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1.
The impact of land-use on distributed groundwater recharge and discharge in the western Jilin (WJ) was analyzed in this study. WJ is a transitional, semi-arid zone with a fragile, hydrological closed ecosystem in the Songhua River Basin (SRB). The research tool includes a seamlessly linked MODFLOW, WetSpass, the Seepage packages, and ArcGIS. The model calibration showed good agreement between simulated water table elevation and measured water table depths, while predicted groundwater discharge zones showed strong correlations with field occurrences of drainage systems and wetlands. Simulated averages for distributed recharge, water table elevation and groundwater drawdown were 377.42mm/yr, 194.43m, and 0.18m respectively. Forest vegetation showed the highest recharge, followed by agricultural farmlands, while open-water and other drainage systems constituted groundwater exit zones. When present land-use conditions were compared with the hypothetical natural pre-development scenario, an overall loss of groundwater recharge (24.09mm/yr) was observed, which for the project area is 18.05 × 108m3. Groundwater abstraction seemed to be the cause of water table drawdown, especially in the immediate vicinities of the supply wells. An important issue of the findings was the ability of the hypothetical forest vegetation to protect, and hence sustain aquifer reserves and dependent ecosystems. The profound data capture capability of ArcGIS makes it particularly useful in spatio-temporal hydroecological modeling. Biography: Moiwo Juana PAUL (1967–), male, a native of Sierra Leone of West Africa, Ph.D. candidate, specialized in wetland ecology.  相似文献   

2.
The changes in soil organic carbon(C) mineralization as affected by anthropogenic disturbance directly determine the role of soils as C source or sink in the global C budget. The objectives of this study were to investigate the effects of anthropogenic disturbance(aquaculture pond, pollutant discharge and agricultural activity) on soil organic C mineralization under different water conditions in the Minjiang River estuary wetland, Southeast China. The results showed that the organic C mineralization in the wetland soils was significantly affected by human disturbance and water conditions(P 0.001), and the interaction between human disturbance activities and water conditions was also significant(P 0.01). The C mineralization rate and the cumulative mineralized carbon dioxide-carbon(CO_2-C)(at the 49th day) ranked from highest to lowest as follows: Phragmites australis wetland soil aquaculture pond sediment soil near the discharge outlet rice paddy soil. This indicated that human disturbance inhibited the mineralization of C in soils of the Minjiang River estuary wetland, and the inhibition increased with the intensity of human disturbance. The data for cumulative mineralized CO_2-C showed a good fit(R~2 0.91) to the first-order kinetic model C_t = C_0(1 – exp(–kt)). The kinetic parameters C_0, k and C_0 k were significantly affected by human disturbance and water conditions. In addition, the total amount of mineralized C(in 49 d) was positively related to C_0, C_0 k and electrical conductivity of soils. These findings indicated that anthropogenic disturbance suppressed the organic C mineralization potential in subtropical coastal wetland soils, and changes of water pattern as affected by human activities in the future would have a strong influence on C cycling in the subtropical estuarine wetlands.  相似文献   

3.
溶解性有机碳（DOC）是地下水中砷释放过程的关键因素,为查明江汉平原高砷地下水稳定碳同位素特征,识别有机质的降解过程对砷富集的影响,采用稳定碳同位素分析测试技术并结合地下水化学特征,对江汉平原典型砷中毒病区的浅层地下水进行了区域采样分析。结果表明:浅层承压水的砷质量浓度为0.23~2 621 μg/L。地表水较地下水具有更负的δ13CDOC、δ13CDIC值。地下水中溶解性无机碳（DIC）的δ13CDIC值在-11.9‰~-3.99‰之间,溶解性有机碳的δ13CDOC值在-28.5‰~-19.6‰之间。地下水的δ13CDIC-δ13CDOC差值与ρ（As）呈一定负相关关系,表明微生物作用下有机质的降解促进了As的富集。δ13CDIC-δ13CDOC差值与δ13CDIC和ρ（DOC）均具有较显著的正相关关系,表明地下水中有机质的氧化分解是导致δ13CDIC贫化的重要过程,微生物作用下溶解性有机质的降解是地下水中无机碳的重要来源。此外,江汉平原少数高砷地下水呈现较大的δ13CDIC值,推断江汉平原高砷含水层强还原环境下可能存在的产甲烷过程导致了明显的碳同位素分馏。   相似文献   

