Ecological responses of typical Antarctic marine organisms to climate change and anthropogenic impacts

To improve our understanding and ability to predict biological responses to global climate change, it is important to be able to distinguish the influences of natural forcing from anthropogenic impacts. In the ice-free areas of Antarctica, lake and terrestrial sediments that contain penguin guanos, seal excrement and other biological remains provide natural archives of ecological, geological and climatic information that range from hundreds to thousands of years old. Our review focuses on the paleoecology of typical Antarctic marine organisms （penguins, seals and Antarctic krill） and their responses to climate change and human activities over centennial and millennial timescales. Land-based seabirds and marine mammals play an important role in linking the marine and terrestrial ecosystems and act as bio-vectors, transporting large amounts of nutrients and contaminants from ocean to land.

Variation Trends of Dust Storms in Relation to Meteorological Conditions and Anthropogenic Impacts in the Northeast Edge of the Taklimakan Desert, China

To reveal the multivariate relationships between man-made and meteorological factors on dust storm frequency, the LUCC data, NDVI remote sensing data and meteorological data for the period of 1983-2013 were combined with dust storm frequency data, and the possible impacts of meteorological and anthropogenic factors on dust storm frequency were analyzed by using regression analysis and PCA (Principal Component Analysis). Results show that the inter-annual dust storm frequency increased gradually. In particular, an increasing trend in recent years, after 2009, is conspicuous. The monthly frequency of dust storms shows higher values between the months of February and May, with the highest mean number of events occurring in April, which accounts for 29% of the annual dust storm frequency. The annual dust storm frequency is positively correlated with wind speed and negatively correlated with precipitation;the monthly dust storm frequency is positively correlated with wind speed, but no significant correlation can be found with precipitation. The relationship between temperature and dust storms is not simply linear, however, a certain correlation with an unremarkable statistical significance can be found between them. Human activities also affect the dynamics of dust storms indirectly via changing vegetation coverage and direct dust emissions. The multivariate analysis further confirmed the association between dust storm frequency and meteorological factors and NDVI. The high loadings of dust storm frequency, wind speed, precipitation and NDVI on a PC indicate that the increased precipitation and NDVI will decrease dust storm frequency, and increased wind speed will increase dust storm frequency.

A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai,China

Recent sediments from Lake Chenghai, China, were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon （TOC）, total nitrogen （TN）, total phosphorus （TP）, organic phosphorus （Po）, inorganic phosphorus （Pi） and organic carbon and nitrogen stable isotopes （~13Corg and 615N） in a 137Cs-dated sediment core. The results indicated that the sedimentary record covers the last 60 years, during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading. Prior to the late 1980s, the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable. Since the late 1980s, increasing TOC, TN and TP concentrations together with the change of 613Corg and 615N suggested anthropogenic perturbations in nutrient loading and lake productivity. Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients. The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s, and domestic wastewater discharged from Yongsheng County since 1993.

Detecting anthropogenic impact on forest succession from the perspective of wood exploitation on the northeast Tibetan Plateau during the late prehistoric period

Human activities are usually considered to have had impacts on forest degradation and/or changes of forest composition in the past.The Tibetan Plateau,an environmentally sensitive area,has witnessed a high intensity of human activities since the late Neolithic,but the evidence is still incomplete concerning how human activities affected the environment,especially vegetation changes.This may result,in part,from the fact that research on prehistoric wood utilization by humans in the northeast Tibetan Plateau(NETP)is scarce,especially from the perspective of charcoal analysis,which is an archaeological index directly related to human activities.To fill this gap,we report new data here concerning charcoal analysis from 24 archaeological sites dated 5200–2300 a BP in the NETP,where this period saw remarkable environmental and social changes.By coupling the results with published paleoenvironment records(especially pollen),we aim to explore the utilization of wood and its spatial-temporal changes,as well as the anthropogenic impacts on past forest dynamics in the NETP.The results suggest that the wood resources collected by humans were mainly needleleaf trees(Picea L.and Pinus L.),broadleaved trees(Populus L.,Salix L.,and Betula)as well as shrubs(Hippophae L.and Tamarix L.),and that these were distributed around the human habitation areas.There was a clear spatial difference in the woody assemblage collected by humans in the period 3600–2300 a BP.This was likely related to the diversity of natural environments in local areas,but there was an abnormal spatial pattern of forest composition with broadleaved trees dominant above 2500 masl caused not by climate change,but by the rapid increase of human settlement and wood collection in high altitude areas of the NETP since 3600 a BP.

