Nearby River Research Articles

Effects of open dumping site on surrounding air, soil, and water: a case study of Biratnagar metropolitan city

Managing solid waste is one of the emerging challenges in urban areas, and open dumping and burning is common practices mostly in developing countries like Nepal. Which affects the overall surroundings. The study has investigated the effects of open dumping and burning in nearby air, soil, and river water in dumping site of Biratnagar metropolitan city. For studying the effects on air, the three samples of air were taken, at center and 100m upstream and downstream to the direction of wind flow. Soil samples were taken at 10m from the dumping site center, at 25m from the first sample and at 60m from the second sample, and the water samples were taken at leachate and 100 m upstream and downstream to the leachate. Soil and water were subjected to the physiochemical test, heavy metals test and microbes test whereas PM 2.5, and PM 10 were tested for air quality. The results showed that the air from upstream has been seen carrying particulate matter from the dumping site to downstream. Similarly, it is found that the quality of water at leachate and downstream is degraded compared to upstream. The soil quality has been found to have degraded due to the harmful and toxic material of the dumping site. Thus, this study shows that open dumping and burning have affected the nearby air, water, and soil.

Horticultural Irrigation Systems and Aquacultural Water Usage: A Perspective for the Use of Aquaponics to Generate a Sustainable Water Footprint

The expansion of food production is becoming more important due to a rising world population, which is relying on food security on regional and local scales. Intensive food production systems exert a negative impact on the regional ecosystem because of agrochemical pollution and nutrient-rich water discharging into nearby rivers. Furthermore, these systems highly depend on regional water resources, causing water scarcity and soil erosion due to the overexploitation of natural resources in general. The objective of this article is to review the water usage in the two most water-intensive food production systems, agriculture and aquaculture, showing lacking areas like system management and climate change, which must be considered in the implementation of a sustainable water footprint. In addition, the review includes an analysis of the combination of both production systems in aquaponic food production and the possibilities of water saving. There are a variety of analyses related to water usage for crop and aquatic animal production, but in these analyses, there is a lack of information about system management in general, which includes cleaning processes, water substitution, pond removal, water evaporation, and, especially in aquaculture, the water usage required for industrially elaborated fish feed.

Assessment of phytodiversity and phytoremediation potential of plants in the vicinity of a thermal power plant

A study was carried out to evaluate phytodiversity along with the metal accumulation potential of native plants growing in the vicinity of a thermal power plant (TPP). We documented 26 tree species, six shrubs, and 35 herbs. Importance value index (IVI), which measures the extent to which a species dominates in an area, was found highest for Senna siamea (95.7) followed by Tectona grandis (56.5), and Pithecellobium dulce (19.6). Soil was acidic (pH 5.4) in nature with higher concentrations of Al and Fe. The pH of ground water was found acidic while pH of nearby river was found slightly alkaline. Values of PM2.5 and PM10 were slightly higher than NAAQS standards for industrial areas. The concentration of metals was found higher in aquatic plants than in terrestrial plants. In general, herbs and shrubs showed more metal accumulation potential than trees. Our results suggest that Senna siamea could be used for revegetation purposes in FA landfills. Further, terrestrial and aquatic plants such as Ageratina adenophora and Stuckenia pectinata could be used for reclamation of Mn, Zn, Al, and Fe from contaminated soils. Hydrilla verticillata (Ni and Mn), Nelumbo nucifera, and Ipomoea aquatica (Cr) can be used for metal removal from contaminated water.

Seasonal variation in metabolic profiles and microbial communities in a subarctic ore processing plant.

The mining industry strives to reduce its water footprint by recycling water in ore processing. This leads to build-up of ions, flotation chemicals and microbial biomass, which may affect the process. The Boliden Kevitsa mine in Northern Finland is exposed to seasonal change and recycles up to 90% of the process water. We studied the variation in size, composition and putative functions of microbial communities in summer and winter in the ore processing plant. The raw water, Cu and Ni thickener overflow waters had statistically significantly higher bacterial numbers in winter compared to summer, and specific summer and winter communities were identified. Metagenomic analysis indicated that Cu and Hg resistance genes, sulphate/thiosulphate, molybdate, iron(III) and zinc ABC transporters, nitrate reduction, denitrification, thiosulphate oxidation and methylotrophy were more common in winter than in summer. Raw water drawn from the nearby river did not affect the microbial communities in the process samples, indicating that the microbial communities and metabolic capacities develop within the process over time in response to the conditions in the processing plant, water chemistry, used chemicals, ore properties and seasonal variation. We propose that the microbial community structures are unique to the Boliden Kevitsa mine and processing plant.

