ABSTRACT
To explore the differences in structure and diversity of nirK-type denitrifying microbial community in marsh soils at different invasion stages of Spartina alterniflora, the mudflat (MF, before invasion) and the S. alterniflora marsh after seaward invasion for 1-2 years (SAN) and 6-7 years (SA) in Shanyutan of the Minjiang River estuary were investigated by high-through put sequencing method. Results showed that the seaward invasion of S. alterniflora reduced the richness and diversity of nirK-type denitrifying microbial community in marsh soils. The nirK-type denitrifying microbial community in soils at different invasion stages included Proteobacteria and Actinobacteria, with Proteobacteria as the dominant one. The seaward invasion of S. alterniflora greatly altered the composition of nirK-type denitrifying microbial community in marsh soils. The highest relative abundance of genus in soils from different invasion stages were Bradyrhizobium, Mesorhizobium and Alcaligenes, respectively. The seaward invasion of S. alterniflora increased the spatial heterogeneity of nirK-type denitrifying microbial community composition in marsh soils. In SAN plot, the enhancement of spatial heterogeneity was primarily due to higher environmental disturbances in plots and the increased spatial heterogeneity of environmental variables caused by the seaward invasion of S. alterniflora. The seaward invasion of S. alterniflora altered the physico-chemical properties (e.g., grain composition, pH and moisture) and N nutrient conditions (total N, NH4+-N and NO3--N) in marsh soils, which greatly altered the structure and diversity of nirK-type denitrifying microbial community. Our findings reveal the microbial mechanism of denitrification process in marsh soils during the seaward invasion of S. alterniflora.
Subject(s)
Microbiota , Wetlands , Soil/chemistry , Estuaries , Rivers , Introduced Species , PoaceaeABSTRACT
We examined the effects of Spartina alterniflora invasion on phosphorus forms of marsh soils, based on the method of space-for-time substitution by selecting S. alterniflora marshes with different invasion years (SA1, 5-6 years; SA2, 8-10 years; and SA3, 12-14 years) in Shanyutan of the Minjiang River estuary. The results showed that in marsh soils of different invasion years, the proportion of hardly decomposable phosphorus (HCl-Pi and Residual-P) was the highest (46.4%-46.7%), followed by moderately decomposable phosphorus (NaOH-Pi, NaOH-Po and Sonic-Pi) (40.0%-44.0%), and the easily decomposable phosphorus (Resin-Pi, NaHCO3-Pi and NaHCO3-Po) was the lowest (9.5%-13.3%). With increasing invasion years of S. alterniflora, soil phosphorus forms and their spatial distributions were greatly altered. The contents of moderately decomposable phosphorus, hardly decomposable phosphorus, and total phosphorus (TP) generally increased, while easily decomposable phosphorus content generally decreased. Compared with SA1, the contents of moderately decomposable phosphorus, hardly decomposable phosphorus and TP in SA2 increased by 11.5%, 9.7% and 10.5%, while those in SA3 increased by 24.8%, 13.2% and 13.5%, respectively. The distribution of phosphorus forms was greatly altered with increasing invasion years, which was dependent on the variations of key factors such as EC, pH value and grain composition. The implementation of regular mowing activities for S. alterniflora in the Minjiang River estuary in recent years, to some extent, reduced the return of phosphorus from residues to soils and decreased the availability of the easily decomposable phosphorus in soils.
Subject(s)
Soil , Wetlands , China , Estuaries , Introduced Species , Phosphorus/analysis , Poaceae , Rivers , Sodium Hydroxide , Soil/chemistryABSTRACT
Sulfur oxidation-reduction process (SORP) in marsh soil is an important link in sulfur cycle, which plays an important role in maintaining the stability and health of marsh. We summarized the SORP in marsh soil and its influencing factors, and analyzed the research progress of its coupling effects with other elements. The influencing factors of SORP in marsh soil mainly involved biotic (plants, microorganisms, zoobenthos, human activities, etc.) and abiotic factors (physical factors such as temperature, moisture and particle size, and chemical factors such as pH, salinity, organic matter, etc.). Related research on the coupling effects of SORP and other elements in marsh soil mainly involved in biogenic elements such as carbon (C), nitrogen (N) and phosphorus (P), and metal elements such as iron (Fe) and manganese (Mn). Currently, the underlying mechanism of SORP was not deeply explored, the research on coupling effects was unbalance, and the ecological effects were insufficient. In the future, key functional microorganisms involved in SORP should be strengthened, the coupling mechanism between SORP and micro-elements should be enhanced, and the ecological effects produced by the coupling effects of SORP with other elements should be emphasized.
