Atmospheric Inputs Research Articles

Using atmospheric inputs for Artificial Neural Networks to improve wind turbine power prediction

A robust machine learning methodology is used to generate a site-specific power-curve of a full-scale isolated wind turbine operating in an atmospheric boundary layer to drastically improve the power predictions, and, thus, the forecasting of the monthly energy production estimates. The study has important implication in measuring the financial feasibility of wind farms by improving the accuracy of monthly energy estimates. The significance of the study is that atmospheric stability and air-density are accounted in the power predictions of the wind turbine. Artificial Neural Networks (ANN) machine learning approach is used to generate multi-parameter input models to estimate the power produced by the wind turbine. The ANN model in this study uses Feed Forward Back Propagation (FFBP) algorithm. The power- and wind-data is obtained from a 2.5 MW wind turbine that has a Meteorological tower located 900 m Southwest of the wind turbine in Kirkwood, Iowa, USA. The study investigates the role of atmospheric boundary-layer metrics – Wind Speed, Density (a measure of stratification), Richardson Number, turbulence intensity, and wind shear as input parameters into the ANN model. The study investigates the influence of FFBP ANN hyper-parameters on the power prediction accuracy. Comparison of the FFBP ANN model to other power curve correction techniques demonstrated an improvement in the Mean Absolute Error (MAE) of 40% when compared to the density correction (the next closest). The five-parameter 4-layer FFBP ANN has an average energy production error of 0.4% for the nine months while the IEC this error is −3.7% and for the air density correction the error is −1.9%, respectively. Finally, the study determines the performance of the FFBP ANN model for different atmospheric stability regimes (Unstable, Stable, Strongly Stable, Strongly Unstable and Neutral) classified using two criterions - Richardson number and Turbulence intensity. The largest MAE occurs during the strongly stable regime of the atmospheric boundary layer for both criteria.

Clear-sky models evaluation of two sites over Algeria for PV forecasting purpose

Clear-sky models are needed in various fields of solar energy, such as solar sensors calibration, quality control of solar data, CSP and PV energy forecasting, etc. The aim of this work is the assessment of the clear-sky models for global solar irradiance estimation. For this end, data of two sites in Algeria have been used. Models accuracy is achieved by comparison between their estimations and measurements (5-minute time steps for the Bouzareah site and 10-minute steps for the Ghardaia site). Atmospheric input data to the models enclose aerosol and water vapor measurements as well as Linke turbidity, which are determined experimentally from available solar and meteorological measurements. Results show that Inchein-Perez and ESRA models are the best clear-sky approaches which ensure excellent accuracies ($ nRMSE = 3.84\%$ and 6.26%) when compared to ground measurements.

Dissolved major and trace geochemical dynamics in Antarctic lacustrine systems

Clearwater Mesa (James Ross Island, northeast Antarctic Peninsula) provides a unique opportunity to study solute dynamics and geochemical weathering in the pristine lacustrine systems of a high latitude environment. In order to determine major controls on the solute composition of these habitats, a geochemical survey was conducted on 35 lakes. Differences between lakes were observed based on measured physico-chemical parameters, revealing neutral to alkaline waters with total dissolved solids (TDS) < 2500 mg L−1. Katerina and Trinidad-Tatana systems showed an increase in their respective TDS, total organic carbon values, and finner sediments from external to internal lakes, indicating an accumulation of solutes due to weathering. Norma and Florencia systems exhibited the most diluted and circumneutral waters, likely from the influence of glacier and snow melt. Finally, isolated lakes presented large variability in TDS values, indicating weathering and meltwater contributions at different proportions. Trace metal abundances revealed a volcanic mineral weathering source, except for Pb and Zn, which could potentially indicate atmospheric inputs. Geochemical modelling was also conducted on a subset of connected lakes to gain greater insight into processes determining solute composition, resulting in the weathering of salts, carbonates and silicates with the corresponding generation of clays. We found CO2 consumption accounted for 20–30% of the total species involved in weathering reactions. These observations allow insights into naturally occurring geochemical processes in a pristine environment, while also providing baseline data for future research assessing the impacts of anthropogenic pollution and the effects of climate change.

The bioavailability and contribution of the newly deposited heavy metals (copper and lead) from atmosphere to rice (Oryza sativa L.)

