Interactions of Microplastics and Methane Seepage in the Deep-Sea Environment

Microplastics(MPs)are important exempla of the Anthropocene and are exerting an increasing impact on Earth’s carbon cycle.The huge imbalance between the MPs floating on the marine surface and those that are estimated to have been introduced into the ocean necessitates a detailed assessment of marine MP sinks.Here,we demonstrate that cold seep sediments,which are characterized by methane fluid seepage and a chemosynthetic ecosystem,effectively capture and accommodate small-scale(<100μm)MPs,with 16 types of MPs being detected.The abundance of MPs in the surface of the sediment is higher in methane-seepage locations than in non-seepage areas.Methane seepage is beneficial to the accumulation,fragmentation,increased diversity,and aging of MPs.In turn,the rough surfaces of MPs contribute to the sequestration of the electron acceptor ferric oxide,which is associated with the anaerobic oxidation of methane(AOM).The efficiency of the AOM determines whether the seeping methane(which has a greenhouse effect 83 times greater than that of CO_(2)over a 20-year period)can enter the atmosphere,which is important to the global methane cycle,since the deep-sea environment is regarded as the largest methane reservoir associated with natural gas hydrates.

Solar radiation effects on leaf nitrogen and phosphorus stoichiometry of Chinese fir across subtropical China

Background:Solar radiation(SR)plays critical roles in plant physiological processes and ecosystems functions.However,the exploration of SR influences on the biogeochemical cycles of forest ecosystems is still in a slow progress,and has important implications for the understanding of plant adaption strategy under future environmental changes.Herein,this research was aimed to explore the influences of SR on plant nutrient characteristics,and provided theoretical basis for introducing SR into the establishment of biochemical models of forest ecosystems in the future researches.Methods:We measured leaf nitrogen(N)and phosphorus(P)stoichiometry in 19 Chinese fir plantations across subtropical China by a field investigation.The direct and indirect effects of SR,including global radiation(Global R),direct radiation(Direct R)and diffuse radiation(Diffuse R)on the leaf N and P stoichiometry were investigated.Results:The linear regression analysis showed that leaf N concentration had no association with SR,while leaf P concentration and N:P ratio were negatively and positively related to SR,respectively.Partial least squares path model(PLS-PM)demonstrated that SR(e.g.Direct R and Diffuse R),as a latent variable,exhibited direct correlations with leaf N and P stoichiometry as well as the indirect correlation mediated by soil P content.The direct associations(path coefficient=−0.518)were markedly greater than indirect associations(path coefficient=−0.087).The covariance-based structural equation modeling(CB-SEM)indicated that SR had direct effects on leaf P concentration(path coefficient=−0.481),and weak effects on leaf N concentration.The high SR level elevated two temperature indexes(mean annual temperature,MAT;≥10°C annual accumulated temperature,≥10℃ AAT)and one hydrological index(mean annual evapotranspiration,MAE),but lowered the soil P content.MAT,MAE and soil P content could affect the leaf P concentration,which cause the indirect effect of SR on leaf P concentration(path coefficient=0.004).Soil N content had positive effect on the leaf N concentration,which was positively and negatively regulated by MAP and≥10℃ AAT,respectively.Conclusions:These results confirmed that SR had negatively direct and indirect impacts on plant nutrient status of Chinese fir based on a regional investigation,and the direct associations were greater than the indirect associations.Such findings shed light on the guideline of taking SR into account for the establishment of global biogeochemical models of forest ecosystems in the future studies.

A global synthesis of the effectiveness and ecological impacts of management interventions for Spartina species

Invasions by Spartina species pose serious threats to global coastal ecosystems.Although many studies have examined the effectiveness and ecological impacts of invasive Spartina management,no comprehensive global synthesis has been conducted to assess the effects of management on Spartina per se and on wider non-targets.Here,we conducted a global meta-analysis of 3,459 observations from 102 studies to quantify the effects of different management interventions(physical,chemical,biological,and integrated control)on Spartina per se and native biodiversity and environments.We found that physical measures quickly suppressed Spartina but that their effectiveness declined over time.By contrast,chemical measures decreased the abundance and growth of Spartina to a lesser degree in the early stage,but the effectiveness increased over time.Different management measures did not significantly decrease the diversity of native biota on the whole,but native-plant diversity significantly decreased with time after physical control.Different management measures did not affect abiotic factors differently.These results support the use of chemical measures to control invasive Spartina,although their effectiveness would depend on the time since the management intervention.Addressing the problem of Spartina regrowth following physical control requires improved techniques.We hold that initial states of invaders and subsequent environmental changes after management interventions should be weighed in evaluating control efficacy.