Subject(s)
Soil , Wetlands , Carbon , Humans , Oxidation-Reduction , Soil/chemistry , SulfurABSTRACT
OBJECTIVE: Propofol is one of the most commonly used intravenous drugs to induce and maintain general anesthesia. In vivo and in vitro studies have shown that propofol can affect neuronal growth, leading to apoptosis and impairing cognitive function. The Abelson nonreceptor tyrosine kinase (c-Abl) is associated with both neuritic plaques and neurofibrillary tangles in the brains of patients with Alzheimer's disease and other neurodegenerative diseases. This study aimed to explore the effect of propofol on apoptosis and neurocognition through its regulation of c-Abl expression in vivo and in vitro. MATERIALS AND METHODS: In this study, primary hippocampal neurons were cultured and exposed to propofol at different concentrations. Protein expression was measured by Western blotting and coimmunoprecipitation. The c-Abl transcription level was verified by fluorescence quantitative PCR. Reactive oxygen species (ROS) levels were detected by flow cytometry. In addition, an animal experiment was conducted to assess neuronal apoptosis by immunofluorescence staining for caspase-3 and to evaluate behavioral changes by the Morris water maze (MWM) test. RESULTS: The in vitro experiment showed that propofol significantly decreased c-Abl expression and ROS levels. In addition, propofol has no cytotoxic effect and does not affect cell activity. Moreover, in the animal experiment, intraperitoneal injection of 50 mg/kg propofol for 5 days obviously decreased the expression of c-Abl in the neonatal rat brain (p < .05) but did not significantly increase the number of caspase-3-positive cells. Propofol treatment did not significantly reduce the number of platform crossings (p > .05) or prolong the escape latency of neonatal rats (p > .05) in the MWM test. CONCLUSIONS: The present data suggest that reduced expression of this nonreceptor tyrosine kinase through consecutive daily administration of propofol did not impair learning or memory function in neonatal rats.
Subject(s)
Propofol , Animals , Animals, Newborn , Hippocampus , Humans , Maze Learning , Propofol/pharmacology , Protein-Tyrosine Kinases , Rats , Rats, Sprague-DawleyABSTRACT
To investigate the distributions and stocks of total phosphorus (TP) in plant-soil systems of marshes in Shanyutan of the Minjiang River estuary and explore its influencing factors, Phragmites australis (PA) marsh and Cyperus malaccensis (CM) marsh before spatial expansion and ecotonal marsh (EM, P. australis and C. malaccensis in EM were denoted by PA' and CM', respectively) during spatial expansion were studied. Results showed that, as affected by spatial expansion, the contents of TP in both plant and soil in different marshes showed great variations. Compared with PA and CM marshes, soil TP in EM increased by 20.0% and 7.1%, respectively. The variation of soil TP in EM might be attributed to the alteration of soil particle composition, plant bio-mass and root/shoot ratio during spatial expansion. Except for leaves, TP in organs of P. australis in P. australis-C. malaccensis community (PA') was lower than that in C. malaccensis in P. australis-C. malaccensis community (CM'), due to the differences in absorption, utilization and translocation way of P among organs between the two species. The competition effect caused by spatial expansion greatly changed plant P allocation ratio of the two species. Compared with PA and CM, the allocations of P in roots and leaves of PA' increased, while only that in roots of CM' rose. During spatial expansion, the two species might adopt different adaptation strategies for P absorption and utilization to maintain their competitiveness. The PA might compete primarily by strengthening the P accumulation capacities of its roots and promoting leaf photosynthesis, whereas the CM might resist the spatial expansion of PA by increasing its underground biomass to enhance P absorption.