4.
1 INTRODUCTION δ13C in organic matters from lacustrine sedi- ments varies with several factors including aquatic plants, vegetation type in the catchment, atmos- pheric CO2 concentration, climate (temperature and precipitation), and properties of water, …  相似文献   

5.
Soil seed banks can act as a potential seed source for natural revegetation and restoration. However, in a saline-alkaline grassland, it remains unclear how the stages of vegetation succession affect the characteristics of soil seed banks and the potential of soil seed banks of different successional stages for vegetation restoration. In this study, seasonal changes of the soil seed bank, and seed production and dispersal dynamics along degradation successional gradients were investigated in a saline-alkaline grassland in Northeast China, where the dominant grass during the 1960 s, Leymus chinensis was replaced with the secondary successional order of Puccinellia chinampoensis, Chloris virgata, and Suaeda salsa, together with bare patches. It was found that the soil seed bank composition varied according to the changing vegetation and had the highest species richness(7–16) in the climax successional stage, but had a low S?rensen similarity(0.22–0.37) with the aboveground vegetation. There was a high seed density of the soil seed bank(21 062–62 166/m2 in August and December) and also high S?rensen similarity index values(0.47–0.60) in the secondary successional stages of P. chinampoensis, C. virgata, and S. salsa. In bare patches, there were many seeds in the soil seed bank and some seedlings also appeared in the aboveground vegetation, indicating the existence of a persistent soil seed bank. Seed density and species richness differed substantially among the different successional stages, which was related to the reproductive characteristics of the standing plants in vegetation communities. Due to the lack of propagules of perennial species, especially the climax species of L. chinensis, in the soil, the successful restoration of the degraded saline-alkaline grassland was not possible. The study proved that in a degraded saline-alkaline grassland dominated by biennial or annual species, the soil seed bank was important for the revegetation of the current dominant plants, but not for the restoration of the original target species. Therefore, it is necessary to induce seeds or other propagules of the target perennial species.  相似文献   

6.
In this study, a coniferous tree species (Pinus tabuliformis Carr.) was investigated at a moderate-altitude mountainous terrain on the southern slope of the middle Qinling Mountains (QLM) to detect the trends in carbon isotope ratio (δ13C), leaf nitrogen content (LNC) and stomatal density (SD) with altitude variation in north-subtropical humid mountain climate zone of China. The results showed that LNC and SD both significantly increased linearly along the altitudinal gradient ranging from 1000 to 2200 m, whereas leaf δ13C exhibited a significantly negative correlation with the altitude. Such a correlation pattern differs obviously from that obtained in offshore low-altitude humid environment or inland high-altitude semi-arid environment, suggesting that the pattern of increasing δ13C with the altitude cannot be generalized. The negative correlation between δ13C and altitude might be attributed mainly to the strengthening of carbon isotope fractionation in plants caused by increasing precipitation with altitude. Furthermore, there was a remarkable negative correlation between leaf δ13C and LNC. One possible reason was that increasing precipitation that operates to increase isotopic discrimination with altitude overtook the LNC in determining the sign of leaf δ13C. The significant negative correlation between leaf δ13C and SD over altitudes was also found in the present study, indicating that increases in SD with altitude would reduce, rather than enhance plant δ13C values.  相似文献   