Despite the global importance of atmospheric heavy metal input into agricultural soils, research has primarily focused on the amount of the depositions with limited attention given to the risk of the newly deposited heavy metals. To understand the remobilization of the newly deposited copper (Cu) and lead (Pb) from the atmosphere and explore the metals’ mobility and bioavailability to rice (Oryza sativa L.), a soil transplant experiment was conducted in three areas along a gradient of atmospheric depositions. Approximately 61% of the Cu and 76% of the Pb depositions tended to be present in potentially mobile fractions. The soil retention of newly deposited Cu and Pb presented as higher mobile fractions than these in the original soil. The newly deposited Cu and Pb in soils only accounted for 0.34–8.7% and 0.07-0.29% of the total soil Cu and Pb pools, but they contributed 30–84% and 6–41% in rice tissues, respectively. A major implication of these findings is that once the heavy metal is deposited, it may be reactivated in soils and transported to aerial parts or foliar uptake into plant tissues, emphasizing the important role of the newly deposited Cu and Pb in contributing to the edible parts of crops.

Climate Change Made Major Contributions to Soil Water Storage Decline in the Southwestern US during 2003–2014

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.

Analysis of hydrochemical characteristics and their controlling factors in the Fen River of China

Water shortage and pollution are threatening the sustainability of cities and society, and it is thus fundamental to analyze the water chemistry and quality in regions subject to water shortages. This study collected surface and groundwater samples from the Fen River of China in the wet seasons of 2015 and 2017, and analyzed the water chemistry, quality and their controlling factors using ternary diagrams, Gibbs diagrams, a fuzzy membership function, correlation analysis, and a forward model. The overall water type was Na+HCO3 and Ca+HCO3 in 2015 and 2017, respectively. HCO3− accounted for 48%–56% of the total anions, while Ca2+ and Na+ accounted for 43%–57% and 18%–27% of the total cations, respectively. Concentrations of HCO3- and Ca2+ decreased along the direction of flow, while the concentrations of other ions increased. Of the surface water and groundwater samples, 63% and 95% complied with environmental quality standards, respectively, in 2015, but only 88% and 44% were compliant in 2017. The dissolved solutes mainly came from rock weathering, to which evaporite dissolution contributed 38%–43%, silicate weathering 7%–34%, and carbonate weathering 17%–44%. Atmospheric and anthropogenic inputs were shown to exert minor effects on the hydrochemistry. Ion exchange and mineral deposits also affected the spatiotemporal hydrochemistry.

Variation in δ15N of fog-dependent Tillandsia ecosystems reflect water availability across climate gradients in the hyperarid Atacama Desert

Abstract The Atacama Desert is considered one of the driest places on Earth, where the availability of water plays a crucial role in determining the presence of plants. The sparse vegetation is limited to the coastal mountains, where abundant fog provides the main source of water and nutrients for unique Tillandsia landbeckii ecosystems. The apparent retreat of this fog-dependent vegetation over the past decades, however, may relate to changing climatic conditions, in particular increasing aridity. In this study, we used the nitrogen isotopic composition (δ15N) of plant organic matter as a measure of water availability and atmospheric nitrogen input in present and past Tillandsia dune fields. We compiled an extensive data set on δ15N values of living plants and corresponding site factors (latitude, elevation, cloud cover and precipitation) along a coastal transect. We present radiocarbon-based ages of relict T. landbeckii layers preserved in sand dunes that evolved episodically over the past 2500 years. Site-averaged δ15N values range from +2‰ to −16‰, with variations of up to 4‰ observed within one site that can be related to changes in elevation. The spread in δ15N values is surprising and considerably larger than previously reported for T. landbeckii. In contrast, δ15N values of Huidobria fruticosa and Ophryosporus spp. leaves collected mostly below and above the fog zone vary between +4‰ and + 17‰, largely in agreement with global observations from water-limited systems. Comparison with satellite-based meteorological data and modelling results revealed significant correlations between δ15N values of T. landbeckii and total cloud cover (r = −0.90; p

Phosphorus and Nitrogen Transport in the Binational Great Lakes Basin Estimated Using SPARROW Watershed Models

AbstractEutrophication problems in the Great Lakes are caused by excessive nutrient inputs (primarily phosphorus, P, and nitrogen, N) from various sources throughout its basin. In developing protection and restoration plans, it is important to know where and from what sources the nutrients originate. As part of a binational effort, Midcontinent SPARROW (SPAtially Referenced Regression On Watershed attributes) models were developed and used to estimate P and N loading from throughout the entire basin based on nutrient inputs similar to 2002; previous SPARROW models only estimated U.S. contributions. The new models have a higher resolution (~2‐km2 catchments) enabling improved descriptions of where nutrients originate and the sources at various spatial scales. The models were developed using harmonized geospatial datasets describing the stream network, nutrient sources, and environmental characteristics affecting P and N delivery. The models were calibrated using loads from sites estimated with ratio estimator and regression techniques and additional statistical approaches to reduce spatial correlation in the residuals and have all monitoring sites equally influence model development. SPARROW results, along with interlake transfers and direct atmospheric inputs, were used to quantify the entire P and N input to each lake and describe the importance of each nutrient source. Model results can be used to compare loading and yields from various tributaries and jurisdictions.