Subject(s)
Cyperus , Estuaries , China , Phosphorus , Poaceae , Rivers , Soil , WetlandsABSTRACT
To explore the effects of Spartina alterniflora invasion in a seaward direction on variations of inorganic sulfur forms in marsh soils, the levels of inorganic sulfur forms (H2O-S, Adsorbed-S, HCl-Soluble-S and HCl-Volatile-S) were determined in bare flat (BF, before invasion), S. alterniflora marsh after seaward invasion for one year (SA') and S. alterniflora marsh after seaward invasion for three years (SA) in Shanyutan of the Minjiang River estuary with the method of space-for-time substitution. Results showed that the seaward invasion of S. alterniflora altered the stocks and distribution of inorganic sulfur form in marsh soils. Compared with BF, the contents of H2O-S, Adsorbed-S and HCl-Volatile-S in soils of SA increased by 52.6%, 78.2% and 21.0%, respectively, while that of HCl-Soluble-S decreased by 3.4%. In contrast, the levels of H2O-S, Adsorbed-S and HCl-Soluble-S in soils of SA' increased by 43.9%, 70.6% and 29.6%, respectively, whereas that of HCl-Volatile-S decreased by 11.6%. The contents of total inorganic sulfur (TIS) in soils of SA and SA' increased by 40.7% and 37.8%, while the stocks of TIS increased by 26.8% and 31.4%, respectively. The key factors affecting different forms of inorganic sulfur in marsh soils had changed due to the seaward invasion of S. alterniflora. In particular, the key factors affecting the variations of H2O-S contents changed from soil grain composition and bulk density in BF to soil organic matter in SA' and SA. The seaward invasion of S. alterniflora significantly increased the content of TIS in marsh soils, which was mainly contributed by H2O-S and Adsorbed-S. Thus, it was concluded that the seaward invasion of S. alterniflora significantly increased the supply capacity of available sulfur in marsh soils, which, to some extent, accelerated its seaward invasion.
Subject(s)
Soil , Wetlands , China , Estuaries , Introduced Species , Poaceae , Rivers , SulfurABSTRACT
BuPiHeWei (BPHW) decoction, a classic Traditional Chinese Medicinal (TCM) prescription, has been widely used in clinical practice to relieve digestive symptoms caused by chemotherapy, such as diarrhea and vomiting. The present study aimed to investigate whether BPHW decoction exerted a protective role in the 5-Fu-induced intestinal mucosal injury in the rats by regulating the mechanisms of TLR-4/NF-κB signaling pathway. There were 35 Sprague Dawley rats randomly divided into four groups: normal control group, 5-Fu group, 5-Fu + BPHW decoction group (10.5 g/kg, for five continuous days), and 5-Fu + Bacillus licheniformis capsule group (0.2 g/kg, for five continuous days). Animal models were established by intraperitoneal injection of 5-Fu (30 mg/Kg, for five consecutive days). At the end of the treatment period, body weight, diarrhea score, and histological examination were examined. Furthermore, the expression of TLR-4/NF-κB pathway was detected to reveal its mechanism. The results showed that BPHW decoction effectively reduced diarrhea score and increased body weight and height of villi after 5-Fu chemotherapy. In addition, BPHW decoction could significantly inhibit the expression of TLR-4, NF-κB, and inflammatory factors (including TNF-α, IL-1ß, and IL-6) in the intestine, and the efficacy was significantly higher than that of Bacillus licheniformis capsule. In summary, BPHW decoction might be considered an effective drug to alleviate intestinal mucosal injury in the rats induced by 5-Fu.
ABSTRACT
The active ingredient of ginseng, ginsenosides Rg1, has been shown to scavenge free radicals and improve antioxidant capacity. This study hypothesized that ginsenosides Rg1 has a protective role in human neuroblastoma cells injured by H2O2. Ginsenosides Rg1 at different concentrations (50 and 100 µM) was used to treat H2O2 (150 µM)-injured SH-SY5Y cells. Results demonstrated that ginsenoside Rg1 elevated the survival rate of SH-SY5Y cells injured by H2O2, diminished the amount of leaked lactate dehydrogenase, and increased superoxide dismutase activity. Ginsenoside Rg1 effectively suppressed caspase-3 immunoreactivity, and contributed to heat shock protein 70 gene expression, in a dose-dependent manner. These results indicate that ginsenoside Rg1 has protective effects on SH-SY5Y cells injured by H2O2 and that its mechanism of action is associated with anti-oxidation and the inhibition of apoptosis.