7.
Trophic interaction among various biomass groups in a swimming crab Portunus trituberculatus polyculture pond was investigated using carbon and nitrogen stable isotope analysis. The polycultured animal species also included white shrimp Litopenaeus vannamei, short-necked clam Ruditapes philippinarum, and redlip mullet Liza haematochila. The mean δ13C value for all the biomass groups in polyculture ecosystem ranged from ?25.61‰ to ?16.60‰, and the mean δ15N value ranged from 6.80‰ to 13.09‰. Significant difference in the δ13C value was found between particulate organic matter (POM) and sediment organic matter (SOM) (P < 0.05), indicating that these two organic matter pools have different material sources. Assuming that a 13C-enrichment factor of 1.00‰ and a 15N-enrichment factor of 2.70‰ existed between consumer and prey, diets of the four cultured animals were estimated using a stable isotope mixing model. The estimated model results indicated that P. trituberculatus mainly feed on Aloidis laevis; L. vannamei mainly feed on shrimp feed; while A. laevis, R. philippinarum and L. haematochelia mainly feed on POM. Shrimp feed was also an important food source of R. philippinarum and L. haematochelia. The diets of P. trituberculatus, L. vannamei, R. philippinarum, and L. haematochila showed complementary effects in this polyculture ecosystem. Our finding indicated that the polyculture of these four organisms with suitable farming density could make an effective use of most of the food sources, which can make a highly efficient polyculture ecosystem.  相似文献   

8.
To evaluate the influence of wetland reclamation on vertical distribution of carbon and nitrogen in coastal wetland soils, we measured the soil organic carbon(SOC), soil total nitrogen(STN) and selected soil properties at five sampling plots(reed marsh, paddy field, corn field, forest land and oil-polluted wetland) in the Liaohe River estuary in September 2013. The results showed that reclamation significantly changed the contents of SOC and STN in the Liaohe River estuary(P 0.001). The SOC concentrations were in the order: oil-polluted wetland corn field paddy field forest land reed marsh, with mean values of 52.17, 13.14, 11.46, 6.44 and 6.16 g/kg, respectively. STN followed a similar order as SOC, with mean values of 1351.14, 741.04, 632.32, 496.17 and 390.90 mg/kg, respectively. Interaction of reclamation types and soil depth had significant effects on SOC and STN, while soil depth had significant effects on SOC, but not on STN. The contents of SOC and STN were negatively correlated with pH and redox potential(Eh) in reed marsh and corn field, while the SOC and STN in paddy field had positive correlations with electrical conductivity(EC). Dissolved organic carbon(DOC), ammonium nitrogen(NH_4~+-N) and nitrate nitrogen(NO_3~–-N) were also significantly changed by human activities. NH_4~+-N and NO_3~–-N increased to different degrees, and forest land had the highest NO_3~–-N concentration and lowest DOC concentration, which could have been caused by differences in soil aeration and fertilization. Overall, the results indicate that reed harvest increased soil carbon and nitrogen release in the Liaohe River Estuary, while oil pollution significantly increased the SOC and STN; however, these cannot be used as indicators of soil fertility and quality because of the serious oil pollution.  相似文献   

9.
Elevation is one of key factors to affect changes in the environment, particularly changes in conditions of light, water and heat. Studying the soil physicochemical properties and vegetation structure along an elevation gradient is important for understanding the responses of alpine plants andtheir growing environment to climate change. In this study, we studied plant coverage, plant height, species richness, soil water-holding capacity, soil organic carbon(SOC) and total nitrogen(N) on the northern slopes of the Qilian Mountains at elevations from2124 to 3665 m. The following conclusions were drawn:(1) With the increase of elevation, plant coverage and species richness first increased and then decreased, with the maximum values being at 3177 m.Plant height was significantly and negatively correlated with elevation(r=–0.97, P0.01), and the ratio of decrease with elevation was 0.82 cm·100 m-1.(2) Both soil water-holding capacity and soil porosity increased on the northern slopes of the Qilian Mountains with the increase of elevation. The soil saturated water content at the 0-40 cm depth first increased and then stabilized with a further increase of elevation, and the average ratio of increase was2.44 mm·100 m-1. With the increase of elevation, the average bulk density at the 0-40 cm depth first decreased and then stabilized at 0.89 g/cm3.(3) With the increase of elevation, the average SOC content at the 0-40 cm depths first increased and then decreased,and the average total N content at the 0-40 cm depth first increased and then stabilized. The correlation between average SOC content and average total N content reached significant level. According to the results of this study, the distribution of plants showed a mono-peak curve with increasing elevation on the northern slopes of the Qilian Mountains. The limiting factor for plant growth at the high elevation areas was not soil physicochemical properties, and therefore,global warming will likely facilitate the development of plant at high elevation areas in the Qilian Mountains.  相似文献   