Rapid nitrogen fixation by canopy microbiome in tropical forest determined by both phosphorus and molybdenum.

Biological nitrogen fixation is critical for the nitrogen cycle of tropical forests, yet we know little about the factors that control the microbial nitrogen fixers that colonize the microbiome of leaves and branches that make up a forest canopy. Forest canopies are especially prone to nutrient limitation because they are (1) disconnected from soil nutrient pools and (2) often subject to leaching. Earlier studies have suggested a role of phosphorus and molybdenum in controlling biological N-fixation rates, but experimental confirmation has hitherto been unavailable. Here we present the results of a manipulation of canopy nutrient availability. Our findings demonstrate a primary role of phosphorus in constraining overall N fixation by canopy cyanobacteria, but also a secondary role of molybdenum in determining per-cell fixation rates. A conservative evaluation suggests that canopy fixation can contribute to significant N fluxes at the ecosystem level, especially as bursts following atmospheric inputs of nutrient-rich dust.

PCB mass budget in a perialpine lake undergoing natural decontamination in a context of global change

Despite the fact that PCB contamination of the global environment has been extensively studied in the last decades, the fate of these compounds in freshwater ecosystems is not fully understood and an important knowledge gap remains regarding the understanding of PCB dynamics and fate in perialpine lakes. This study relied on both field sampling performed and modeling to accurately identify the main fluxes involved in the PCB dynamics into the French perialpine Lake Bourget from 2013 to 2017. Our results show that the main inputs responsible for the PCB loading of the water column are tributaries inflows (~90%) rather than atmospheric inputs which could be related to the high catchment area over lake surface area ratio (i.e., 13). The main mechanism responsible for the lake natural decontamination was sediment burial (76%) due to the effect of the biological pump coupled with a high sedimentation rate. Volatilization represented 19% of the loss of PCBs from the water column and was mainly controlled by the high PCB concentration in water. These mechanisms are susceptible to be affected by the impact of the global change (increase of temperature, modification of the primary production rate) in the near future.

Toward Large‐Eddy Simulations of Dust Devils of Observed Intensity: Effects of Grid Spacing, Background Wind, and Surface Heterogeneities

AbstractDust devils are convective vortices with a vertical axis of rotation made visible by lifted soil particles. Currently, there is great uncertainty about the extent to which dust devils contribute to the atmospheric aerosol input and thereby influence Earth's radiation budget. Past efforts to quantify the aerosol transport and study their formation, maintenance, and statistics using large‐eddy simulation (LES) have been of limited success. Therefore, some important features of dust devil‐like vortices simulated with LES still do not compare well with those of observed ones. One major difference is the simulated value of the core pressure drop, which is almost 1 order of magnitude smaller compared to the observed range of 250 to 450 Pa. However, most of the existing numerical simulations are based on highly idealized setups and coarse grid spacings. In this study, we investigate the effects of various factors on the simulated vortex strength with high‐resolution LES. For the fist time, we are able to reproduce observed core pressures by using a high spatial resolution of 2 m, a model setup with moderate background wind and a spatially heterogeneous surface heat flux. It is found that vortices mainly appear at the lines of horizontal flow convergence above the centers of the strongly heated patches, which is in contrast to some older observations in which vortices seemed to be created along the patch edges.

