Seasonal Variation of Dissolved Lead Speciation in Tagus Estuary, Portugal

The behavior of lead species from Tagus estuarine water collected during winter (January), spring (April), and summer (June) seasons were evaluated. Water samples were titrated with Pb+2 followed by differential pulse anodic stripping voltammetry (DPASV). Experimental voltammetric values were interpreted assuming a macromolecular heterogeneous ligand described in a simple way by two types of binding sites, CL1 and CL2, where CL1 is related to stronger binding groups with lower concentration compared to CL2. Water quality parameters like dissolved organic matter (DOC), pH, salinity, temperature, and total lead concentration were measured during the period under study. The results pointed to a higher concentration of CL1 and CL2 sites in April probably due to the phytoplankton bloom. The decrease of KL1 with the increase of salinity from winter to summer may be caused by the increase of major cations (as Ca2+) in solution. The trend of KL2 followed the pH shift in all seasons since an increase of pH favors Pb2+ complexation with CL2 sites. Finally, the decrease of DOC in summer could be responsible for the decrease in the concentration of the different sites in solution from April to June, with a similar decrease of 35±3% for all of them.

A hydrogeochemical approach to evaluate groundwater quality in the vicinity of three tributaries of the Beas River, North-West India

The present study focused on the seasonal investigation of hydro-geochemical characteristics of groundwater samples collected from the vicinity of three tributaries of the Beas River, Punjab, India. Total 45 samples were analyzed during the pre- and post-monsoon season for physico-chemical parameters and heavy metals along with health risk assessment. Results revealed that the majority of samples were below the permissible limits set by the BIS and WHO. The relative abundance of major cations was Ca2+ > Mg2+ > Na+ > K+ and Ca2+ > Na+ > Mg2+ > K+, while that of the major anions was HCO3− > SO42− > Cl− > CO32− in the pre- and post-monsoon season, respectively. Groundwater was alkaline and hard in nature at most of the sites. Bicarbonate content exceeded the desirable limit having an average concentration of 337.26 mg/L and 391.48 mg/L, respectively, during the pre- and post-monsoon season. Tukey’s multiple comparison test was applied for finding significant differences among samples at p < 0.05. The dominant hydrochemical face of water was Ca–Mg–HCO3 type. US salinity (USSL) diagram indicated that during the pre-monsoon, 48.9% samples were C2S1 type and remaining 51.1% were C3S1 type while during the post-monsoon all samples were C3S1 type. It indicates that groundwater of the study area is at risk of salinity hazards in future and is not to be ignored. Such monitoring studies are recommended to design future safety plans to combat soil and human health risks.

Geochemical Analysis of Groundwater for Drinking, Irrigation, and Human Health Impacts in Uddanam Area of Srikakulam District of Andhra Pradesh, India

The current study's goal is to discover the geochemical analysis of groundwater in the uddanam area of the Srikakulam district of Andhra Pradesh, India. In the current study area, 50 groundwater samples were collected and analyzed for physicochemical properties such as cations, anions, total hardness, conductivity, and alkalinity. This was assessed for its suitability for drinking and irrigation purposes by calculating pH, EC, TDS, hardness, and alkalinity in addition to major cations (Na+, K+, Ca2+, Mg2+) and anions (HCO3-, Cl-, SO42-, NO32-, F-). Chemical indices such as SAR, percent Na, permeability index, RSC, Kelly's Ratio, Magnesium Ratio, and Non-carbonate hardness (NCH) have been calculated based on the analytical results. Water with high alkalinity may be aesthetically unfit for drinking, whereas water with high TDS and TH may not be recommended for consumption by people suffering from kidney and related diseases. Geogenic, anthropogenic influence, agricultural activity, and mineral dissolution, Presence of high TDS and TH levels were the primary causes for chronic kidney disease (CKD), not suitable for drinking and irrigation purposes.

Hydrochemical Assessment of the Irrigation Water Quality of the El-Salam Canal, Egypt

