Air–water CO2 flux in an algae bloom year for Lake Hongfeng,Southwest China:implications for the carbon cycle of global inland waters

The carbon cycle of global inland waters is quantitatively comparable to other components in the global carbon budget. Among inland waters, a significant part is man-made lakes formed by damming rivers. Manmade lakes are undergoing a rapid increase in number and size. Human impacts and frequent algae blooms lead to it necessary to make a better constraint on their carbon cycles. Here, we make a primary estimation on the air–water CO_2 transfer flux through an algae bloom year for a subtropical man-made lake—Hongfeng Lake, Southwest China. To do this a new type of glass bottles was designed for content and isotopic analysis of DIC and other environmental parameters. At the early stage of algae bloom,CO_2 was transferred from the atmosphere to the lake with a net flux of 1.770 g·C·m^(-2). Later, the partial pressure(pCO_2) of the aqueous CO_2 increased rapidly and the lake outgassed to the atmosphere with a net flux of 95.727 g·C·m^(-2). In the remaining days, the lake again took up CO_2 from the atmosphere with a net flux of 14.804 g·C·m^(-2). As a whole, Lake Hongfeng released 4527 t C to the atmosphere, accounting for one-third of the atmosphere/soil CO_2 sequestered by chemical weathering in the whole drainage. With an empirical mode decomposition method, we found air temperature plays a major role in controlling water temperature, aqueous pCO_2 and hence CO_2 flux. This work indicates a necessity to make detailed and comprehensive carbon budgets in man-made lakes.

Marine and Inland Water Resources in Eneolithic Communities. New Data from Sardinia （Italy）

This paper presents research aimed at identifying the methods with which prehistoric man interacted with marine and inland water environments. The objective is to determine the degree to which resources from these environments influenced the socio-economic organization of these peoples. The coastline around Cagliari and its hinterland （southern Sardinia, Italy） were chosen as the subject, on the basis of the presence of both the sea and several ponds. The territory is noted as being home to both Neolithic and Eneolithic settlements. Among these the archaeological excavation of the village of Su Coddu/Canelles produced a large quantity of malacofauna. Data has been processed from part of the settlement that gave radiocarbon dating from the period between 3640 and 2900 cal. BC, and in which it was possible to carry out the level of sampling that was necessary to complete the research. In particular this interdisciplinary project, which aims to make an overall study of the settlement, the data relating to the geography of the area, the archaeological documentation, the fauna and shell artefacts will be extrapolated. Numerous methods are applied above all in reference to the marines and ponds resources. Additionally, the morphological anatomical-comparative analysis （in order to determine the typology of the faunal remains and to identify each individual species） and the technological analysis of the manufactured shells （so as to detect the selection and the transformation type of raw materials） are accomplished. The research has led to the identification of a settlement model in which agriculture formed the primary means of subsistence, that was complemented by the rearing of livestock, through hunting and gathering. The exploitation of marine and inland waters resources, as food source, have to be important because 99% of the faunal remains are shells. Different shell species are recognized, among those the Ostrea edulis provides the raw material to produce bevelled objects, which are documented inside the settlement in considerable number. Some plant species, typical of the lagoon ecosystem, were used for building and craft production.

Review of 15 Years of Research on Sediment Heavy Metal Contents and Sediment Nutrient Release in Inland Aquatic Ecosystems,Turkey

Turkey’s inland water ecosystem consists of 33 rivers (177.714 miles), 200 natural lakes (906.118 ha), 159 reservoirs (342.377 ha) and 750 ponds (15.500 ha). Sedimentological studies conducted on inland water ecosystems during the last 15 years in Turkey can be categorized into two main topics. The first group of studies is concerned with heavy metal levels in sediment, with especial reference to the interaction between water, sediment and aquatic organisms. Additionally, the studies in question deal with the potential impacts of heavy metal concentrations on the ecosystem. The second group of studies is concerned with the role of eutrophication in the sediment as a result of serious contamination of inland water ecosystems. It is known that the sediment can directly influence the nutrient level in standing inland waters such as lakes and ponds by way of internal nutrient loading. In this context, studies regarding sediment, overlying water, sediment pore water and nutrient release from the sediment should be emphasized as these are important steps with respect to the eutrophication process. By keeping these studies in mind, the researcher in this study compiled and analyzed studies dealing with inland water ecosystems with differing nutrient levels and uses, including for drinking water, in Turkey’s drainage basins. In addition, field and laboratory studies regarding nutrient release from sediment into Turkey’s inland water ecosystems were evaluated in light of lake management practices.