How Slow Rock Weathering Balances Nutrient Loss During Fast Forest Floor Turnover in Montane, Temperate Forest Ecosystems

Mineral nutrient cycling between trees and the forest floor is key to forest ecosystem nutrition. However, in sloping, well-drained landscapes the forest floor experiences permanent nutrient loss in particulate form by plant litter erosion and as solute after plant litter decomposition, solubilisation and export. To prevent nutrient deficit, a replenishing mechanism must be in operation that we suggest to be sourced in the subsoil and the weathering zone beneath it, provided that atmospheric input is insufficient. To explore such a mechanism, we quantified deep (up to 20 m depth) weathering and mineral nutrient cycling in two montane, temperate forest ecosystems in Southern Germany: Black Forest (CON) and Bavarian Forest (MIT). From measurements of the inventories, turnover times, and fluxes of macronutrients (K, Ca, Mg, P) we found evidence for a fast, shallow `organic nutrient cycle´, and a slow, deep `geogenic nutrient pathway´. We found that the finite nutrient pool size of the forest floor persists for a few years only. Despite this loss, foliar nutrient concentrations in Picea abies and Fagus sylvatica do not indicate deficiency. We infer that ultimately the biologically available fraction in the deep regolith (CON: 3 - 7 m, MIT: 3 - 17 m) balances nutrient loss from the forest floor and is also decisive for the level of the forest trees’ mineral nutrient stoichiometry. Intriguingly, although the nutrient supply fluxes from chemical weathering at CON are twice those of MIT, nutrient uptake fluxes into trees do not differ. The organic nutrient cycle apparently regulates its efficiency to cater for differences in its replenishment by the deep geogenic nutrient pathway, and thereby ensures long-term forest ecosystem nutrition.

Bushmeat biogeochemistry: hunting tropical mammals alters ecosystem phosphorus budgets.

Wild meat (or 'bushmeat') hunting is nearly ubiquitous across the tropics and is very often unsustainable-driving declines and extirpation of numerous mammal populations. Loss of these animals can alter the transport of nutrients within and between ecosystems. But whether the physical removal of vertebrate carcasses and the nutrients that they store can reduce overall nutrient availability in ecosystems has been little explored. At 32 sites on three continents, we show that annual phosphorus (P) loss via mammal exploitation was low relative to the rate of atmospheric P deposition. But at four sites in Africa and Southeast Asia, removal of P in the skeletons of hunted mammals exceeded the atmospheric input of this nutrient by 10-fold or more. Because P is the growth-limiting nutrient for many tropical terrestrial ecosystems and certain large mammals, the imbalance created by the removal of mammal biomass under very high hunting scenarios could reduce ecosystem carrying capacity if no compensatory P additions occur in the system. This biogeochemical perspective on bushmeat exploitation raises further concerns about harvest sustainability and human food security in areas where hunting rates are high and ecosystem P inputs low.

Contrasting biogeochemical processes revealed by stable isotopes of H2O, N, C and S in shallow aquifers underlying agricultural lowlands.

Lowland coastal areas as the Po Delta (Italy) are often intensively cultivated and affected by nitrogen imbalance due to fertilizers leaching to groundwater and export via run-off. To address this issue several agricultural best practices have been proposed, like limiting the amount of fertilizers and increasing soil organic matter content. In this study, groundwater samples were analysed for major ions and stable isotopes of H2O, C, N and S using multi-level sampler (MLS) from two contrasting depositional environments, one representative of alluvial plain (AP) and the other representative of a reclaimed coastal plain (RCP). In each site, controlled plots with different agriculture practice including fertilizers and tillage and compost amendment and no tillage were considered in the study. Tracer test results highlight that recharge water infiltrated at the start of the controlled study has not yet reached the saturated zone, thus current groundwater concentrations are representative of former agricultural practices. Stable isotopes show a clear distinction between different sources of nitrogen in both sites, from synthetic fertilizers to sedimentary nitrogen pool and atmospheric input. The main source of sulphate in groundwater is pyrite and fertilizers. Denitrification, sulphate reduction and methanogenesis were involved in the C, N and S cycle in the RCP site characterized by low hydraulic conductivity sediments and high SOM. These processes were not relevant in the AP site characterized by oxic condition and low SOM, but some evidence of denitrification was found in one of the AP sites. High resolution monitoring was a key tool to identify the different redox zones responsible for N, C and S cycling in these aquifers. This study shows that a clear understanding of transit times in the vadose zone is a key prerequisite to evaluate the effect of controlled agriculture practice on the quality of shallow groundwater.

