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1.
BMC Plant Biol ; 20(1): 155, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32276592

RESUMO

BACKGROUND: Glycine soja is a halophytic soybean native to saline soil in Yellow River Delta, China. Photosystem I (PSI) performance and the interaction between photosystem II (PSII) and PSI remain unclear in Glycine soja under salt stress. This study aimed to explore salt adaptability in Glycine soja in terms of photosystems coordination. RESULTS: Potted Glycine soja was exposed to 300 mM NaCl for 9 days with a cultivated soybean, Glycine max, as control. Under salt stress, the maximal photochemical efficiency of PSII (Fv/Fm) and PSI (△MR/MR0) were significantly decreased with the loss of PSI and PSII reaction center proteins in Glycine max, and greater PSI vulnerability was suggested by earlier decrease in △MR/MR0 than Fv/Fm and depressed PSI oxidation in modulated 820 nm reflection transients. Inversely, PSI stability was defined in Glycine soja, as △MR/MR0 and PSI reaction center protein abundance were not affected by salt stress. Consistently, chloroplast ultrastructure and leaf lipid peroxidation were not affected in Glycine soja under salt stress. Inhibition on electron flow at PSII acceptor side helped protect PSI by restricting electron flow to PSI and seemed as a positive response in Glycine soja due to its rapid recovery after salt stress. Reciprocally, PSI stability aided in preventing PSII photoinhibition, as the simulated feedback inhibition by PSI inactivation induced great decrease in Fv/Fm under salt stress. In contrast, PSI inactivation elevated PSII excitation pressure through inhibition on PSII acceptor side and accelerated PSII photoinhibition in Glycine max, according to the positive and negative correlation of △MR/MR0 with efficiency that an electron moves beyond primary quinone and PSII excitation pressure respectively. CONCLUSION: Therefore, photosystems coordination depending on PSI stability and rapid response of PSII acceptor side contributed to defending salt-induced oxidative stress on photosynthetic apparatus in Glycine soja. Photosystems interaction should be considered as one of the salt adaptable mechanisms in this halophytic soybean.

2.
Ying Yong Sheng Tai Xue Bao ; 31(1): 319-325, 2020 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-31957410

RESUMO

Investigating the composition of food sources with stable isotope method can provide direct evidence for the top-down control in the coastal wetland. In this study, we examined food source and feeding habit of Helice tientsinensis of common reed (Phragmites australis) vegetation in high marsh of Yellow River Delta. The results showed that the density of crab was (5.5±1.5) ind·m-2, with the behavior of climbing P. australis to feed on the leaves at night. Under the same indoor experimental condition, H. tientsinensis showed feeding preference on fresh leaves of P. aus-tralis. The stable isotope food source analysis showed that the leaves of P. australis were one of the important food sources of H. tientsinensis in the field. There were temporal variations in the proportion of fresh leaves [May: (6.4±4.9)%, July: (5.8±4.9)%, September: (12.5±8.8)%] and dead leaves [May: (12.4±7.8)%, July: (15.5±9.9)%, September: (15.1±9.4)%]. Therefore, H. tientsinensis could inhibit P. australis's growth and affect litter decomposition through feeding disturbance behavior.


Assuntos
Braquiúros , Áreas Alagadas , Animais , China , Hábitos , Poaceae , Rios
3.
Mar Pollut Bull ; 150: 110666, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31669713

RESUMO

Un-restored (R0) and restored (in 2006 (R2006) and in 2002, (R2002)) coastal wetlands were selected to study phosphorus (P) storage capacity and the risk of P loss in the Yellow River Delta (YRD). The results showed that the maximum P sorption capacity (Qmax) in the wetland sediments varied between 201.8-1168.6 mg kg-1; the average value was 576.2 mg kg-1. Qmax increased with increasing time since restoration (R2002 > R2006 > R0). The eutrophication risk index (ERI) ranged between 0.27-2.07% and decreased with increasing time since restoration, but the relationship was not statistically significant (P > 0.05). A correlation analysis demonstrated that Feox, Mg, and Alox are the main P sorption agents in wetland sediments, whereas TOC, pH, and clay particles have an important effect on P sorption and release. The analysis suggests that we should restore degraded coastal wetlands to help reduce the P load to offshore waters.

