Alkalinity Research Articles

Evaluation of Ground Water Quality in Yeliyur Grama Panchayath Villages, Kunigal Taluk

Life on Earth is dependent on water, which is an essential component of the atmosphere. The source of household water for millions of homes in both rural and urban areas is the tube well. Groundwater is the most alternative is facing threats. Tube well and open well samples were collected at different sites of Yeliyur grama panchayath Villages, Kunigal Taluk. The Physico- Chemical properties of all the collected 20 groundwater samples were analyzed. The quality of groundwater in and around Yeliyur grama panchayath Villages, Kunigal Taluk has been studied various parameter such as pH, Total Dissolved Solid (TDS), total hardness, total alkalinity, turbidity, Na+, K+, Cl-, F-, Ca2+, Mg2+, SO42-, NO32-, DO, Chromium and Pb. The final experimental results were compared with the WHO variable standards (2021).

Seasonal Controls of Seawater CO2 Systems in Subtropical Coral Reefs: A Case Study from the Eastern Coast of Shenzhen, China

In situ field investigations coupled with coral culture experiments were carried out in the coral reef waters of the eastern coast of Shenzhen, Da’ao Bay (DAB), Dalu Bay (DLB), and Yangmeikeng Sea Area (YMKSA) to study the dynamics of the carbon dioxide (CO2) system in seawater and its controlling factors. The results indicated that the CO2 parameters were highly variable over a range of spatiotemporal scales, forced by various physical and biochemical processes. Comprehensively, DAB acted as a sink for atmospheric CO2 with exchange flux of –1.51 ± 0.31 to 0.27 ± 0.50 mmol C m−2 d−1, while DLB and YMKSA acted as a CO2 source with exchange fluxes of –0.42 ± 0.36 to 1.69 ± 0.74 mmol C m−2 d−1 and –0.58 ± 0.48 to 1.69 ± 0.41 mmol C m−2 d−1, respectively. The biological process and mixing effect could be the most important factor for the seasonal variation in total alkalinity (TA). In terms of dissolved inorganic carbon (DIC), in addition to biological process and mixing, its seasonal variation was affected by air–sea exchange and coral metabolism to some extent. Different from the former, the other CO2 parameters, total scale pH (pHT), partial pressure of CO2 (pCO2), and aragonite saturation state (ΩA), were mainly controlled by a combination of the temperature change, biochemical processes, air–sea exchange, and coral metabolism, while water mixing has little effect on them. In addition, our results indicated that coral communities could significantly increase the DIC/TA ratio by reducing the TA concentration and increasing the DIC in the reef waters, which may promote the acidification of local seawater and need attention.

An assessment of HgII to preserve carbonate system parameters in organic‐rich estuarine waters

AbstractThis work assesses the effectiveness of sample preservation techniques for measurements of pHT (total scale), total dissolved inorganic carbon (CT), and total alkalinity (AT) in organic‐rich estuarine waters as well as the internal consistency of measurements and calculations (e.g., AT, pHT, and CT) in these waters. Using mercuric chloride (HgCl2)‐treated and untreated water samples, measurements of these carbonate system parameters were examined over a period of 3 months. Respiration of dissolved organic matter in untreated samples created large discrepancies in CT concentrations (~37 μmol kg−1 increase, p < 0.0001), while CT was effectively constant in treated samples (3095.0 ± 1.14 μmol kg−1). AT changes were observed for both treated and untreated samples, with HgCl2‐treated samples showing the greatest variation (~ 26 μmol kg−1 decrease, p < 0.001). In response to changing AT/CT ratios, pHT changes occurred in both treated and untreated samples but were relatively small in treated samples. Results in organic‐rich estuarine waters that reflect the in situ carbonate system characteristics of the samples at the time of collection can be improved when samples obtained for CT and AT analysis are collected and stored separately. Accurate analyses of CT can be obtained by filtration and preservation with HgCl2. Accuracy of AT analyses can be improved by filtration and storage without adding HgCl2. The quality of pHT measurements can be improved by prompt analysis in the field and, if this cannot be accomplished, then samples can be preserved with HgCl2 and measured in the laboratory within 1 week.