Analysis on Chemical and Physical Properties of Dried Sago Bagasse

The uncontrollable of sago bagasse waste from sago industry production become an environmental issue as it just dumping directly into nearby rivers which can affect a river pollution if not treated well. As it still has about 70% starch content, it has a potential to be converted to the others value-added product such as animal feed. However, before it can be converted to others product, it should go through a drying process to reduce its higher moisture content (90 wt.%), as well to prevent any micro bacteria growth and for long lasting packaging. Thus, this study focused on the evaluation of drying process at T=70 and 80 °C on reducing of its final moisture content by using three drying approaches: fluidized bed dryer (FBD), micro-oven and direct sunlight drying. Then, these samples of dried sago were analysed to determine its properties of starch, fibre, and ash, as well to study its functional organic chemical group by using Fourier infrared transform (FTIR) method. The results show the reduction of sago water content by FBD shown a significant result as compared to others drying methods as the FBD method produces a good solid mixed between particles. Besides, the drying rate using the FBD was achieved in a shorter time within 30 min as compared to oven which within 2 hours and sunlight drying within 6 days to achieve similar final desired moisture content at 11 wt.%. The analysis on the starch properties using the FBD was also almost 75% more higher than oven, which is about 70% starch content. Moreover, the presence of starch was successful proven by the presence of acrylic acid at a wavelength of 1539.72 cm-1 for FBD sample by using FTIR. In addition, using the FBD, the sago waste can maintain its quality as an animal feed by reached a brightness level, W1 as compared to the slurry sago waste where the dried sago using FBD is 58.78%, meanwhile the fresh slurry sago waste is 93.31%. In conclusion, the sago drying in the FBD at T=80 °C was selected as the optimum drying condition as it had achieved a short drying rate for desired final 11 wt.% moisture content and resulted in better on the chemical and physical analysis.

The Impact of Beaver Dams on the Dynamic of Groundwater Levels at Łąki Soleckie

Areas excluded from agricultural production are susceptible to the presence of beaver families. The most significant changes occur during the initial period, when agricultural utilization is abandoned and beavers establish their presence on the land. During this period, some parcels remain uncultivated, while agricultural activities persist in neighboring areas. This situation is accompanied by the destruction of beaver dams, especially during periods of abundant water resources, and notably during intensive fieldwork. The article presents field studies aimed at determining the extent to which constructed and operational beaver dams contribute to changes in groundwater levels in drained peatland areas. In order to protect and sustainably use peat soils, it is necessary to maintain their high moisture content by ensuring a high groundwater level elevation. This can be achieved through the use of existing damming structures in the area (levees, weirs). Beaver dams can also serve a similar function, blocking the outflow of water from peat lands by raising the water level and consequently retaining it naturally. The specific objective was to develop principles for verifying factors influencing the effects of beaver dam construction on groundwater levels in fields within their range of influence. The water table levels within the study area during rainless periods were influenced by water levels in ditches, dependent on beaver activity in the nearby river. Beaver activities, manifested through dam construction, were influenced by periodic water resources in the river, defined by the cumulative monthly precipitation. Factors affecting groundwater levels in rainless periods on the plots also included the distance from the river cross-section and the permeability of soils expressed by the filtration coefficient of the active layer. Beaver dams had the greatest impact on stabilizing the water table in the soil profile closest to the river.

Long‐term environmental flows restore benthic invertebrate communities in a highly regulated river

The construction of dams and other in‐stream structures for human use has altered river ecosystems worldwide. Dams degrade rivers, and environmental flow releases aim to mitigate flow alterations and restore rivers downstream of dams by returning elements of the pre‐regulation flow regime, resulting in an ecosystem that resembles a more natural state. We examined the responses of benthic invertebrate communities in riffles and pool‐edge habitats to an environmental flow regime (EFR) in the highly regulated Snowy River over 17 years (2000–2016). Benthic invertebrate communities significantly changed in response to prolonged increases in the magnitude of all components of the flow regime. The composition of the benthos in the regulated river became more dissimilar to pre‐EFR communities and more closely resembled those of nearby unregulated rivers. These changes were apparent in both riffle and pool‐edge habitats and were most pronounced when flow magnitudes were highest. Scrapers increased as flows increased, and in contrast, the relative abundances of gatherers declined with prolonged high flows and could be attributed to increased daily flows and high flow events mobilizing fine sediment and scouring benthic substrates. These results indicated that the EFR altered abiotic conditions or resources that previously limited invertebrate abundances, facilitating changes to the benthic community. Community changes we observed were in response to a flow regime that remained drastically lower than natural, demonstrating that restoration targets can be achieved with small flow increases that mimic natural flow patterns.