The coordinated development of China’s inland water transport

The coordinated development is the core of sustainable development and the hot issue of international research.Inland water transport(IWT) is an important part of the water resources exploiting system and comprehensive transport system under socio-economic context of river basin,and also the country's sustainable development priorities to achieve resource-conserving and environment-friendly strategy.Based on the coordinated development content,the paper combined Germany's successful development experience,explored the elements and problem of the coordinated development of IWT system of China's national economic strategy and basin economy,water resourse system,comprehensive transport system,and system itself,and their countermeasures and suggestions,in order to facilitate rapid and coordinated development of China's inland water transport.

Greenhouse Gas Emission from Inland Open Water Bodies and Their Estimation Process—An Emerging Issue in the Era of Climate Change

The persistent rise in concentrations of greenhouse gases (GHGs) in the earth’s atmosphere is responsible for global warming and climate change. Besides the known source of GHGs emissions like energy, industry, and agriculture, intrinsic emissions from natural inland water bodies like wetland, rivers, reservoirs, estuaries, etc. have also been identified as other hotspots of GHGs emission and gaining the attention of the scientific communities in recent times. Inland fisheries in India are threatened by climate changes such as a change in temperature, precipitation, droughts, storm, sea-level rise, saltwater intrusion, floods that affect mostly the production, productivity and ultimately affect the fishers’ livelihood. There are, however, different mitigation and adaptation strategies to cope with the effects of climate change. Carbon sequestration and other related management interventions are one of the options available minimizing GHGs emissions from inland open waters, particularly the wetlands and coastal mangroves which are well known worldwide for their significant role in the storage of carbon. Assessment of C efflux from exposed sediments in dry streams, reservoirs, lakes, rivers, and ponds into the atmosphere can be considered imperative for a better understanding of their role as a C-sink or as a C-source to the atmosphere.

Application of Multivariate Model Based on Three Simulated Sensors for Water Quality Variables Estimation in Shitoukoumen Reservoir,Jilin Province,China

This study applied a multivariate model based on three simulated sensors to estimating water quality variables in Shitoukoumen Reservoir,Changchun City,Jilin Province,China,including concentration of total suspended matter,concentration of chlorophyll-a and non-pigment matter absorption.Two field campaigns for spectra measurements with a total of 40 samples were carried out on June 13 and September 23,2008.The in-situ spectra were recalculated to the spectral bands and sensitivities of the instruments applied in this paper,i.e.Landsat TM,Alos and P6,by using the average method.And the recalculated spectra were used for estimating water quality variables by the single model and multivariate model.The results show that the multivariate model is superior to the single model as the multivariate model takes the combined effects of water components into consideration and can estimate water quality variables simultaneously.According to R2 and RMSE,Alos is superior to other sensors for water quality variables estimation although the precision of non-pigment matter absorption inversion performed the second.

Significant decline of water pollution associated with inland fishery across China

Water pollution seriously threatens the sustainable development of fisheries in China.To inform effective pollution control policies,a comprehensive understanding of the fishery environment status is needed.However,nationwide data on the temporal changes of major pollutants in the fishery waters of China are scarce.This study collected data on the major water pollutants,including total nitrogen,total phosphorus,heavy metals,and total petroleum hydrocarbons(TPHs),from 2003 to 2017 to evaluate dynamic changes in the inland fishery water environment across China.We discovered that the levels of four heavy metals(Cu,Zn,Pb,and Cd)and TPH decreased during the 15-year period,corresponding to the reduced national discharge of pollution sources from 2003 to 2015.However,nitrogen and phosphorus levels in the inland fishery waters showed no significant changes during this period.A comparative analysis of water quality in different periods indicated that these improvements were highly associated with effective measures for water pollution control in China.In addition,the decline in pollution was consistent among the three regions of China(north,west,and southeast)from 2003 to 2017,while southeast China exhibited the weakest pollution mitigation among the three regions.These findings suggest that the inland fishery water quality improved during 2003–2017,but still faced eutrophication risk.