Hydrological Response to Climate and Land Use Changes in the Dry–Warm Valley of the Upper Yangtze River

The hydrological process in the dry–warm valley of the mountainous area of southwest China has unique characteristics and has attracted scientific attention worldwide.Given that this is an area with fragile ecosystems and intensive water resource conflicts in the upper reaches of the Yangtze River,a systematic identification of its hydrological responses to climate and land use variations needs to be performed.In this study,MIKE SHE was employed and calibrated for the Anning River Basin in the dry–warm valley.Subsequently,a deep learning neural network model of the long short-term memory(LSTM)and a traditional multi-model ensemble mean(MMEM)method were used for an ensemble of 31 global climate models(GCMs)for climate projection.The cellular automata–Markov model was implemented to project the spatial pattern of land use considering climatic,social,and economic conditions.Four sets of climate projections and three sets of land use projections were generated and fed into the MIKE SHE to project hydrologic responses from 2021 to 2050.For the calibration and first validation periods of the daily simulation,the coefficients of determination(R)were 0.85 and 0.87 and the Nash–Sutcliffe efficiency values were 0.72 and 0.73,respectively.The advanced LSTM performed better than the traditional MMEM method for daily temperature and monthly precipitation.The average monthly temperature projection under representative concentration pathway 8.5(RCP8.5)was expected to be slightly higher than that under RCP4.5;this is contrary to the average monthly precipitation from June to October.The variations in streamflow and actual evapotranspiration(ET)were both more sensitive to climate change than to land use change.There was no significant relationship between the variations in streamflow and the ET in the study area.This work could provide general variation conditions and a range of hydrologic responses to complex and changing environments,thereby assisting with stochastic uncertainty and optimizing water resource management in critical regions.

Toxic effects of long-term dual or single exposure to oxytetracycline and arsenic on Xenopus tropicalis living in duck wastewater

Direct discharge of aquaculture wastewater may have toxic effects,due to the presence of heavy metals,antibiotics,and even resistant pathogens,but little attention has been given.Here,tanks simulating a wild ecosystem were built to study the effects of long-term exposure to duckwastewater containing oxytetracycline(OTC)and/or arsenic(As)on the growth,physiological function,and gut microbiota evolution of Xenopus tropicalis.The results showed that duck wastewater had no apparent impact on X.tropicalis,but the impact increased significantly(P<0.05)with exposure to OTC and/or As,especially the impact on body weight and growth rate.Biochemical indicators revealed varying degrees of oxidative stress damage,hepatotoxicity(inflammation,necrosis,and sinusoids),and collagen fibrosis of X.tropicalis in all treated groups after 72 days of exposure,which indirectly inhibited X.tropicalis growth.Moreover,16S rDNA amplicon sequencing results showed that the gut microbiota structure and metabolic function were perturbed after chronic exposure,which might be the leading cause of growth inhibition.Interestingly,the abundance of intestinal resistance genes(RGs)increased with exposure time owing to the combined direct and indirect effects of stress factors in duck wastewater.Moreover,once the RGs were expressed,the resistance persisted for at least 24 days,especially that conferred by tetA.These results provide evidence of the toxic effects of DW containing OTC(0.1–4.0 mg/L)and/or As(0.3–3.5μg/L)on amphibians and indicate that it is vital to limit the usage of heavy metals and antibiotics on farms to control the biotoxicity of wastewater.

Numerical investigation of ocean waves generated by three typhoons in offshore China

