Major Ions in Atmospheric Deposition in Lake Kivu Basin

This study investigated the major ion composition and sources in wet and dry deposition samples collected over 15 months (December 2017 to February 2019) at four stations representing four different land use/cover types on the western side of Lake Kivu basin in D.R. Congo. The samples were collected every 13 days for dry deposition and two to three times per month for wet deposition. Samples were analyzed for major ionic components (Cl-, NO-3, SO2-4, Na+, K+, NH+4, Ca2+, CO2-3, HCO-3 and Mg2+). Electrical conductivity and pH were analyzed immediately in the field while major ion measurements were in the laboratory. Results showed the pH of both the dry and the wet depositions were higher than what would have been expected based on equilibration with atmospheric CO2 (pH > 5.6) at all four sites, with conductivity less than 50 μS/cm. The neutralization process in dry and wet atmospheric deposition is due to Ca2+, NH+4, HCO-3 and CO2-3. The anion: cation ratio in dry deposition was close to 1 for Iko and Bukavu, and it was greater than 1.0 (1.1 - 1.2) for Lwiro and Goma in wet deposition. The dominant anions in wet deposition were SO2-4 and NO-3, found around the rural area near cement factory and the urban area near active volcanoes, respectively. The most abundant cation was Na+ followed by K+. The enrichment factors and correlation analysis suggest that the main sources of Ca2+, Na+ and Mg2+ were disintegration of soil processes, aeolian suspension of soil and volcanic ash, biomass burning and the cement/lime factory around the Lake Kivu basin.

Water quality,natural chemical weathering and ecological risk assessment of the contaminated area of vanadium ore in Yinhua River,China:Evidence from major ions and trace elements

There are abundant vanadium ores in the Cambrian strata in southern Shaanxi,China.Many years of mining activities and surface leaching have polluted the surface water to a certain extent,but the researches on the water quality characteristics and pollution degree are relatively weak.This contribution was organized to investigate the surface water quality by general parameters,including TDS,Eh,pH,DO,TOC,COD,and EC,in the vanadium ore belt(Yinhua River basin).Major ions were determined to detect the water type and natural chemical weathering,while trace elements were used to illustrate their geochemical characteristics and ecological risk assessment of heavy metals.The study found that the surface water was weakly alkaline and mainly dominated from normal to pool grade.The particle size with1000–10,000 nm of suspended particles was the main carrier of organic matter.The concentration of HCO_(3)^(-)and SO_(4)^(2-)in the anions and Ca^(2+)and Mg^(2+)ions in the cations were relatively high,and the water type was Ca-Mg-HCO_(3)-SO_(4) type.Rock weathering had a great influence on surface water,and the weathering products were mainly silicate and carbonate.Compared with the Type river,the contents of V elements showed an obvious positive anomaly,which may be affected by mining activities of vanadium ore and the annual leaching of the tailings pond.As and Cd in the surface water was polluted seriously.The integrated pollution index suggested that the surface water pollution was serious,and the main stream was more serious with the increasing tailings ponds.

Multivariate analysis and geochemical investigations of groundwater in a semi-arid region, case of superficial aquifer in Ghriss Basin, Northwest Algeria

This study aims to investigate the hydrochemical characteristics of shallow aquifer in a semi-arid region situated in northwest Algeria,and to understand the major factors governing groundwater quality.The study area is suffering from recurring droughts,groundwater resource over-exploitation and groundwater quality degradation.The approach used is a combination of traditional hydrochemical analysis methods of multivariate statistical techniques,principal component analysis(PCA),and ratios of major ions,based on the data derived from 33 groundwater samples collected in February 2014.Results show that groundwater in the study area are highly mineralized and collectively has a high concentration of chloride(as Cl^(−)).The dominant water types are Na-Cl(27%),Mg-HCO_(3)(24%)and Mg-Cl(24%).According to the(PCA)approach,salinization is the main process that controls the hydrochemical variability.The PCA analysis reveal the impact of anthropogenic factor especially the agricultural activities on the groundwater quality.The PCA highlighted two types of recharge:Superficial recharge from effective rainfall and excess irrigation water distinguished by the presence of nitrate and lateral recharge or vertical leakage from carbonate formations marked by the omnipresence of HCO_(3)^(−).Additionally,three categories of samples were identified:(1)samples characterized by good water quality and receiving notable recharge from carbonate formations;(2)samples impacted by the natural salinization process;and(3)samples contaminated by anthropogenic activities.The major natural processes influencing water chemistry are the weathering of carbonate and silicate rocks,dissolution of evaporite as halite,evaporation and cation exchange.The study results can provide the basis for local decision makers to ensure the sustainable management of groundwater and the safety of drinking water.

