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1.
In order to reveal transpiration rates of wetland plants and its relationships to micro- meterological factors in a mountain valley wetland, relative humidity, air temperature, leaf temperature, soil temperature, photo flux density and transpiration rates were measured once two hours in a Carex meyeriana wetland of the Changbai Mountain valley in dry (July) and wet (September) of 2003, respectively. Results showed that the tendency of "decreasing after increasing" was obvious in wet season. However, a relatively stable trend was observed for the transpiration in dry season.. Generally, the photon flux density of Carex meyeriana was higher in wet season than that in dry season. However, the variabilities of leaf temperature, air temperature and relative humidity were similar in both seasons. Higher transpiration rates of Carex meyeriana leaves were observed in July (varied from 40 to 150 mol.m^-2.s^-1) compared to those (varied from 7 to 14 mol.m^-2.s^-1) in September. Transpiration rates were significantly correlated with air temperature (P〈0.01), leaf temperature (P〈0.01), and wind speed (P〈0.05), but correlationship between relative humidity and photo flux density was not significant (P〈0.05).  相似文献   

2.
The temporal dynamics of the biomass, as well as the carbon (C), nitrogen (N), phosphorus (P) concentrations and accumulation contents, in aboveand below-ground vegetation components were determined in the alpine steppe vegetation of Northern Tibet during the growing season of 2010. The highest levels of total biomass (311.68 g m−2), total C (115.95 g m−2), total N (2.60 g m−2), and total P (0.90 g m−2) accumulation contents were obtained in August in 2010. Further, biomass and nutrient stocks in the below-ground components were higher than those of the above-ground components. The dominant species viz., Stipa purpurea and Carex moorcrofti had lower biomass and C, N, P accumulations than the companion species which including Oxytropis. spp., Artemisia capillaris Thunb., Aster tataricus L., and so on.  相似文献   

3.
1INTRODUCTIONPlant canaccumulatemercuryfromair,soilandwa-ter.Theconcentrationofmercuryinplantisaffectedbythesource,form ofmercury andthephysiology ofplant.Theconcentrationsofinorganicmercuryandor-ganicmercuryinvariousplantsaredifferent,sotheenvironmentalexposureofmercuryandthebiotopeofplantscanbereflected bytheconcentrationofmer-curyinplants.Wetlandplaysanimportantroleinthetransportandcycleofmercury(DRISCOLLetal.,1994),andisanimportantsourceofmethylmercury ofsomelakesandrivers(STLOUI…  相似文献   

4.
Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in the Sanjiang Plain, China using different mesh litterbags. The results show that in each succession stage of wetland, soil fauna can obviously increase litter decomposition rates. The average contribution of whole soil fauna to litter mass loss was 35.35%. The more complex the soil fauna group, the more significant the role of soil fauna. The average loss of three types of litter in the 4mm mesh litterbags was 0.3–4.1 times that in 0.058mm ones. The decomposition function of soil fauna to litter mass changed with the wetland succession. The average contribution of soil fauna to litter loss firstly decreased from 34.96% (Carex lasiocapa) to 32.94% (Carex meyeriana), then increased to 38.16% (Calamagrostics angustifolia). The contributions of soil fauna to litter decomposition rates vary according to the litter substrata, soil fauna communities and seasons. Significant effects were respectively found in August and July on C. angustifolia and C. lasiocapa, while in June and August on C. meyeriana. Total carbon (TC), total nitrogen (TN) and total phosphorus (TP) contents and the C/N and C/P ratios of decaying litter can be influenced by soil fauna. At different wetland succession stages, the effects of soil fauna on nutrient elements also differ greatly, which shows the significant difference of influencing element types and degrees. Soil fauna communities strongly influenced the TC and TP concentrations of C. meyeriana litter, and TP content of C. lasiocapa. Our results indicate that soil fauna have important effects on litter decomposition and this influence will vary with the wetland succession and seasonal variation. Foundation item: Under the auspices of State Key Development Program for Basic Research of China (No. 2009CB421103), Key Program of National Natural Science Foundation of China (No. 40830535/D0101), Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-BR-16, KSCX2-YW-N-46-06)  相似文献   