4.
PeerJ ; 7: e7655, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31534866

RESUMO

Spartina alterniflora is one of the most noxious invasive plants in China and many other regions. Exploring environmentally friendly, economic and effective techniques for controlling Spartina alterniflora is of great significance for the management of coastal wetlands. In the present study, different approaches, including mowing and waterlogging, mowing and tilling and herbicide application, were used to control Spartina alterniflora. The results suggest that the integrated approach of mowing and waterlogging could eradicate Spartina alterniflora, the herbicide haloxyfop-r-methyl could kill almost all the Spartina alterniflora, and the integrated approach of mowing and tilling at the end of the growing season was a perfect way to inhibit the germination of Spartina alterniflora in the following year. However, no matter which control approach is adopted, secondary invasion of Spartina alterniflora must be avoided. Otherwise, all the efforts will be wasted in a few years.

5.
Sci Total Environ ; 695: 133866, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31422323

RESUMO

Human activities have altered the environmental nitrogen (N) and phosphorus (P) supply from both aspects of overall supply level and relative supply ratio. However, the effects of the two aspects on plant community composition are still not clear. In this study, a field manipulation experiment combining 3 overall nutrient supply levels (Low, Medium and High) and 3 N:P supply ratios (5,1, 15:1 and 45:1) was conducted in a supratidal wetland in the Yellow River Delta from 2015 to 2018. The effects of the two aspects on soil properties, performance of dominant species and plant community diversity were examined. The results showed that the N:P supply ratio and overall supply level both affected the concentration of soil inorganic N and available P, and N:P ratio significantly, while only overall supply level exerted a significant effect on the importance value of the dominant species, species richness and Shannon diversity. There were big gaps in the N and P supply amounts among the treatments that having same overall supply level with different supply ratio, but the plant composition displayed no significant difference among these treatments, which suggested that P may be also very important in affecting plant community composition in the study area. The species richness and the Shannon diversity were negatively correlated with the importance value of Suaeda glauca. With the rise of overall supply level, S. glauca became increasingly dominant and suppressed other species. Compared with the control treatment, the species richness and the Shannon diversity declined significantly only at high supply level (minimum N supply amount of 26.01 g m-2 yr-1), indicated that the supratidal wetland had high resilience to nutrient enrichment. Our results revealed that the N:P supply ratio has little influence on plant composition, compared with overall supply, in relative short-term in the supratidal wetland.


Assuntos
Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise , Plantas , Poluentes da Água/análise , Áreas Alagadas , China
6.
Sci Total Environ ; 693: 133600, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31377360

RESUMO

Vegetation plays a key role in influencing the morphodynamics of river deltas, yet channelization of most of the world's rivers limits delta movement and resulting vegetation patterns. Thus, our understanding of vegetation dynamics in newly formed and abandoned deltaic wetlands is still poor. The artificial channel diversion of the mouth of the Yellow River in 1996 created conditions that mimic a natural delta lobe shift by increasing freshwater, sediment, and nutrient supply to wetlands along the new Yellow River course (NYR) and allowing seawater encroachment in the abandoned Yellow River course (OYR). To examine the effects of this river channel shift on the vegetation and seed bank structure, above-ground vegetation and seed bank species richness and diversity were examined from the channel to the marsh interior in wetlands of both OYR and NYR. A total of 17 plant species were found growing across both sites, 9 species were in OYR and 16 species in NYR. Soil depth did not influence seed bank density in OYR, but the seed bank density in the 0-5 cm soil layer was significantly greater than in the 5-10 cm soil layer in NYR. Species diversity of the vegetation and soil seed bank was strongly influenced by soil salinity and hydrology, which varied along the gradient from seaside to river bank. There was a greater separation in species composition between seed bank and vegetation in the OYR than in the NYR. The findings suggest that channel diversion of the Yellow River Had a significant effect to the above-ground vegetation. However, the species richness and diversity of soil seed banks in the OYR was similar to that of the NYR, indicating that seed banks had a greater tolerance to external disturbance compared with vegetation.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Rios , Solo/química , Biodiversidade , Plantas , Banco de Sementes , Sementes
7.
Sci Total Environ ; 686: 118-130, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31176811