Simulating the spread of disinfection by-products and anthropogenic bromoform emissions from ballast water discharge in Southeast Asia

Abstract. Ballast water treatment is required for vessels to prevent the introduction of potentially invasive neobiota. Some treatment methods use chemical disinfectants which produce a variety of halogenated compounds as disinfection by-products (DBPs). One of the most abundant DBPs from oxidative ballast water treatment is bromoform (CHBr3), for which we find an average concentration of 894±560 nmol L−1 (226±142 µg L−1) in the undiluted ballast water from measurements and the literature. Bromoform is a relevant gas for atmospheric chemistry and ozone depletion, especially in the tropics where entrainment into the stratosphere is possible. The spread of DBPs in the tropics over months to years is assessed here for the first time. With Lagrangian trajectories based on the NEMO-ORCA12 model velocity field, we simulate DBP spread in the sea surface and quantify the oceanic bromoform concentration and emissions to the atmosphere from ballast water discharge at major harbours in the tropical region of Southeast Asia. The exemplary simulations of two important regions, Singapore and the Pearl River Delta, reveal major transport pathways of DBPs and anthropogenic bromoform concentrations in the sea surface. Based on our simulations, we expect DBPs to spread into the open ocean, along the coast and through advection with monsoon-driven currents into the North Pacific and Indian Ocean. Furthermore, anthropogenic bromoform concentrations and emissions are predicted to increase locally around large harbours. In the sea surface around Singapore, we estimate an increase in bromoform concentration by 9 % compared to recent measurements. In a moderate scenario in which 70 % of the ballast water is chemically treated, bromoform emissions to the atmosphere can locally exceed 1000 pmol m−2 h−1 and double climatological emissions. In the Pearl River Delta all bromoform is directly outgassed, which leads to an additional bromine (Br) input into the atmosphere of 495 kmol Br a−1 (∼42 t CHBr3). For Singapore ports the additional atmospheric Br input is calculated as 312 kmol Br a−1 (∼ 26 t CHBr3). We estimate a global anthropogenic Br input from ballast water into the atmosphere of up to 13 Mmol a−1. This is 0.1 % of global Br input from background bromoform emissions and thus not relevant for stratospheric ozone depletion.

Deciphering the atmospheric signal in marine sulfate oxygen isotope composition

Atmospheric O2 and CO2 levels inform us of the changes in chemical and biological environments, yet the history of atmospheric compositions, and pO2 in particular, is not well-constrained. The triple oxygen isotope (16,17,18O) composition of marine SO42− has been proposed to directly record the ratio pO2/pCO2 in the contemporaneous atmosphere. To resolve this atmospheric signal, both a precise measurement of the 17O composition of sulfate and a model with which to interpret the measurement are needed. Here we present precise measurements of the triple oxygen isotope composition of modern marine sulfate and then forward a novel sulfur cycle model that deconvolves the potential atmospheric and microbial inputs to this signal. Our interpretation of marine sulfate oxygen isotope composition provides a framework for calculating atmospheric composition, relative rates of biogeochemical activity, and can be applied to geologic records of marine sulfate to constrain the pO2/pCO2 ratio over time.

Atmospheric inputs of nutrients to the Mediterranean Sea

The Mediterranean Sea is an oligotrophic semi-closed environment where atmospheric deposition is expected to be an important driver for biological activity. The present study uses a three-dimensional atmospheric chemistry transport model to evaluate the nitrogen (N), phosphorus (P) and iron (Fe) atmospheric deposition fluxes to the Mediterranean Sea. The model takes into account both the inorganic and organic fractions of these fluxes and compares them to other sources of these nutrients that are external to the ocean. The estimated atmospheric deposition fluxes of soluble nutrients amount to 1281 Gg-N y−1, 4.31 Gg-P y−1 and 6.32 Gg-Fe y−1 for the present day, and are within the range of the few estimates available in literature. An almost 6-fold increase in the atmospheric deposition of soluble N is also calculated to be the result of the increase in anthropogenic and biomass burning emissions since 1850, while soluble P and Fe deposition fluxes have increased by 59% and 114%, respectively. For future (2100) emissions, however, N deposition is projected to increase only slightly (4%) while soluble P and Fe fluxes will decrease by 34% and 32% compared to current estimates.The soluble organic N and P annual deposition fluxes are calculated to be 12% and 28–83% of total soluble N and P present-day annual deposition fluxes into the Mediterranean Sea, respectively. However, to reconcile with the observed fluxes in the west and the east Mediterranean, ∼14 times higher flux of soluble P, in particular organic P, and at least 2.5 times higher flux of soluble Fe need to be considered in the model. Such high fluxes can be due to higher combustion emissions of soluble Fe and P, to higher dust emissions or solubilisation of Fe and P contained in dust aerosols, and also higher organic P flux associated with bioaerosols than currently used in the global models. Overall, the calculated deposition fluxes provide an integrated spatially complete picture of the atmospheric inputs to the Mediterranean marine ecosystem, which are potentially important for net primary production and the ocean carbon cycle.

