Chinese Wetland Research Articles

Towards a better understanding of ethylmercury in the environment: Addressing propylation derivatization artifact and verifying its occurrence in Chinese wetlands

Ethylmercury (EtHg), similar to methylmercury (MeHg), is highly neurotoxic and bioaccumulative. Although recent studies suggested its occurrence in natural soils and sediments, the common propylation derivatization for EtHg analysis might generate EtHg artifacts, potentially leading to its overestimation in environmental samples. Furthermore, the extensive environmental prevalence of EtHg remains unverified, keeping its importance largely uncertain. This study investigated the formation of EtHg artifacts during propylation derivatization, evaluating artifacts formation and recoveries under different extraction methods with real samples, and confirmed the widespread occurrence of EtHg in Chinese wetlands. EtHg artifacts were obviously present during the propylation derivatization and strongly dependent on the levels of Hg2+ (0.1–10 ng) in the derivatization solution (R² = 0.99), accounting for 1.38–2.14% of Hg2+. CuSO4-HNO3CH2Cl2 extraction (effectively removing Hg2+) combined with propylation derivatization offers excellent recovery (81–86%) and low artifacts (< LOD: 1.98 × 10−4 ng/g) for EtHg measurement in soils/sediments, with results aligning with those from online solid phase extraction-high performance liquid chromatography-inductively coupled plasma mass spectrometry (R2 = 0.99). Additionally, we observed the occurrence of EtHg in soil and sediment samples across 14 Chinese wetlands, with concentrations varying from 6.08 to 171 pg/g, similar to MeHg concentrations at some sites. EtHg positively correlates with MeHg, total Hg, and total organic carbon across all samples, indicating a possible biological formation. These findings help better understand and predict the prevalence of EtHg in wetlands and its key role in environmental Hg cycle.

Pollutant Exposure for Chinese Wetland Birds: Ecotoxicological Endpoints and Biovectors

Pollutant Exposure for Chinese Wetland Birds: Ecotoxicological Endpoints and Biovectors

RETRACTED ARTICLE: Dynamics of wetland tourism in China: studying wetland tourism park service quality with post-trip tourist intention and tourism value co-creation.

The research intends to assess the dynamics of wetland tourism in China using nexus between tourism service quality, post-trip tourist intention and tourism value co-creation. The study taken the visitors of wetland parks of China as study sample and applied the fuzzy AHP analysis technique and Delphi analysis method. The results of study confirmed reliability and validity of the constructs. It is found that there is significant connection between tourism service quality and value co-creation of Chinese wetland park tourists with the mediating role of tourists' re-visit intention. The findings also lend credence to the "wetland tourism dynamics" which postulates that an increase in capital investment in wetland tourism parks increases tourism service quality and value co-creation and decrease environmental pollution in larger extent. Moreover, findings state that sustainable tourism policy and practice for wetland tourism parks of China has also a significant role in enhancing the stability in wetland tourisms dynamics. The research recommends that administrations obligation urgencies in enhancing scope of wetland tourism in a manner to enhance tourism service quality, which is essential for tourists' re-visit intention after a trip and tourism value co-creation.

Geographic factors explain soil nitrogen and phosphorus stoichiometry in the Chinese wetlands

Generally, the contents of nitrogen (N) and phosphorus (P), and their stoichiometry, in the soil of terrestrial ecosystems exhibit certain geographic patterns. However, it remains poorly understood whether these patterns also exist for wetland soils. Here, we compiled a dataset of 731 observations among 468 sites from both published reports and field investigations, to examine the continental-scale geographic patterns in soil N and P stoichiometry of the Chinese wetlands. The results showed that the averaged soil N contents, P contents and N:P ratio were 1.98 mg g−1, 0.70 mg g−1, and 3.59, respectively, which were also dependent on wetland types and vegetation. Moreover, soil N and P contents and N:P ratio concurrently exhibited clear latitudinal, longitudinal and altitudinal patterns, more diversified patterns than those in terrestrial ecosystem. The observed patterns were explained primarily based on geographic factors, particularly the altitude, rather than vegetation and climate conditions. These findings advance our understanding of biogeographical nutrient cycles in wetlands and highlight the critical role of geographic factors in regulating soil N and P stoichiometry under global climate change.