Anthropogenic impacts to the sediment budget of São Francisco River navigation channel using SWAT

The São Francisco River Basin,located in eastern Brazil,has undergone a significant amount of anthropogenic changes in the last several decades,such as agricultural expansion,irrigation activities,mining,and the construction of large dams.Together,these changes have altered the historic sediment budget and have led to an aggradation of sediments in the navigation channel,impacting the ability to efficiently ship agricultural commodities to regional ports.In an effort to aid decision makers in future waterway navigation planning,an international partnership between the Brazilian government agency CODEVASF and the US Army Corps of Engineers(USACE)was created.Through this partnership a SWAT model of the 630000 km2 São Francisco River basin was developed to better understand both the historic and current sediment budget within the navigation channel.The SWAT model of the São Francisco River Basin was calibrated for hydrology and sediment loads.Monthly discharges were calibrated at 17 Agência Nacional deÁguas(ANA)gages,with Nash-Sutcliffe efficiency(NSE)values ranging from 0.42 to 0.75 for an eleven year simulation.Sediment loads were calibrated to an ANA sediment gage located in the Middle São Francisco River Navigation Channel,with a PBIAS(Percent Bias)of 11.6.Based on model results,the aggradation rate of sediment in the São Francisco River and major tributaries has increased by approximately 20 Mt since Pre-European settlement of the basin(from approximately 7 Mt/a to 27 Mt/a).This increase has contributed to an impaired navigation channel due to shoaling of sandy sediments in the navigation channel.

Assessment and impact of anthropogenic disturbances in protected areas of northern Togo

These days, human activities in the savanna and the remaining dry and riparian forests of the Sudanian ecoregions continue to have their impact. These anthropogenic practices are still the main cause of disturbances in these areas. In order to investigate and assess the importance of these disturbances, caused by people bordering on protected areas and to determine the relation between these activities and the environment in which they are carried out, 220 samples were selected in the three main protected areas of northern Togo. The investigation was mainly qualitative, considering the floristic sampling of this drought area; any anthropogenic activities observed were recorded. A simple investigative questionnaire about the activities of rural people in the reserved areas was distributed to individuals encountered in the study area. Each sample in the investigation ended with a site description of its ecologi- cal characterization, i.e., soil features, topography, fauna footprints, dominant plant species and GPS position; we also took photo- graphs of the site. Data processing was entirely based on descriptive statistics and a factor analysis. The results show that eight kinds of human activities, i.e., the use of pastures, tree cutting, bush fires, charcoal production, harvesting of plant material, fanning, honey harvesting and hunting, were noted to be serious disturbances to the integrity of the ecosystems. Among these disturbances, three are recurrent in all the sampled areas of which the use of pastures accounts for 31.88%, tree cutting for 30.35% and bush fires for 30.13%. Fire and pasture disturbances are closely linked and are responsible for the current features of the savanna area of the region. Tree cutting is more a direct function of the need for the production of wood fuel, generally used by city populations. Hunting, farm- ing and honey production are of lesser importance in the area and therefore, do not pose a significantly negative effect on the growth of fauna and flora. Knowledge of these disturbances in the context of requalification and a renewed demarcation of protected areas in Togo is essential for their sustainable management.

Impacts of Anthropogenic Forcings and El Nio on Chinese Extreme Temperatures

This study investigates the potential influences of anthropogenic forcings and natural variability on the risk of summer extreme temperatures over China. We use three multi-thousand-member ensemble simulations with different forcings （with or without anthropogenic greenhouse gases and aerosol emissions） to evaluate the human impact, and with sea surface temperature patterns from three different years around the E1 Nino-Southern Oscillation （ENSO） 2015/16 event （years 2014, 2015 and 2016） to evaluate the impact of natural variability. A generalized extreme value （GEV） distribution is used to fit the ensemble results. Based on these model results, we find that, during the peak of ENSO （2015）, daytime extreme tem- peratures axe smaller over the central China region compared to a normal year （2014）. During 2016, the risk of nighttime extreme temperatures is largely increased over the eastern coastal region. Both anomalies are of the same magnitude as the anthropogenic influence. Thus, ENSO can amplify or counterbalance （at a regional and annual scale） anthropogenic effects on extreme summer temperatures over China. Changes are mainly due to changes in the GEV location parameter. Thus, anomalies are due to a shift in the distributions and not to a change in temperature variability.