Groundwater quality evaluation of Narmada district, Gujarat using principal component analysis

In the present study, the ground water quality parameters were monitored during pre- and post-monsoon seasons across Narmada district, Gujarat, India. Monitoring was done in 89 drinking water samples collected by grid sampling method from the study area. Uranium and fluoride were analyzed along with associated parameters such as pH, dissolved oxygen, Cl−, NO3−, F−, SO42−, total alkalinity, total dissolved solids and hardness. In 4% samples the fluoride content was found to be above WHO permissible limits of 1.5 mg/L (2.36 mg/L in Undaimandava, 1.55 mg/L in Shira, 3.04 mg/L in Fatehpur and 1.83 mg/L in Dholivav) during pre-monsoon season (PRM) and 4.74 mg/L, 2.41 mg/L, 2.34 mg/L and 3.99 mg/L respectively in Bantawadi, Shira, Undai Mandava and Fatepur villages during post-monsoon (POM). The uranium level was within WHO limits in both POM and PRM seasons. The quality of the water was evaluated by Principal Component and Pearson Correlation statistical analysis techniques. The PRM and POM correlation study indicated a strong correlation of TDS with EC, Chloride, total alkalinity and bicarbonate and U while moderately strong correlation of TDS with fluoride were observed indicating that chloride, total alkalinity, bicarbonate, U and fluoride contributed to TDS and EC. Principal component analysis was applied for 14 variables, from which 3 factors were extracted during PRM and POM seasons. The extracted components, contributed 84.391% and 83.315%, to variation during PRM and POM seasons respectively. The study indicated that the analyzed water samples in Narmada district were safe for drinking purpose. However, Tilakwada tehsil groundwater was observed to be unsustainable for drinking, without further water treatment, but was appropriate for agricultural purposes. The study will help the residents of the district to understand the present water quality status and will also help in future management to protect the ground water of Narmada district.

Evaluation of the physicochemical properties and bacterial loads of selected rivers in Ondo State, Nigeria.

Water is crucial to human existence but may be contaminated with microorganisms, thus making it unfit for consumption. This study aimed to evaluate the physicochemical properties and bacterial loads of selected river waters in Ondo State, Nigeria. Ten major rivers were sampled between April and August, 2021. The pH, temperature, total alkalinity, colour, turbidity, electrical conductivity, dissolved oxygen, ammonium, aluminium, organic matters, nitrate levels including the microbial loads were determined according to standard procedures. Confirmation of identified isolates was achieved by API 20E and API 20NE. The turbidity, colour, conductivity, ammonium, and aluminium ranged from 4.3 to 15.2 NTU, 4 to 20 NTU, 123.5 to 580.2 mgL-1, 0 to 3.5 mgL-1, and 0.05 to 1.7, respectively. Most physicochemical parameters showed no significant differences from the WHO permissible limits for drinking water (p > 0.05). The total viable bacterial count in the rivers ranged from 1.5 × 105 to 6.3 × 105 CFUmL-1, while the total coliform count ranged from 1.3 × 103 to 4.8 × 103 CFUmL-1. The predominant bacteria were Escherichia coli and Pseudomonas aeruginosa. This study revealed that the physiochemical properties of the waters were majorly within the WHO permissible standards but with significantly higher bacterial loads.

AN EXPERIMENTAL STUDY TO EVALUATE THE EFFICACY OF SPHATIKA IN THE PURIFICATION OF CONTAMINATED WATER W.S.R TO QUARTZ.

Water being the most essential and basic of life; it must be pure and free from any contaminants. Polluted water is main reason for waterborne diseases. Considering this, an experiment has conducted to study the efficacy of quartz in the purification of contaminated water which is simple and easy. Aims and Objectives: To carry out the experiment using Sphatika (Quartz) to evaluate its efficacy in the purification of contaminated water. Meth-odology: The water sample was taken in a glass bottle of 500ml; 1st group was used without any materials. Sec-ond group was subjected to filtration. Third group was added with Sphatika (quartz) in the quantity of 10, 25 and 50 grams. Each of the samples was assessed after 6, 12 and 24 hrs: for the physical, chemical and microbial pa-rameters. Results: Quartz reduces Salinity, Total Hardness (TH) and Magnesium; and increases pH, Conductivi-ty, Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Total Alkalinity (TA), Carbonate and Bicarbonate. While there was no change in Calcium. After adding of quartz, the microbial colony count further increased. Conclusion: Quartz showed positive results in some of the parameters. It doesn’t possess an antibacterial effect. It can be used as a medium in filters.