Greenhouse gas emissions and environmental drivers in different natural wetland regions of China

Wetlands sequestrate carbon at the highest rate than any other ecosystems on Earth. However, the spatial and temporal dynamics of GHGs emissions from the wetland ecosystems in China are still elusive. We synthesized 166 publications that contain 462 in situ measurements of GHGs emissions from the natural wetlands in China, and further analyzed the variability and the drivers of GHGs emissions in eight subdivisions of China's wetlands. The results show that the current studies are mainly concentrated in the estuaries, Sanjiang Plain, and Zoige wetlands. The average CO2 emissions, CH4 fluxes and N2O fluxes from Chinese wetlands were 218.84 mg·m−2·h−1, 1.95 mg·m−2·h−1 and 5.8 × 10−2 mg·m−2·h−1, respectively. The global warming potential (GWP) of China's wetlands was estimated to be 1881.36 TgCO2-eq·yr−1, with CO2 emissions contributing more than 65% to the GWP value. The combined GWP values of Qinghai-Tibet Plateau wetlands, coastal wetlands and northeastern wetlands account for 84.8% of GWP of China's wetlands. Correlation analysis showed that CO2 emissions increased with the increasing mean annual temperature, elevation, annual rainfall, and wetland water level, but decreased with soil pH. CH4 fluxes increased with the mean annual temperature and soil water content but decreased with the redox potential. This study analyzed the drivers of GHGs emissions from wetland ecosystems at the national scale, and GWP values of eight wetland subregions of China were comprehensively assessed. Our results are potentially useful for the global GHGs inventory, and can help assess the response of GHGs emissions of wetland ecosystem to environmental and climate change.

A new perspective on the impacts of Spartina alterniflora invasion on Chinese wetlands in the context of climate change: A case study of the Jiuduansha Shoals, Yangtze Estuary

Spartina alterniflora, an invasive plant, was introduced to the Chinese coastal zone in the early 90s. As an eco-engineering species, S. alterniflora not only alters saltmarsh species distributions, previously described as habitat degradation, but it also plays a vital role in coastal protection, especially for the development of recently emerged intertidal shoals. To provide a reference for coastal management under global change, we quantified the impact of the invasion process on provided ecological and coastal protection functions, exemplified at the emerging Jiuduansha Shoals (JDS) in the Yangtze Estuary. Results obtained by high-precision satellite monitoring and numerical modelling showed that the establishment and growth of S. alterniflora can exert considerable changes on local environment. The invasion of S. alterniflora to JDS wetland can be divided into three distinct phases, (1) establishment 1998–2003, (2) expansion 2003–2009, and (3) dominant 2009–2018 stages according to the changes in saltmarsh composition. Spatially, S. alterniflora continuously replaced Scirpus mariqueter, forcing S. mariqueter and Phragmites australis slowly to the lower and higher intertidal habitats, respectively. Notably, S. alterniflora expansion was the main driver that contributed to over 70 % of recent JDS wetland expansion even under sediment deficit conditions. Established S. alterniflora marsh (directly) dampens more waves because of aboveground stems, but it also causes more accretion and indirectly leads to higher “morphological” wave dampening. Thus, it increases coastal defense provided by the saltmarsh in the context of sea-level rise and strengthening storms. In conclusion, the role of S. alterniflora invasion to the local environment under global changes is controversial. For sustainable coastal management, we need context-dependent S. alterniflora management to maximize the benefit of coastal protection and minimize the impact on local ecology, especially in sediment-starving estuaries with expected coastline retreat.