The influences of the three types of reanalysis wind fields on the simulation of three typhoon waves occurred in2015 in offshore China were numerically investigated.The typhoon wave model was based on the simulating waves nearshore model(SWAN),in which the wind fields for driving waves were derived from the European Centre for Medium-Range Weather Forecasts(ECMWF)Re-Analysis-Interim(ERA-interim),the National Centers for Environmental Prediction climate forecast system version 2(CFSv2)and cross-calibrated multi-platform(CCMP)datasets.Firstly,the typhoon waves generated during the occurrence of typhoons Chan-hom(1509),Linfa(1510)and Nangka(1511)in 2015 were simulated by using the wave model driven by ERA-interim,CFSv2 and CCMP datasets.The numerical results were validated using buoy data and satellite observation data,and the simulation results under the three types of wind fields were in good agreement with the observed data.The numerical results showed that the CCMP wind data was the best in simulating waves overall,and the wind speeds pertaining to ERA-Interim and CCMP were notably smaller than those observed near the typhoon centre.To correct the accuracy of the wind fields,the Holland theoretical wind model was used to revise and optimize the wind speed pertaining to the CCMP near the typhoon centre.The results indicated that the CCMP wind-driven SWAN model could appropriately simulate the typhoon waves generated by three typhoons in offshore China,and the use of the CCMP/Holland blended wind field could effectively improve the accuracy of typhoon wave simulations.

Impact of biochar amendment on soil aggregation varied with incubation duration and biochar pyrolysis temperature

Soil aggregation is one of the crucial processes that facilitate carbon sequestration and maintain soil fertility.So far,the effect of biochar amendment on soil aggregation remains inconclusive.Here,we tested the hypothesis that the response of soil aggregation to biochar addition varied with incubation duration and biochar chemistry.A one year microcosm experiment of soil with biochar was conducted that included biochar produced at three different temperatures(300,450,and 600°C),and three biochar application rates,i.e.,0,1,and 3 wt%.It was observed that after one and three months,biochar mainly(>90%)distributed in the micro-aggregates,and slightly reduced aggregate stability and increased proportion of micro-aggregates,which was demonstrated to result from the mechanical mixture of amended biochar with soil.Contrastingly,when the duration was prolonged to six months and one year,a significant increase in macro-aggregates(6.6-38.5%)and aggregate stability(7.3-29.4%)was detected,with the increasing extent being apparently higher for low-temperature biochar.This was related to the comparatively strong interaction of biochar particles with soil minerals or microbes after long-time incubation.The strong interaction was directly supported by the significant increase in H/C,O/C ratios of isolated biochar from treated soils,the detection of typical soil mineral elements on the surface of isolated biochar,and the increase in microbial biomass carbon of treated soils.The findings of this study highlighted the role of biochar type and amendment duration in mediating the effect of biochar application on soil aggregation.

The frontier evolution and emerging trends of hydrological connectivity in river systems:a scientometric review

With the intensification of climate change and human activities,the watershed ecosystem is seriously fragmented,which leads to the obstruction of hydrological connectivity,and further causes the degradation of the ecosystem.As the value of wetlands continues to be exploited,hydrological connectivity becomes increasingly significant.In this paper,the characteristics and development of hydrological connectivity research from 1998 to 2018 were analyzed through the scientometric analysis based on Web of Science database.CiteSpace,an analytical software for scientific measurement,is used to visualize the results of the retrieval.The analysis results of co-occurrence,co-operative and co-cited network indicate that the hydrological connectivity is a multidisciplinary field which involves the Environment Science and Ecology,Water Resources,Environmental Sciences,Geology and Geosciences.According to Keyword cooccurrence analysis,ecosystem,floodplain,dynamics,climate change and management are the main research hotspots in each period.In addition,the co-cited analysis of references shows that“amphibians”is the largest cluster of hydrological connectivity,and the“channel network”is the most important research topic.It is worth noting that the“GIWS”(Geographically Isolated Wetlands)is the latest research topic and may be a major research direction in the future.

Placental transfer of bisphenol diglycidyl ethers (BDGEs) and its association with maternal health in a population in South of China

