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Radionuclides dating have been applied in the chronological series of sediment core recovered from Satopanth Tal to estimate the sedimentation rate and its age. Several models include CRS and slope method, and 137Cs peak methods have been adopted. The depth concentration of 210Pbexc in the core determines the various parameters like sedimentation rate, geochronology, inventory, and mass fluxes. The CRS model and slope method infer the sediments deposited at a rate of 0.79 ± 0.04 cm/year dated to 120 years. Distinct peaks on 1963 and 1986AD, the 137Cs record estimate the mean sedimentation rate is 0.745 ± 0.03 cm/year respectively and dated to 77 years.

Estuaries are highly dynamic zones. They are confluence of sea, river, tributaries, effluents, and runoff water that modify constantly their physical conditions and affect growth, productivity, and survival of inhabiting biota. In the current study, we investigated the extent to which estuarine sediment fractions explain variation of grain size parameters (mean size: Mz, standard deviation: σI, skewness: Ski and kurtosis: KG), fish diversity, and phytoplankton richness in estuaries. We applied series of multivariate regression models and controlled for the effect of sediment origin, season, and measurement method. The models output showed that sand fraction explained consistently variation of all the four grain size parameters. However, silt fraction was significantly associated with Mz, Ski, and KG but not σI. We couldn't detect any significant relationship between sand or silt fraction with fish diversity. In contrast, we found that high richness in phytoplankton species was associated with low sand and low silt conditions. We therefore conclude that it is possible to reliably estimate Mz, σI, Ski, KG, and phytoplankton richness from sand and silt fractions. Moreover, managing sand and silt fractions ejected in estuaries may be an alternative of protecting and restoring estuarine biodiversity.

This work presents a piece of initial information about the estimation of the sedimentation rate for Lake Pykara. In this investigation, a chronological sequence of sediment core was set up dependent on 137 Cs and 210 Pb ex analysis to study sediment accumulation rates in Lake Pykara. Caesium-137 (Cs) is an artificial radionuclide and is regularly utilized in building up the chronology of lake sediments in the Anthropocene period. The unsupported 210 Pb profile shows a non-exponential decline of 210 Pb activity with sediment depth. Sedimentation rates dependent on global atmospheric nuclear weapon maximum fallout of 137 Cs (1963) bolster the utilization of the consistent rate of 210 Pb supply (CRS) model in core sediments. The geochronology studies of the core were performed using the 137 Cs method, to evaluate the model of time changes in the sediment. The 137 Cs radioactivity was resolved directly by gamma spectrometry and fluctuated from 13.11 ± 1.3 Bq kg −1 for top layers to 1.21 ± 0.1 Bq kg −1 for the bottom of the core. Two trademark peaks of 137 Cs radioactivity identified with the global fallouts after atomic weapons testing and the Chernobyl mishap were observed and used to affirm the 210 Pb dating method. Radioactivity of 210 Pb ex ranged from 8.00 ± 1.0 to 1.40 ± 0.1 Bq kg −1 . The mean sedimentation rate evaluated from both models was 0.71 ± 0.06 cm year −1 , while the estimated age of Lake Pykara was 514.08 years ( 137 Cs) and 521.43 years ( 210 Pb ex ), respectively.

In the current scenario, the pristine Himalayan Wetlands are under endangerment due to higher sedimentation rate, including siltation, reduction of ecological value, pollution, and significant anthropogenic encroachment along with advanced civilization. The more increased sedimentation reduces the depth and existing expansion of the Wetland. This study articulates the record of sedimentation in the Chandratal present in Western Himalaya, Himachal Pradesh, India, at the altitude of 4300 m. The sedimentation rate of the Chandratal was calculated based on a 1-m core sample considering isotopes of 137 Cs and 210 Pb dating techniques. The present study based on the Constant Rate of Supply (CRS) model of 210 Pb reveals that the Wetland experienced an average sedimentation rate of 1.75 ± 0.04 cm/year during the last 63 years observed from 1953 to 2016. The 137 Cs peak method–based calculated sedimentation rate of the Chandratal is 1.6 ± 0.02 cm/year representing the years for about 62 years from 1954 to 2016. The Wetland’s functional survival prevalence was estimated to be 420 and 459 years based on 210 Pb and 137 Cs dating techniques, respectively. The study communicates that the magnified human interference in the catchment area of the Chandratal is accountable for the faster sedimentation in recent years.