Hydrogeochemistry of River Water in the Upper Reaches of the Datong River Basin,China:Implications of Anthropogenic Inputs and Chemical Weathering

This research investigated anthropogenic inputs and chemical weathering in the upper reaches of the Datong River Basin,a tributary of the upper Yellow River,NW China.Multiple approaches were applied to data from 52 water and 12 soil samples from the Muli,Jiangcang,and Mole basins to estimate the chemical component concentrations and to analyze hydrochemical characteristics,distribution patterns,and origins in this coal mining-affected river basin.Coal mining has enhanced the weathering of the lithosphere in the study region.The total dissolved solids in the river range from 145.4 to 701.9 mg/L,which is higher than the global average for rivers.Ion concentration spatial distributions increase around mining areas.River geochemistry is mainly controlled by coal mining activity,carbonate weathering,and silicate weathering,with variances of 33.4%,26.2%,and 21.3%,respectively.Ca^(2+),Mg^(2+),and HCO_(3)^(-)are mainly due to the dissolution of carbonate minerals(calcite>dolomite);Si and K+are mainly from potassium(sodium)feldspar weathering;and Na+and SO_(4)^(2-)mainly from coal mine production.A conceptual model of the river water ion origins from the study area is presented and management implications for improving the adverse effects of coal mining are proposed.These results provide an important standard reference for water resource and environmental management in the study region.

Determination of the major geochemical processes of groundwater along the Cretaceous-Tertiary boundary of Trichinopoly,Tamilnadu,India

The hydrogeochemical variations in groundwater are mainly influenced by lithology,residence time of water in the aquifer matrix,and anthropogenic activities.This study was focused on the geochemical variations of groundwater in different lithological units(Archaean,Cretaceous,Tertiary,and Quaternary)by understanding the major factors governing the geochemical variations in each lithology.The 71 groundwater samples were collected from these rock types,namely,Archaean(14),Cretaceous(37),Tertiary(11),Quaternary(9).The collected samples were measured for major ions and they were used for preparation of standard geochemical plots and ionic ratios.Factor analysis and factor score were used to identify the major factors controlling the hydrochemistry and their spatial distribution in the study area.In addition,geochemical model,WATEQ 4 F was used to determine the saturation condition of carbonate and sulphate minerals in the groundwater.Na–Cl and mixed Ca–Na–HCO3 were the dominant hydrochemical facies irrespective of lithological units.The overall interpretation of geochemical data revealed that leaching of secondary salts,weathering and ion exchange reaction along the groundwater flow path through various lithological units,and anthropogenic influence from domestic sewages and agricultural activities constitute the major geochemical processes in the study area.Hence,this study brings out the multiple hydrogeochemical process in the complex geological terrain along the Cretaceous-Tertiary boundary.

Hydrochemistry of Rara Lake: A Ramsar lake from the southern slope of the central Himalayas,Nepal

High-altitude Himalayan lakes act as natural storage for environmental evidence related to climate change and environmental factors.A great number of lakes are distributed in the southern slope area of the central Himalayas;however,research concerning the hydrochemical processes of these lakes is still insufficient.Herein,we present a comprehensive study on the water chemistry of the lake waters and the inlet stream waters from Rara Lake in western Nepal based upon samples collected in November 2018.The p H,dissolved oxygen,chlorophyll-aconcentration(chl-a),water temperature,electric conductivity(EC)and total dissolved solids(TDS)were measured in situ,and the concentrations of major ions(Ca^(2+),Mg^(2+),K^(+),Na^(+),Cl^(-),SO_(4)^(2-),and NO_(3)^(-))were analyzed in the laboratory.The results revealed that the water in Rara Lake is slightly alkaline,with p H values ranging from 7.6-7.98.The cations,in decreasing order of concentration in the lake water,are Ca^(2+)>Mg^(2+)>K^(+)>Na^(+)with average concentrations of20.64 mg·L^(-1),11.78 mg·L^(-1),1.48 mg·L^(-1) and 0.72 mg·L^(-1),respectively;the order and concentrations for the anions is HCO_(3)^(-)>SO_(4)^(2-)>Cl^(-)>NO_(3)^(-),with average concentrations of 122.15 mg·L-1,2.15 mg·L-1,0.46mg·L-1 and 0.55 mg·L-1,respectively.The dominant cation and anion in the lake water are Ca2+and HCO3-and they account for 48.14%and 71.8%of the totals,respectively.The range of lake water TDS is from 95mg·L^(-1) to 98 mg·L^(-1),with an average of 96.85 mg·L^(-1).The high ratio of(Ca^(2+)+Mg^(2+))to total cations and the low ratio of(Na^(+)+K^(+))to total cations indicate that Rara Lake receives ions from rock weathering,especially from carbonate rocks.Similarly,Gibbs boomerang diagrams and Piper diagrams also support the hydrochemistry of Rara Lake as being dominated by rock-weathering patterns.Likewise,other statistical analysis tools,such as Principal Component Analysis(PCA)and correlation strongly suggest the dominance of weathering of calcium and magnesium bicarbonate rocks as the major source of ions in Rara Lake.However,several traces of anthropogenic inputs into the lake were noticed,and the hypolimnion in the lake appears to be oxygen deficient,which may not be an issue at present but cannot be ignored in the future.