A spatial framework for detecting anthropogenic impacts on predator-prey interactions that sustain ecological integrity in Mexico

Background:This paper presents several spatial indicators developed to evaluate anthropogenic impacts on predator-prey interactions and their relationship with ecological integrity loss in Mexico.Ecological integrity loss is defined as the inability to sustain viable populations,habitat functions,and species interactions of Nearctic and Neotropical apex predators as a result of anthropogenic effects.As direct impacts,the indicators evaluate habitat loss and the number of inhospitable habitats.As indirect impacts,the indicators evaluate the avoidance of human features such as highways,roads,and human locations.The total impact level is described at 1 km^(2) resolution,and registered within the domain defined by the spatial habitat requirements of apex predators.The impact level is associated with ecological integrity loss,or the ecosystem capacity to reorganize habitat functions and sustain predator-prey interactions as the most visible elements of ecological integrity.Ecological integrity loss is evaluated for different groups of apex predators that are classified with different levels of anthropogenic threat.Results:The framework presented here identifies the spatial information needed for the assessment of cumulative anthropogenic impacts.By characterizing their distribution range,Nearctic predators have significantly larger intact habitats than neotropical predators but with higher ecological degradation,less landscape transformation,and overall less ecological integrity.As observed within their distribution areas,indirect impacts have a generalized effect in the broad range of landscapes in Mexico.Ecological integrity loss is the result of road,highway,and human settlement avoidance;but landscape transformation and human activity control the threshold for which ecological integrity loss becomes critical.On the other hand,there are no significant differences in impact levels among threat conservation categories for apex predators,which indicate that all predator species have the same threat level and should be all included in protection efforts.Conclusions:With the application of this spatial framework,the significance,scale,and baseline conditions can be established for evaluating anthropogenic impacts on ecological integrity.The analysis of the current condition shows the status for apex predator in the country,and identifies the ecological integrity threshold when human activities have severe to highly severe impacts in the landscape,threatening the viability of populations and their habitat.

Increasing Anthropogenic Mercury Pollution over the Last 200 Years Revealed by Lagoonal Sediments from Hainan Island,South China

The toxic heavy metal mercury(Hg)has significantly enhanced the global Hg cycle influenced by human activities over the last century.In this study,we presented a high-resolution Hg deposition history between∼1780 and 2015 AD in a sediment core from Xincun Lagoon,located in the southeastern Hainan Island,South China,and analyzed it in conjunction with geochemical elements,grain-size distribution,organic matter,and HYSPLIT backward trajectory simulation.The objective was to investigate the influencing factors affecting historical Hg deposition in relatively remote regions and assess the extent of the effects of natural background and human activities.The results showed that the Hg in the sediment was deposited primarily through atmospheric deposition,which was closely related to regional and even global human activities.Anthropogenic Hg contamination increased gradually from the 1830s to 1850s,possibly due to Hg emissions from Opium Wars I and II occurring in southeastern China.High broad peaks of anthropogenic Hg were observed during the 1910s to 1950s and in the 1980s,likely associated with the two world wars and modern Chinese wars.In addition,a further sharp increase in anthropogenic Hg from the mid-1970s to the present occurred,likely originating from the intense industrial activities in China triggered by the reform and opening-up policy of China in 1978 and some countries in Southeast Asia.

Hydro-geochemistry of groundwater and surface water in Dschang town(West Cameroon):Alkali and alkaline-earth elements ascertain lithological and anthropogenic constraints

The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south India.It also aims to define depth to granitoid and structural elements which traverse the selected area.Magnetic data(n=84)measured,processed and interpreted as qualitative and quantitatively.The results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative bodies.The magnetic values ranged from-137 nT to 2345 nT with a mean of 465 nT.Reduction to equator shows significant shifting of causative bodies in the southern and northern directions.Analytical signal map shows exact boundary of granitic bodies.Cosine directional filter has brought out structural element trending NE-SW direction.Results of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile lines.Sudden decrease of magnetic values from 2042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault occurrence.Magnetic breaks obtained from these maps were visualized,interpreted and identified two suitable sites for open and bore well.Radially averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m,respectively.Euler method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0,1,2,and 3 and found depth ranges from<10 m to>90 m.Study indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells.