Biodegradation Assay of Heavy Metals and Dyes Decolorization in Textile Industrial Effluent using Laccase Isolated from Pleurotus ostreatus

This study focused on the isolation of laccase enzyme from the fungus Pleurotus ostreatus and its application in the biodegradation of various pollutants present in textile industrial effluent, including chemicals, ions, salts, heavy metals, brittle metals, total suspended solids, total dissolved solids, chemical oxygen demand, biological oxygen demand, minerals, total hardness, total alkalinity, turbidity, electrical conductivity, and dyes. Textile industrial effluent poses a significant threat to the environment, contaminating water bodies and posing risks to human, animal, and plant life. This study employed an economical and ecofriendly biological approach for wastewater treatment, distinguishing it from traditional physical and chemical methods. The optimum temperature of laccase is found to be 30 degree Celsius and pH is 3. Enzyme activity of laccase is 7.25 U/ml. This fugal laccase decolorizes textile Industrial dye effluent containing various dyes, such as Turquoise VG, Black B, Yellow R, Methyl red, Trypan blue, and Acid Orange 7. Laccase depicts maximum decolorization efficacy on Black B dye. Similarly, Laccase from P.ostreatus shows higher decolorization efficacy when compared to other fungal laccase. Additionally, the study assessed the biodegradation of various wastewater quality parameters, including physical and chemical parameters like toxic heavy metals and ions. This research of isolation, characterization, and utilizing laccase from P. ostreatus for the bioremediation of textile industrial effluent wastewater containing dyes, toxic chemicals, ions and metals is effective, economical and ecofriendly.

Water Quality Assessment of Lower Usuma Dam Water from Treatment plant to points of Consumption in Federal Capital Territory, Nigeria

This study investigated and compared the bacteriological, physicochemical and heavy metals concentrations of drinking water quality of Lower Usuma Dam from treatment plant to the points of consumption in three Area Councils (Bwari, Abuja Municipal and Gwagwalada) of the Federal Capital Territory, Abuja, Nigeria. Most probable number technique was employed for coliform detection. Molecular characterization of isolated bacteria was carried out. Seven out of the 26 water samples analyzed in this study were contaminated in the range of 7 MPN/100ml to >23 MPN/100ml. Physicochemical parameters such as colour, pH, temperature, turbidity, total dissolved solids (TDS), total hardness, electrical conductivity, total alkalinity and seven heavy metals were also determined using Atomic absorption spectrophotometry. Results showed that Bwari had the highest value for colour, 16.67 Pt.Co while AMAC had the least with 1.00 Pt. Co, Gwagwalada had the highest pH value (7.33±0.12) and Bwari the lowest pH of 6.77±0.06. Bwari also had highest temperature of 30.23±2.80oC while AMAC recorded the least (27.29±0.26oC). Turbidity ranged from 1.86 to 2.83 NTU. The highest level of the other parameters [(TDS 54.27 mg/L, conductivity 90.10 µs/cm, total hardness 34.00 mg/L, total alkalinity 28.00 mg/L, Cl– 20.82 mg/L)] was observed in water samples from Gwagwalada Area Council. Gwagwalada recorded the highest values for iron and zinc at 0.09mg/l and 0.003mg/l respectively. Copper concentration was highest in AMAC (0.043mg/l) and lowest in Bwari area council (0.007mg/l). There was no significant difference (p>0.05) in the concentration of Cr detected in all the water samples. There is need for provision of adequate sanitation facilities and improvement on monitoring of distribution system in order to maintain drinking water quality and prevent water borne disease outbreaks.