ABSTRACT
The effects of exogenous nitrogen on N2O production processes in the soils of un-restoration wetland (R0), restoration wetland since 2007 (R2007) and restoration wetland since 2002 (R2002) of the Yellow River estuary were studied, and the contributions of different processes in N2O production were determined. Results showed that the N2O production of restoration wetland soils (R2002 and R2007) with NO3--N addition was much higher than that with NH4+-N addition, but both NH4+-N and NO3--N additions demonstrated inhibition on the N2O production of soils in R0. Although the effect of NO3--N addition on the total N2O production of topsoil in R2002 was significantly higher than those in R2007, the values in R2002 and R2007 were greatly increased with increasing NO3--N addition. The denitrification and nitrifier denitrification processes in restoration wetland soils (R2002 and R2007) were greatly affected by NO3--N addition, but no significant influence on the non-biological processes of soil in R0 was observed. Although NH4+-N addition did not produce significant effects on the total N2O production of wetland soils, the nitrifier denitrification process in R0 soil, the nitrification process in R2007 soil and the non-biological process in R2002 soil were generally stimulated. In R0 and R2002 soils, the N2O produced by non-biological processes was generally eleva-ted with NH4+-N addition, while with NO3--N addition, the non-biological processes generating N2O in R0, R2002 and R2007 soils were generally inhibited, which was closely correlated with the regulation of soil pH caused by the import of exogenous nitrogen. This study found that the enrichment of NO3--N greatly enhanced the total N2O production of wetland soils and significantly altered the original contribution patterns of biological and non-biological processes to N2O production. Thus, special attention should be paid on the influences of nutrient import (particularly NO3--N enrichment) induced by ecological restoration project on N2O production of wetland soils.
Subject(s)
Nitrogen/chemistry , Nitrous Oxide/chemistry , Soil/chemistry , Wetlands , China , Denitrification , Estuaries , Nitrification , RiversABSTRACT
Based on the laser particle size and X-ray diffraction (XRD) analysis, 28 sediment samples collected from the inshore region of the Yellow River estuary in October 2013 were determined to discuss the influence of long-term implementation of the flow-sediment regulation scheme (FSRS, initiated in 2002) on the distributions of grain size and clay components (smectite, illite, kaolinite and chlorite) in sediments. Results showed that, after the FSRS was implemented for more than 10 years, although the proportion of sand in inshore sediments of the Yellow River estuary was higher (average value, 23.5%) than those in sediments of the Bohai Sea and the Yellow River, silt was predominated (average value, 59.1%) and clay components were relatively low (average value, 17.4%). The clay components in sediments of the inshore region in the Yellow River estuary were close with those in the Yellow River. The situation was greatly changed due to the implementation of FSRS since 2002, and the clay components were in the order of illite > smectite > chlorite > kaolinite. This study also indicated that, compared to large-scale investigation in Bohai Sea, the local study on the inshore region of the Yellow River estuary was more favorable for revealing the effects of long-term implementation of the FSRS on sedimentation environment of the Yellow River estuary.
Subject(s)
Aluminum Silicates , Estuaries , Geologic Sediments , China , Clay , Kaolin , Minerals , Rivers , X-Ray DiffractionABSTRACT
Estuary is an important area contributing to the global carbon cycle. In order to analyze the spatial-temporal distribution characteristics of the dissolved inorganic carbon (DIC) in the surface water of Yellow River estuary. Samples were collected in spring, summer, fall, winter of 2013, and discussed the correlation between the content of DIC and environmental factors. The results show that, the DIC concentration of the surface water in Yellow River estuary is in a range of 26.34-39.43 mg x L(-1), and the DIC concentration in freshwater side is higher than that in the sea side. In some areas where the salinity is less than 15 per thousand, the DIC concentration appears significant losses-the maximum loss is 20.46%. Seasonal distribution of performance in descending order is spring, fall, winter, summer. Through principal component analysis, it shows that water temperature, suspended solids, salinity and chlorophyll a are the main factors affecting the variation of the DIC concentration in surface water, their contribution rate is as high as 83% , and alkalinity, pH, dissolved organic carbon, dissolved oxygen and other factors can not be ignored. The loss of DIC in the low area is due to the calcium carbonate sedimentation. DIC presents a gradually increasing trend, which is mainly due to the effects of water retention time, temperature, outside input and environmental conditions.