Local Residents Becoming Local Tourists: Value Co-Creation in Chinese Wetland Parks during the COVID-19 Pandemic

Despite their ecological value, wetland parks can be expensive to preserve and maintain, so local governments endeavor to design financially sustainable models by exploiting the ecotourism value of wetland parks. This trend has been facilitated by telecommunication technologies that enable value co-creation. Unlike previous studies that primarily assume tourists to be outsiders far from home, this study addresses a unique situation: travel restrictions during the COVID-19 pandemic generated a unique ecotourism market for local residents. This study responds to the above issue by examining the factors responsible for local tourists’ value co-creation intention. Specifically, we drew on the theory of planned behavior to develop an extended model to address the research objective. The hypothesized model was empirically tested using an online survey of 386 local tourists who traveled to a wetland park in the Liangping district of Chongqing, China. Our results suggest that social norms, destination awareness, experience expectations, and facilitating conditions could affect local tourists’ attitudes, which further influences local customers’ value co-creation intention. Moreover, social norms, destination awareness, and experience expectations could affect local tourists’ perceived value of a wetland park, thus further influencing local customers’ value co-creation intention. In doing so, we made interesting insights and implications for ecotourism at a local level. Drawing on our survey in a specific wetland park, we highlight how local tourists’ attitude and perceived value positively affect their value co-creation intention and identify one more possible source of destination awareness: friends’ sharing of destination information and experience through social media. Practically, we suggest local tourism to offset the maintenance costs of wetland parks during the COVID-19 pandemic. That requires leveraging social norms and understanding residents’ expectations, in addition to improving infrastructure.

Microbial habitat specificity largely affects microbial co-occurrence patterns and functional profiles in wetland soils

Microbial species have different niche breadth, leading to distinct habitat ranges. Specialists have narrow niche breadth and high habitat specificity in comparison with the generalists, which possess extensive habitat ranges. Since specialists have low probabilities to occur in various habitats at a specific spatio-temporal scale, communities with different ratios of specialists and generalists may exhibit different species co-occurrence patterns and functional characteristics. However, it is still not clear how the assemblages of specialists and generalists can affect microbial co-occurrence and functional potential at a large biogeographical scale. In this study, we explored the relationship between microbial habitat specificity and the co-occurrence patterns of prokaryotic communities in Chinese wetland soils and the contribution of functional profiles to this relationship. We first identified some specialists and generalists which hold significant roles in the co-occurrence network. Then, we found that communities with more specialists have more simple co-occurrence patterns (fewer linkages in network) than those with more generalists. Soil electrical conductivity was the most significant abiotic factor in structuring this relationship. The biological mechanisms that contribute to this relationship were closely associated with functional differences of taxa. With the increase of specialists in communities, aerobic ammonia oxidation and cellulolysis guilds decreased, and photoautotrophy and sulfate/sulfide respiration populations increased. Furthermore, the abundances of metabolic pathways altered along with the abiotic gradients (e.g., conductivity and pH), including carbohydrate degradation, fermentation, inorganic nutrient metabolism and stress resistance-related pathways. Especially, there were higher abundances of metabolism-related pathways in communities with more specialists compared to those with more generalists. Functional differences at traits, genes, and metabolic pathways reflected the characteristics of microbial co-occurrence patterns and biogeochemical cycles of habitats. In summary, microbial habitat-specificity can modulate the co-occurrence patterns of prokaryotic communities along the environmental gradients in wetland soils. Our findings provide a mechanistic understanding on how microbial niche breadth can affect microbial co-occurrence in wetland soils.