RESUMO

Marine submerged aquatic angiosperms (seagrasses) are declining globally. The species Zostera japonica Asch. & Graebn. is endangered in its native range in Asia, but has been successfully introduced to North America. A large area (1031.8 ha) of Z. japonica meadow has recently been discovered in the intertidal zone of Yellow River Delta, China. This seagrass occurs along both sides of the river mouth, forming dense meadows in turbid water conditions. Seasonal investigations over two years were conducted to examine the distribution, biomass, seed reproduction, seed bank, and population recruitment of the seagrass meadows at three sites in the intertidal zone. The meadows generally showed relatively high coverage, biomass, reproductive effort, and seed production in August. The seed bank was found to be large and contributed to population recruitment. There were significant inter-annual variations overall, and at individual sites. These variations are likely due to winter temperatures, which determine the abundance of overwintering shoots and seedling success. Differences in micro-topography may also play a role in producing variations in seedling success between sites. Microsatellite analysis revealed a high genetic exchange between the two sides of the river mouth. The results indicate that the seagrass bed in the Yellow River Delta shallow waters is in good condition, which can be attributed to its location within a national nature reserve. Establishment of protected areas might act as an effective way to mitigate the anthropogenic disturbance, conserve the seagrass meadows, and then enhance critical ecosystem functions.


Assuntos
Ecossistema , Zosteraceae/crescimento & desenvolvimento , Biomassa , China , Pradaria , Rios
8.
Sci Total Environ ; 656: 129-139, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30504015

RESUMO

Alkyl nitrates (RONO2) are important reservoirs of nitrogen oxides and play key roles in the tropospheric chemistry. Two phases of intensive campaigns were conducted during February-April and June-July of 2017 at a rural coastal site and in open oil fields of the Yellow River Delta region, northern China. C1-C5 alkyl nitrates showed higher concentration levels in summer than in winter-spring (p < 0.01), whilst their parent hydrocarbons showed an opposite seasonal variation pattern. The C3-C5 RONO2 levels in the oil fields were significantly higher than those in the ambient rural air. Alkyl nitrates showed well-defined diurnal variations, elucidating the effects of in-situ photochemical production and regional transport of aged polluted plumes. Backward trajectory analysis and fire maps revealed the significant contribution of biomass burning to the observed alkyl nitrates and hydrocarbons. A simplified sequential reaction model and an observation-based chemical box model were deployed to diagnose the formation mechanisms of C1-C5 RONO2. The C3-C5 RONO2 were mainly produced from the photochemical oxidation of their parent hydrocarbons (i.e., C3-C5 alkanes), whilst C1-C2 RONO2 compounds have additional sources. In addition to parent hydrocarbons, longer alkanes with >4 carbon atoms were also important precursors of alkyl nitrates in the oil fields. This study demonstrates the significant effects of oil field emissions and biomass burning on the volatile organic compounds and alkyl nitrate formation, and provides scientific support for the formulation of control strategies against photochemical air pollution in the Yellow River Delta region.

9.
Int J Mol Sci ; 19(12)2018 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-30544576

RESUMO

The aim of the study was to examine the role of root abscisic acid (ABA) in protecting photosystems and photosynthesis in Jerusalem artichoke against salt stress. Potted plants were pretreated by a specific ABA synthesis inhibitor sodium tungstate and then subjected to salt stress (150 mM NaCl). Tungstate did not directly affect root ABA content and photosynthetic parameters, whereas it inhibited root ABA accumulation and induced a greater decrease in photosynthetic rate under salt stress. The maximal photochemical efficiency of PSII (Fv/Fm) significantly declined in tungstate-pretreated plants under salt stress, suggesting photosystem II (PSII) photoinhibition appeared. PSII photoinhibition did not prevent PSI photoinhibition by restricting electron donation, as the maximal photochemical efficiency of PSI (ΔMR/MR0) was lowered. In line with photoinhibition, elevated H2O2 concentration and lipid peroxidation corroborated salt-induced oxidative stress in tungstate-pretreated plants. Less decrease in ΔMR/MR0 and Fv/Fm indicated that PSII and PSI in non-pretreated plants could maintain better performance than tungstate-pretreated plants under salt stress. Consistently, greater reduction in PSII and PSI reaction center protein abundance confirmed the elevated vulnerability of photosystems to salt stress in tungstate-pretreated plants. Overall, the root ABA signal participated in defending the photosystem's photoinhibition and protecting photosynthesis in Jerusalem artichoke under salt stress.


