by human activities in Northeast China. The wetlands of the Sanjiang Plain and the Songnen Plain have shrunk severely in the past 60 years, and wetland functions have been reduced substantially because of climate change, unreasonable land use, fire episodes, engineering and construction works and urbanization. Large-scale agricultural development started in the 1950 s has been the most important driving factor for wetland loss and degradation in the Sanjiang Plain. Water shortage has been the most important factor for degradation and fragmentation of wetlands in the Songnen Plain. To mitigate wetland degradation and better protect wetlands, special regulations, long-term mechanisms and technical support of wetland protection should be established. A wetland compensation program should be implemented, and technologies for increasing the adaptive capacity of wetlands should be developed. Moreover, it is most important to find the balanced threshold between agricultural development and wetland protection.
文摘In this paper, the environment characteristics, micro-environment division and evolution of the mangrove tidal flats, peats and their genetic markers are discussed. It proves that the mangrove tidal flat is a kind of tidal flats and the peat flats are developed in a specific evolution stage of mangrove tidal flats; the mangrove peats are the products of a specific evolution stage of the mangrove tidal flats.
文摘Over the past five decades, the natural wetlands in Sanjiang Plain, Northeast China, have been extensively reclaimed for agriculture with a total loss of nearly 80% of the surface area and the undrained marshes have received a large amount of exogenous nitrogen (N) input from the adjacent agricultural land because of fertilization. In the present study, the effects of nitrogen additions on seed germination and seedling biomass of Calamagrostis angustifolia in freshwater marsh were tested in a greenhouse study. Seed bank soil was exposed to different N additions (0, 5, 10, 20 and 40 g/m^2) under non-flooded water regime. Results revealed that, low level of N additions (less than 10 g/m^2) did not significantly affect the species richness and seedling density, while the seedling biomass at 5 g/m^2 of N addition was higher than other nutrient conditions. But species richness, seedling emergence and biomass decreased significantly at high level of N additions (20-40 g/m^2). The responses were species-specific. High level of N additions had negative impacts on seed germination, seedling growth and biomass of dominant species Eleocharis ovata, Calamagrostis angustifolia, duncus effusus in the seed bank. To protect and restore the wetland vegetation community in the Sanjiang plain, fertilization, irrigation and land management strategies will need to be implemented to reduce the nutrient input from the agricultural land to the wetlands.
文摘Elements (vanadium and zinc) were determined in the two most abundant species of shell mollusks (Unio tigridis and Fiviparous bengalensis) and the water where they live in five stations in the Iraqi marshes. The study of concentrations elements was a target organ for aquatic environmental. Comparison between the mean concentrations of the elements in the water concentration levels of all studied elements was the highest with the mollusks. The results show that the station 5 is where the highest concentrations are found in water and in the two species. There is a significant correlation (P = 0.224) for concentrations of vanadium and P = 0.735 for zinc in two species of mollusks relative to their concentrations in surface water. All significant differences were accepted at a level of P 〈 0.05. The potential uptake of elements including V and Zn, as Viviparous bengalensi 〉 Unio tigridis, The mechanism for elements uptake determined by water for organisms confined to the contaminated areas seemed to be largely independent of species, mollusks demonstrated a significant positive relationship with water. These results have important implications for the utility of marshes biota as subjects for elements monitoring program.
文摘There is a variety of nice results about strongly Gorenstein flat modules over coherent rings. These results are done by Ding, Lie and Mao. The aim of this paper is to generalize some of these results, and to give homological descriptions of the strongly Gorenstein flat dimension (of modules and rings) over arbitrary associative rings.
基金supported by National Natural Science Foundation of China (Grant No.10871041)Key Natural Science Foundation of Anhui Educational Committee (Grant No. KJ2011A139)
文摘Let B^Hi,Ki ={ Bt^Hi,Ki, t ≥ 0}, i= 1, 2 be two independent bifractional Brownian motions with respective indices Hi ∈ (0, 1) and K∈ E (0, 1]. One of the main motivations of this paper is to investigate f0^Tδ(Bs^H1 ,K1 - the smoothness of the collision local time, introduced by Jiang and Wang in 2009, IT = f0^T δ(Bs^H1,K1)ds, T 〉 0, where 6 denotes the Dirac delta function. By an elementary method, we show that iT is smooth in the sense of the Meyer-Watanabe if and only if min{H-1K1, H2K2} 〈-1/3.