5.
From April 2008 to November 2009,the nitrogen(N) cycle of plantsoil system in seepweed(Suaeda salsa) wetland in the intertidal zone of the Huanghe(Yellow) River estuary was studied.Results showed that soil N had sig-nificant seasonal fluctuations and vertical distribution,and the net N mineralization rates in topsoil were significantly different in growing season(p < 0.01).The N/P ratio(9.87 ± 1.23) of S.salsa was less than 14,indicating that plant growth was limited by N.The N accumulated in S.salsa litter at all times during decomposition,which was ascribed to the N immobilization by microbes from the environment.Soil organic N was the main N stock of plant-soil system,accounting for 97.35% of the total N stock.The N absorption and utilization coefficients of S.salsa were very low(0.0145 and 0.3844,respectively),while the N cycle coefficient was high(0.7108).The results of the N turnovers among compartments of S.salsa wetland showed that the N uptake amount of aboveground part and root were 7.764 g/m2and 4.332 g/m2,respectively.The N translocation amounts from aboveground part to root and from root to soil were 3.881 g/m2 and 0.626 g/m2,respectively.The N translocation amount from aboveground living body to litter was 3.883 g/m2,the annual N return amount from litter to soil was more than 0.125(-) g/m2(minus represented immobilization),and the net N mineralization amount in topsoil(0-15 cm) in growing season was 1.190 g/m2.The assessment of N biological cycle status of S.salsa wetland indicated that N was a very important limiting factor and the ecosystem was situated in unstable and vulnerable status.The S.salsa was seemingly well adapted to the low-nutrient status and vulnerable habitat,and the N quantitative relationships determined in the compartment model might provide scientific base for us to reveal the special adaptive strategy of S.salsa to the vulnerable habitat in the following studies.  相似文献   

6.
CARBON DYNAMICS OF WETLAND IN THE SANJIANG PLAIN   总被引:2,自引:0,他引:2  
1INTRODUCTIONWetlandsplayanimportant roleintheprocessofcar-bonstorage.Thetotalcarbonstoredindifferentkindsofwetlandsisabout15%-35%ofthetotalcarboninthegloballandsoils(POSTetal.,1982;GORHAM,1991).Inaddition,wetlandsaresignificantnaturalsources fortheatmospheric CH4 (MOORE,1994).It isestimatedthatabout110×1012gCH4 originates fromanaerobicdecompositioninthenaturalwetlands,CH4 emission fromthenaturalwetlandsis15%-30%oftheglobalCH4 emission andtheCH4 emission from thepeat land at hi…  相似文献   

7.
Du  Guoying  Zhao  Ezi  Liu  Chunrong  Tang  Xianghai 《中国海洋湖沼学报》2019,37(1):93-101
The community dynamics and potential carbon ?xation of intertidal macroalgae were investigated monthly from April 2014 to April 2015 in the northwest coast of Yellow Sea. Seasonal variations in biomass and carbon ?xation were presented and showed close relationship with community structure.The carbon ?xation rate ranged from 0.48±0.13 mg C/(g FW ·d) to 4.35±0.12 mg C/(g FW ·d). Sargassum thunbergii, Chondrus ocellatus and Ulva intestinalis were three most in?uential species which contributed27%, 21.9% and 18.5% variation of carbon ?xation rate, respectively. Standing carbon stocks ranged from7.52 g C/m~2 to 41.31 g C/m~2, and estimated carbon stocks varied from 11.77 g C/m 2 to 96.49 g C/m~2. The larger dif ference between estimated and standing carbon stocks implied that more ?xed carbon was exported from the community in summer and autumn than in winter. This study suggested that intertidal macroalgal community could provide a potential function in carbon ?xation of coastal ecosystem.  相似文献   