Wetlands in China: Evolution, Carbon Sequestrations and Services, Threats, and Preservation/Restoration

China has a wetland area of 53.42 million hectares, the fourth largest in the world; it includes all types of wetlands defined by the Ramsar Convention and has a carbon sink capacity of more than 1.71 million metric tons per year. Inland wetlands in China are mainly distributed in 10 major catchments, among which the Yellow River, the Yangtze River, the rivers in the northwest, and the rivers in the northeast each have more than 8 million hectares of wetlands. There are 4220 species of plants and 4015 species of animals in China’s wetland ecosystem. The wetland resources that have been developed and utilized include edible products, reeds for paper making, peat for fertilizer, fuel for power generation, and chemical, pharmaceutical, ceramic, and building materials. However, wetland areas in China have shrunk by about 54% since 1980. In recent years, China’s central government has set great store by Chinese wetlands, and although 49.03% of wetland area is now officially protected, many issues have confounded the implementation of that protection. It is imperative that knowledge gained from scientific research be used to formulate a sound wetland protection and management plan that takes into consideration social, economic, and ecological issues in a way that facilitates the sustainable use of wetland resources and informs decision-makers of the paths that must be followed to achieve that goal.

中国湿地温室气体清单编制研究进展

中国湿地温室气体清单编制研究进展

Taxonomy and Molecular Phylogeny of Two New Urostylid Ciliates (Protozoa: Ciliophora) From Chinese Wetlands and Establishment of a New Genus.

Hypotrich ciliates with evolutionary novelties are continually being discovered, challenging the current taxonomic system and attracting increased attention. In the present work, two new urostylid ciliates, Heterobakuella bergeri gen. nov., sp. nov. and Anteholosticha perezuzae sp. nov., isolated from Chinese wetland samples, were identified based on morphology and 18S rRNA gene sequences. Heterobakuella gen. nov. is defined by three frontal cirri, single buccal cirrus, one parabuccal cirrus, midventral complex composed of cirral pairs and one cirral row, one left and two right marginal cirral rows, transverse and pretransverse cirri present, caudal and frontoterminal cirri absent. Heterobakuella can be easily distinguished from the morphologically most similar genus, Apobakuella, mainly by the single buccal cirrus (vs. one buccal cirral row) and one parabuccal cirrus (vs. several parabuccal cirral rows originated from different anlagen). Phylogenetic analyses show that H. bergeri branches within the clade formed by Bergeriella ovata, Monocoronella carnea, Anteholosticha gracilis, and Neourostylopsis spp., rather than the clade represented by Apobakuella. The other species, A. perezuzae, is mainly characterized by a distinctly slender body shape with an average length:width ratio about 7, distinctively shaped biconcave and greenish cortical granules, as well as one or two pretransverse cirri. Phylogenetic analyses indicate the genus Anteholosticha is non-monophyletic.

Effects of soil moisture on Phragmites australis (Cav.) allelochemicals in soil and on growth of Phalaris arundinacea L. in Chinese Wetland

Effects of soil moisture on Phragmites australis (Cav.) allelochemicals in soil and on growth of Phalaris arundinacea L. in Chinese Wetland

Hydrochemical Characteristics Jointly Determine the Transport and Cycling of Soil Carbon, Nitrogen, and Phosphorus in an Arid Chinese Wetland

AbstractSalt accumulation gradually changes the cycling of carbon (C), nitrogen (N), and phosphorus (P) and may even transform sinks into sources in arid wetlands. However, it's not clear how hydrochemical characteristics affect the wetland's source or sink function or how they affect C, N, and P cycling in arid regions. To clarify these relationships, we conducted field measurement in arid northern China. We simulated the variations of hydrochemical characteristics and the storage and stoichiometry of C, N, and P using the process‐based DeNitrification‐DeComposition (DNDC) and Hydrus‐1D models. The meteorological and hydrological processes had obvious characteristics of seasonal and interannual changes. The measured evapotranspiration averaged 660.23 and 587.94 mm year−1 in the saltmarsh and riparian wetlands, respectively. The soil showed a clear trend with higher SO42−, Na+, Ca2+, and Cl− fractions in comparison with lower Mg2+, K+, and HCO3− fractions, with the major ion and nutrient concentrations gradually decreasing with increasing depth in the soil. The major ion types had characteristics of Na+‐Ca2+‐SO42−‐Cl− in the saltmarsh wetland and riparian wetland. The storage of total C, N, and P were 372.72 ± 66.52 t C/hm2, 10.92 ± 2.59 t N/hm2, and 17.55 ± 1.54 t P/hm2 in the saltmarsh wetland versus 119.72 ± 27.88 t C/hm2, 4.38 ± 1.24 t N/hm2, and 13.17 ± 1.46 t P/hm2 in the riparian wetland. Therefore, wetland salinization in our study led to increased soil C, N, and P contents and storage and thereby enhanced the sink function of the wetlands.