Hydrothermal amorphous silica, barite and orpiment from the crater area of seamount (SM-13) off Nicobar island, Andaman sea: Indications for the development of a new hydrothermal field

The Andaman sea characterized by trench-arc-backarc elements (Andaman-Nicobar island-arc, the Andaman back-arc spreading center, the seamount complex, and the back-arc basin) is a complex active basin and is known for hydrothermal activity in some of the seamounts (subaerial and submarine) of the volcanic arc. In the present study, 13 submarine seamounts (SM1- SM13) in the southern Andaman volcanic arc, extending from 6°47′N: 94°43′E to 7° 56′ N: 94° 2.47′E, were surveyed onboard RV Sindhu Sadhana (November 2021) to find the evidences for the hydrothermal activity. Out of the 13 seamounts, at one crater seamount (SM-13) we have observed evidence for hydrothermal activity characterized by plumes rich in dissolved gases (mainly CO2) in the water column, live chemosymbiotic organisms (Bathymodiolus species), and neoforming minerals such as amorphous silica, barite and orpiment. We observed two plumes rich in dissolved gases (mainly CO2), called GP1 and GP2, in the water column at two different water depths i.e. 400 and 380 mbsl respectively. Geochemical analysis of the water samples shows enhanced TCO2 concentrations within the plumes rich in dissolved gases (mainly CO2) observed in sub-bottom profiler data, however, the dissolved methane concentrations do not show any enrichment when compared with ambient seawater concentrations. Apart from the enhancement in the TCO2 concentrations, pH and total alkalinity data also show fluctuations within the same depth zone which may be attributed to the hydrothermal plume exhausting from the crater seamount. The occurrence of live chemosymbiotic organism Bathymodiolus species indicate an active and continuous supply of H2S. The precipitation of neoforming hydrothermal minerals such as amorphous silica, tabular barite, and orpiment on the surface of the rock samples further supports the hydrothermal activity. Previous studies carried out in 2007 have reported hydrothermal ferromanganese oxides precipitated from low-temperature hydrothermal fluids (Surya prakash et al., 2012) and inferred SM-13 as a dormant submarine volcano (Kamesh Raju et al., 2012). However, after 14 years, we observe volatile emissions to the water column, hydrothermal mineral precipitation and live chemosymbiotic organisms from the same seamount. These observations of the present study infer development of a new hydrothermal field in the least explored Andaman Sea. This study adds up a new active site to the global hydrothermal inventory which may allow better estimation of global hydrothermal flux and its role in oceanic elemental cycle.

Acidity in rainwater and airborne suspended particles in the southwestern coast of the East Sea (Sea of Japan): Their potential impact on seawater total alkalinity

Our understanding of the impact of atmospheric acid deposition on marine carbonate system remains limited, largely due to a lack of data regarding acidity present in atmospheric particles and precipitation. Previous research has relied on the electroneutrality-based ion balance method for indirect estimation of atmospheric acidity. In this study, atmospheric samples collected at a coastal site of South Korea were mixed with seawater to measure the change in seawater total alkalinity (ΔTAAPL) associated with atmospheric proton loading. For the precipitation samples, the measured ΔTAAPL and electroneutrality-based estimates showed a significant correlation. However, we did not observe similar results for the atmospheric particle samples. Furthermore, the decrease in oceanic TA due to ΔTAAPL was substantially smaller than that in dissolved inorganic carbon from concurrent nitrogen fertilization. Consequently, the adverse impact of acid deposition on ocean acidification or air-sea exchange of CO2 appears to be insignificant on a short-term scale.

Water quality management of Shrimp culture in Temporary Ponds

Studies were carried out on the physico-chemical parameters of pond water used for shrimp culture. The physical parameters studied were air and water temperature, water depth and transparency, total solids (TS), total dissolved solids (TDS) and total suspended solids (TSS). Chemical parameters studied were pH, salinity, total alkalinity and dissolved inorganic phosphates. These were recorded from the day of culture till the harvest period at 30 days interval. Air and water temperature were increased from the day of culture till the harvest period. Transparency of the water used for the culture was high (40±0.1cm) during initial days and reduced thereafter. Water depth was increased from the day of culture till the harvest period. Suspended and total solids recorded were high on day 90 and total dissolved solids were high (20±1.2mg/l) on the day of culture and harvest. The level of pH recorded was high (8.3±0.0) on day 60 and the level of salinity and total alkalinity recorded was high on day 30. The dissolved inorganic phosphate level was high (1.0±0.0mg/l) on the day of culture which became reduced during the growth and harvest period of shrimp. The feed consumption and gain of body weight were also recorded on each 10 days interval. The body weight was increased as the day of culture was increased and it was positively correlated with the quantity of the feed consumed.