Subject(s)
Carbon/analysis , Environmental Monitoring , Estuaries , Seasons , Calcium Carbonate , Carbon Isotopes , China , Chlorophyll , Chlorophyll A , Rivers , Spatio-Temporal Analysis , TemperatureABSTRACT
By using the method of time-space mutual substitution, the contribution of different processes in wetland soil N2O production was studied in the un-restoration wetland (R0), restoration wetland since 2007 (R2007) and restoration wetland since 2002 (R2002) of the Yellow River estuary to evaluate the effectiveness of the restoration projects. Results showed wetland soil total N2O production had a significant difference in different restoration phases, but the N2O release was the main source. The N2O production in restoration wetland was higher than that in un-restoration wetland. The N2O production wss mainly due to the nitrification and nitrifier denitrification processes, while the denitrification process had great weakening effects on N2O production, which was closely related to the physical and chemical properties of wetland soils in different restoration phases. The non-biological processes made greater contributions to N2O production and these were mainly due to that iron was reductive, while the Yellow River estuary was an area of highly active iron. Although N2O production in wetland soils was the results of biological processes combined with non-biological processes in different restoration phases, non-biological processes had larger influences and should be paid a special attention. There were different influences on wetland soil processes generating N2O between temperature and water content, indicating responses of soil microbial activities to temperature and water content were different. In addition, the N2O production contents ranged from 0.37 +/- 0.08 nmol x (kg x h) (-1) to 9.75 +/- 7.64 nmol x (kg x h) (-1) in marshes of the Yellow River estuary, which was slightly higher than those in the S. alterniflora wetland soils of the Min River estuary, but significantly lower than those in the C. malaccensis wetland soils of the Min River estuary, the grassland soils and the aerobic forest soils. We found that the long-term implements of ecological restoration project in the Yellow River estuary obviously promoted N2O production, so we should consider two factors of landscape restoration and weakening greenhouse gases in the next wetland restoration project.
Subject(s)
Environmental Restoration and Remediation , Estuaries , Nitrous Oxide/chemistry , Soil/chemistry , Wetlands , China , Denitrification , Nitrification , RiversABSTRACT
OBJECTIVE: To observe the effects of Shuyu Ningxin Recipe (SNR) on the praxiology and the expressions of hippocampal brain-derived neurotrophic factor (BDNF) and its receptor tyrosine kinase B (TrkB) of model rats with chronic stress-induced depression, thus exploring its anti-depression mechanisms. METHODS: Sixty adult SD rats were randomly divided into 6 groups, i.e., the normal control group, the model group, the fluoxetine group, the high dose SNR group, the medium dose SNR group, and the low dose SNR group, 10 in each group. All rats were subjected to establish chronic stress-induced depression model for 21 consecutive days. Except those in the normal control group, rats in the rest groups received gastrogavage from the 22nd day. Mice in the model group were administered with normal saline by gastrogavage. SNR at 25.0, 7.5, and 2.5 g/kg was respectively administered to rats in the high dose SNR group, the medium dose SNR group, and the low dose SNR group by gastrogavage. Fluoxetine suspension (12 mg/kg) was given to rats in the fluoxetine group by gastro-gavage. All medication lasted for 3 successive weeks. The weight, open-field test, and the immobility time in forced swimming test were determined before modeling, 3 weeks (after successful modeling), and 6 weeks (by the end of medication). The expressions of hippocampal BDNF and TrkB were measured after the brain tissues were drawn by the end of the experiment. RESULTS: Compared with the normal control group, the body weight grew slowly, the behavior index decreased, the immobility time in forced swimming test was prolonged, and the expressions of BDNF and TrkB were weaken in the model group (P <0.05, P <0.01).The body weight increased, the behavior was improved, the immobility time in forced swimming test was shortened, and the expressions of BDNF and TrkB were enhanced in the high dose SNR group and the fluoxetine group by the and of medication, showing statistical difference when compared with the model group (P <0.05, P <0.01). CONCLUSION: SNR could exert anti-depression by improving the expression levels of hippocampal BDNF and TrkB.