Accuracy analysis in CH4MODwetland in the simulation of CH4 emissions from Chinese wetlands

Process-based models have been widely used to simulate the CH4 budget in natural wetlands, but there are still large uncertainties in the simulation processes. Accuracy analysis of process-based models is important to evaluate the reliability of model estimates for different wetlands. In this study, we analyzed the three sources of the model bias from a process-based model (CH4MODwetland) when simulating CH4 emissions from different wetland sites and types in China. On a national scale, the root-mean-square error (RMSE) decreased from 70.6% at daily scale to 27.1% at annual/seasonal scale. On a national scale, more than 90% of the model errors were from random error. At most of the sites random error contributed more than 60% to the model errors, except the Guangzhou, Haikou, Wuliangsu lake and Yancheng Estuary sites, which showed lower RMSE values. The model simulated higher RMSE at the tidal marsh sites. The model had capability to simulate the daily and annual/seasonal CH4 emissions from all wetland types (model efficiency > 0), and performed better for coastal wetlands than peatlands and marshes, with model efficiency values of 0.75 and 0.99, respectively. When applied the model at annual/seasonal scale for peatlands, marshes, and coastal wetlands, the RMSE decreased a lot. The study indicated that CH4MODwetland is more accurate at annual/seasonal scale than daily scale for different wetland types across China. The non-stochastic portion of CH4 emissions from peatlands, marshes and coastal wetlands can be well predicted by the model.

Eco-physiological Responses of Carex Schmidtii to Soil Salinization in a Chinese Wetland

Eco-physiological Responses of Carex Schmidtii to Soil Salinization in a Chinese Wetland

Soil bacterial community structure in Chinese wetlands

Soil microbial communities are crucial in maintaining the functions of wetland ecosystems. Understanding the microbial community structure and the key factors driving the assemblages of wetland soil microbiota are important to reveal the connections between microorganisms and functions of wetland ecosystems. In this study, soil bacterial community compositions and the factors shaping them were investigated in three groups of wetlands across China, including Tibet plateau wetlands (TW), inland wetlands (IW) and coastal wetlands (CW). Overall, Bacterial community structure and turnover showed distinct patterns in different groups. Bacterial phyla were mainly composed of Proteobacteria followed by Chloroflexi, Acidobacteria, Actinobacteria and Bacteroidetes in all groups of wetland samples. At genus level, random forest model showed that Coprothermobacter and Acetobacter were two most important genera explaining the differences among groups. The abundances of these genera were very low in IW relative to the other two groups. The alpha diversity of IW was significantly higher than those of TW and CW. The relative contribution of environmental factors was larger in the assemblages of bacterial communities in TW and CW than that in IW. The pH and conductivity were recognized as the most important measured environmental factors influencing bacterial community structure. Our results suggested that the bacterial communities of wetlands in different regions were shaped with different mechanisms. The communities in CW and TW regions owned lower alpha diversity and were more influenced by deterministic processes than those in IW. In conclusion, the spatial pattern of soil bacterial community assembly in Chinese wetland was scale-dependent.

