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Great efforts have been made in investigating the neurotoxicity of dopamine (DA) in the presence of manganous ions. In contrast, here, we probe the possibility of DA-based cancer chemotherapy by le...

The changing climate in recent decades has caused rapid, widespread frozen ground degradation of the cryosphere, and changes in frozen ground may largely affect the ecosystem function. This study presents the long-term shrinkage of frozen ground, driven forces and resultant ecological impacts at three high-latitude sites (namely Nenjiang, Jiagedaqi, and Tahe, from low to high latitude) in Northeast China, an area that has received less attention in previous permafrost studies. As the key indicators of frozen ground, the ground surface and subsurface soil temperature (down to 40 cm) were found to increase in the period from the 1970s to the 2000s. The annual mean air temperatures at observation sites have increased significantly at rates of 0.24~0.40 °C/decade from 1971 to 2019, and were found to be negatively correlated to the change in soil freeze depth at the Jiagedaqi and Tahe sites. The annual snow depth at Jiagedaqi was found to decrease at a rate of 1.8 cm/decade, and positively correlate to the soil freezing index. The vegetation status of the three watersheds improved, as indicated by the increased normalized difference vegetation index (NDVI) from 2000 to 2017. Our results can make a valuable contribution to knowledge of climate–frozen ground interactions, and can highlight the importance of examining such interaction for permafrost protection in similar high-latitude permafrost-dominated basins.

Mimicking the coordination geometry of the active metal sites of natural enzymes is an efficient strategy in designing therapeutic chemicals with enzymelike in vivo reaction thermodynamics and kinetics. In this study, this chemical concept has been applied for the in situ synthesis of natural antioxidase mimics for catalytic anti-inflammatory treatment by using rheumatoid arthritis, a common and hardly curable immune-mediated diseases, as an example. Briefly, a composite nanomedicine has been first constructed by loading cationic porphyrin ligands into a manganese-engineered mesoporous silica nanocarrier, which can respond to a mildly acidic environment to concurrently release manganous ions and porphyrin ligands, enabling their subsequent coordination and synthesis of manganese porphyrin with a coordination environment of an active Mn site similar to those of the metal sites in natural superoxide dismutase (SOD) and catalase. Due to the strong metal-ligand exchange coupling enabled by the

Nanocatalytic medicine is one of the most recent advances in the development of nanomedicine, which catalyzes intratumoral chemical reactions to produce toxins such as reactive oxygen species in situ for cancer specific treatment by using exogenous-delivered catalysts such as Fenton agents. However, the overexpression of reductive glutathione and Cu-Zn superoxide dismutase in cancer cells will significantly counteract the therapeutic efficacy by reactive oxygen species-mediated oxidative damages. Additionally, the direct delivery of iron-based Fenton agents may arouse undesired detrimental effects such as anaphylactic reactions. In this study, instead of exogenously delivering Fenton agents, the endogenous copper ions from intracellular Cu-Zn superoxide dismutase have been employed as the source of Fenton-like agents by chelating the Cu ions from the superoxide dismutase using a common metal ion chelator, N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN), followed by the TPEN-Cu(II) chelate reduction to TPEN-Cu(I) by reductive glutathione. Briefly, TPEN was loaded in a disulfide bond-containing link poly(acrylic acid) shell-coated hybrid mesoporous silica/organosilicate (MSN@MON) nanocomposite as a reductive glutathione-responsive nanoplatform, which features inter-related triple functions: intratumoral reductive glutathione-responsive link poly(acrylic acid) disruption and TPEN release; the accompanying reductive glutathione consumption and Cu-Zn superoxide dismutase deactivation by TPEN chelating Cu ions from this superoxide dismutase; and the Fenton reaction catalyzed by TPEN-Cu(I) chelate as a Fenton-like agent generated from TPEN-Cu(II) reduction by the remaining reductive glutathione in cancer cells, thereby cutting off the self-protection pathway of cancer cells under severe oxidation stress and ensuring cancer cell apoptosis by reactive oxygen species produced by the catalytic Fenton-like reactions. Such a nanocatalyst demonstrates excellent biosafety and augmented therapeutic efficacy by simultaneous nanocatalytic oxidative damage and intrinsic protection pathway breakage of cancer cells.