Subject(s)
Behavior, Animal , Brain-Derived Neurotrophic Factor/metabolism , Depression/metabolism , Drugs, Chinese Herbal/pharmacology , Hippocampus/metabolism , Receptor, trkB/metabolism , Stress, Psychological/metabolism , Animals , Male , Rats , Rats, Sprague-DawleyABSTRACT
The spatial distribution characteristics of Fe and Mn contents in soils of nine different vegetation communities, located in the new-born marshes of the northern Yellow River estuary, were studied in May 2009. The results showed that the horizontal distributions of Fe and Mn contents showed an increasing tendency from Sparganiaceae-Potentilla supina marsh to bare flat. The vertical distribution characteristics of Fe and Mn contents in different marsh soils fluctuated significantly with the vegetation succession. The soil parent materials determined the Fe, Mn contents in the new-born marshes, and seawater, vegetations and soil fine particle also had important influences on their contents. Further analysis showed that Fe contents had significant positive correlation with Mn contents (P < 0.01). Fe, Mn contents also showed significant correlations with silt, clay, TN, NO3(-) -N and organic matter (P < 0.05), indicating that Fe and Mn had close relationships with nitrogen, and the contents of soil fine particles and organic matter were the dominant factors affecting the distribution of Fe and Mn in soils. In addition, the Fe contents ranged from 16.49 g x kg(-1) to 33.11 g x kg(-1) and the average was 22.54 g x kg(-1), which was close to the Fe contents in the tidal marshes of north Jiangsu, the Loess Plateau and the China soil background value, but slightly lower than those in the marshes of the Yangtse River estuary, the mangrove swamps and inland lake wetland. The Mn contents ranged from 305.87 mg x kg(-1) to 711.39 mg x kg(-1) and the average was 451.09 mg x kg(-1), which was lower than the Mn contents in the Loess Plateau and the China soil background value. Hydrology and Water Resources Survey Bureau of the Yellow River Estuary, Dongying 257091, China)
Subject(s)
Iron/analysis , Manganese/analysis , Rivers/chemistry , Wetlands , China , Estuaries , Nitrogen/chemistry , Seawater/chemistry , Soil/chemistryABSTRACT
Using static chamber-GC techniques, the short-term effects of nitrogen input on the emission fluxes of CH4 and N2O from a Cyperus malaccensis wetland were determined. The results showed that the emission of CH4 was increased by high nitrogen input at all sampling times, whereas the low nitrogen input exhibited different variation characteristics at different time points. Compared to the control treatment, the CH4 emission flux in the two nitrogen input treatments (N1, N2) was increased by -44.35%-1 057.35% and 7.15%-667.37%, respectively. The input of exogenous nitrogen had positive priming effect on N2O emission flux within 24 hours, increased by up to 171.60 folds and 177.79 folds, respectively. After 8 days, the priming effect by the nitrogen input weakened or disappeared. There was no significant effect of nitrogen input on the Ec, pH and Eh of soil at different depths in the salt marsh during the experiment. In the control treatment, the CH4 emission flux was negatively correlated solely with Eh of soil at 5 cm depth, whereas in the N1 treatment, it was negatively correlated solely with soil temperature at 10 cm depth. In the N2 treatment, there was negative correlation between the CH4 emission flux and Ec of soil at 5cm depth, pH of soil at 0, 5 cm depths, and Eh of soil at 0, 5, 10 cm depths. However, no significant correlation between the N2O emission flux and the environmental variables in the wetland was found. This study indicated that the temporal variability should be taken into consideration when examining the effects of nitrogen input on the emission of greenhouse gases in the wetlands.