Evaluate the use of flower waste biosorbents for treatment of contaminated water

Human and industrial activities have contaminated the groundwater and surface water. This is a significant issue today. Therefore, the analysis of water quality is crucial. The purpose of this study is to evaluate the water quality index (WQI) of groundwater at various locations for physiochemical analysis. For calculating the current water quality status using statistical analysis and in the water quality index, the following parameters were considered: pH, total dissolved solids, total alkalinity, chlorides, hardness, dissolved oxygen, Biochemical oxygen demand, and chemical oxygen demand. The acquired results are compared to the Indian drinking water standard IS: 10500–2012. The investigation of the physicochemical and biological characteristics of this ground water sample indicates that the evaluation of water quality parameters and resources is necessary. In the water quality index of six different places Gudlavalleru, Ainampudi, Penjendra, Gudlavalleru Gudem, Angaluru and Kondiparru. In the six locations the pH value vary from (6.72–8.3), temperature vary from (34 °C-36.5 °C), acidity vary from (15–40), alkanity vary from (10–25), turbidity vary from (0.8–60.4), DO vary from (3.7–6.2), COD vary from (209–477), Iron vary from (3–5), fluorides is zero, phosphorous vary from (0–0.5), ammonium vary from (0–1), nitrates vary from (0–5), chlorides vary from (375–575), hardness vary from (200–505), nitrites vary from (0–1), total solids vary from (729–1573), suspended solids vary from (468–971) and dissolved solids vary from (301–602). Using dry flowers biosorbents for biosorptions of heavy metals from polluted water or treat contaminated groundwater. Biological reactions occur to control the concentration of contaminated water when fine, dried powder of flower waste biosorbents is added to contaminated water. In this study, we employ four different flower waste biosorbents, including Targets or marigold flower waste, Ixora-coccinea flower waste, Hibiscus flower waste, and Allamanda flower waste. The Targets or marigold flower waste biosorbents have the highest performance for removing toxic metals from contaminated water among the four flower waste biosorbents. Further optimization of the various parameters, i.e. biosorbents dosage, contact time, pH, temperature, and agitation speed, was performed on Targets or marigold flowers waste biosorbents in order to increase pollutant biosorption. Further research is required into the mechanisms of biosorbents, the kinetics and reusability of metal uptake, the recovery and regeneration of biosorbents, process design, and the commercial application of Targets or marigold flower refuse biosorbents.

Isolation, characterization, structural elucidation and in vivo hepatoprotective studies of phytoconstituents obtained from the fruits of <i>Cordia obliqua</i> Willd

Purpose: To isolate, characterize, and investigate the hepatoprotective effect of phyto-constituents from fruits of Cordia obliqua Wild in paracetamol-induced hepatotoxicity in Wistar rats.
 Methods: Ethanol and aqueous extracts of C. obliqua fruits were screened for phytochemicals. The extracts were subjected to column chromatography and preparative thin-layer chromatography (TLC) to isolate four novel compounds. Compounds were characterized using infrared spectroscopy (IR), mass spectroscopy (MS), as well as 1H and 13C nuclear magnetic resonance (NMR). The isolated compounds were assessed for acute toxicity, in vivo hepatoprotective and antioxidant potential (dose: 5 mg/kg) in paracetamol-induced (75 mg/kg) hepatotoxicity through oral route in Wistar rats.
 Results: Phytochemical analysis of ethanol (COE) indicated the presence of fatty acids, anthraquinones, glycosides, saponins, alkaloids, tannins, flavonoids, coumarins, phenolics, triterpenes, and sterols. Compounds A, B, and C were identified from COE. Treatment at 50 mg/kg significantly reduced aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGTP), and total bilirubin (TB), as well as increased total protein and total alkalinity levels in serum compared to the positive control. Liver histo-architecture showed improvements compared to the positive control, indicating hepatic protection.
 Conclusion: The isolated compounds (A, B and C) from COE exhibit hepatoprotective effects attributed to flavonoids and phenolics with free radical scavenging properties. Further research is needed to identify key mechanisms responsible for hepatoprotective effects.