Water or soil—What is the dominant driver controlling the vegetation pattern of degraded shallow mountain peatlands?

AbstractThe aim of this paper was to evaluate the link between environmental conditions and the vegetation pattern of mountain peatlands drained for forestry. We assumed that (a) water chemistry and soil properties differ between the investigated peatlands types—from fen to bog, (b) the vegetation pattern is dependent on water chemistry and soil properties, and (c) water chemistry and soil properties play different roles in determining peatland patterning. For our study, five ecologically and topographically diverse forestry‐drained shallow peatlands in Central Sudetes, Poland, were selected. A comparison between the studied peatlands and environmental variables was done by discriminant analysis, whereas vegetation–environmental relationship was analysed by canonical correspondence analysis. Results demonstrated that pH, HCO3−, NO3−, and Ca2+ best explained the variation in water chemistry (approximately 74%), whereas base saturation, pHwater, and plant‐available phosphorus best explained the variation in soil properties. Plant assemblages within the peatlands exhibited three vegetation clusters that did not always correspond to peatland ecological type. The vegetation was mostly affected by water chemistry (explained up to 54% of variation), rather than by soil properties. Vegetation within such ecosystems seems to be a good indicator of differences in water chemistry, caused by differences in bedrock (soligenic fen peatlands) or atmospheric inputs (ombrogenic bogs). Our results will help improve our understanding of vegetation–environment relationships in degraded mountain peatland ecosystems in the temperate climate zone. They might also be useful for proper planning of restoration and monitoring of these ecosystems.

Major Impact of Dust Deposition on the Productivity of the Arabian Sea

AbstractIn the Arabian Sea (AS), spatiotemporal nutrient limitation patterns of primary production and the possible role of nutrient inputs from the atmosphere are still not well understood. Using a biogeochemical model forced by modeled aerosol deposition, we show that without high atmospheric iron inputs through dust deposition during the summer monsoon, primary production over the AS would be reduced by half. Atmospheric iron deposition also supports most of the nitrogen fixation over the AS. However, our ocean biogeochemistry modeling results suggest that dinitrogen fixation constitutes a negligible fraction of the primary production. Finally, we show that atmospheric inputs of nitrogen, mostly from anthropogenic activities in India, have a negligible impact on primary production.

Tracing controlling factors of riverine chemistry in a headwater tributary of the Yangtze River, China, inferred from geochemical and stable isotopic signatures.

The Jialing River is the second largest headwater tributary of the Yangtze River in China, therefore, the river water has been contaminated and water quality is deteriorated. Hence, this study aims to find the maincontroling factors of riverine chemistry. 52 water samples were collected for the determination of major ions and environmental isotopes of δ18O and δ2H. Stoichiometry of geochemical data with mixing end members and multivariate statistical analysis were employed with integrated GIS approach for data interpretations. The δ18O and δ2H of the Jialing River Basin (JRB) were used to define the origin of river water from meteoric water and waterin the spring season is affected by high evaporation and evaporates dissolution. The average TDS 301mg/L that is higher than the Yangtze River. Inthe JRB, 80% of the anion in water samples represented HCO3- (207mg/L) and SO42- (80mg/L) while 80% of the cations were accounted by Ca2+ (59.8mg/L) and Mg2+ (17.9mg/L). The water chemistry mainly derived from the water rock interaction. Piper plot indicated that Ca-Mg-HCO3- was the most dominant water type and most ions derived from carbonate weathering by H2SO4 and H2CO3. The stoichiometry results further confirmed carbonate weathering is dominant than silicate weathering. Evaporate ions were modified by anthropogenic sources. Agricultural inputs are higher than the industry and atmospheric inputs. Redundancy analysis showed that most contributive land-use type in explaining riverine chemistry was the cultivate land (62.6, 66.4, and 67.9%) at all buffer scales of 30, 20, and 10km, respectively. Forest and grasslands mostly correlate with Ca2+, Mg2+, Cl-, SO42-, EC, pH, and HCO3- while anthropogenic land-use types such as cultivated and construction lands correlate with Na+, K+, Cl-, and NO3-. These results revealed that the lithology of the basin mainly controlled the upstream water chemistry while downstream riverine chemistry was controlled by both lithology and anthropogenic inputs. Nevertheless, this study suggested that explicitly determining the controlling factors of riverine chemistry involves a complex process and combination of different chemical constituents and factors on river water. However, this study managed to provide useful information to further understanding of the geochemical process in JRB.