Hydrochemical characterization and irrigation suitability of the Ganges Brahmaputra River System:review and assessment

The hydrochemical characterization and irrigation suitability assessment of the GangesBrahmaputra River System(GBRS)has immense importance for the livelihoods of people and ecosystem sustainability in the region.This study aims to assess the hydrochemical characteristics and evaluate the irrigation suitability of water in the GBRS by reviewing published literature of the major tributaries.The studied rivers were categorized into two groups namely Group-1 and Group-2 considering the similarities of climatic patterns,hydrochemical attributes,and drainage characteristics.The hydrochemistry of the river water was characterized by the Piper diagram,Gibbs plot,mixing plots,and ionic ratios.Furthermore,irrigation water qualities were evaluated by electrical conductivity(EC),sodium percentage(Na%),sodium adsorption ratio(SAR),magnesium hazard(MH),and Wilcox diagram.The results indicated that the hydrochemistry of the GBRS was slightly alkaline to alkaline(7.42-8.78)in nature.The average concentrations of most of the chemical attributes showed higher in Group-1,whereas the average concentrations of K^(+) and NO_(3)^(-) were found higher in Group-2.The average concentration of the major ions followed the dominancy order Ca^(2+)>Mg^(2+)>Na^(+)>K^(+) for cations and HCO_(3)^(-)>SO_(4)^(2-)>Cl^(-)>NO_(3)^(-) for anions in both groups.Gibbs plot and mixing plot indicated that carbonate rock weathering dominates the hydrochemical process,which was further confirmed by the Piper diagram and the ionic ratios.From the analyses of irrigational water quality,almost all the rivers(except Gomti River in terms of MH and Rangit River in terms of Na%)in the GBRS were found to be suitable based on EC,SAR,Na%,MH,and Wilcox diagram.Finally,the majority of river systems in the GBRS were characterized by carbonate dominated lithology and irrigational water quality is mostly suitable for utilization.This study could be useful for water quality management in the glacial-fed Himalayan river under the context of global climate change.

Groundwater Geochemistry and Saltwater Intrusion in the Dakar Coastal Area, Senegal

Groundwater levels and water samples were collected from 20 drinking water pumping and piezometer wells in the urban area of Dakar coastal region in the year 2019. The pH-value, electrical conductivity, as well as calcium, magnesium, sodium, potassium, chloride, sulfate, bicarbonate, and nitrate concentrations were measured to assess the hydrochemical quality of the infrabasaltic aquifer in the area. The present work carried out a hydrochemical analysis to interpret the groundwater chemistry of the aquifer. The results of this chemical analysis indicate that Na+ > Mg2+ > Ca2+ > K+ was the most dominant cation sequence in the groundwater, while Cl- > HCO3- > SO42- > NO3- was the most dominant one for anions. The chemical analysis of our samples showed, that the Cl-Ca-Mg facies was dominant in the aquifer, while Cl-Na-K and HCO3-Na-K facies represent 20% and 10% of the groundwater sampled, respectively. A comparison of the measured groundwater quality in relation to WHO drinking water quality standards revealed that 80% of the water samples are suitable for drinking purposes. Ca enrichment, Simpson ratio, ratio of sodium chloride, and calculating Base Exchange (BEX) indices for the samples revealed that the groundwater is mainly affected by three factors: seawater intrusion due to aquifer overexploitation on one hand, and freshening processes and nitrate pollution, on the other, mainly caused by the groundwater flow from the unconfined aquifer.