Globally, the concentration of heavy metals and sediment toxicity analysis are significant liabilities to aquatic environments. This scrutiny outlines the sediment textures, heavy metals and toxicity status associated with environmental pollution indices in the core sediment of the Cauvery and Vettar estuaries, East coast of India. The impact of rapid industrialization, urbanization, harbour activities and agricultural activities influences on the twain estuary is a significant concern to designate the environment. The contamination status of the sediments affects the potential biodiversity, ecological risks and human health. A total of two core sediments were recovered from the Cauvery and Vettar estuaries in March 2023 to decipher the environmental pollution status. Meticulous observation of the textural studies underscores the prevalence of sand content in Cauvery, and Vettar sediments consist of predominate clay content and minor silt contents. Furthermore, the organic matter is augmented in the Vettar River due to the higher input of waste disposal, seaweeds and algae due to the surrounding landmass. Twain core sediments argue that heavy metal concentration is decreasing in order as Fe > Zn > Ni > Pb > Cu > Cr by using portable X-ray fluorescence (pXRF) spectrometry. Remarkable results of environmental pollution indices such as I geo , E f , C f , C d and m C d state very highly polluted, extreme enrichments, high contamination and very high degree of contamination. Furthermore, the potential ecological risk indices such as PLI, SQG s, and PERI argue polluted, medium to high toxicity and moderate adverse ecological risk to the estuarine regions. Statistical analysis of the heavy metal affirms the enrichment of Fe metals may derive from lithogenic and/or anthropogenic influences, and the other studied metals such as Cu, Ni, Zn, Pb and Cr may be influenced by the anthropogenic activities in the aspect of point and non-point pollution sources. This could result from both estuaries undergoing higher pollution, in which the Vettar estuary is a considerable environmental risk zone compared to the Cauvery river due to the impact of industrial effluents and rapid urbanization activities. This finding underscores the urgent need for enhanced estuarine sediment quality study and comprehensive assessment of sediment toxicity, regulating the beneficial acumen for the government to follow the suitable remediation on the embellish policy of river and marine environments.

The research article appraises the environmental pollution status and health risk assessments associated with heavy metal concentration in the Gadilam (study site I) and Uppanar (study site II) river surface sediments within the quaternary formation, part of Kallakurichi and Cuddalore district, Tamil Nadu, India. By analyzing the heavy metal concentration and environmental pollution zone and health risk assessments, the outcome fosters the insights of an intensifying risk to riverine regions and their ecological implications due to anthropogenic activities. Totally 27 sediment samples were collected from study sites I and II to assess the contagion status of the sediments and monitor the riverine environment. Heavy metal (Fe, Al, Ti, Mn, Cu, Zn, Ni, Pb, and Cr) concentrations were determined in surface sediments, addressing the influences arising from anthropogenic activities. To decipher the pollution status, the pollution monitoring indices, like geoaccumulation indices ( I geo ), enrichment factor ( E f ), contamination factor ( C f ), degree of contamination ( C d ), and modified degree of contamination ( m C d ), pollution load index (PLI), potential ecological risk indices (PERI), and sediment quality guidelines (SQGs) such as mean effects range median quotient (MERMQ), toxic risk index (TRI), and modified hazard quotient (mHQ), were used in the study area. Health hazard assessment stated non-carcinogenic risk and carcinogenic risk were analyzed for adults and children in study sites I and II. Subsequently, statistical analysis were performed. The outcome possessed the pollution assessment of study site I (location – 05 and 06) and study site II (location—03), which implies that they are extremely polluted and have high potential adverse biological effects. This study emphasized the non-carcinogenic risk assessment of hazard index (HI) for study sites I and II sediments shown to be endangered to adults and children in the surrounding region. Furthermore, the carcinogenic risk assessment accounted for no hazards for adults and children in the study site. This study revealed heavy metal contamination in the Cuddalore district, likely arising from industrial effluents, residential wastages, and anthropogenic activities in the surface sediments of riverine environment, and it provide insights into health risk assessment and environmental pollution status to foster the local communities’ awareness and an invaluable dataset to generate environmental safety management measures.

A study describes the use of natural (210Pb) and anthropogenic (137Cs) radiometric dating techniques to determine sedimentation rates and age of Kodaikanal Lake. The core sediment from 46 cm was collected and analyzed for 210Pb and 137Cs using an Alpha spectrometer 7200-04 and a Gamma-ray spectrometer GC-3520. Bathymetry studies aided in selecting a representative sample location and measuring the lake's underwater depth, with maximum and mean depths of 11 and 3.38 m, respectively. The maximum and minimum dry bulk density ranged from 0.57 to 1.05 g/cm3 (mean of 0.73 g/cm3), and the weight percentage of porosity collected sediment sample ranged from 60.33 to 78.63 wt.% (mean of 72.32 wt.%). This study determined the sediment grain size and the percentages of sand, silt, and clay. The findings indicate that the core sediment samples contain 56.05 to 69.62 wt.% (mean of 63.21 wt.%) sand, 28.03 to 41.71 wt.% (mean of 34.55 wt.%) silt, and 1.81 to 3.98 wt.% (mean of 2.34 wt.%) clay. The 210Pb technique was used to assess a model of time changes in the deposit for geochronology studies in core sediments. The sedimentation rate depended on the consistent rate supply (CRS) of the 210Pb model. The 210Pb model was confirmed using 137Cs radioactivity released into the global fallout after nuclear testing (1963) and the Chernobyl accident (1986). The depth concentration of 210Pb ranged from 3.89 ± 0.1 to 15.4 ± 1.6 Bq/kg, with a mean of 210Pb concentration is 7.23 ± 0.86 Bq/ kg. The 137Cs radioactivity varied from the upper and lower peaks that appeared clearly at depths of 16 and 29 cm, respectively, with successive phases of 18.68 ± 1.36 and 22.04 ± 1.4 Bq/kg. According to the CRS model, the mean sedimentation rate was 0.51 ± 0.14 cm/year, and the core age was 86 years. The 137Cs have likely been the mean sedimentation rate of 0.535 ± 0.07 cm/year and 83 years. The evaluated life of Kodaikanal Lake as an average of 210Pb and 137Cs sedimentation rate since 1933 is about 650 ± 24 years and 582.75 ± 19 years.