Despite high production and usage,little is known about exposure to bisphenol diglycidyl ethers(BDGEs)and their derivatives in pregnant women and fetuses.In this study,we determined nine BDGEs in 106 paired maternal and cord serum samples collected from e-waste dismantling sites in South of China.Bisphenol A bis(2,3-dihydroxypropyl)glycidyl ether(BADGE⋅2H_(2)O),bisphenol A(3-chloro-2-hydroxypropyl)(2,3-dihydroxypropyl)glycidyl ether(BADGE⋅HCl⋅H_(2)O),and bisphenol F diglycidyl ether(BFDGE)were the major BDGEs,with median concentrations of 0.57,4.07,and 1.60 ng/mL,respectively,in maternal serum,and of 3.58,5.61,and 0.61 ng/mL,respectively,in cord serum.The transplacental transfer efficiencies(TTEs)were estimated for BDGEs found in samples,and median values were in the range of 0.98(BFDGE)to 5.91(BADGE⋅2H_(2)O).Our results suggested that passive diffusion plays a role in the placental transfer of BADGE⋅HCl⋅H_(2)O and BFDGE,whereas several mechanisms contribute to the high accumulation of BADGE⋅2H_(2)O in cord serum.Multiple linear regression analysis indicated significant associations between maternal serum concentrations of BDGEs and blood clinical biomarkers,especially those related to liver injuries,such as alanine aminotransferase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),and adenosine deaminase(ADA)(P<0.05).To our knowledge,this is the first study to report the occurrence of BDGEs in paired maternal–fetal serum samples and provide new insights into prenatal and fetal exposures.The newly discovered TTEs in maternal–fetal pairs contribute to a fuller inventory of the transmission activity of pollutants in the human body,ultimately adding to a more significant comprehensive risk evaluation.

Cellular Cd^(2+)fluxes in roots confirm increased Cd availability to rice(Oryza sativa L.)induced by soil acidifications

Soil acidifications become one of the main causes restricting the sustainable development of agriculture and causing issues of agricultural product safety.In order to explore the effect of different acidification on soil cadmium(Cd)availability,soil pot culture and hydroponic(soil potting solution extraction)were applied,and non-invasive micro-test technique(NMT)was combined.Here three different soil acidification processes were simulated,including direct acidification by adding sulfuric acid(AP1),acid rain acidification(AP2)by adding artificial simulated acid rain and excessive fertilization acidification by adding(NH_(4))_(2)SO_(4)(AP3).The results showed that for direct acidification(AP1),DTPA-Cd concentration in field soils in Liaoning(S1)and Zhejiang(S2)increased by 0.167-0.217 mg/kg and 0.181-0.346 mg/kg,respectively,compared with control group.When soil pH decreased by 0.45 units in S1,the Cd content of rice stems,leaves and roots increased by 0.48 to 6.04 mg/kg and 2.58 to 12.84mg/kg,respectively,When the pH value of soil S1 and S2 decreased by 0.20 units,the average velocity of Cd^(2+)at 200μm increased by 10.03-33.11 pmol/cm~2/sec and 21.33-52.86pmol/cm^(2)/sec,respectively,and followed the order of AP3>AP2>AP1.In summary,different acidification measures would improve the effectiveness of Cd,under the same pH reduction condition,fertilization acidification increased Cd availability most significantly.

对冲效应弱化了土地利用变化对干流水文情势的影响——以中国金沙江流域为例

Global extreme hydrological events pose considerable challenges to the sustainable development of human society and river ecology.Land use/cover change(LUCC)is a visible manifestation of human activity and has caused substantial alterations in extreme hydrological regimes across rivers worldwide.The Jinsha River lies upstream of the Yangtze River and its hydrological variability has had profound socioeconomic and environmental effects.In this study,we developed Hydrological Simulation Program–FORTRAN(HSPF)and land-use simulation models of the entire watershed to simulate the effects of LUCC on hydrological extremes and quantify the inter-relationships among them.The main land-use changes between 1995 and 2015 were those associated with cropland,forest land,and grassland.Between 2015 and 2030,it is estimated that the coverage of forest land,grassland,construction land,and unused land will increase by 0.64%,0.18%,69.38%,and 45.08%,respectively,whereas that of cropland,water bodies,and snow-and ice-covered areas will decline by 8.02%,2.63%,and 0.89%,respectively.LUCC has had irregular effects on different hydrological regimes and has most severely altered stream flows.The responses of hydrological extremes to historical land-use change were characterized by spatial variation.Extreme low flows increased by 0.54%–0.59%whereas extreme high flows increased by 0%–0.08%at the lowest outlet.Responses to future land-use change will be amplified by a 0.72%–0.90%reduction in extreme low flows and a 0.08%–0.12%increase in extreme high flows.The hedging effect caused by irregular changes in tributary stream flow was found to alleviate the observed flow in mainstream rivers caused by land-use change.The extreme hydrological regimes were affected mainly by the net swap area transferred from ice and snow area to forest(NSAIF)and thereafter to cultivated land(NSAIC).Extreme low flows were found to be positively correlated with NSAIF and NSAIC,whereas extreme high flows were positively correlated with NSAIC and negatively correlated with NSAIF.