8.
INTRODUCTIONBenthicdiatomscomPrisethemaininitialfoodforjuvenileabalone.ItisimPortanttocIJlturehighqualitybenthicdiatornsduringtheeariystageofjuvenileabaloneculture.AtpresentthespeCesofbenthicdiatomsusedinabalonebedingfannsprirnarilycomefromnaturalpopulations.SomespedesinseveralgenerasuchasNavicula,Ntzchia,Caroneis,Achnanthes,AmPhoraareusuallythedothenantspch(Chen,etal.,l977,Ukiandaxuchi,l979,Nonnan-Boudnauetal.,l986,Austinetal.l990).Inordertoselodsornespedeswithhighadaptability,fas…  相似文献   

9.
April, 1996 to March, 1997 studies on the abundance and secondary production of Limnodrilus hoffmeisteri in an algae-dominated lake showed that the worm density and biomass peaked in December at 152 ind/m^2 and 0.087 g/m^2 , respectively. The secondary production of the animal was 0.294g/m^2 fresh wt/a. The turnover rate (P/B ratio) was 11.4.  相似文献   

10.
Qi  Yarong  Wang  Xin  Cheng  Jay Jiayang 《中国海洋湖沼学报》2017,35(3):668-680
In this study, biosilica of high purity was successfully prepared from marine diatom( Nitzschia closterium and Thalassiosira) biomass using an optimized novel method with acid washing treatment followed by thermal treatment of the biomass. The optimal condition of the method was 2% diluted HCl washing and baking at 600°C. The SiO_2 contents of N. closterium biosilica and Thalassiosira biosilica were 92.23% and 91.52%, respectively, which were both higher than that of diatomite biosilica. The SiO_2 morphologies of both biosilica are typical amorphous silica. Besides, N. closterium biosilica possessed micropores and fibers with a surface area of 59.81 m~2/g. And Thalassiosira biosilica possessed a mesoporous hierarchical skeleton with a surface area of 9.91 m~2/g. The results suggest that the biosilica samples obtained in this study present highly porous structures. The prepared porous biosilica material possesses great potential to be used as drug delivery carrier, biosensor, biocatalyst as well as adsorbent in the future.  相似文献   

11.
Shoot density, standing crop (above- and below-ground biomass) and habitat of salt marsh grass Porteresia coarctata were investigated along the coast of Bakkhali estuary, Cox’s Bazar, Bangladesh from January to December 2006. Shoot density of P. coarctata was influenced by season and was found to be higher (>2 500 shoots/m 2 ) in post-monsoon and minimal in monsoon season; plants were particularly active in vegetative propagation during pre-monsoon. Above-ground biomass was greater along the protected coast compared with the exposed one in this estuary. Below-ground biomass was higher (7.75-269.53 g DW/m 2 ) than that above ground (2.20-114.75 g DW/m 2 ). Standing crops of P. coarctata showed a negative relationship (R=-0.77; P<0.05) with sedimentation rate, while seasonal activity influenced sedimentation. The recorded sedimentation rate was lower (6.09 mg/(cm 2 ·d)) in pre-monsoon and highest (14.55 mg/(cm 2 ·d)) in monsoon season. The mean value of pore water salinity was higher (34.25±5.05) during post-monsoon and lowest (18.0±3.71) in monsoon season. The soil was sandy clay in this P. coarctata bed; it consisted of 86% sand, 13% clay and 1% silt. Soil organic matter dropped during the monsoon season (0.78%-0.67%) and was highest ((2.17±1.42)%-(2.3±1.47)%) during post-monsoon, probably owing to accumulation of decomposed peat on the marsh surface. The mean pore water NH 4 -N concentration ranged from 2.44±1.65 to 3.33±1.82 μg/L, with a minimum air temperature of 22.09°C in post-monsoon and a maximum of 31.16°C in pre-monsoon. Variations of physico-chemical parameters in the soil, water, and climate governed biological parameters of P. coarctata in the Bakkhali estuary, and were comparable with estuarine environments elsewhere.  相似文献   