This present investigation delves into the intricate 210 Pb and 137 Cs radionuclides dating to govern the study of sedimentation rate, age modeling, and lifespan of the Perumal lake in the Cuddalore district, Tamil Nadu. In the study area, the 01 core sediment was excavated at the length of 51 cm, and concern for the 210 Pb and 137 Cs radionuclides dating using an Alpha spectrometer 7200-04 and a Gamma-ray spectrometer GC-3520 instruments. From the robust outcome, the bathymetry survey investigates the bottom topography, with a mean depth of 3.1 m and a maximum length of 11.54 km. Subsequently, the mean value of bulk density, porosity, and water content in the vertical profile of the sediment esteems as 1.52 g/cm 3 , 32.47 g/cm 3 , and 1.61%, and sediment textures unveils predominately consists of clay composition and attributes with higher content of 210 Pb radionuclide in the sediments to affirms the rate and accumulation of the sediments in the aquatic environment. From the Constant Rate Supply (CRS) method, the 210 Pb radionuclide activity shows the mean accumulation rate (kg/m 2 /year) and sedimentation rate (cm/year) indicates 0.57 ± 0.05 (kg/m 2 /year) and 0.84 ± 0.07 (cm/year) dated since 1944AD to 2023AD. The mean sedimentation rate of 137 Cs radionuclides activity for 1963AD and 1986AD implies 0.57 ± 0.04 (cm/year) and 0.43 ± 0.03 (cm/year). From the computation, the lifespan of the lake is 369.05 years and 543.86 years with respect to 210 Pb and 137 Cs activities, respectively. The sedimentation rate is crucial in diminishing the lake from the future accumulation of water and sediments in the aquatic environments.

The manuscript investigates the sediment textures, heavy metals, and magnetic susceptibility analysis of the Cauvery and Vettar core sediments to affirm the pollution status by coupling environmental magnetism and geochemical studies. Pollution indices such as the Geoaccumulation Index, enrichment factors, and contamination factors were used to evaluate the pollution status. Fastidious inspection of the textural characteristics of the core sediments implies that the Cauvery core chiefly comprises sand and silt, whereas Vettar core sediments consist of silt and clay compositions. The magnetic susceptibility of the Vettar sediments implies higher magnetic contents than the Cauvery sediments. Notably, the profound inquisition illustrates the mean concentration of the studied heavy metal concentrations (Fe, Cu, Cr, Zn, Pb, Ni) for both core sediments did not exceed the mean world sediments and the Earth’s crust standards. Employing the pollution indices reflects the concentration of heavy metals in both core sediments, which infers environmental contamination. The result implies that the Vettar estuarine sediments show a mixed nature of magnetic grains (maghemite minerals) coupled with clay and silt composition, followed by the Cauvery estuarine sediments showing slighter magnetic susceptibility, which reflects that the Cauvery core sediments are less prone to pollution. However, the non-superparamagnetic grains indicate primarily sand and minor silt composition, reflecting ferromagnetic lithogenic minerals such as magnetite and hematite magnetic components. The statistical techniques establish the relationship between the magnetic susceptibility of χlf value higher in the core sediments depending on the heavy metal contents, clay, and organic matter.

The current study examines physicochemical parameters and the water quality index and spatial interpolation analysis of water samples collected from the sacred, emerald green snow-fed lakes of Satopanth Tal in Uttarakhand, India. It is near Badrinath, a Hindu pilgrimage site, at an elevation of 4600 m above sea level. The lake is covered with snow between the end of October and May. This is a glacial corrie moraine-dammed lake having a maximum depth of 17.5 m. To determine the suitability of the water for various purposes, thirteen physicochemical parameters were assessed and the water quality was determined. The spatial distribution of the physicochemical parameters throughout the lake was studied using the ArcGIS interpolation tool. The physicochemical parameters and water quality index values showed that the lake's water quality is excellent for domestic purposes based on World Health Organization/Bureau of Indian Standards drinking water standards. The Piper and Johnson plots revealed that the dominance of carbonate weathering contributed major ions to the lake. The sodium adsorption ratio, soluble sodium percentage, magnesium hazard, residual sodium concentration used to evaluating the irrigation water quality index indicated all water samples were good and can be used for irrigation. The lake has so far remained relatively unpolluted. This study will provide more information for future research and long-term management of the sacred lakes by taking corrective action and drafting a development plan.