Glucose and glutamine are two principal nutrients in mammalian cells that provide energy and biomass for cell growth and proliferation. Especially in cancer cells, glutamine could be a main alternative for energy and biomass supply once glucose metabolism is suppressed. Therefore, single inhibition of enzymes in either glucose metabolism or glutaminolysis, though maybe efficient in vitro, is far from being satisfactory for efficient in vivo cancer therapy. Here, we proposed a new strategy for dual inhibitions on both glucose and glutamine metabolisms concurrently by silencing mutated gene Kras and glutaminase 1 (GLS1) via nanomaterial-based siKras and siGLS1 delivery, rather than conventional highly toxic chemodrugs. Such a combination therapy could overcome the challenge that glucose and glutamine are alternatives to each other in the biosynthesis and energy production for cancer cells, resulting in much elevated treatment efficacy. In addition, layered double hydroxide (LDH), the siRNA carrier, enables an enhanced gene delivery efficiency compared to the commercial transfection agent Lipofectamine 2000. Briefly, Mg-Al LDH nanosheets, loaded with siKras and siGLS1 onto their surfaces by electrostatic adsorption, could release siRNA from lysosomes into the cytoplasm via the proton sponge effect of LDH, favoring the siRNA stability and gene silencing efficiency enhancements. The thus released siRNA could downregulate the expressions of Kras, GLS1, and other enzymes involved in glucose metabolism, resulting in the downregulations of ATP and other metabolites. Such a biosafe LDH/siRNA nanomedicine is able to efficiently suppress the growth of xenografts through cancer cell proliferation suppression, displaying its great potential as a simultaneous glucose/glutamine metabolism coinhibitor for treating pancreatic cancer.

The extraordinarily rapid growth of malignant tumors depends heavily on the glucose metabolism by the pathways of glycolysis and mitochondrial oxidative phosphorylation to generate adenosine 5′-triphosphate (ATP) for maintaining cell proliferation and tumor growth. This study reports a tumor chemical suffocation therapeutic strategy by concurrently suppressing both glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) via the co-deliveries of EDTA and rotenone into a glutathione (GSH)-overexpressed tumor microenvironment. EDTA is to block the glycolytic pathway through inhibiting the activity of glycolytic enzymes via the chelation of magnesium ion, a co-worker of glycolytic enzymes, despite the presence of Ca2+. Meanwhile rotenone is to inhibit the mitochondrial OXPHOS. This work provides a novel tumor suffocation strategy by the co-deliveries of glucose metabolism inhibitors, especially by de-functioning glycolytic enzymes via eliminating their co-worker magnesium., The EDTA- and Rotenone-loaded MPER nanoparticles have been synthesized to suffocate tumor cells to death through inhibiting glycolytic process and mitochondrial oxidative phosphorylation simultaneously in vitro and in vivo.

Summary Surgery and subsequent chemotherapy are still the most adopted clinical modalities for bladder cancer treatments with the inevitable operation risks, chemotherapy toxicity, and high recurrence rate. Here, we report an unprecedented tumor cell dissociation strategy for malignant bladder tumor removal without the needs of conventional surgery and chemotherapy. A common metal ion chelator, ethylene diamine tetraacetic acid (EDTA), has been loaded into the interlayers of neurotensin (NT)-modified Zn-Al layered double hydroxide (LDH). Under the targeting by NT, such a nano-platform shows high affinity to bladder tumor cells, leading to the highly selective and efficient accumulation at the bladder tumor site. The released EDTA molecules deprive Ca2+ from the intercellular calcium-dependent connexin by EDTA-Ca2+ chelation, resulting in the tumor disaggregation that is then safely excreted out of body rather than killed using toxic chemodrugs, thus, ensuring excellent biosafety and extraordinarily high effectiveness.

The wetland plants are very sensitive to hydrological regimes. In this study, the individual sizes of a widely distributed species (i.e., Deyeuxia angustifolia) at three typical marshes with different water table depths (i.e., wet meadow (WM) marsh; seasonal inundated (SI) marsh; perennial inundated (PI) marsh) were investigated in the Sanjiang Plain of Northeast China. Concurrently, three primary point pattern processes (homogeneous Poisson (HP) process, homogeneous Thomas (HT) process, and inhomogeneous Thomas (IT) process) were used to model spatial patterns in the distribution at 0-50 cm scale for this tillering-cloning species. The plant height, diameter at breast height (d.b.h), internode number, branches number, and individual aboveground biomass of D. angustifolia decreased sharply with rising water level; however, its density and coverage increased first and then decreased as water level increases. The distribution of D. angustifolia totally diverged from the complete spatial randomness (CSR) model (i.e., HP process) suggesting strong aggregation at 0-50 cm scale in all marshes, and aggregated intensity enhanced with increasing water level. Interestingly, the spatial distribution of D. angustifolia fits better with the nested double-cluster model (i.e., IT process) at all scales in WM and SI marshes, indicating that there is a series of clustered patterns under the slight flood stress. However, the spatial pattern fits well with the Poisson cluster model (i.e., HT process) at all scales in PI marsh, implying the small-scale clustering disappeared with the intensification of flooding stress. Our results highlight that the D. angustifolia population could adapt to flooding stress in a certain degree via individual miniaturization strategies and multi-aggregation mechanisms in the freshwater wetlands.