Spatio-temporal variability of surface chlorophyll and pCO2 over the tropical Indian Ocean and its long-term trend using CMIP6 models

Under the global climate change scenario, ever-increasing ocean temperatures and elevated carbon dioxide (CO2) concentration levels in the ocean and atmosphere significantly affect ocean biogeochemistry. The spatiotemporal distribution of chlorophyll and partial pressure of CO2 (pCO2) over the Indian Ocean (IO) are investigated using satellite, in-situ, and simulations from eleven Coupled Model Inter-comparison Project phase 6 models. All the models show negative bias near the Somali region over the Arabian Sea (AS) during the southwest monsoon season. The CESMs and CanESM5 models show relatively less bias over the tropical IO except for the AS in all seasons compared to other models. The annual cycle of pCO2 shows a bimodal characteristic, with the first peak in May and the other in October over the northern IO, which the CanESM5, IPSL, and MPIs models reasonably well capture. All the models produce the phase of the annual cycle of pCO2 reasonably well for the southern IO. The pCO2 distribution and its trend decomposition are estimated using the multimodel mean from the CanESM5, IPSL-CM6A-LR, and MPIs models, suggesting that the increase in dissolved inorganic carbon is the dominant factor that contributes to about 70 % of the rise in the total pCO2 trend, and the total alkalinity and sea surface temperature have a secondary role. Region-wise analysis manifests that the southern IO and AS exhibit maximum susceptibility to the long-term variations in the pCO2 trend caused by the changes in dissolved inorganic carbon levels in the ocean. The study discusses substantive factors leading to the variability in the biogeochemical properties of the IO as simulated by these models and, thus, the possibilities for future improvements.

Seasonal Variations of some Physico-chemical Properties of Drinking Water in Akre District, Kurdistan Region – Iraq

Drinking water considers one of the main concerns in most developing countries. The current study aimed to evaluate the quality of drinking water in Akre district, Kurdistan Region – Iraq in four different seasons, and to compare them with WHO standards. Drinking water samples were collected from seven densely populated quarters of the city. The samples were analyzed for their physico-chemical and heavy metal quality. Physico-chemical parameters were temperature, turbidity, Electrical conductivity “EC”, pH, Total Dissolved Solids “TDS”, Chlorine “Cl- ”, Sulphate “SO4-2”, Nitrate “NO3”, Sodium “Na+”, Zinc “Zn”, Copper “Cu”, total alkalinity, total hardness, Cadmium “Cd” and Plumbum “Pb”. These are indications of polluted water and weak treatment practice, which in turn will cause many human health problems. The results from this study showed that almost all the water samples were normal in compare to the WHO guidelines, except for the total alkalinity, total hardness, Cd and Pb, were showed to be higher than WHO standards in some locations. Therefore, the study recommends the city authorities to improve their drinking water treatment or use alternative water supply to have a better drinking water.

Autonomous high-frequency time-series observations of total alkalinity in dynamic estuarine waters