10.
Soil respiration is a main dynamic process of carbon cycle in wetland. It is important to contribute to global climate changes. Water table and nutritious availability are significant impact factors to influence responses of CO2 emission from wetland soil to climate changes. Twenty-four wetland soil monoliths at 4 water-table positions and in 3 nitrogen status have been incubated to measure rates of CO2 emission from wetland soils in this study. Three static water-table controls and a fluctuant water-table control, with 3 nitrogen additions in every water-table control, were carried out. In no nitrogen addition treatment, high CO2 emissions were found at a static low water table (I) and a fluctuant water table (IV), averaging 306.7mg/(m2·h) and 307.89mg/(m2·h), respectively, which were 51%–57% higher than that at static high water table (II and III). After nitrogen addition, however, highest CO2 emission was found at II and lowest emission at III. The results suggested that nutritious availability of wetland soil might be important to influence the effect of water table on the CO2 emission from the wetland soil. Nitrogen addition led to enhancing CO2 emissions from wetland soil, while the highest emission was found in 1N treatments other than in 2N treatments. In 3 nutritious treatments, low CO2 emissions at high water tables and high CO2 emissions at low water tables were also observed when water table fluctuated. Our results suggested that both water table changes and nutritious imports would effect the CO2 emission from wetland. Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 90211003) and the Knowledge Innovation Program of Chinese Academy of Sciences (No. KACX3-SW-332) Biography: YANG Ji-song (1978-), male, a native of Chengwu of Shandong Province, Ph.D. candidate, specialized in environmental ecology and wetland biogeochemistry. E-mail: yangjisong@neigae.ac.cn  相似文献   

11.
Changes in the fungal and bacterial biomass and community structure in litter after the volcanic eruptions of Mount Usu, northern Japan were investigated using a chronosequence approach, which is widely used for analyzing vegetation succession. The vegetation changed from bare ground(10 years after the eruptions) with little plant cover and poor soil to monotonic grassland dominated by Polygonum sachalinense with undeveloped soil(33 years) and then to deciduous broad-leaved forest dominated by Populus maximowiczii with diverse species composition and well-developed soil(100 years). At three chronosequential sites, we evaluated the compositions of phospholipid fatty acids(PLFAs), carbon(C) and nitrogen(N) contents and the isotope ratios of C(δ13C) and N(δ15N) in the litter of two dominant species, Polygonum sachalinense and Populus maximowiczii. The C/N ratio, δ13C and δ15N in the litter of these two species were higher in the forest than that in the bare ground and grassland. The PLFAs gradually increased from the bare ground to the forest, showing that microbial biomass increased with the development of the soil and/or vegetation. The fungi-to-bacteria ratio of PLFA was constant at 5.3 ± 1.4 in all three sites, suggesting that fungi were predominant. A canonical correspondence analysis suggested that the PLFA composition was related tothe successional ages and the developing soil properties(P 0.05, ANOSIM). The chronosequential analysis effectively detected the successional changes in both microbial and plant communities.  相似文献   