Fenton reactions have been recently applied in tumor catalytic therapy, whose efficacy suffers from the unsatisfactory reaction kinetics of Fe

Cancer immunotherapy shows promising potential in future cancer treatment but unfortunately is clinically unsatisfactory due to the low therapeutic efficacy and the possible severe immunotoxicity. Here we show a combined magnetic hyperthermia therapy (MHT) and checkpoint blockade immunotherapy for both primary tumor ablation and mimetic metastatic tumor inhibition. Monodispersed, high-performance superparamagnetic CoFe2O4@MnFe2O4 nanoparticles were synthesized and used for effective MHT-induced thermal ablation of primary tumors. Simultaneously, numerous tumor-associated antigens were produced to promote the maturation and activation of dendritic cells (DCs) and cytotoxic T cells for effective immunotherapy of distant mimetic metastatic tumors in a tumor-bearing mice model. The combined MHT and checkpoint blockade immunotherapy demonstrate the great potentials in the fight against both primary and metastatic tumors.

Eurasian permafrost serves as an important nitrogen source for linked aquatic and oceanic ecosystems. To fill in the data gaps in the southern margin of the Eurasian permafrost, nitrogen dynamics in the two rivers that drain the permafrost in the Great Xing'an Mountains of northeast China were investigated during the 2012–2015 growing seasons. The mean concentration of total dissolved nitrogen (TDN) in the two catchments was 0.63 mg L−1, which is generally higher than other permafrost catchments around the Arctic Ocean. The dissolved organic nitrogen (DON) constituted the majority of TDN, and the mean DON:TDN ratio was as high as 0.84. The seasonal flood patterns broadly influenced the concentrations and annual loads of DON, as well as the dissolved organic carbon (DOC):DON ratios in the two rivers. River discharge was positively related to DON concentration during growing seasons, while the concentrations of dissolved inorganic nitrogen (DIN), namely ammonium and nitrate, demonstrated no relationship with discharge. The estimated annual TDN yield, 190 kg km−2 yr−1 on average, was much higher than in the large Arctic rivers that drain permafrost. This yield accounts for 42.7% of the total atmospheric nitrogen deposition in the study area, which indicates a great potential for dissolved nitrogen export from the permafrost area in the Great Xing'an Mountains.

Eurasian permafrost serves as an important carbon pool and water resource for linked aquatic ecosystems. To investigate the effects of expected warmer climate under climate change, and also to fill the data gaps in the south margin of the Eurasian permafrost, the seasonal runoff and the associated dissolved carbon fluxes in a pair of catchments in the Great Khingan Mountains of northeast China were investigated in 2018-2019. Two similar small catchments, a south-facing (SF) and a north-facing (NF), were used to check the effects of warmer climate on the dynamics of runoff and dissolved carbon yields. The SF catchment, with a warmer condition compared to the NF catchment, presented much larger snowmelt runoff during spring and more gentle rainfall flood peaks in the summer-autumn period, but similar concentrations of dissolved carbons during both the periods. As a result, the dissolved carbon fluxes were greatly elevated during the snowmelt period. However, the runoff and carbon yield in the two catchments showed no significant difference during the summer rainfall periods, in spite of a much deeper active layer of permafrost in the SF. As indicated by two fluorescence indices, the humification (HIX) and biological index (BIX), the chemical characteristics of dissolved carbon were similar in both the snowmelt and rainfall runoff periods in the two catchments. These results emphasize that warmer climate would largely alter the seasonal runoff patterns and promote dissolved carbon export in the snowmelt period, which would lead to more unexpected ecological impacts on the aquatic systems in the south Eurasian permafrost.