Subject(s)
Cyperus/metabolism , Methane/analysis , Nitrogen/chemistry , Nitrous Oxide/analysis , Wetlands , Air Pollutants/analysis , Air Pollutants/chemistry , China , Cyperus/genetics , Methane/chemistry , Nitrous Oxide/chemistry , RiversABSTRACT
The characteristics of methane (CH4) fluxes from tidal wetlands of the Yellow River estuary were observed in situ with static-chamber and GC methods in September and October 2009, and the key factors affecting CH4 fluxes were discussed. From the aspect of space, the CH4 flux ranges in high tidal wetland, middle tidal wetland, low tidal wetland, bare flat are - 0.206-1.264, -0.197-0.431, -0.125-0.659 and -0.742-1.767 mg x (m2 x h)(-1), the day average fluxes are 0.089, 0.038, 0.197 and 0.169 mg x (m2 x h)(-1), respectively, indicating that the tidal wetlands are the sources of CH4 and the source function of CH4 differed among the four study sites, in the order of low tidal wetland > bare flat > high tidal wetland > middle tidal wetland. From the aspect of time, the ranges of CH4 fluxes from the tidal wetland ecosystems are -0.444-1.767 and - 0.742- 1.264 mg x (m2 x h)(-1), and the day average fluxes are 0.218 and 0.028 mg x (m2 x h)(-1) in September and October, respectively. The CH4 fluxes in each tidal wetland in September are higher than those in October except that the high tidal wetland acts as weak sink in September. Further studies indicate that the changes of environmental factors in the Yellow River estuary are complicated, and the CH4 fluxes are affected by multiple factors. The differences of CH4 fluxes characteristics among different tidal wetlands in autumn are probably related to temperature (especially atmospheric temperature) and vegetation growth status, while the effects of water or salinity condition and tide status on the CH4 flux characteristics might not be ignored.
Subject(s)
Air Pollutants/analysis , Environmental Monitoring , Methane/analysis , Water Pollutants, Chemical/analysis , Wetlands , China , Oceans and Seas , Rivers , Seasons , Tidal WavesABSTRACT
Well-understand the organic carbon status in the Yellow River delta is the most important for studying the biogeochemical processes of the muddy-sandy coastal wetland and ecological restoration. The spatial distribution characteristics and its impact factors of organic carbon in the plant-soil systems of new-born tidal flat wetland in the Yellow River estuary were studied. The results showed that the difference of plant organic carbon content in different plant communities were not obvious, however significant difference of the plant organic carbon density was observed. Moreover, the M-shaped spatial distribution of the plant organic carbon density, which was similar to the plant biomass, was found in the study. The organic carbon contents in top soils were varied from 0.75 to 8.35 g x kg(-1), which was much lower than that in the typical freshwater marsh wetlands ecosystem. The spatial distribution trend of soil organic carbon density was similar to the soil organic carbon. The correlation analysis showed that soil organic carbon density was negatively correlated with pH, and positively correlated with TN, C/N and salinity. However, the correlations of plant organic carbon density with the soil organic carbon density, TN, C/N, pH and salinity were not significant.
Subject(s)
Carbon/analysis , Organic Chemicals/analysis , Plants/chemistry , Soil Pollutants/analysis , Wetlands , Biodegradation, Environmental , China , Environmental Monitoring , Rivers , Soil/analysisABSTRACT
From May to October 2004, the seasonal changes of K, Ca, and Mg contents and accumulation in Calamagrostis angustifolia, the dominant species in the typical meadow and marsh meadow communities of Sanjiang Plain, were studied. There was a greater difference in the seasonal changes of K, Ca, and Mg contents in different parts of typical meadow C. angustifolia (TMC) and marsh meadow C. angustifolia (MMC). The K content in aboveground parts of the two communities had an overall decreasing trend, according with linear model K = A + B(t), the Ca content had a smaller change in stem but an overall increasing trend in leaf and vagina, being accorded with parabola model Ca = A +B1t + B2t2 and exponential growth model Ca = Aexp(t/B1) + B2, respectively, while the Mg content had the greatest change in stem but changed relatively smoothly in leaf and vagina. The differences of K, Ca, and Mg contents in different parts of TMC and MMC were obvious. The K content in aboveground parts of TMC was generally higher than that of MMC, while the Ca and Mg contents in the root and vagina of MMC were higher than those of TMC. The K, Ca, and Mg storage and accumulation in different parts of TMC and MMC also differed. Root had the greatest K, Ca, and Mg storage, occupying 63.82 +/- 23.19%, 78.68 +/- 15.44%, and 76.48 +/- 19.06% of the total storage in TMC and 85.23 +/- 9.20%, 93.51 +/- 3.46%, and 92.39 +/- 3.22% in MMC, respectively. The aboveground parts of TMC had a higher storage of K, Ca and Mg than those of MMC, while the root was in adverse. Such a difference was mainly due to ecological characteristics of C. angustifolia and its habitat conditions.