12.
An April 1996 to March 1997 comparative study on the abundance and secondary production ofBranchiura sowerbyi Beddard, 1892 in two typical shallow lakes showed that in Houhu, an algae-dominated lake, the worm density (68 ind·m−2) peaked in July, biomass (1.930 g·m−2) peaked in June, while in Biandantang, a macrophyte-dominated lake, standing stock (density: 60 ind·m−2; biomass: 1.019 g·m−2 in wet weight) peaked in December. Secondary production of the animal in Houhu Lake was 3.413 g wet wt m−2 a−1, a little more than that (2.675 g wet wt m−2 a−1) in Biandantang Lake. Their turnover rates (P/B ratios) were 4.0 and 5.0, respectively. Project (39600019 and 39430101) supported by NSFC.  相似文献   

13.
Freshwater mussels are a major component of the zoobenthos and they therefore play an important role in freshwater ecosystems. The community composition and the standing crop of freshwater mussels in Poyang Lake, the largest freshwater lake in China and one of two lakes connected to the Changjiang (Yangtze) River, were investigated from February 2008 to May 2009. Mussels were sampled in hydrologically and geographically distinct sampling areas. A total of 42 species and 13 genera were identified, of which 32 species were endemic to China. Two species, Unio douglasiae and Lamprotula caveata, dominated all sampling areas. The number of genera and species, and the number of species within each genus, differed significantly among sampling areas. Freshwater mussels were very abundant, with an overall density of 0.28 ± 0.22 ind./m2 and biomass of 4.08 ± 3.96 g/m2. Significant variation observed among sampling areas and among genera was probably due to the variety of habitats among the areas sampled and to the adaptability of different freshwater mussels to environments. This study suggests that Poyang Lake and other freshwater lakes in the region are important sites of freshwater mussel biodiversity and conservation.  相似文献   

14.
Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. The search of marine actinobacteria with potential heavy metal biosorption ability resulted in the identification of a novel alkalophilic Streptomyces VITSVK5 species. The biosorption property of Streptomyces VITSVK5 spp. was investigated by absorbing heavy metals Cadmium (Cd) and Lead (Pb). Physiochemical characteristics and trace metal concentration analysis of the backwater showed the concentrations of different metals were lead 13±2.1 μg L−1, cadmium 3.1±0.3μg L−1, zinc 8.4±2.6μg L−1 and copper 0.3±0.1μg L−1, whereas mercury was well below the detection limit. The effect of pH and biomass dosage on removal efficiency of heavy metal ions was also investigated. The optimum pH for maximal biosorption was 4.0 for Cd (II) and 5.0 for Pb (II) with 41% and 84% biosorption respectively. The biosorbent dosage was optimized as 3 g L-1 for both the trace metals. Fourier transform infrared absorption spectrum results indicated the chemical interactions of hydrogen atoms in carboxyl (-COOH), hydroxyl (-CHOH) and amine (-NH2) groups of biomass with the metal ions. This could be mainly involved in the biosorption of Cd (II) and Pb (II) onto Streptomyces VITSVK5 spp. The results of our study revealed Streptomyces metabolites could be used to develop a biosorbent for adsorbing metal ions from aqueous environments.  相似文献   

15.
Estimating carbon sequestration and nutrient accumulation rates in Northeast China are important to assess wetlands function as carbon sink buffering greenhouse gas increasing in North Asia. The objectives of this study were to estimate accreting rates of carbon and nutrients in typical temperate wetlands. Results indicated that average soil organic carbon(SOC), total nitrogen(TN) and total phosphorus(TP) contents were 37.81%, 1.59% and 0.08% in peatlands, 5.33%, 0.25% and 0.05% in marshes, 2.92%, 0.27% and 0.10% in marshy meadows, respectively. Chronologies reconstructed by 210 Pb in the present work were acceptable and reliable, and the average time to yield 0–40 cm depth sediment cores was 150 years. Average carbon sequestration rate(Carbonsq), nitrogen and phosphorus accumulation rates were 219.4 g C/(m~2·yr), 9.16 g N/(m~2·yr) and 0.46 g P/(m~2·yr) for peatland; 57.13 g C/(m~2·yr), 5.42 g N/(m~2·yr) and 2.16 g P/(m~2·yr) for marshy meadow; 78.35 g C/(m~2·yr), 8.70 g N/(m~2·yr) and 0.71 g P/(m2·yr) for marshy; respectively. Positive relations existed between Carbonsq with nitrogen and precipitations, indicating that Carbonsq might be strengthened in future climate scenarios.  相似文献   