12.
CARBON CYCLE OF MARSH IN THE SANJIANG PLAIN   总被引：1，自引：0，他引：1  
Peat~hisaprocessofbeinghelpfulfordecreasingtheincrementofopcontentintheair,whichiscausedbycombustionofdineralfuelsandhumanactivitiesinterrestrialecosystem.But,exploitingrnaxsh,eSPeCiallyPeatedtObefuels,impliesthatorgbocsubstanceaccUInulatedfroma~hereduringthepastthousandsofyearsisrapidlyOxidized.aamthemarShplaysanimPOrtantroleinthecycleofbiogaxhdristry.TheSanjiangPlainisalowplainformedbythecommonreactionoftheHeilongRiver,SonghuaherandWUSuliabover.Thetotalareais10.89X104klnZandmarsharea…  相似文献   

13.
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 0.612 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.  相似文献   

14.
水文地球化学是识别地下水流系统的重要方法,然而区域尺度上多级嵌套地下水流系统的复杂性使地下水化学组成的分析和解释难度增加。以鄂尔多斯北部盆地湖泊集中区典型的胡同察汗淖地下水流系统为例,基于丰水期和枯水期3个期次不同深度地下水样品的物理化学数据,应用时空聚类与主成分分析方法,揭示地下水化学组成的空间分布特征、变化规律及其作用机制,分析水化学时空聚类结果对多级嵌套地下水流系统划分的可行性。该聚类结果将地下水样品分为3类,其中C1为以Na-HCO3型为主的深层地下水,具有偏负的氢氧同位素组成（δD < -70‰,δ18O < -9‰）和极低浓度的NO3-;C2为Ca-HCO3为主的浅层地下水,具有偏正的氢氧同位素组成（δD > -70‰,δ18O > -9‰）和高浓度的NO3-;而C3呈无优势阳离子、δD和δ18O变化范围大且显著线性相关等深、浅地下水混合特征。呈南北条带分布在苏贝淖-胡同察汗淖排泄区的C2和部分C3水化学组成有一定的季节变化。研究验证了研究区受地形和湖泊排泄控制的浅层局部和深层区域地下水流系统的空间分布,识别了苏贝淖-胡同察汗淖排泄区受浅循环和深循环共同影响的强烈作用带,证明了水化学时空聚类方法识别多级嵌套地下水流系统的可行性。   相似文献   

15.
Wetland Is an important landscape existing almost DEFINITIONS OF WETLANDall over the world．In China，wetlands are distributedeverywhe。加mfrlgld－tern。。。ie zone to tropical zone，XU QI et al．dehned wetland as the soil which isfrom lmoral！o Inland from paln to pforeau and moisten by under－ground water or Is permanently ormountains．＞ome ot the wetlands share the sam。char－temno。rllv soak。d by ground。ater（XU，1995）．Thisacterlstlcs of other countries，and some are un…  相似文献   

16.
Hydrology plays a dominant role in wetland plant distribution and microbial composition, but few studies explicitly attempted to relate the linkage between wetland vegetation and microbial community. The present study consisted of five wetland plant communities along three adjacent flood gradients zones (zone 1 dominated by Carex appendiculat, zone 2 dominated by Eleocharis ovate, and zone 3 dominated by Phragmites australis/Bidens pilosa/Calamagrostis angustifolia, which formed separate, monoculture patches). Gram negative and arbuscular mycorrhizal fungal phospholipid fatty acid (PLFA) are more abundant in the site with short flooding period (zone 3) than in the site with long flooding period (zone 1), and they are also different in the P. australis, B. spilosa and C. angustifolia of zone 3. Principle Component Analysis (PCA) showed that the flooding period could explain 92.4% of variance in microbial composition. Redundancy Analysis (RDA) showed that available nitrogen (AN), total nitrogen (TN) and soil organic matter (SOM) could explain the 79.5% of variance in microbial composition among E. ovata, P. australis, B. pilosa and C. angustifolia. Results demonstrated that flooding period was the main factor in driving the microbial composition and plant-derived resources could influence soil microbial composition in the seasonally flooded zones.  相似文献   