Effect of storage condition on the viability of sago effluents as carbon source in fermentation medium for bioethanol production

In Sarawak, Malaysia, approximately 237 tons/day of sago effluent is commonly discharged into nearby river due to the sago starch extraction process. Due to the high concentration of polymeric compounds, particularly starch, in sago wastewater, which petrifies easily, this condition severely pollutes the environment in the affected area. This study was conducted to determine the viability of using sago effluent as a carbon source and fermentation medium for bioethanol production which indirectly help to minimize the environmental impact as well as the economics of the sago industry. The sago effluent obtained from the local sago mill was analysed for starch content and pH profile while stored at room and cold (4°C) temperature facility. Enzymatic hydrolysis was conducted to convert the residual starch into glucose as carbon source for bioethanol fermentation. Fresh sago effluent can be stored for up to 5 days in cold temperature where the starch content remains constant. The highest starch concentration in sago effluent was 61.33 g/L, in which 50.57 g/L glucose was obtained through the enzymatic hydrolysis process. Hence 82.5% of the starch to glucose conversion yield is revealed. Then, the sago effluent hydrolysate which acts as a carbon source as well as a fermentation medium able to generate 23.14 g/L of bioethanol, displays a 91% theoretical yield of glucose to ethanol. In conclusion, the utilization of sago wastewater as feasible alternative to cheap and locally available and sustainable source of raw materials to produce bioethanol.

Changes in crystallinity of sago palm (Metroxylon sago spp.) waste during cellulose extraction

Changes in crystallinity of sago palm (Metroxylon sago spp.) waste during cellulose extraction

The study of environmental impact from fabric dyeing process in Lahanam area, Songkhone district, Lao PDR

The aim of this research was to examine water contamination resulting from the fabric dyeing process in the Lahanam area, located in Songkhone district, Lao PDR. Lahanam is a famous village known for its fabric dyeing and weaving activities, utilizing both natural and chemical dyes which result in the discharge of colors into local water resources. Water samples were collected from three different sources: household dyeing water (HD), community wastewater (CW) and the nearby river, Xebanghieng (XR). Qualitative and quantitative analyses were performed on the water samples. Atomic Absorption Spectroscopy (AAS) was employed to measure the presence of heavy metals such as lead (Pb), arsenic (As), cadmium (Cd) and mercury (Hg). Additionally, tests were conducted to determine the biological oxygen demand (BOD), dissolved oxygen (DO), ammonia contents and pH in the water of Xebanghieng. The results revealed that HD samples contained significantly higher amounts of all four heavy metals (lead 0.217 mg L–1, cadmium 0.105 mg L–1, arsenic 0.029 mg L–1 and mercury 0.0014 mg L–1), with lead, cadmium and arsenic exceeding standard limits. These data indicate potential environmental impact of chemical dyeing in the village in the future. Therefore, it is recommended to replace the current dyeing process with more sustainable alternatives, such as natural dyes. GRAPHICAL ABSTRACT HIGHLIGHTS The water quality of the river in the dyeing village in Lao PDR Heavy metals in wastewater after dyeing process. The impact of chemical dyeing.

Post-glacial small delta process uncovered by luminescence and radiocarbon chronology of core sediments from coastal South China Sea