Impact of the Iron Gates on the Sediments with an Emphasis on the Area of the Future Belene Nuclear Power Plant

The present investigation has been fulfilled with a view to the future nuclear power station constriction near the Belene Island.Sediment loads and sediment transportation are important factors for the technical water supply of the nuclear station Belene.The paper deals with change of suspended sediment load at Bulgarian part of the Danube River downstream of the Iron Gates.Recent data on suspended sediment loads for the hydrometric gauge station at Svishtov have been collected,computed and presented.The results obtained discover the time variability of the sediment loads,climate change and the anthropogenic impact on the suspended sediments.The tendency of alteration and inter-annual variability of the suspended sediments are investigated and characteristics of average annual,monthly and maximal values are shown.In the material archive granulometric data are presented for this part of the Bulgarian stretch before the Iron Gates construction in the conditions of the natural sediment regime.There are statistical parameters of the studied characteristics of the river turbidity and discharge before and after the anthropogenic impact.The increase of the absolute minimal turbidity has been determined after the Iron Gate I as a result of activation of the bed processes and hydro-morphological changes.

Decadal variations in diatoms and dinoflagellates on the inner shelf of the East China Sea, China

Diatoms and dinoflagellates are two major groups ofphytoplankton that flourish in the oceans, particularly in coastal zone and upwelling systems, and their contrasting production have been reported in several world seas. However, this information is not available in the coastal East China Sea （ECS）. Thus, to investigate and compare the decadal trends in diatoms and dinoflagellates, a sediment core, 47-cm long, was collected from the coastal zone of the ECS. Sediment chlorophyll-a （Chl-a）, phytoplankton-group specifc pigment signatures of diatoms and dinoflagellates, and diatom valve concentrations were determined. The sediment core covered the period from 1961 to 2011 AD. The chlorophyll-a contents ranged from 2.32 to 73 gg/g dry sediment （dw） and averaged 9.81 gg/g dw. Diatom absolute abundance ranged from 29 152 to 177 501 valve/gram （v/g） dw and averaged 72 137 v/g dw. Diatom valve and diatom specific pigment marker concentrations were not significantly correlated. Peridinin increased after the 1980s in line with intensified use of fertilizer and related increases in nutrient inputs into the marine environment. The increased occurrence of dinoflagellate dominance after the 1980s can be mostly explained by the increase in nutrients. However, the contribution of dinoflagellates to total phytoplankton production （Chl-a） decreased during the final decade of this study, probably because of the overwhelming increase in diatom production that corresponded with the construction of the Three Gorges Dam （TGD） and related light availability. Similarly, the mean ratio of fucoxanthin/peridinin for the period from 1982 to 2001 was 6% less than for 1961 to 1982, while the ratio for 2001 to 2011 was 45.3% greater than for 1982 to 2001. The decadal variation in the fucoxanthirdperidinin ratio implies that dinoflagellate production had been gradually increasing until 2001. We suggest that the observed changes can be explained by anthropogenic impacts, such as nutrient loading and dam construction.

Habitat preferences of diurnal raptors in relation to human access to their breeding territories in the Balkan Mountain Range,Bulgaria

Background:In this study we examined the habitat preferences of three diurnal raptors in relation to human access.We aimed to identify the selection of breeding habitat by the Golden Eagle(Aquila chrysaetos),the Long-legged Buz-zard(Buteo rufinus),and the Peregrine Falcon(Falco peregrinus)in response to site accessibility by humans,and in turn,the response of these species to human presence.Methods:Data about the nest locations were collected.Analyses and maps were created using ArcGIS.The“least cost path”was defined using the Cost Path tool.Results:The lowest values of the Cost Path were established for Long-legged Buzzard and the highest values were estimated for Golden Eagle.Intermediate Cost Path values for Peregrine Falcon were found.Conclusions:The Long-legged Buzzard could be considered as the most tolerant to human presence in its breeding territories.The Golden Eagle have the lowest degree of tolerance and the Peregrine Falcon is ranked in an intermedi-ate position compared to the other two species,but closer to Golden Eagle.