17.
Carbon sequestration occurs when cultivated soils are re-vegetated. In the hilly area of the Loess Plateau, China, black locust(Robinia pseudoacacia) plantation forest and grassland were the two main vegetation types used to mitigate soil and water loss after cultivation abandonment. The purpose of this study was to compare the soil carbon stock and flux of these two types of vegetation which restored for 25 years. The experiment was conducted in Yangjuangou catchment in Yan′an City, Shaanxi Province, China. Two adjacent slopes were chosen for this study. Six sample sites were spaced every 35–45 m from summit to toe slope along the hill slope, and each sample site contained three sampling plots. Soil organic carbon and related physicochemical properties in the surface soil layer(0–10 cm and 10–20 cm) were measured based on soil sampling and laboratory analysis, and the soil carbon dioxide(CO2) emissions and environmental factors were measured in the same sample sites simultaneously. Results indicated that in general, a higher soil carbon stock was found in the black locust plantation forest than that in grassland throughout the hill slope. Meanwhile, significant differences in the soil carbon stock were observed between these two vegetation types in the upper slope at soil depth 0–10 cm and lower slope at soil depth 10–20 cm. The average daily values of the soil CO2 emissions were 1.27 μmol/(m2·s) and 1.39 μmol/(m2·s) for forest and grassland, respectively. The soil carbon flux in forest covered areas was higher in spring and less variation was detected between different seasons, while the highest carbon flux was found in grassland in summer, which was about three times higher than that in autumn and spring. From the carbon sequestration point of view, black locust plantation forest on hill slopes might be better than grassland because of a higher soil carbon stock and lower carbon flux.  相似文献   

18.
1 INTRODUCTION There is no single and universally recognized wetland definition so far. More than 50 of wetland definitions have been developed (YANG, 2002; DUGAN, 1993; MITCH and GOSSELINK, 1996; NRC, 1995). Because wetlands form part of a continuous gradient between u- plands and open water, the problem on wetland defini- tion usually arises on the edges of wetlands, toward ei- ther wetter or drier conditions (NRC, 1995; MITSCH and GOSSELINK, 1996). What frequency, dept…  相似文献   

19.
地下水是重要的水资源,地下水的有机污染已引起了包括中国在内的许多国家的重视。该文通过对山东省滨州市浅层地下水污染调查,在获取大量第一手资料的基础上对滨州市浅层地下水持久性有机污染特征进行了分析,对浅层地下水中有机污染物的来源、污染途径、分布规律等进行了研究。研究结果表明,滨州地区浅层地下水已遭受有机物污染,有机物检出项目较多,共有20种,主要为卤代烃类和单环芳烃类,但总体浓度均较低,仅有3种有机指标超标,主要分布在工业园区、化工厂及皮革城附近。滨州地区有机污染物的来源主要为工业厂家"三废"的不合理排放和处置,导致流经污染源附近的地表水体受到不同程度的有机污染,而这些受污染水体又通过不同方式如污灌等进入不同地段的土壤,以垂向入渗形式进入并污染到浅层地下水。典型地段和污染源附近,有机指标检出率和超标率明显高于其他区域。  相似文献   

20.
In order to investigate the transformation among the precipitation,groundwater,and surface water in the Sanjiang Plain,Northeast China,precipitation and groundwater samples which were collected at the meteorological station of the Sanjiang Mire Wetland Experimental Station,Chinese Academy of Sciences and the surface water which collected from the Wolulan River were used to identify the transformation of three types of water.The isotope composition of different kinds of water sources were analyzed via stable isotope(deuterium and oxygen-18) investigation of natural water.The results show a clear seasonal difference in the stable isotopes in precipitation.During the cold half-year,the mean stable isotope in precipitation in the Sanjiang Plain reaches its minimum with the minimum temperature.The δ18O and δD values are high in the rainy season.In the Wolulan River,the evaporation is the highest in August and September.The volume of evaporation and the replenishment to the river is mostly same.The groundwater is recharged more by the direct infiltration of precipitation than by the river flow.The results of this study indicate that the water bodies in the Sanjiang Plain have close hydrologic relationships,and that the transformation among each water system frequently occurs.  相似文献   

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