Subject(s)
Calcium/metabolism , Magnesium/metabolism , Poaceae/metabolism , Potassium/metabolism , China , Poaceae/classification , SeasonsABSTRACT
From May to October in 2004, the characteristics of nitrogen (N) accumulation and allocation in Calamagrostis angustifolia, the dominant species in the typical meadow and marsh meadow communities of Sanjiang Plain, were studied. The results showed that the total nitrogen (TN) content in the aboveground organs and litters of typical meadow C. angustifolia (TMC) and marsh meadow C. angustifolia (MMC) decreased during growth season, which could be described by exponential decay model (TN = Aexp (-t/B1) + B2, R2 > or = 0.94). The TN content in TMC and MMC roots fluctuated greatly, and a significant N accumulation period (15-30 d) was observed before the coming of growth midseason. The N accumulation amount and rate of different organs and litters had obvious seasonal changes, and their values of the aboveground organs were much higher for TMC than for MMC, while the values of the roots were in adverse. The N allocation ratio of different parts of TMC and MMC also had significant differences. Root was the important N storage, and the root N allocation ratio of TMC and MMC was (59.38 +/- 12.86)% and (84.58 +/- 3.38)%, respectively. Among the aboveground parts, leaf had the highest N allocation ratio, being (24.28 +/- 12.09)% for TMC and (8.18 +/- 3.32)% for MMC. The change patterns of the N allocation ratio of aboveground and underground parts were just in adverse, which reflected the osculation contact in N supplement aspect. The annual N absorption amount and maximum standing crop of TMC and MMC were 23.02, 36.30 g x m(-2), and 28.18, 51.43 g x m(-2), respectively. The N absorption coefficient and utilization coefficient of TMC were much higher than those of MMC (0.017 and 0.634 relative to 0.015 and 0.548, respectively), illustrating that TMC had higher capability of N absorption and utilization than MMC.
Subject(s)
Nitrogen/metabolism , Poaceae/metabolism , China , Nitrogen/analysis , Plant Leaves/metabolism , Plant Roots/metabolism , Poaceae/classification , SeasonsABSTRACT
From May 2005 to September 2006, the potential effects of wetland water change on the decomposition and nitrogen (N) dynamics of the typical meadow Calamagrostis angustifolia (TMC) and marsh meadow C. angustifolia (MMC) litters were studied by litterbag technique in the typical depressional wetland in the Sanjiang Plain. In this study, the natural water gradient in the depressional wetland was applied to simulate the changes of wetland water conditions, and six decomposition sub-zones were laid in turn in the six communities, Carex pseudocuraica (PF), Carex lasiocarpa (MG), Carex meyeriana (WL), Marsh meadow C. angustifolia (XII), Typical meadow C. angustfolia (XI), and Island forest (DZL), along the water gradient. The results show that water condition has significant effects on the decomposition of litters. If the hydrous environment is formed in C. angustfolia wetland due to the change of precipitation pattern in the future, the litter weightless rates of TMC and MMC will increase 4.33%-16.76% and 24.84%-53.97%, the decomposition rates will increase 10.51%-32.73% and 77.85%-93.92%, and the 95% decomposition time will decrease 0.72-1.85 a and 3.67-4.05 a, respectively. The changes of N contents and N accumulation indices of TMC and MMC litters are relatively consistent, but the change patterns indifferent sub-zones are different. In general, the N in litters in DZL, XI, WL, MG and PF sub-zones show the alternant change characteristics of release and accumulation, but the release process is predominated. In contrast with that, the N in litters in XII sub-zone show release at all times. The C/N ratios have important regulation functions to the changes of N in litters in decomposition process. The estimation results show that the N standing crops of TMC and MMC litters are 12.75 g x m(-2) and 8.29 g x m(-2), and the N annual returning amounts are larger than 1.95 g x (m2 x a)(-1) and 2.25 g x (m2 x a)(-1), respectively. The studies of affecting factors indicate that temperature has promotion effects on the relative decomposition rates of litters, while water condition has restraint effects on them. Further analysis shows that the relative decomposition rates, to some extent, depend on the substrate quality of litters if the nutrient status of decomposition environment does not change greatly. In reverse, if the nutrient status of decomposition environment changes greatly, the relative decomposition rates, to some extent, depend on the supply status of nutrient in decomposition environment.