Assuntos
Ácido Abscísico/metabolismo , Helianthus/metabolismo , Raízes de Plantas/metabolismo , Helianthus/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema I/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Estresse Salino , Cloreto de Sódio/farmacologia , Compostos de Tungstênio/farmacologia
10.
Environ Pollut ; 242(Pt B): 1379-1386, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30138830

RESUMO

Regional sources of nitrogen oxides (NOx) in North China during summer were explored using both a Bayesian isotopic mixing model and a positive matrix factorization (PMF) model. Results showed that the nitrogen isotope (δ15N) composition of particulate nitrate (NO3-) varied between -8.9‰ and +14.1‰, while the oxygen isotope (δ18O) composition ranged from +57.4‰ to +93.8‰. Based on results from the Bayesian isotopic mixing model, the contribution of the hydroxyl radical (•OH) NOx conversion pathway showed clear diurnal fluctuation; values were higher during the day (0.53 ±â€¯0.16) and lower overnight (0.42 ±â€¯0.17). Values peaked at 06:00-12:00 and then decreased gradually until 00:00-06:00 the next day. Coal combustion (31.34 ±â€¯9.04%) was the most significant source of NOx followed by biomass burning (25.74 ±â€¯2.58%), mobile sources (23.83 ±â€¯3.66%), and microbial processes (19.09 ±â€¯5.21%). PMF results indicated that the contribution from mobile sources was 19.83%, slightly lower as compared to the Bayesian model (23.83%). The PMF model also reported a lower contribution from coal combustion (28.65%) as compared to the Bayesian model (31.34%); however, the sum of biomass burning and microbial processes in the Bayesian model (44.83%) was lower than the aggregate of secondary inorganic aerosol, sea salt, and soil dust in PMF model (51.52%). Overall, differences between the two models were minor, suggesting that this study provided a reasonable source quantification for NOx in North China during summer.


Assuntos
Poluentes Atmosféricos/análise , Óxidos de Nitrogênio/análise , Aerossóis , Teorema de Bayes , China , Carvão Mineral , Poeira/análise , Monitoramento Ambiental/métodos , Nitratos/análise , Isótopos de Nitrogênio/análise , Isótopos de Oxigênio/análise , Centrais Elétricas , Estações do Ano
11.
Sci Rep ; 8(1): 10825, 2018 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-30018389

RESUMO

Studying the carbon dynamics of estuarine sediment is crucial to understanding of carbon cycle in the coastal ocean. This study is to evaluate the mechanisms regulating the dynamics of organic (TOC) and inorganic carbon (TIC) in surface sediment of the Yellow River Estuary (YRE). Based on data of 15 surface sediment cores, we found that TIC (6.3-20.1 g kg-1) was much higher than TOC (0.2-4.4 g kg-1). Both TOC and TIC were generally higher to the north than to the south, primarily due to the differences in kinetic energy level (i.e., higher to the south). Our analysis suggested that TOC was mainly from marine sources in the YER, except in the southern shallow bay where approximately 75% of TOC was terrigenous. The overall low levels of TOC were due to profound resuspension that could cause enhanced decomposition. On the other hand, high levels of TIC resulted partly from higher rates of biological production, and partly from decomposition of TOC associated with sediment resuspension. The isotopic signiture in TIC seems to imply that the latter is dominant in forming more TIC in the YRE, and there may be transfer of OC to IC in the water column.

12.
Front Plant Sci ; 9: 479, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29868040

RESUMO

Fusarium fungi are soil-borne pathogens, and the pathological effects on plant photosystems remain unclear. This study aimed to deeply reveal pathological characterization in apple seedlings infected with Fusarium solani by investigating photosystems performance and interaction. Roots were immersed in conidial suspension for inoculation. Thereafter, prompt and delayed chlorophyll a fluorescence and modulated 820 nm reflection were simultaneously detected. After 30 days of infection, leaf relative water content and dry weight were remarkably decreased by 55.7 and 47.1%, suggesting that the infected seedlings were subjected to Fusarium-induced water deficit stress. PSI reaction center was more susceptible than PSII reaction center in infected seedlings due to greater decrease in the maximal photochemical efficiency of PSI than that of PSII, but PSI reaction center injury was aggravated slowly, as PSII injury could partly protect PSI by restricting electron donation. PSII donor and acceptor sides were also damaged after 20 days of infection, and the restricted electron donation induced PSII and PSI disconnection by blocking PSI re-reduction. In accordance with greater damage of PSI reaction center, PSI oxidation was also suppressed. Notably, significantly increased efficiency of electron transport from plastoquinone (PQ) to PSI acceptors (REo/ETo) after 20 days of infection suggested greater inhibition on PQ reduction than re-oxidation, and the protection for PSI acceptors might alleviate the reduction of electron transport efficiency beyond PQ upon damaged PSI reaction center. Lowered delayed fluorescence in microsecond domain verified PSII damage in infected seedlings, and elevated delayed fluorescence in sub-millisecond domain during PQ reduction process conformed to increased REo/ETo. In conclusion, F. solani infection depressed PSII and PSI performance and destroyed their coordination by inducing pathological wilting in apple seedlings. It may be a pathogenic mechanism of Fusarium to induce plant photosystems damage.