Assessments and diagnoses of aquatic ecosystem integrity based on integrity requirements of ecosystem service targets

This paper critically reviews the progress in ecosystem integrity(health)assessment of inland waters and provides future directions for assessment.Current biotic integrity assessments mainly use multimetric indices and predictive models to evaluate overall health status;the criteria largely rely on pristine reference sites,but such an approach is not applicable to unique natural waters and irreversibly modified waters.Biotic diagnostic assessments are still in the exploratory stage and can only diagnose possible stressor types and wide-ranges of their intensities through empirical models linking stressors and species-trait-indices.Current chemical integrity assessments mainly use criteria determined by small-scale ecotoxicity tests,rather than quantitative relationships developed between chemical factors and biotic effects in real ecosystems,thus potentially under or overestimating pollutant toxicity.Current physical integrity assessments focus on overall habitat quality,rather than quantitative habitat requirements,and thus cannot provide quantitative support for ecological restoration and conservation.Current hydrological integrity(environment flow)assessments largely depend on quantitative relationships between hydrological regimes with a few species and single groups,rather than with whole communities,and fail to comprehensively diagnose hydrological causes of biotic resource decline.In the future,integrity assessments need to be based on ecosystem integrity requirements of ecosystem service targets:first,there is a need to build quantitative relationships between biotic integrity and ecosystem services,assess requirements of community structure and function for service goals,and establish biotic integrity assessment methods;second,we must build quantitative relationships between biotic integrity and abiotic integrity in real ecosystems,assess chemical,physical,and hydrological integrity requirements of biotic needs,and establish diagnostic assessment methods.

A global,high-resolution(30-m)inland water body dataset for 2000:first results of a topographic-spectral classification algorithm

The science and management of terrestrial ecosystems require accurate,high-resolution mapping of surface water.We produced a global,30-m-resolution inland surface water dataset with an automated algorithm using Landsat-based surface reflectance estimates,multispectral water and vegetation indices,terrain metrics,and prior coarse-resolution water masks.The dataset identified 3,650,723 km2 of inland water globally–nearly three quarters of which was located in North America(40.65%)and Asia(32.77%),followed by Europe(9.64%),Africa(8.47%),South America(6.91%),and Oceania(1.57%).Boreal forests contained the largest portion of terrestrial surface water(25.03%of the global total),followed by the nominal‘inland water’biome(16.36%),tundra(15.67%),and temperate broadleaf and mixed forests(13.91%).Agreement with respect to the Moderate-resolution Imaging Spectroradiometer water mask and Landsat-based national land-cover datasets was very high,with commission errors<4%and omission errors<14%relative to each.Most of these were accounted for in the seasonality of water cover,snow and ice,and clouds–effects which were compounded by differences in image acquisition date relative to reference datasets.The Global Land Cover Facility(GLCF)inland surface water dataset is available for open access at the GLCF website(http://www.landcover.org).

Cultivation of Chlorella sp.HQ in inland saline-alkaline water under different light qualities

Inland saline-alkaline water can be used for the low-cost cultivation of microalgae,but whether algal biomass under various light sources has the potential to produce biodiesel remains to be developed.Herein,the influence of different light-emitting diode(LEDs)light colors(blue,red,white,mixed blue-red,and mixed blue-white LED)on the growth performance,lipid accumulation,and fatty acid composition of Chlorella sp.HQ cultivated in inland saline-alkaline water was investigated.The highest algal density was obtained under blue LEDs at the end of cultivation,reaching 1.93±0.03 × 10^(7) cells/mL.White LEDs can improve biomass yield,total lipid yield,and triacylglycerol yield per algal cell.The main fatty acid components of Chlorella from inland saline-alkaline water were palmitic acid and linoleic acid.The Biodiesel Analyzer software was used to predict algal biodiesel quality by estimating different quality parameters.The cetane number,kinematic viscosity,and density of Chlorella biodiesel were 51.714-67.69,3.583-3.845 mm^(2)/s,and 0.834-0.863 g/cm^(3),respectively.This flirther proved that the Chlorella biomass obtained from inland saline-alkaline water has the potential to be used as a high-quality biodiesel feedstock.