16.
Total mercury in soil,water,plant,insects,fishes and bird feathers were determined to study mercury distribution and accumulation in typical wetland ecosystems in the Sanjiang Plain,Northeast China.Results show that total mercury concentrations in soils of Deyeuxia angustifolia wetland and Carex lascarpa wetland are 0.046 mg/kg and 0.063 mg/kg,respectively.Total mercury concentration in water bodies is 0.053 μg/L on average.Of four plants studied,total mercury in moss is the highest with the mean of 0.132 mg/kg.Of 10 terrestrial insect species studied,total mercury in centipede(Scolopendra spp.) is the highest with the mean of 0.515 mg/kg while total mercury in grasshopper(Oxya spp.) bodies is the lowest.Total mercury concentrations in the herbivorous,omnivorous and predatory insects are 10.18 ng/g,16.47 ng/g and 213.35 ng/g on average,respectively.Total mercury concentrations of the adult feather(549.88 ± 63.04 ng/g),nestling feather(55.15 ± 23.53 ng/g),and eggshell(22.05 ± 5.96 ng/g) of the Grey heron(Ardea cinerea) are higher than those of the Great egret(Egretta alba)(adult feather:446.57 ± 90.89 ng/g;nestling feather:32.99 ± 17.15 ng/g;eggshell:21.02 ± 3.17 ng/g) in the wetlands of the Sanjiang Plain.The bioconcentration factors decrease in the order of piscivorous fish muscle > omnivorous fish muscle > herbivorous fish > insect.  相似文献   

17.
In recent years,wetland ecological water requirements (EWRs) have been estimated by using hydrological and functional approaches,but those approaches have not yet been integrated for a whole ecosystem.This paper presents a new method for calculating wetland EWRs,which is based on the response of habitats to water level,and determines water level threshold through the functional integrity of habitats.Results show that in the Huanghe (Yellow) River Delta water levels between 5.0 m and 5.5 m are required to maintain the functional integrity of the wetland at a value higher than 0.7.One of the dominant plants in the delta,Phragmites australis,tolerates water level fluctuation of about ± 0.25 m without the change in wetland functional integrity.The minimum,optimum and maximum EWRs for the Huanghe River Delta are 9.42×106 m3,15.56×106 m3 and 24.12×106 m3 with water levels of 5.0 m,5.2 m and 5.5 m,corresponding to functional integrity indices of 0.70,0.84 and 0.72,respectively.A wetland restoration program has been performed,which aims to meet these EWRs in attempt to recover from losses of up to 98% in the delta's former wetland area.  相似文献   

18.
Estuarial saline wetlands have been recognized as a vital role in CO2 cycling. However, insufficient attention has been paid to estimating CO2 fluxes from estuarial saline wetlands. In this study, the static chamber-gas chromatography (GC) method was used to quantify CO2 budget of an estuarial saline reed (Phragmites australis) wetland in Jiaozhou Bay in Qingdao City of Shandong Province, China during the reed growing season (May to October) in 2014. The CO2 budget study involved net ecosystem CO2 exchange (NEE), ecosystem respiration (Reco) and gross primary production (GPP). Temporal variation in CO2 budget and the impact of air/soil temperature, illumination intensity and aboveground biomass exerted on CO2 budget were analyzed. Results indicated that the wetland was acting as a net sink of 1129.16 g/m2during the entire growing season. Moreover, the values of Reco and GPP were 1744.89 g/m2 and 2874.05 g/m2, respectively; the ratio of Reco and GPP was 0.61. Diurnal and monthly patterns of CO2 budget varied significantly during the study period. Reco showed exponential relationships with air temperature and soil temperature at 5 cm, 10 cm, 20 cm depths, and soil temperature at 5 cm depth was the most crucial influence factor among them. Meanwhile, temperature sensitivity (Q10) of Reco was negatively correlated with soil temperature. Light and temperature exerted strong controls over NEE and GPP. Aboveground biomass over the whole growing season showed non-linear relationships with CO2 budget, while those during the early and peak growing season showed significant linear relationships with CO2 budget. This research provides valuable reference for CO2 exchange in estuarial saline wetland ecosystem.  相似文献   