The iron gall ink-triggered chemical corrosion of hand-written documents is a big threat to Western cultural heritages, which was demonstrated to result from the iron gall (GA-Fe) chelate-promoted reactive oxygen species generation. Such a phenomenon has inspired us to apply the pro-oxidative mechanism of GA-Fe to anticancer therapy. In this work, we construct a composite cancer nanomedicine by loading gallate into a Fe-engineered mesoporous silica nanocarrier, which can degrade in acidic tumor to release the doped Fe3+ and the loaded gallate, forming GA-Fe nanocomplex in situ. The nanocomplex with a highly reductive ligand field can promote oxygen reduction reactions generating hydrogen peroxide. Moreover, the resultant two-electron oxidation form of GA-Fe is an excellent Fenton-like agent that can catalyze hydrogen peroxide decomposition into hydroxyl radical, finally triggering severe oxidative damage to tumors. Such a therapeutic approach by intratumoral synthesis of GA-Fe nano-metalchelate may be instructive to future anticancer researches., Iron gall chelate (GA-Fe) can promote oxygen reduction reactions and reactive oxygen species generation which causes chemical corrosion. Here, the authors, inspired by this phenomenon, develop a composite nanomedicine for tumour therapy constructed by loading gallate into Fe-engineered and PEGylated mesoporous silica nanocarrier, and show that it inhibits tumour growth.

It is well-known that relative growth rate (RGR) is closely related to C:N:P stoichiometry at the whole-plant level, yet it remains a misgiving to determine whether the growth-rate hypothesis is consistent between plant organs. Here, we examined RGR, C, N, P concentrations and their ratios of N:C, P:C, and N:P for four marsh herbaceous species (two gramineous species, Deyeuxia angustifolia and Glyceria spiculosa; two sedge species, Carex pseudocuraica and Carex lasiocarpa) grown in an increasing water level gradient (−5, 0, +5, and +15 cm relative to the soil surface) in the Sanjiang Plain of Northeast China. The applicability of the growth-rate hypothesis to leaf, stem, root, and total biomass was subsequently tested. With the increase of flooding stress, RGR and root mass ratio decreased to a certain degree for all species, whereas the above-ground biomass allocation was increased. The variation of N was much greater than that of P; hence the change in N:P ratios was determined mainly by N concentration. RGR was positively correlated with N concentration, N:C, and N:P for stem and total biomass when the data were pooled for all species but was negatively correlated with those for leaf and root organs. Furthermore, the theoretical predictions regarding the relationship between RGR and nutrient ratios were not always the case for each of the marsh herbs. Therefore, our results indicated that the organ-specific and species-specific for vascular plants should be carefully considered when using the theoretical association of growth rate with C:N:P stoichiometry.

Keywords: palustrine wetlands, soil organic carbon storage, spatial distribution, environmental factors

Global warming may have a great impact on soil organic carbon (SOC) turnover in permafrost peatlands. The response of microbial residues, as precursors of SOC, to climate warming remains unknown. A 6-year in situ warming experiment was conducted in the permafrost peatlands of Great Hing'an Mountains. Three commonly used amino sugars (glucosamine, GluN; galactosamine, GalN; muramic acid, MurA), for the quantification of microbial residues, were determined in two depths (0–15 cm, shallow soil; 15–30 cm, deep soil) of the bulk and rhizosphere soil of the shrub and Eriophorum vaginatum L. The amount of GluN, GalN, and MurA in deep shrub rhizosphere soil in the warming treatment decreased by 12.65%, 26.11%, and 14.78%, respectively, as compared to that in the control treatment. Yet, warming did not alter the amount of amino sugars in shallow and deep bulk soil. Warming decreased the concentrations of GluN, MurA, and total amino sugars in the deep rhizosphere soil of Eriophorum vaginatum L. by 22.04%, 26.14%, and 18.71%, respectively. Amino sugars in the deep rhizosphere soil of Eriophorum vaginatum L. had a higher temperature sensitivity than those in the deep bulk soil, while total amino sugars in the shallow rhizosphere soil of Eriophorum vaginatum L. had a lower temperature sensitivity than those in the deep rhizosphere soil.