The El-Salam canal in Egypt is considered an important stream of fresh water for the agricultural sector that extends from the Nile River to Sinai, while it is subjected to several anthropogenic stresses. In this study, five-georeferenced stations (named from S1 to S5) were monitored along the El-Salam Canal before El-Sahara of the Suez Canal, via the estimation of the WQ index based on major cations and anions analysis including salinity hazard, permeability index, residual sodium carbonate, magnesium hazard, sodium percentage, sodium adsorption ratio, Kelley index, potential salinity, total hardness, and irrigation water quality index (IWQI). The sequence of average concentration of cations in water were Na+ > Ca2+ > Mg2+ > K+. The major cations constitute around 60% of the total dissolved salts. While the sequence of major anions in water were SO42− > HCO3− > Cl− > CO32−. These cations and anions showed an increasing trend from S1 (intake of the canal) to S5 (before El-Sahara) of the El-Salam Canal. Moreover, the order of heavy metals was Zn < Cd < Cr < Ni < Fe < Mn < Co < Cu < Pb. According to the US EPA (1999) guidelines, the levels of Fe and Zn in the El-Salam Canal are within the permissible limits for drinking and irrigation purposes, while Mn, Pb, Cu, Co, Ni, Cr, and Cd were detected at higher concentrations than those recommended. The value of IWQI in water samples varied from 40.26 to 114.82. The samples of S1 showed good water, the samples of region S2 (after mixing with Faraskour drainage) showed poor water quality, samples of regions S3 (after mixing with the El-Serw drain waters) and S5 (before El-Sahara) fell under the very poor water category and samples of region S4 (after mixing with the Hadous drainage) showed unsuitable water. Croplands irrigated with such water will not be exposed to any alkaline risks but will be exposed to the risk of salinity, which is more severe after mixing at the S3 and S4 sites. It is recommended to treat the drainage water before mixing with the irrigation water of El-Salam Canal to raise the suitability of irrigation water for crops, particularly for the Hadous drain.

Effects of Wildfires and Ash Leaching on Stream Chemistry in the Santa Ynez Mountains of Southern California

Wildfires can change ecosystems by altering solutes in streams. We examined major cations in streams draining a chaparral-dominated watershed in the Santa Ynez Mountains (California, USA) following a wildfire that burned 75 km2 from July 8 to October 5, 2017. We identified changes in solute concentrations, and postulated a relation between these changes and ash leached by rainwater following the wildfire. Collectively, K+ leached from ash samples exceeded that of all other major cations combined. After the wildfire, the concentrations of all major cations increased in stream water sampled near the fire perimeter following the first storm of the season: K+ increased 12-fold, Na+ and Ca2+ increased 1.4-fold, and Mg2+ increased 1.6-fold. Our results suggested that the 12-fold increase in K+ in stream water resulted from K+ leached from ash in the fire scar. Both C and N were measured in the ash samples. The low N content of the ash indicated either high volatilization of N relative to C occurred, or burned material contained less N.

Hydrochemical Evaluation of Groundwater in Al-Khasfa Area within Haditha, Western Iraq

The main aim of the research is to study the groundwater quality in Al-Khasfa area within Haditha district, western Iraq. To assess the groundwater, eighteen groundwater samples in the study area were collected and analyzed for major cations and anions. Results indicated that groundwater samples in the study area are between neutral and light alkaline, slightly brackish, and highly mineralized. The hydrochemical formula of the groundwater samples indicates the Ca-SO4 type dominance, except wells number 16 and 17 were of Ca-Cl water type. According to Piper diagram, the type of water is Earth-Alkaline waters. All groundwater samples are unsuitable for human drinking, industrial, and building uses, but it is suitable for livestock. For irrigation purposes, it is characterized by no Mg-harmful, good with SAR, Na%, RSC, and PI but unsuitable for salinity hazard due to very high salinity. The Water Quality Index for Euphrates aquifer in the study area in both periods are poor water for human drinking, except W-1 in dry period indicate very poor water and W-6, W-7, W-8, W-13, W-14, W-15, W-16 in wet period indicate good water.

The toxicity of cadmium-copper mixtures on daphnids and microalgae analysed using the Biotic Ligand Model

For the prediction of metals mixture ecotoxicity, the BLM approach is promising since it evaluates the amount of metals accumulated on the biotic ligand on the basis of water chemistry, i.e. species (major cations) competing with metals, and related toxicity. Based on previous work by Farley et al. 2015 (MMME research project), this study aimed at modelling toxicity of Cd:Cu mixtures (0:1–1:1–1:0–1:2 − 1:3 − 2:1–3:1–4:1–5:1–6:1) to the crustacean Daphnia magna (48h immobilization tests) and the microalga Pseudokirchneriella subcapitata (72h growth inhibition tests). The USGS model was chosen, assuming additivity of effects and accumulation of metals on a single site. The assumption that EDTA could contribute to toxicity through metals complexing was also tested, and potential effects due to reduction of ions Ca2+ absorption by metals were considered. Modelling started with parameter values of Farley et al. 2015 and some of these parameters were adjusted to fit modelled data on observed data. The results show that toxicity can be correctly predicted for the microalgae and that the hypothesis of additivity is verified. For daphnids, the prediction was roughly correct, but taking into account CuEDTA led to more realistic parameter values close to that reported by Farley et al. 2015. However, It seems that, for daphnids responses, metals interact either antagonistically or synergistically depending on the Cu:Cd ratio. Furthermore, synergy could not be explained by additional effects linked to a reduction of Ca absorption since this reduction, mainly due to Cd, increased inversely to synergy. Finally, the USGS model applied to our data was able to predict Cu:Cd mixture toxicity to microalgae and daphnids, giving rise to estimated EC50s roughly reflecting EC50s calculated from observed toxicity.