The effects of climate warming on microbe-mediated mechanisms of sediment carbon emission

Due to significant differences in biotic and abiotic properties of soils compared to those of sediments,the predicted underlying microbe-mediated mechanisms of soil carbon emissions in response to warming may not be applicable for estimating similar emissions from inlandwater sediments.We addressed this issue by incubating different types of sediments,(including lake,small river,and pond sediments)collected from 36 sites across the Yangtze River basin,under short-term experimentalwarming to explore the effects of climatewarming on sediment carbon emission and the underlying microbe-mediated mechanisms.Our results indicated that under climate warming Cc emissions were affected more than CH_(4) emissions,and that pond sediments may yield a greater relative contribution of CO_(2) to total carbon emissions than lake and river sediments.Warming-induced CO_(2) and CH_(4) increases involve different microbe-mediated mechanisms;Warming-induced sediment CO_(2) emissions were predicted to be directly positively driven by microbial community network modularity,which was significantly negatively affected by the quality and quantity of organic carbon and warming-induced variations in dissolved oxygen,Conversely,warminginduced sediment CH_(4) emissionswere predicted to be directly positively driven bymicrobial community network complexity,which was significantly negatively affected by warminginduced variations in pH.Our findings suggest that biotic and abiotic drivers for sediment CO_(2) and CH_(4) emissions in response to climate warming should be considered separately when predicting sediment organic carbon decomposition dynamics resulting from climate change.

Anthropogenic land use substantially increases riverine CO_(2) emissions

Carbon dioxide(CO_(2)) emissions from inland waters to the atmosphere are a pivotal component of the global carbon budget. Anthropogenic land use can influence riverine CO_(2) emissions, but empirical data exploring cause-effect relationships remain limited. Here, we investigated CO_(2) partial pressures(pCO_(2)) and degassing in a monsoonal river(Yue River)within the Han River draining to the Yangtze in China. Almost 90% of river samples were supersaturated in CO_(2) with a mean ± standard deviation of 1474 ± 1614 μatm, leading to emissions of 557-971 mmol/m^(2)/day from river water to the atmosphere. Annual CO_(2) emissions were 1.6-2.8 times greater than the longitudinal exports of riverine dissolved inorganic and organic carbon. pCO_(2) was positively correlated to anthropogenic land use(urban and farmland), and negatively correlated to forest cover. p CO_(2) also had significant and positive relationships with total dissolved nitrogen and total dissolved phosphorus. Stepwise multiple regression models were developed to predict p CO_(2) . Farmland and urban land released nutrients and organic matter to the river system, driving riverine p CO_(2) enrichment due to enhanced respiration in these heterotrophic rivers. Overall, we show the crucial role of land use driving riverine pCO_(2) , which should be considered in future large-scale estimates of CO_(2) emissions from streams. Land use change can thus modify the carbon balance of urban-river systems by enhancing river emissions, and reforestation helps carbon neutral in rivers.

Atmospheric correction of CBERS CCD images with MODIS data

China Brazil Earth Resource Satellite(CBERS)CCD images have much potential for inland water environmental monitoring.However,their atmospheric accuracy correction can affect their quantitative applications.This paper contains an atmospheric correction algorithm for CBERS CCD images with MODIS data from the same day,the use of which improves the atmospheric correction algorithm of ocean color remote sensing developed by Gordon(1993,1994)and makes it applicable to inland waters.The improved algorithm retrieves atmospheric parameters from MODIS data and uses them to perform the atmospheric correction of CBERS CCD images.Experimental results show that the atmospheric correction algorithm of CBERS CCD images assisted by MODIS data is reliable.Furthermore,MODIS data can be freely obtained on a daily basis,making the algorithm developed in this paper useful for environmental monitoring of inland waters.