Carbonaceous matter in glacier at the headwaters of the Yangtze River:Concentration,sources and fractionation during the melting process

Carbonaceous matter has an important impact on glacial retreat in the Tibetan Plateau,further affecting the water resource supply.However,the related studies on carbonaceous matter are still scarce in Geladaindong(GLDD)region,the source of the Yangtze River.Therefore,the concentration,source and variations of carbonaceous matter at Ganglongjiama(GLJM)glacier in GLDD region were investigated during the melting period in 2017,which could deepen our understanding on carbonaceous matter contribution to glacier melting.The results showed that dissolved organic carbon(DOC)concentration of snowpit samples(283±200μg/L)was much lower than that of precipitation samples(624±361μg/L),indicating that large parts of DOC could be rapidly leached from the snowpit during the melting process.In contrast,refractory black carbon(rBC)concentration measured by Single Particle Soot Photometer of snowpit samples(4.27±3.15μg/L)was much higher than that of precipitation samples(0.97±0.49μg/L).Similarly,DOC with high mass absorption cross-section measured at 365 nm value was also likely to enrich in snowpit during the melting process.In addition,it was found that both r BC and DOC with high light-absorbing ability began to leach from the snowpit when melting process became stronger.Therefore,rBC and DOC with high light-absorbing ability exhibited similar behavior during the melting process.Based on relationship among DOC,rBC and K^+ in precipitation,the main source of carbonaceous matter in GLJM glacier was biomass burning during the study period.

Nitrogenous and carbonaceous aerosols in PM_(2.5) and TSP during pre-monsoon:Characteristics and sources in the highly polluted mountain valley

This study reports for the first time a comprehensive analysis of nitrogenous and carbona-ceous aerosols in simultaneously collected PM_(2.5) and TSP during pre-monsoon(March-May 2018)from a highly polluted urban Kathmandu Valley(KV)of the Himalayan foothills.The mean mass concentration of PM_(2.5)(129.8 μg/m^(3))was only-25%of TSP mass(558.7 μg/m^(3))indicating the dominance of coarser mode aerosols.However,the mean concentration as well as fractional contributions of water-soluble total nitrogen(WSTN)and carbonaceous species reveal their predominance in find-mode aerosols.The mean mass concentration of WSTN was 17.43±4.70 μg/m^(3)(14%)in PM_(2.5) and 24.64±8.07 μg/m^(3)(5%)in TSP.Moreover,the fractional contribution of total carbonaceous aerosols(TCA)is much higher in PM_(2.5)(~34%)than that in TSP(~20%).The relatively low OC/EC ratio in PM_(2.5)(3.03±1.47)and TSP(4.64±1.73)suggests fossil fuel combustion as the major sources of carbonaceous aerosols with contributions from secondary organic aerosols.Five-day air mass back trajectories sim-ulated with the HYSPLIT model,together with MODIS fire counts indicate the influence of local emissions as well as transported pollutants from the Indo-Gangetic Plain region to the south of the Himalayan foothills.Principal component analysis(PCA)also suggests a mixed contribution from other local anthropogenic,biomass burning,and crustal sources.Our re-sults highlight that it is necessary to control local emissions as well as regional transport while designing mitigation measures to reduce the KV's air pollution.

Concentration,sources and wet deposition of dissolved nitrogen and organic carbon in the Northern Indo-Gangetic Plain during monsoon

Precipitation represents an important phenomenon for carbon and nitrogen deposition.Here,the concentrations and fluxes of dissolved organic carbon(DOC)and total dissolved nitrogen(TDN)with their potential sources were analyzed in wet precipitation during summer monsoon from the Northern Indo-Gangetic Plain(IGP),important but neglected area.The volume-weighted mean(VWM)concentration of DOC and TDN were 687.04 and 1210.23μg/L,respectively.Similarly,the VWM concentration of major ions were in a sequence of NH_(4)^(+)>Ca^(2+)>SO_(4)^(2-)>Na^(+)>K^(+)>NO_(3)~->Cl~->Mg^(2+)>F~->NO_(2)~-,suggesting NH_(4)^(+)and Ca^(2+)from agricultural activities and crustal dust played a vital role in precipitation chemistry.Moreover,the wet deposition flux of DOC and TDN were 9.95 and 17.06 kg/(ha year),respectively.The wet deposition flux of inorganic nitrogen species such as NH_(4)^(+)-N and NO_(3)^(-)-N were 14.31 and 0.47 kg/(ha year),respectively,demonstrating the strong influence of emission sources and precipitation volume.Source attribution from different analysis suggested the influence of biomass burning on DOC and anthropogenic activities(agriculture,animal husbandry)on nitrogenous species.The air-mass back trajectory analysis indicated the influence of air masses originating from the Bay of Bengal,which possibly carried marine and anthropogenic pollutants along with the biomass burning emissions to the sampling site.This study bridges the data gap in the less studied part of the northern IGP region and provides new information for policy makers to deal with pollution control.