Spatial and seasonal variability in the water chemistry of Kabar Tal wetland (Ramsar site), Bihar, India: multivariate statistical techniques and GIS approach

This study was performed to evaluate the spatial and temporal distribution of major ions in water samples of a newly designated Ramsar site, namely Kabar Tal (KT) wetland of Bihar. Samples were collected during summer, monsoon, and winter seasons. The analytical and GIS results show that concentration of electrical conductivity, chloride, and nitrate are higher in summer than monsoon and winter. However, the concentration of major cations such as sodium, potassium, calcium, and magnesium are higher in winter than monsoon and summer. In addition, major anions like sulphate and phosphate concentration is higher during monsoon than summer and winter. Multivariate statistical tool (Discriminant Analysis) results suggest that temperature, pH, electrical conductivity, sulphate, and potassium are the major parameters distinguishing the water quality in different seasons. The study confirms that seasonal variations are playing a major role in the hydrochemistry of KT wetland. Overall, this work outlines the approach towards proper conservation and utilization of wetlands and to assess the quality of surface water for determining its suitability for agricultural purposes. Overall, this work highlights the approach towards estimating the seasonal dynamics of chemical species in KT wetland and its suitability for irrigation purposes.

HYDROCHEMICAL CLASSIFICATION OF AMAZONIAN RIVERS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Water and soil chemistry provide important parameters for the study of river ecology and biogeochemical cycles. Furthermore, they determine management options of rivers and connected wetlands. The first scientific classification of Amazonian water bodies was elaborated in the 1950s by Harald Sioli. He used water color, as well as physical and chemical parameters, to explain limnological characteristics of the large Amazonian rivers and related these characteristics to the geological and geomorphological properties of their catchments. Today, an increasing amount of hydrochemical data indicate that the chemical composition of Amazonian water bodies varies much more than assumed by Sioli. Nevertheless, his simplified classification is useful for describing the natural physical and chemical variability of Amazonian rivers and wetlands. The electrical conductivity, pH-value and the distribution of major cations and anions allow to distinguish well among the three classical water types and to categorize other water bodies in order to subsidize a more detailed classification system of Amazonian fresh waters.

In Situ Growth of Halophilic Bacteria in Saline Fracture Fluids from 2.4 km below Surface in the Deep Canadian Shield

Energy derived from water-rock interactions such as serpentinization and radiolysis, among others, can sustain microbial ecosystems deep within the continental crust, expanding the habitable biosphere kilometers below the earth’s surface. Here, we describe a viable microbial community including sulfate-reducing microorganisms from one such subsurface lithoautotrophic ecosystem hosted in fracture waters in the Canadian Shield, 2.4 km below the surface in the Kidd Creek Observatory in Timmins, Ontario. The ancient groundwater housed in fractures in this system was previously shown to be rich in abiotically produced hydrogen, sulfate, methane, and short-chain hydrocarbons. We have further investigated this system by collecting filtered water samples and deploying sterile in situ biosampler units into boreholes to provide an attachment surface for the actively growing fraction of the microbial community. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and DNA sequencing analyses were undertaken to classify the recovered microorganisms. Moderately halophilic taxa (e.g., Marinobacter, Idiomarina, Chromohalobacter, Thiobacillus, Hyphomonas, Seohaeicola) were recovered from all sampled boreholes, and those boreholes that had previously been sealed to equilibrate with the fracture water contained taxa consistent with sulfate reduction (e.g., Desulfotomaculum) and hydrogen-driven homoacetogenesis (e.g., Fuchsiella). In contrast to this “corked” borehole that has been isolated from the mine environment for approximately 7 years at the time of sampling, we sampled additional open boreholes. The waters flowing freely from these open boreholes differ from those of the long-sealed borehole. This work complements ongoing efforts to describe the microbial diversity in fracture waters at Kidd Creek in order to better understand the processes shaping life in the deep terrestrial subsurface. In particular, this work demonstrates that anaerobic bacteria and known halophilic taxa are present and viable in the fracture waters presently outflowing from existing boreholes. Major cations and anions found in the fracture waters at the 2.4 km level of the mine are also reported.