Permafrost thawing in peatlands has the potential to alter the catchment export of dissolved organic carbon (DOC), thus influencing the carbon balance and cycling in linked aquatic and ocean ecosystems. Peatlands along the southern margins of the Eurasian permafrost are relatively underexplored despite the considerable risks associated with permafrost degradation due to climate warming. This study examined dynamics of DOC export from a permafrost peatland catchment located in northeastern China during the 2012 to 2014 growing seasons. The estimated annual DOC loads varied greatly between 3211 and 19 022 kg yr−1, with a mean DOC yield of 4.7 g m−2 yr−1. Although the estimated DOC yield was in the lower range compared with other permafrost regions, it was still significant for the net carbon balance in the studied catchment. There were strong linkages between daily discharge and DOC concentrations in both wet and dry years, suggesting a transport-limited process of DOC delivery from the catchment. Discharge explained the majority of both seasonal and interannual variations of DOC concentrations, which made annual discharge a good indicator of total DOC load from the catchment. As indicated by three fluorescence indices, DOC source and chemical characteristics tracked the shift of flow paths during runoff processes closely. Interactions between the flow path and DOC chemical characteristics were greatly influenced by the seasonal thawing of the soil active layer. The deepening of the active layer due to climate warming likely increases the proportion of microbial-originated DOC in baseflow discharge.

Under the joint effects resulted from different changes of climate and land-use regimes, spatial-temporal variations of hydrological processes took place in certain principles. Identifying the impact of changes in individual land-use types/climatic factors on hydrological processes is significant for water management and sustainability of watersheds. In this study, seven simulation scenarios were developed using the soil and water assessment tool (SWAT) model to distinguish the impacts of climate and land-use changes on the hydrological processes in the Amur River Basin (ARB) for four periods of 1980&ndash, 1990, 1991&ndash, 1999, 2000&ndash, 2006, and 2007&ndash, 2013, respectively. Based on the multi-period simulation scenario data, partial least squares regression and ridge regression analyses were performed to further evaluate the effects of changes in individual land-use types/climatic factors on hydrologic components. The results suggested that summer precipitation and summer average temperature were the dominant climatic factors, and crops and wetlands were the principal land-use types contributing to the hydrological responses. In addition, the drastic changes in crop and wetland areas and a clear decline in summer precipitation between the periods of 1991&ndash, 1999 and 2000&ndash, 2006 may account for the highest-intensity impacts of climate and land-use changes on the runoff at the outlet (&minus, 31.38% and 16.17%, respectively) during the four periods.

Soil water shortage is a critical issue for the Southwest US (SWUS), the typical arid region that has experienced severe droughts over the past decades, primarily caused by climate change. However, it is still not quantitatively understood how soil water storage in the SWUS is affected by climate change. We integrated the time-series data of water storage and evapotranspiration derived from satellite data, societal water consumption, and meteorological data to quantify soil water storage changes and their climate change impacts across the SWUS from 2003 to 2014. The water storage decline was found across the entire SWUS, with a significant reduction in 98.5% of the study area during the study period. The largest water storage decline occurred in the southeastern portion, while only a slight decline occurred in the western and southwestern portions of the SWUS. Net atmospheric water input could explain 38% of the interannual variation of water storage variation. The climate-change-induced decreases in net atmospheric water input predominately controlled the water storage decline in 60% of the SWUS (primarily in Texas, Eastern New Mexico, Eastern Arizona, and Oklahoma) and made a partial contribution in approximately 17% of the region (Central and Western SWUS). Climate change, primarily as precipitation reduction, made major contributions to the soil water storage decline in the SWUS. This study infers that water resource management must consider the climate change impacts over time and across space in the SWUS.

The net ecosystem CO2 exchange (NEE) is a critical parameter for quantifying terrestrial ecosystems and their contributions to the ongoing climate change. The accumulation of ecological data is calling for more advanced quantitative approaches for assisting NEE prediction. In this study, we applied two widely used machine learning algorithms, Random Forest (RF) and Extreme Gradient Boosting (XGBoost), to build models for simulating NEE in major biomes based on the FLUXNET dataset. Both models accurately predicted NEE in all biomes, while XGBoost had higher computational efficiency (6~62 times faster than RF). Among environmental variables, net solar radiation, soil water content, and soil temperature are the most important variables, while precipitation and wind speed are less important variables in simulating temporal variations of site-level NEE as shown by both models. Both models perform consistently well for extreme climate conditions. Extreme heat and dryness led to much worse model performance in grassland (extreme heat: R2 = 0.66~0.71, normal: R2 = 0.78~0.81; extreme dryness: R2 = 0.14~0.30, normal: R2 = 0.54~0.55), but the impact on forest is less (extreme heat: R2 = 0.50~0.78, normal: R2 = 0.59~0.87; extreme dryness: R2 = 0.86~0.90, normal: R2 = 0.81~0.85). Extreme wet condition did not change model performance in forest ecosystems (with R2 changing −0.03~0.03 compared with normal) but led to substantial reduction in model performance in cropland (with R2 decreasing 0.20~0.27 compared with normal). Extreme cold condition did not lead to much changes in model performance in forest and woody savannas (with R2 decreasing 0.01~0.08 and 0.09 compared with normal, respectively). Our study showed that both models need training samples at daily timesteps of >2.5 years to reach a good model performance and >5.4 years of daily samples to reach an optimal model performance. In summary, both RF and XGBoost are applicable machine learning algorithms for predicting ecosystem NEE, and XGBoost algorithm is more feasible than RF in terms of accuracy and efficiency.