13.
Plant Physiol Biochem ; 125: 239-246, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29477087

RESUMO

Jerusalem artichoke (Helianthus tuberosus L.) is an important energy crop for utilizing coastal marginal land. This study was to investigate waterlogging tolerance of Jerusalem artichoke through photosynthetic diagnose with emphasis on photosystem II (PSII) and photosystem I (PSI) performance. Potted plants were subjected to severe (liquid level 5 cm above vermiculite surface) and moderate (liquid level 5 cm below vermiculite surface) waterlogging for 9 days. Large decreased photosynthetic rate suggested photosynthesis vulnerability upon waterlogging. After 7 days of severe waterlogging, PSII and PSI photoinhibition arose, indicated by significant decrease in the maximal photochemical efficiency of PSII (Fv/Fm) and PSI (△MR/MR0), and PSI seemed more vulnerable because of greater decrease in △MR/MR0 than Fv/Fm. In line with decreased △MR/MR0 and unchanged Fv/Fm after 9 days of moderate waterlogging, the amount of PSI reaction center protein rather than PSII reaction center protein was lowered, confirming greater PSI vulnerability. According to positive correlation between △MR/MR0 and efficiency that an electron moves beyond primary quinone and negative correlation between △MR/MR0 and PSII excitation pressure, PSI inactivation elevated PSII excitation pressure by depressing electron transport at PSII acceptor side. Thus, PSI vulnerability induced PSII photoinhibition and endangered the stability of whole photosynthetic apparatus under waterlogging. In agreement with photosystems photoinhibition, elevated H2O2 concentration and lipid peroxidation in the leaves corroborated waterlogging-induced oxidative stress. In conclusion, Jerusalem artichoke is a waterlogging sensitive species in terms of photosynthesis and PSI vulnerability. Consistently, tuber yield was tremendously reduced by waterlogging, confirming waterlogging sensitivity of Jerusalem artichoke.


Assuntos
Helianthus/metabolismo , Fotossíntese , Complexo de Proteína do Fotossistema I/metabolismo , Estresse Fisiológico , Água
14.
Sci Total Environ ; 595: 337-343, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28390312

RESUMO

Atmospheric nitrogen deposition caused by human activities has been receiving much attention. Here, after long-term simulated ammonium and nitrate nitrogen deposition (NH4Cl, KNO3, and NH4NO3) in the Yellow River Delta (YRD), a sensitive coastal wetland ecosystem typified by a distinct wet and dry season, methane fluxes were measured, by adopting a closed static chamber technique. The results showed that deposition of ammonium nitrogen accelerated methane emissions all year round. Ammonium nitrogen deposition transformed the YRD from a methane sink into a source during the dry season. Methanocellaceae is the only methanogen with increased abundance after the application of NH4Cl and NH4NO3, which promoted methane emissions, during the wet season. The findings suggested that Methanocellaceae may facilitate methane emissions in response to increased ammonium nitrogen deposition. Other methanogens might have profited from ammonium supplementation, such as Methanosarcinaceae. Deposition of nitrate nitrogen did not affect methane flux significantly. To the best of our knowledge, this study is the first to show that Methanocellaceae may be responsible for methane production in coastal wetland system. This study highlights the significant effect of ammonium nitrogen and slight effect of nitrate nitrogen on methane emission in the YRD and it will be helpful to understand the microbial mechanism responding to increased nitrogen deposition in the sensitive coastal wetland ecosystem.