Toward an ecological civilization: Mass comprehensive ecotourism indications among domestic visitors to a Chinese wetland protected area

Large-scale park-visitor symbiosis remains an aspiration despite the need for new models to address the challenges of managing contemporary protected area systems. A survey of 1050 visitors to the Red Beach National Scenic Corridor in Northeast China, however, indicates a latent potential, with 36.0% qualifying as “enthused ecotourists” and 32.4% as “ecotourists” based on claimed adherence to basic ecotourism characteristics. Another 17.2% are “hands-on greens” also amenable to participation in on-site park enhancement activities but neutral about nature learning. “Ambivalents” account for the remaining 14.4% of the sample. High overall proclivity to participate, report misbehavior, and behave in a more environmentally responsible manner as a result of their Red Beach visit constitutes a basis for mass comprehensive ecotourism that can achieve park-visitor symbiosis and contribute significantly to the creation of an ecological civilization, as long as attendant strategies incorporate distinctive Chinese tendencies in ecotourism and outdoor recreation.

Storage and release of nutrients during litter decomposition for native and invasive species under different flooding intensities in a Chinese wetland

Projections of climate change impacts over the coming decades suggest that rising sea level will flood coastal wetlands. We studied the impacts of three intensities of flooding on litter decomposition in the native Cyperus malaccensis, and the invasives Spartina alterniflora and Phragmites australis in Shanyutan wetland (Minjiang River estuary, China). Invasive species had larger C, N and P stocks in plant-litter compartments and higher fluxes among plant-litter-soil, which increased with flooding intensity. Litter mass remaining (% of initial mass) were correlated with the N:P ratio in remaining litter, consistently with the N-limitation in this wetland. P. australis had the highest accumulated N release (P < 0.001) in all flooding intensities, whereas C. malaccensis had higher N accumulated release than S. alternifolia but only at low flooding intensity. At high flooding intensity, the N released in the first year of litter decomposition (g m−2 y−1) were 9.56 ± 0.21, 2.38 ± 0.18 and 1.92 ± 0.03 for P. australis, S. alternifolia and C. malaccensis, respectively. The higher rates of nutrient release from litter decomposition in invasive species provided better nutrient supply during the growing season coinciding with the initial phases of decomposition. Thus, this study shows that invasive species may gain a competitive advantage over the native C. malaccensis under the projected scenarios of sea level rises.

Progress of Chinese Coastal Wetland based on Remote Sensing

Progress of Chinese Coastal Wetland based on Remote Sensing

Biogeographic distribution of bacterial, archaeal and methanogenic communities and their associations with methanogenic capacity in Chinese wetlands

Natural wetlands and anthropogenic paddy fields are the dominant biogenic sources of atmospheric methane emission which have been speculated as the most probable sources for the increase of post-2006 atmospheric methane. Regional differences in CH4 emission is possibly due to microbial biogeographic distribution. Here we collected soils from 19 wetlands from different regions in China. The methane production capacity (MPC) was measured for each soil samples and varied from 1.11 to 841.94mg/kg dry soil. High throughput sequencing was employed to investigate the diversity and composition of bacterial, archaeal and methanogenic communities. Similar biogeographic patterns for bacterial, archaeal and methanogenic communities along the latitudinal gradient were observed, and the biogeographic assemblies of different microbial groups were driven by concurrent factors, including edaphic variables (total organic carbon, total phosphorus and pH) and climatic variables (annual frost days, mean annual temperature, direct solar radiation and mean annual precipitation). MPC was significantly correlated with TOC concentration, and in addition, various functional taxa were positively correlated with MPC (P<0.05), for example, Sphingomonas, Syntrophomonas, Methanospirillum and Methanoregula, indicating their potential contributions in the methanogenic process, and many of them were fermentative bacteria and methanogens. Network analysis showed that some syntrophs, sulfate-reducers and methanogens were tightly co-occurred in one module, suggesting their involvements in cross-linked functional processes. Our study implicated both temperature and substrate availability altered the biogeographic patterns of microbial community as well as methane production potential in Chinese wetlands.