The innate immune system plays a key role in protecting the human body from tumors, which, unfortunately, is largely counteracted by their immune-suppression function. Such an immune suppression has been reported to be induced by the immunosuppressive microenvironment, including the exhausted cytotoxic T lymphocytes (CTLs) and tumor-promoting M2-polarized macrophages. Here, a novel tumor-immunotherapeutic modality based on the nanocatalytic innate immunity activation by tumor-specific mitochondrial DNA (mtDNA) oxidative damage is proposed. In detail, a nanocatalytic medicine, Fe2+ -Ru2+ -loaded mesoporous silica nanoparticle named as MSN-Ru2+ /Fe2+ (MRF), is constructed to induce oxidative damage in the mtDNA of tumor cells. Such an oxidative mtDNA is able to escape from the tumor cells and acts as an immunogenic damage-associated molecular pattern to M1-polarize tumor-associated macrophages (TAMs), resulting in the reactivated immunoresponse of macrophages against cancer cells, and the subsequent inflammatory response of innate immunity. Most importantly, the treatment strategy based on regulating the innate immune response of TAMs not only stops the primary tumor progression, but also almost completely inhibits the growth of distant tumors in the periods of treatments.

Freeze-thaw (FT) events and increasing nitrogen (N) availability may alter N turnover and nitrous oxide (N2O) emissions in permafrost peatlands. However, the responses of N2O emissions to different N levels and additions during FT events are far from clear. We conducted an incubation study to investigate the impacts of different N addition levels (LN: 0.07 mg N g−1, HN: 0.14 mg N g−1) and N addition forms (AC: ammonium chloride, NS: sodium nitrate) on the emissions of N2O under FT and non-freeze-thaw (NFT) conditions in boreal peatlands of Northeast China. Results indicated that the FT condition significantly increased N2O emissions compared with the NFT condition and peaks occurred during thawing. Compared with AC treatments, NS treatments significantly elevated the accumulation of N2O emissions under the FT condition, exhibiting significant differences in different NS levels. N2O emissions were also positively dependent on soil NO3− concentrations to supply nitrate for denitrification. Nitrate-N addition was mainly responsible for the burst of N2O with denitrification as the main process during FT events. Therefore, these results suggest that N2O emissions potentially increase during FT events with increasing nitrate-N deposition in permafrost peatlands, which would contribute to global climate warming.

This study, conducted at the Emuer River in northern China during the growing season of 2014, investigated the concentrations and sources of dissolved CH 4 and CO 2 in wetland rivers in the permafrost region, as well as the total export of dissolved gaseous carbon (C) transported by streamflow. CH 4 and CO 2 concentrations in these rivers, ranging from 0.410–1.045 to 107.838–190.925 μmol L −1 , respectively, were among the highest levels of gaseous C concentrations reported from studies around the world. The concentrations of the C gases varied greatly with streamflow, but the influence of hydrological, as well as meteorological parameters, was not significant, except for the influence of the thaw depth of the soil active layer of adjacent wetlands on CH 4 concentrations. δ 18 O‰ values suggest the observed dissolved gases originated mainly from soil pore water in the active layers of the wetlands, as opposed to organic-rich sediments in river beds, which serves as a common source for riverine CH 4 and CO 2 according to many other studies. A total of 444.30 t C was exported by the 3rd order main Emuer river during the growing season, and an export coefficient of 4.65 mg C m −2 day −1 was calculated for the wetland ecosystem. The dataset in this study is significant with regard to the global carbon balance because it is representative of the extensive wetlands occurring throughout the Eurasian permafrost.