Total alkalinity (TA) is a variable that reflects the acid buffering capacity of seawater, and is key to studies of the global carbon cycle. Daily and seasonal TA variations are poorly constrained due to limitations in observational techniques, and this hampers our understanding of the carbonate system. High quality and high temporal resolution TA observations are required to constrain the controlling factors on TA. Estuarine and coastal waters usually have low TA values and may experience enhanced remineralization of organic matter in response to processes such as eutrophication and terrestrial organic matter input. Therefore, these waters are considered vulnerable to acidification as a consequence of ongoing atmospheric anthropogenic carbon dioxide uptake. An In Situ Analyzer for seawater Total Alkalinity (ISA-TA) was deployed for the first time in low salinity, dynamic estuarine waters (Kiel Fjord, southwestern Baltic Sea). The ISA-TA and a range of additional sensors (for pH, pCO2, nitrate and temperature, salinity, dissolved oxygen) used to obtain ancillary data to interpret the TA variability, were deployed on a pontoon in the inner Kiel Fjord for approximately four months. Discrete samples (for TA, nutrients including NO3−, soluble reactive phosphorus (SRP) and H4SiO4, chlorophyll a) were collected regularly to validate the ISA-TA and to interpret the TA data. The effects on TA in the study area of nitrate uptake and of other processes such as precipitation, run-off and mixing of different waters were observed. The difference between the TA values measured with the ISA-TA and TA of discretely collected samples measured with the Gran titration method was −2.6 ± 0.9 μmol kg−1 (n = 106), demonstrating that the ISA-TA provides stable and accurate TA measurements in dynamic, low salinity (13.2–20.8), estuarine waters. The TA and ancillary data recorded by the sensor suite revealed that physical mixing was the main factor determining the variability in TA in Kiel Fjord during the study period.

Arctic Permafrost Thawing Enhances Sulfide Oxidation

AbstractPermafrost degradation is altering biogeochemical processes throughout the Arctic. Thaw‐induced changes in organic matter transformations and mineral weathering reactions are impacting fluxes of inorganic carbon (IC) and alkalinity (ALK) in Arctic rivers. However, the net impact of these changing fluxes on the concentration of carbon dioxide in the atmosphere (pCO2) is relatively unconstrained. Resolving this uncertainty is important as thaw‐driven changes in the fluxes of IC and ALK could produce feedbacks in the global carbon cycle. Enhanced production of sulfuric acid through sulfide oxidation is particularly poorly quantified despite its potential to remove ALK from the ocean‐atmosphere system and increase pCO2, producing a positive feedback leading to more warming and permafrost degradation. In this work, we quantified weathering in the Koyukuk River, a major tributary of the Yukon River draining discontinuous permafrost in central Alaska, based on water and sediment samples collected near the village of Huslia in summer 2018. Using measurements of major ion abundances and sulfate () sulfur (34S/32S) and oxygen (18O/16O) isotope ratios, we employed the MEANDIR inversion model to quantify the relative importance of a suite of weathering processes and their net impact on pCO2. Calculations found that approximately 80% of in mainstem samples derived from sulfide oxidation with the remainder from evaporite dissolution. Moreover, 34S/32S ratios, 13C/12C ratios of dissolved IC, and sulfur X‐ray absorption spectra of mainstem, secondary channel, and floodplain pore fluid and sediment samples revealed modest degrees of microbial sulfate reduction within the floodplain. Weathering fluxes of ALK and IC result in lower values of pCO2 over timescales shorter than carbonate compensation (∼104 yr) and, for mainstem samples, higher values of pCO2 over timescales longer than carbonate compensation but shorter than the residence time of marine (∼107 yr). Furthermore, the absolute concentrations of and Mg2+ in the Koyukuk River, as well as the ratios of and Mg2+ to other dissolved weathering products, have increased over the past 50 years. Through analogy to similar trends in the Yukon River, we interpret these changes as reflecting enhanced sulfide oxidation due to ongoing exposure of previously frozen sediment and changes in the contributions of shallow and deep flow paths to the active channel. Overall, these findings confirm that sulfide oxidation is a substantial outcome of permafrost degradation and that the sulfur cycle responds to permafrost thaw with a timescale‐dependent feedback on warming.

The assessment of Plankton diversity in Yamuna River at selected sites in Haryana: A post-COVID-19 Study