Remote determination of chromophoric dissolved organic matter in lakes, China

Chromophoric dissolved organic matter(CDOM)strongly influences the water-leaving radiance from aquatic ecosystems.In most inland waters,the remote determination of CDOM absorption presents a central challenge due to their complex optical conditions.However,identifying the temporal and spatial variability of CDOM is fundamental to the understanding of aquatic biogeo-chemical dynamics.In the present study,semi-analytical and empirical modeling approaches were used to examine CDOM absorption in four,shallow,inland water bodies using the spectral bands and sensitivities of major satellite observational systems.Of the models examined,an empirical multiband model was found to provide the highest correlation with measured CDOM absorption.The spectral characteristics of the MERIS sensors yielded the best results with respect to the other available satellite sensors.High detrital load was observed to be a major impediment to estimating CDOM absorption,while lakes with elevated phytoplankton biomass did not present similar problems.

MODIS observations of water color of the largest 10 lakes in China between 2000 and 2012

Forel-Ule(FU)index of water color is an important parameter in traditional water quality investigations.We retrieved the FU index of the largest 10 lakes in China during 2000-2012 from MODerate-resolution Imaging Spectroradiometer surface reflectance product(MOD09)images.Since FU index is an optical parameter,it can be derived from optical remote sensing data by direct formulas,which is invariant with region and season.Based on validation by in situ measured reflectance data,the FU index products are reliable,with average relative error of 7.7%.FU index can be used to roughly assess water clarity:the clearer a water body is,and the bluer it is in color,the smaller its FU index is.FU index can also be used to roughly classify trophic state into three classes:oligotrophic,mesotrophic,and eutrophic.We analyzed the spatial,interannual,and seasonal variations of the FU index and its implications for water clarity and trophic state,and the findings are mostly consistent with the results from related literature.All in all,it might be a feasible way to roughly assess inland water quality by FU index in large region and over long time period.

Chlorophyll-a concentrations in 82 large alpine lakes on the Tibetan Plateau during 2003–2017: temporal–spatial variations and influencing factors

As essential parts of the unique ecosystem of Tibetan Plateau(TP),the sizes and associated physical properties of alpine lakes have long been investigated.However,little is known about one of the most critical biogeochemical properties,i.e.the Chlorophyll-a(Chl-a)concentrations.Here,for the first time,we presented a comprehensive investigation of the temporal–spatial variations in Chl-a in 82 lakes(>50 km^(2))across the entire TP region,based on MODIS observations in the period of 2003–2017.The results showed that the 82 lakes exhibited an average longterm mean Chl-a of 3.3±4.3 mg m^(−3),with high Chl-a lakes concentrated in the eastern and southern inner TP basin and northeastern parts of the TP.An interannual trend analysis revealed that lakes exhibiting(significantly)decreasing Chl-a trends and(significantly)increasing Chl-a trends were comparable in numbers but differed in distribution patterns.A correlation analysis indicated that at least 70%of the interannual variability in Chl-a values of lakes was significantly correlated with one of the four environmental factors(wind speed,ice cover duration,lake water surface temperature and surface runoff)and lake size.In addition,glacier meltwater tended to reduce lake Chl-a while salinity levels showed minor influences.

Development and application of a new random walk model to simulate the transport of degradable pollutants

To simulate the pollutant transport with seif-purification in inland waters,the widely used random walk model(RWM)is modified to include a source term for the degradation and to consider the impact of land boundaries.The source term for the degradation is derived from the assumption of the first-order reaction kinetics.Parameters for the new model are determined by a comparison to the analytical results.The proposed model is then applied to simulate and analyze the transport of a test pollutant and its spatial distribution in a large reservoir in northeast China.Reasonable results are obtained,and the effects of the runoff,the flow structure,and the wind on the pollutant transport are analyzed.The results may help the risk assessment and the management of the water pollution in inland waters.