19.
Limited information has been available about the influence of loading density on the performances of Scophthalmus maximus, especially in recirculating aquaculture systems (RAS). In this study, turbot (13.84±2.74 g; average weight±SD) were reared at four different initial densities (low 0.66, medium 1.26, sub-high 2.56, high 4.00 kg/m2) for 10 weeks in RAS at 23±1°C. Final densities were 4.67, 7.25, 14.16, and 17.47 kg/m2, respectively, which translate to 82, 108, 214, and 282 percent coverage of the tank bottom. Density had both negative and independent impacts on growth. The final mean weight, specific growth rate (SGR), and voluntary feed intake significantly decreased and the coefficient of variation (CV) of final body weight increased with increase in stocking density. The medium and sub-high density groups did not differ significantly in SGR, mean weight, CV, food conversion rate (FCR), feed intake, blood parameters, and digestive enzymes. The protease activities of the digestive tract at pH 7, 8.5, 9, and 10 were significantly higher for the highest density group, but tended to be lower (not significantly) at pH 4 and 8.5 for the lowest density group. The intensity of protease activity was inversely related to feed intake at the different densities. Catalase activity was higher (but not significantly) at the highest density, perhaps because high density started to induce an oxidative effect in turbot. In conclusion, turbot can be cultured in RAS at a density of less than 17.47 kg/m2. With good water quality and no feed limitation, initial density between 1.26 and 2.56 kg/m2 (final: 7.25 and 14.16 kg/m2) would not negatively affect the turbot cultured in RAS. For culture at higher density, multi-level feeding devices are suggested to ease feeding competition.  相似文献   

20.
Grassland is a major carbon sink in the terrestrial ecosystem. The dynamics of grassland carbon stock profoundly influence the global carbon cycle. In the published literatures so far, however, there are limited studies on the long-term dynamics and influential factors of grassland carbon stock, including soil organic carbon. In this study, spatial-temporal substitution method was applied to explore the characteristics of Medicago sativa L.(alfalfa) grassland biomass carbon and soil organic carbon density(SOCD) in a loess hilly region with different growing years and management patterns. The results demonstrated that alfalfa was the mono-dominant community during the cutting period(viz. 0–10 year). Community succession began after the abandonment of alfalfa grassland and then the important value of alfalfa in the community declined. The artificial alfalfa community abandoned for 30 years was replaced by the S. bungeana community. Accordingly, the biomass carbon density of the clipped alfalfa showed a significant increase over the time during 0–10 year. During 0–30 year, the SOCD from 0–100 cm of the soil layer of all 5 management patterns increased over time with a range between 5.300 ± 0.981 kg/m2 and 12.578 ± 0.863 kg/m2. The sloping croplands had the lowest SOCD at 5.300 ± 0.981 kg/m2 which was quite different from the abandoned grasslands growing for 30 years which exhibited the highest SOCD with 12.578 ± 0.863 kg/m2. The ecosystem carbon density of the grassland clipped for 2 years increased 0.1 kg/m2 compared with the sloping cropland, while that of the grassland clipped for 10 years substantially increased to 10.30 ± 1.26 kg/m2. Moreover, the ecosystem carbon density for abandoned grassland became 12.62 ± 0.50 kg/m2 at 30 years. The carbon density of the grassland undisturbed for 10 years was similar to that of the sloping cropland and the grassland clipped for 2 years. Different management patterns imposed great different effects on the accumulation of biomass carbon on artificial grasslands, whereas the ecosystem carbon density of the grassland showed a slight increase from the clipping to abandonment of grassland in general.  相似文献   

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