The study was conducted in three sampling sites: Yamunanagar, Panipat, and Faridabad, along the Yamuna River. The samples were collected monthly from selected sampling sites from September 2021 to April 2022. Depending on their nature, plankton can be separated into two major groups, phytoplankton and Zooplankton. The qualitative analysis of these four samples in one site revealed that there are 17 genera of phytoplankton in total, belonging to four major groups, (i) Bacillariophyceae (consisting of 3 genera), (ii) Chlorophyceae (consisting of 10 genera), (iii) Euglenophyceae (consisting two genera), (iv) Cyanophyceae ( consisting three genera). A total of 30 genera of Zooplankton belong to four classes i) Protozoa, ii) Copepoda, iii) Cladocera and iv) Rotifers. Copepoda included ten genera, Cladocera included 13 genera, Rotifers included 05 genera, and Protozoa represented by two genera only. The diversity of phytoplankton was maximum in a segment first Yamunanagar (value of Simpson’s index is lower than 0.3416). The diversity of Zooplankton was maximum in segment first and almost equal to segment second Panipat. The temperature of river water ranged from 8.38±0.08 –21.33±0.13 °C, pH range from 6.00±0.11 - 8.03±0.11, D.O. from 1.68±0.06 – 8.10±0.007mg/l, total alkalinity from 83.25±0.48 – 351.75±11.89mg/l and total hardness 121.75±1.93 – 279.25±6.29mg/l.

Risk assessment for the distribution and levels of fluoride and nitrate in groundwater in a semi-arid area of northern Mexico

This study assessed groundwater quality and associated risks in a semi-arid region located in a city in the Northern zone of Mexico. To conduct this study, we collected 92 groundwater samples and analyzed 14 physicochemical parameters across 18 sectors. Only fluoride (F−) and nitrate (NO3–N) exceeded Mexican regulations and WHO guidelines for drinking water. Approximately 65 % of samples surpassed the 1.5 mg/L permissible limit for F−, with the highest recorded concentration reaching 3.60 mg/L in two sectors among the 18 studied, 34 % of samples exhibited NO3−-N concentrations in the 10.64–17.27 mg/L range across three sectors, surpassing permissible levels. Pearson Correlation Analysis revealed strong positive correlations with HCO3−, EC, Mg2+, Ca2+, NO3−, Cl−, SO42−, and Na+. Moderate correlations existed for the total hardness, alkalinity, Cl−, NO3−, SO42−, Na+, Mg2+, and EC. K+ showed weak correlations. PIG values indicated significant pollution of F− in all of 18 sectors (PIG <1). HQ for F− exceeded tolerable levels in 14 adult and 16 child sectors, posing an intolerable risk. Nitrate's HQ was below <1 for all age groups, suggesting non-carcinogenic effects. THI indicated high F− and NO3−-N exposure risks for children in the study area. It is recommended to implement effective water treatment technologies, such as reverse osmosis or adsorptive materials, in those sectors reported as a potential risk to human health to ensure access to safe drinking water.

Variability of total alkalinity in coastal surface waters determined using an in-situ analyzer in conjunction with the application of a neural network-based prediction model

Total alkalinity (TA) is an important variable of the ocean carbonate system. In coastal oceans, carbonate system dynamics are controlled by a range of processes including photosynthesis and respiration, calcification, mixing of water masses, continental inputs, temperature changes, and seasonal upwelling. Assessments of diel, seasonal and interannual variations in TA are required to understand the carbon cycle in coastal oceans. However, our understanding of these variations remains underdeveloped due to limitations in observational techniques. Autonomous TA measurements are therefore required. In this study, an in situ TA analyzer (ISA-TA) based on a single-point titration with spectrophotometric pH detection was deployed in Tong'an Bay, Xiamen, China, over a five-month period in 2021 to determine diel and seasonal TA variations. The TA observations were combined with an artificial neural network (ANN) model to construct TA prediction models for this area. This provided a simple method to investigate TA variations in this region and was applied to predict surface water TA between March and April 2021. The in situ TA observations showed that TA values in Tong'an Bay varied within a range from 1931 to 2294 μmol kg−1 over the study period, with low TA in late winter, early summer and late summer, and high TA in early winter. The TA variations in late summer and early winter were mainly controlled by mixing of water bodies. The diel variations of TA were greatly determined by tides, with a diel amplitude of 9 to 247 μmol kg−1. The ANN model used temperature, salinity, chlorophyll, and dissolved oxygen to estimate TA, with a root-mean-square error (RMSE) of ∼14 μmol kg−1, with salinity as the input variable with the greatest weight. The approach of combining ISA-TA observations with an ANN model can be extended to study the carbonate system in other coastal regions.