Drivers of Change in Estuarine and Coastal Marine Environments: An Overview

Anthropogenic climate and non-climate drivers of change are causing significant impacts on estuarine and coastal marine environments. Climate change poses a particular threat to the structure and function of biotic communities in these environments because it acts on the most extensive temporal and spatial scales relative to other anthropogenic drivers of change. The interaction of multiple environmental drivers exacerbates degradation of ecosystem condition. Estuaries are most susceptible to climate-change mediated biotic shifts and direct anthropogenic impacts due to burgeoning human population growth and development in coastal watersheds. Multiple anthropogenic drivers of change, which often interact synergistically, alter physical, chemical, and biological characteristics. Ecological responses may be increasingly nonlinear, with cumulative effects manifested by marked changes in organism abundance, distribution, diversity, and productivity. Detrimental biotic effects in impacted coastal environments cascade up from individual organisms to population and community levels, culminating in ecosystem-level changes including reduced services. Multiple drivers of change and their impacts are increasing in estuarine and coastal marine environments with greater anthropogenic forcing in the coastal zone and global effects of climate change, creating greater challenges for environmental management and conservation programs.

Potential triggers for large earthquakes in open-pit mines:A case study from Kuzbass,Siberia

The extraction and movement of rock during mining operations is considered a possible trigger for slip along the fault.In this study,possible anthropogenic causes were analyzed for triggering the earthquake with the local magnitude ofML=6.1(at a depth of 4km just beneath the quarry),in the vicinity of the large coal open-pit mine in Russia.This event was the largest earthquake associated with a quarry(an open pit).A sufficiently deep occurrence of the source testified that seismic vibrations were produced in a dynamic slip along a preexisting and prestressed tectonic fault.Analytical calculations were conducted of increments of normal and shear stresses at fault planes with several dip angles at depths corresponding to the probable location of the hypocenter of the Bachat earthquake.As the results show,long-term rock excavations bring a prestressed thrust fault closer to the ultimate Coulomb strength,and stress variations at those depths may suffice to initiate a movement along the fault.By measuring seismic vibrations at different quarries and mines in Russia,the dynamic effect at the supposed depth of the source occurrence could be reliably estimated.As is shown,the ultimate anticipated dynamic deformations are noticeably lower than corresponding values produced by seismic waves of distant earthquakes in the case when the effects of dynamic triggering were observed.Accordingly,the seismic effect of explosions cannot trigger a large earthquake with deep source occurrence.Operations in open-pit mines can only bring forward the moment of an earthquake at a potentially seismogenic fault.At the same time,the numerical calculations reveal that a branching network of underground tunnels located at several horizons can noticeably reduce the effective shear modulus of the host rock.This effect can even provoke a dynamic movement at a previously aseismic fault.

Human impact on current environmental state in Chinese lakes

Anthropogenic and natural disturbance to inland aquatic ecosystems displays a notable spatial difference, yet data to measure these differences are scarce. This study encompasses 217 lakes distributed over five lake regions of China and elucidates the environmental factors determining the spatial variability of the water quality and trophic status. A significant correlation between human modification index in surrounding terrestrial systems(HMT)and trophic status of lake ecosystems(TSI) was found, and the regression slope in each region was similar except in the Qinghai-Tibet Plateau region. It was further noted that the pattern of environmental factor network(EF network) differed among freshwater and saline lakes. The EF network was complex for freshwater lakes in less human-influenced areas, but intensive man-made influence disrupted most relationships except for those between total nitrogen, total phosphorus, chlorophyll-a, and water turbidity. As for regions including saline lakes, correlations among water salinity and organic forms of carbon and nitrogen were apparent. Our results suggest that HMT and EF network can be useful indicators of the ecological integrity of local lake ecosystems, and integrating spatial information on a large scale provides conservation planners the option for evaluating the potential risk on inland aquatic systems.