Permafrost play an important role in regulating global climate system. We analyzed the gross primary productivity (GPP), net primary productivity (NPP), and evapotranspiration (ET) derived from MODIS and three earth system models participated in the Coupled Model Inter-comparison Project Phase 6 (CMIP6) in the Asian permafrost region. The water use efficiency (WUE) was further computed. The simulated GPP, NPP, and ET show slightly increasing trends during historical period (1900-2014) and strong increasing trends in projection period (2015-2100), and projected impacts of climate change on all variables are greater under high-emission scenarios than low-emission scenarios. Further analysis revealed higher increases in GPP and NPP than that of ET, indicating that vegetation carbon sequestration governs the growing WUE under historical and projected periods in this region. The GPP, NPP and ET showed higher changing rates in western, central and southeast areas of this region, and WUE (WUEGPP, and WUENPP) shows the similar spatial pattern. Compared to MODIS-derived GPP, NPP, and ET during 2000-2014, Earth system models yield the best estimates for NPP, while slight underestimations for GPP and ET, and thus slight overestimations for WUEGPP and WUENPP. This study highlights the predominant role of vegetation activity in regulating regional WUE in Asian permafrost region under future climate change. Vegetation domination of the growing water use efficiency implies that the permafrost region may continue acting efficiently in sequestrating atmospheric carbon in terms of water consumption throughout the 21st century.

Influences of climatic change and anthropogenic activities on the terrestrial water storage (TWS) change are significant in the mid- and high-latitude areas. Since 2002, the Gravity Recovery and Climate Experiment (GRACE) satellite mission has provided quantitative measurements of TWS changes with unprecedented accuracy at global, regional and basin scales. In this study, the noise level of various GRACE-derived TWS anomalies (TWSA) data were evaluated by using a generalized three-cornered hat (GTCH) method. A time-dependent weights approach was adopted to obtain a combined TWSA series over the Songhua River Basin (SRB) from 2003 to 2013. Monthly TWSA data during the past decades (1982–2002) were reconstructed by using an artificial neural network (ANN) approach with the good performance evaluated by the correlation coefficient of 0.89 and the Nash-Sutcliff efficiency of 0.79 over the study region. In-situ groundwater level measurements were used for validation of the groundwater storage (GWS) changes (estimated by using GRACE-derived TWS changes in association with the other simulated components of water storage changes from land surface models (LSMs)). The primary driving factors of spatiotemporal variations of GWS, as well as their inter-/intra-annually varying characteristics, were explored. The present study revealed that the variations of GWS featured a “downward fluctuations” (1982–1994), “stable upward” (1998–2008) and “decreasing dramatically” (2009–2013) period, respectively, over the SRB. In general, GWS had varied in a steady decline trend at a decreasing rate of 1.04 ± 0.59 mm year−1 from 1982 to 1994. With the enhanced climatic and anthropogenic influences over the region since 2000, several severe fluctuations characterized the GWS variations with occurrences of spring droughts and flooding over the region, which suggested significant effects of global changes posed on GWS variations of the region.

To quantify the fluxes and examine the controls on greenhouse gas emissions from the permafrost marshes where the fate of the large quantity of soil organic carbon remains poorly understood, we measured carbon dioxide (CO2) and methane (CH4) emissions in the northern region of the Great Xing'an Mountains, northeast China, in the thawing seasons of 2011 and 2012. The mean CO2 and CH4 fluxes from the marshes were estimated at 403.47 and 0.14 mg m−2 h−1 on average during the two years. Soil temperature was determined as the primary control on the seasonal greenhouse gas emissions during the growing period. The Q10 values, calculated from the exponential regression between soil temperature and CO2 emissions, suggest that the sensitivity of CO2 flux to climate warming has a high spatially variability in the study area. Absorption of atmospheric CH4 was seasonally detected at the sites with lower water table, which confirms the potential of the natural marshes as CH4 sink when water table goes down due to climate change. When viewed from the ecosystem scale, the mean annual water table level and aboveground primary production were deemed as the dominant influencing factors for the mean annual fluxes, which suggests that there were different controls on the gas emissions at different spatial scales. Therefore, the primary controls of the CO2 and CH4 emissions at different spatial scales need to be surveyed in more detail when focusing on the future alteration of greenhouse gas emissions from permafrost marshes due to climate warming.