Assuntos
Compostos de Amônio/metabolismo , Metano/biossíntese , Methanomicrobiaceae/metabolismo , Nitrogênio/metabolismo , Áreas Alagadas , China , Rios
15.
Sci Rep ; 6: 36550, 2016 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-27824160

RESUMO

Coastal ecosystems play significant ecological and economic roles but are threatened and facing decline. Microbes drive various biogeochemical processes in coastal ecosystems. Tidal flats are critical components of coastal ecosystems; however, the structure and function of microbial communities in tidal flats are poorly understood. Here we investigated the seasonal variations of bacterial communities along a tidal flat series (subtidal, intertidal and supratidal flats) and the factors affecting the variations. Bacterial community composition and diversity were analyzed over four seasons by 16S rRNA genes using the Ion Torrent PGM platform. Bacterial community composition differed significantly along the tidal flat series. Bacterial phylogenetic diversity increased while phylogenetic turnover decreased from subtidal to supratidal flats. Moreover, the bacterial community structure differed seasonally. Canonical correspondence analysis identified salinity as a major environmental factor structuring the microbial community in the sediment along the successional series. Meanwhile, temperature and nitrite concentration were major drivers of seasonal microbial changes. Despite major compositional shifts, nitrogen, methane and energy metabolisms predicted by PICRUSt were inhibited in the winter. Taken together, this study indicates that bacterial community structure changed along the successional tidal flat series and provides new insights on the characteristics of bacterial communities in coastal ecosystems.


Assuntos
Bactérias/crescimento & desenvolvimento , Biodiversidade , Consórcios Microbianos/fisiologia , Rios/microbiologia , Ondas de Maré , Microbiologia da Água , Bactérias/genética , China , RNA Bacteriano/genética , RNA Bacteriano/metabolismo , RNA Ribossômico 16S/genética
16.
Sci Rep ; 6: 37940, 2016 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-27892492

RESUMO

The delivery and distribution of nutrients in coastal wetland ecosystems is much related to the land use. The spatial variations of TOC, TN, NH4+-N, NO3--N and TP and associated soil salinity with depth in 9 kinds land uses in coastal zone of the modern Yellow River Delta (YRD) was evaluated based on monitoring data in field from 2009 to 2015. The results showed that the average contents of soil TOC, TN, NO3--N, NH4+-N and TP were 4.21 ± 2.40 g kg-1, 375.91 ± 213.44, 5.36 ± 9.59 and 7.20 ± 5.58 and 591.27 ± 91.16 mg kg-1, respectively. The high N and C contents were found in cropland in southern part and low values in natural wetland, while TP was relatively stable both in profiles and in different land uses. The land use, land formation age and salinity were important factors influencing distributions of TOC and N. Higher contents of TOC and N were observed in older formation age lands in whole study region, while the opposite regulation were found in new-born natural wetland, indicating that the anthropogenic activities could greatly alter the original distribution regulations of nutrients in coastal natural wetlands by changing the regional land use.

17.
Sci Rep ; 5: 10540, 2015 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-26014107

RESUMO

The characteristic of particle size distribution (PSD) in the newly formed wetlands in coast has seldom been studied. We applied fractal-scaling theory in assessing soil particle size distribution (PSD) features of newly formed wetlands in the Yellow River Delta (YRD), China. The singular fractal dimensions (D) values ranged from 1.82 to 1.90, the capacity dimension (D0) values ranged from 0.84 to 0.93, and the entropy dimension (D1) values ranged from 0.66 to 0.84. Constrained corresponding analysis revealed that 43.5% of the variance in soil PSD can be explained by environmental factors, including 14.7% by seasonal variation, 8.6% by soil depth, and 8.0% by vegetation type. The fractal dimensions D and D1 were sensitive with fine particles with size ranging less than 126 µm, and D0 was sensitive with coarse particles with size ranging between 126 µm to 2000 µm. Fractal analysis makes full use of soil PSD information, and offers a useful approach to quantify and assess the soil physical attributes in the newly formed wetland.