Information Technology in Environmental Monitoring for Territorial System Ecological Assessment

The environmental monitoring dataset of Rivne region territory （Ukraine） was analyzed using remote sensing technology and statistical analysis. The article reveals approaches to anthropogenic impact specificity assessment based on methods of correlation analysis. The information technology to assess soil quality based on satellite images decoding was created.

Natural and anthropogenic sources of lead, zinc, and nickel in sediments of Lake Izabal, Guatemala

Sediments in Lake Izabal,Guatemala,contain substantial lead (Pb),zinc (Zn),and nickel (Ni).The lack of historical data for heavy metal concentrations in the sediments makes it difficult to determine the sources or evaluate whether inputs of metals to the lake have changed through time.We measured the relative abundances and concentrations of Pb,Zn,and Ni by X-Ray Fluorescence core scanning and by Inductively Coupled Plasma Optical Emission Spectrometry in three sediment cores to explore stratigraphic distributions of metals in the lake deposits.High amounts of Pb and Zn in the core taken near the Polochic Delta suggest that galena and sphalerite mining increased Pb and Zn delivery to Lake Izabal between ~1945 and 1965 CE.An up-core Ni increase in the core taken near a different mine on the north shore of Lake Izabal suggests that recent nickel mining operations led to an increase in Ni concentrations in the local sediments,but amounts in the other cores indicate that Ni is not widely distributed throughout the lake.Sediment cores from Lake Izabal are reliable recorders of heavy metal input to the lake,and were measured to establish background metal levels,which would otherwise be unavailable.Concentrations of Pb,Zn,and Ni in older,pre-20th-century Lake Izabal sediments reflect input from natural erosion of bedrock.Our results provide previously unavailable estimates of background metal concentrations in Lake Izabal before the onset of mining.These results are necessary for future monitoring related to mining contamination of the lake ecosystem.

Plastic occurrence,sources,and impacts in Antarctic environment and biota

Several studies have documented that plastic pollution is affecting one of the most remote and pristine regions of our planet,Antarctica.Plastics of different size and polymeric composition have been retrieved in Antarctic sea ice,surface waters and sediments,with microplastics(mostly fibers)found both in terrestrial and marine organisms.Such evidence raises concerns about potential detrimental effects on biodiversity and ecosystem functions.The present review aims to report the most up-to-date knowledge on occurrence and distribution of plastic pollution in the Antarctic environment and biota including interaction with microorganisms,potential sources,and its impact on Antarctic biota.Our understanding of plastic pollution in this polar region will help us define the human footprint in Antarctica and predict future ecological risks.

Hydrochemical evolution of groundwater in northwestern part of the Indo-Gangetic Basin,India:A geochemical and isotopic approach

The present study aims to understand the hydrochemical evolution of groundwater in the Ghaggar River Basin,representing a zone of excessive abstraction of groundwater in the northwestern Indo-Gangetic Basin.The study comprises a regional scale and high-resolution sampling of groundwater during preand post-monsoon seasons of 2013 and their analyses for major ions,δ^(18)O,δ^(2)H,and 3 H.Variation in hydrochemical and isotopic data is found both in spatial and vertical scales.The significant vertical variation of TDS,NO_(3)and K^(+)allowed the classification of the aquifer system into two major groups:shallow(depth<80 m bgl)and deep(depth>80 m bgl).The depthwise variations ofδ^(18)O andδ^(2)H support this categorization of the aquifers.The Ca-HCO_(3)and Ca-Mg-Na-HCO_(3)water facies with higher values of 3 H in the proximal part of the basin characterize recharge areas under humid conditions.The dominance of Mg-Na-HCO_(3)and Na-HCO_(3)facies in shallow and deep aquifers in central part of the basin,illustrate the intermediate to advanced stages of hydrochemical evolution in the system.Dominance of brackish Ca-Mg-Cl-SO_(4)and Na-Cl-SO_(4)water types in the discharge areas is due to the prevailing geological conditions and anthropogenic activities.Geochemical modelling supports the reverse cation exchange and mixing during lateral and vertical flows,weathering of silicate minerals,dissolution of crustal salts,and evaporative enrichment are the natural processes governing the evolution of groundwater chemistry along the flowpaths.The developed process-based conceptual model will aid in the formulation of a suitable plan for groundwater resource management in the region.