Water level is important in determining plant zonation distribution patterns in freshwater wetlands. However, the role of whole-plants’ morphological traits in response to water level gradients in accounting for the distribution of marsh species is far from clear. Four typical dominant vascular plants with different distribution patterns (high-elevation species Deyeuxia angustifolia, mid-elevation species Carex lasiocarpa and Glyceria spiculosa, and low-elevation species Carex pseudocuraica) in freshwater marshes in the Sanjiang Plain of Northeast China were treated with four static water level conditions (−5, 0, +5, and +15 cm relative to the soil surface), and each plant’s growth characteristics, biomass allocation and root traits were investigated. With the rising water level, the growth of D. angustifolia performed worse than other species, whereas the total biomass, plant height and relative growth rate (RGR) of C. pseudocuraica increased steadily. Compared with the other three species, C. pseudocuraica showed a distinct pattern with increasing water levels in the biomass allocation to photosynthetic and non-photosynthetic organs, as well as for coarse and fine roots. Flooding stress significantly reduced root diameter and C/N ratio but simultaneously increased the specific root length (SRL), specific root area (SRA) and root nitrogen concentration (RNC) for both coarse roots (1st order, >0.2 mm) and fine roots (2nd and 3rd orders

Northern peatlands contain a considerable share of the terrestrial carbon pool, which will be affected by future climatic variability. Using the static chamber technique, we investigated ecosystem respiration and soil respiration over two growing seasons (2012 and 2013) in a Carex lasiocarpa -dominated peatland in the Sanjiang Plain in China. We synchronously monitored the environmental factors controlling CO 2 fluxes. Ecosystem respiration during these two growing seasons ranged from 33.3 to 506.7 mg CO 2 –C m −2 h −1 . Through step-wise regression, variations in soil temperature at 10 cm depth alone explained 73.7% of the observed variance in log 10 (ER). The mean Q 10 values ranged from 2.1 to 2.9 depending on the choice of depth where soil temperature was measured. The Q 10 value at the 10 cm depth (2.9) appears to be a good representation for herbaceous peatland in the Sanjiang Plain when applying field-estimation based Q 10 values to current terrestrial ecosystem models due to the most optimized regression coefficient (63.2%). Soil respiration amounted to 57% of ecosystem respiration and played a major role in peatland carbon balance in our study. Emphasis on ecosystem respiration from temperate peatlands in the Sanjiang Plain will improve our basic understanding of carbon exchange between peatland ecosystem and the atmosphere.

Peatlands are the significant source of atmospheric methane (CH4), which is produced during peat accumulation. In this study, we investigated CH4 emissions over two growing seasons from a Carex lasiocarpa-dominated peatland in the Sanjiang Plain in China using the static chamber technique. We also investigated the environmental factors controlling emissions during the two years of study, 2012 and 2013. CH4 emissions ranged from 0.07 to 56.01 mg CH4–C m−2 h−1 with mean values of 7.33 ± 1.65 mg C m−2 h−1, showing significant temporal patterns in both years with peak values in early June and middle August respectively. Variations in water table, soil temperature at 25 cm depth and soil's water-filled pore space together explained 66.7% of the observed temporal variation of CH4 fluxes by the step-wise regression. Rapid and short-lived precipitation events might have no immediate influence on CH4 emissions, which primarily depended on the actual soil aeration and moisture conditions. A simple relationship between single parameter and CH4 fluxes would be overruled once the water table dropped below the critical threshold for CH4 release. The amount of CH4 emitted from the herbaceous peatland in the Sanjiang Plain during the growing season was about 6.93 × 1012 mg C. Our results suggested that the herbaceous peatland in the Sanjiang Plain is an important source of atmospheric CH4.

Nitrogen deposition and global warming each have potential to alter soil carbon storage via changing decomposition, but combined effects of N addition and temperature on CO2 production in wetland soils are less studied. In this study, we conducted laboratory incubations to examine this problem using soil from a freshwater marsh in Sanjiang Plain, China. We found that N addition and temperature had a negative and positive effect on CO2 production, respectively. Despite low decomposition rates, heavy fractions had a notable contribution to CO2 production due to greater mass proportion in soil. Short-term combined effect of N addition and temperature on CO2 production was antagonistic. Based on greater N availability as N addition and temperature increasing, extra release of soil-derived N may further suppress CO2 production. We suggest that short-term soil CO2 production under simultaneous influence of temperature and N addition may be overestimated based on their single effects in this site.