18.
PLoS One ; 10(3): e0121368, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25816240

RESUMO

BACKGROUND: The tidal flat is one of the important components of coastal wetland systems in the Yellow River Delta (YRD). It can stabilize shorelines and protect coastal biodiversity. The erosion risk in tidal flats in coastal wetlands was seldom been studied. Characterizing changes of soil particle size distribution (PSD) is an important way to quantity soil erosion in tidal flats. METHOD/PRINCIPAL FINDINGS: Based on the fractal scale theory and network analysis, we determined the fractal characterizations (singular fractal dimension and multifractal dimension) soil PSD in a successional series of tidal flats in a coastal wetland in the YRD in eastern China. The results showed that the major soil texture was from silt loam to sandy loam. The values of fractal dimensions, ranging from 2.35 to 2.55, decreased from the low tidal flat to the high tidal flat. We also found that the percent of particles with size ranging between 0.4 and 126 µm was related with fractal dimensions. Tide played a great effort on soil PSD than vegetation by increasing soil organic matter (SOM) content and salinity in the coastal wetland in the YRD. CONCLUSIONS/SIGNIFICANCE: Tidal flats in coastal wetlands in the YRD, especially low tidal flats, are facing the risk of soil erosion. This study will be essential to provide a firm basis for the coast erosion control and assessment, as well as wetland ecosystem restoration.


Assuntos
Solo/química , Ondas de Maré , China , Monitoramento Ambiental/métodos , Fractais , Tamanho da Partícula , Rios , Áreas Alagadas
19.
Ying Yong Sheng Tai Xue Bao ; 26(10): 2978-90, 2015 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-26995905

RESUMO

Wetland can be a potential efficient sink to reduce global warming due to its higher primary productivity and lower carbon decomposition rate. While there has been a series progress on the influence mechanism of ecosystem CO2 exchange over China' s wetlands, a systematic metaanalysis of data still needs to be improved. We compiled data of ecosystem CO2 exchange of 21 typical wetland vegetation types in China from 29 papers and carried out an integrated analysis of air temperature and precipitation effects on net ecosystem CO2 exchange (NEE), ecosystem respiration (Reco), gross primary productivity (GPP), the response of NEE to PAR, and the response of Reco to temperature. The results showed that there were significant responses (P<0.05) of NEE (R2 = 50%, R2=57%), GPP (R2 = 60%, R2 = 50%) Reco (R2 = 44%, R2=50%) with increasing air temperature and enhanced precipitation on the annual scale. On the growing season scale, air temperature accounted for 50% of the spatial variation of NEE, 36% of GPP and 19% of Reco, respectively. Both NEE (R2 = 33%) and GPP (R2 =25%) were correlated positively with precipitation (P<0.05). However, the relationship between Reco and precipitation was not significant (P>0.05). Across different Chinese wetlands, both precipitation and temperature had no significant effect on apparent quantum yield (α) or ecosystem respiration in the daytime (Reco,day, P>0.05). The maximum photosynthesis rate (Amax) was remarkably correlated with precipitation (P <0.01), but not with air temperature. Besides, there was no significant correlation between basal respiration (Rref) and precipitation (P>0.05). Precipitation was negatively correlated with temperature sensitivity of Reco (Q10, P<0.05). Furthermore, temperature accounted for 35% and 46% of the variations in temperature sensitivity of Reco (Q10) and basal respiration (Rref P<0.05), respectively.


Assuntos
Ciclo do Carbono , Dióxido de Carbono/análise , Chuva , Temperatura , Áreas Alagadas , China , Fotossíntese , Estações do Ano
20.
ScientificWorldJournal ; 2014: 952051, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25147872

RESUMO

The 26 sample sites in 7 study plots adjacent to asphalt road and earth road in coastal wetland in the Yellow River Delta were selected to quantify plant diversity using quadrat sampling method in plant bloom phase of July and August 2012. The indice of ß T and Jaccard's coefficient were applied to evaluate the species diversity. The results showed that the plant diversities and alien plants were high in the range of 0-20 m to the road verge. There were more exotics and halophytes in plots of asphalt roadside than that of earth roadside. However, proportion of halophytes in habitats of asphalt roadsides was lower than that of earth roadside. By comparing ß-diversity, there were more common species in the asphalt roadsides than that in the earth roadsides. The similarity of plant communities in studied plots of asphalt roadsides and earth roadsides increased with increasing the distance to road verge. The effect range of roads for plant diversity in study region was about 20 m to road verge. Our results indicate that the construction and maintenance of roads in wetland could increase the plant species diversities of communities and risk of alien species invasion.


Assuntos
Ecossistema , Plantas , Rios , Áreas Alagadas , Biodiversidade , China , Geografia
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