Reliable chronology is crucial for reconstructing delta processes. The past decades witnessed a boost of dating works on the most economically influential large deltas (i.e., subaerial area >1000 km2), but chronology remains lacking on many small deltas (i.e., subaerial area <1000 km2) that are also densely populated and economically active. Luohe River Delta (LRD) in the coastal South China Sea is such a small delta, whose evolution concerns hundreds of thousands of people, and literally no reliable dating results have been reported to support research of its processes. Herein, dating work combining radiocarbon (14C) on mollusk shells and quartz Optically Stimulated Luminescence (OSL) methods were performed on core LFZK06 from LRD, to test applicability of both methods by age comparison and to establish a chronological framework, using Bayesian age-depth models, of LRD for the first time. 14C ages are systematically c. 0.5–1 ka younger than OSL ages from the same depths. Such young bias of 14C ages in LRD contrasts with previously observed overestimated 14C results in the nearby Pearl River Delta (PRD), likely due to the distinction in bedrock types between Luohe River (granites and sandstones only) and Pearl River (limestone prevalence causing hardwater effect) drainages. Ages of core LFZK06 span from 57 ± 7 ka to 3.42 ± 0.05 cal ka BP and contain a hiatus between 57±7–11.9 ± 1.7 ka. Holocene deltaic sequence of the core shows three-stage sedimentary processes: (1) rapid deposition of prodelta/delta front sediments at 10.2‐0.4+0.5 ka–7.7‐0.3+0.4 ka related to rapid sea level rise, (2) hiatus during 7.7‐0.3+0.4 ka–5.7‐0.8+0.5 ka likely due to reduced sediments input or river channel migration, (3) rapid accumulation of delta plain sediments during 5.7‐0.8+0.5 ka–3.42‐0.85+0.42 ka reflecting depocenter shift toward core location. Moreover, changes of quartz OSL sensitivity were detected, indicative of sediment provenance transition. A change in sediment source from nearby granite weathering towards fluvial long-transported materials occurred at a depth of 24.7 m, with low quartz OSL sensitivity in the gravelly layer below (11.9 ± 1.7 ka) and one magnitude higher quartz OSL sensitivity in prodelta deposits above (10.2‐0.4+0.5 ka).

Comparing the migration behavior and survival of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) smolts.

Many organisms rely on migrations between habitats to maximize lifetime fitness, but these migrations can be risky due to a suite of factors. In anadromous salmonids, the smolt migration from fresh water to sea is a critical life stage, during which smolts can experience high mortality from multiple sources. This study investigated the migratory behavior and survival of Atlantic salmon (Salmo salar) and anadromous brown trout (Salmo trutta) smolts during their seaward migration using acoustic telemetry between March and May 2021. Due to the extinction of wild salmon in the River Gudenaa after the construction of the Tange hydropower plant, this study used hatchery-reared salmon originating from a nearby Danish river. A total of 75 hatchery-reared salmon smolts, 75 hatchery-reared trout smolts, and 75 wild trout smolts were tagged with acoustic transmitters and released into River Gudenaa, Denmark. The downstream movements of tagged fish were monitored using acoustic receivers deployed in the river and fjord. Hatchery-reared trout initiated migration first, followed by hatchery-reared salmon, with wild trout being the last to migrate. There was no difference in riverine progression rates among the three smolt groups, but noticeable differences emerged once in the fjord: trout (wild and hatchery) slowed down, whereas hatchery-reared salmon maintained their speed. Riverine migration was predominantly nocturnal for all smolts; however, daytime migration increased at the fjord arrays. Day-of-year significantly influenced diurnal patterns in the river and fjord, where daytime migration increased later in the year. Hatchery-reared salmon and wild trout had reasonably good overall survival from river to sea entry (≥66%), whereas hatchery-reared trout had poor survival (c.26%). The fjord was the major bottleneck for survival of hatchery-reared trout. We found no strong evidence for differences in progression rate or diurnal patterns between wild and hatchery-reared trout to explain the lower survival. This study demonstrates that salmon and trout differ in their life-history strategy already in the post-smolt phase, and that stocking is a sub-optimal strategy to aid wild populations.

Regional Precipitation Regimes and Evaluation of National Precipitation Datasets against Satellite-Based Precipitation Estimates, Republic of Georgia

Abstract Analyzing water resources in areas with few hydrometeorological stations, such as those in post-Soviet countries, is difficult due to station closures after 1989. In Caucasus, evaluations often rely on outdated data from nearby rivers. We evaluated one national-level precipitation dataset, the Water Balance of Georgia (WBG) with two satellite-based precipitation products from 1981 to 2021, including the Climate Hazards Group Infrared Precipitation with Station (CHIRPS) data and CHIRPS blended with a dense rain gauge network (geoCHIRPS). We modeled mean annual precipitation from geoCHIRPS as a function of coastal distance and elevation. CHIRPS underestimated precipitation in the cold and wet seasons (R2 = 0.74, r = 0.86) and overestimated dry season precipitation, while geoCHIRPS performed well in all seasons (R2 = 0.86, r = 0.92). Distance from the coast was a more important predictor of precipitation than elevation in western Georgia, while precipitation correlated positively with elevation in the east. At four hydroelectric plants, the underperformance as a percentage of capacity (∼37%) corresponds with the percentage difference between differences in precipitation products (∼38%), suggesting that plants designed based on WBG may be systematically overdesigned, but further work is needed to determine the reasons for the underperformance of the plants and frequency. We conclude that 1) the existing WBG does not accurately reflect elevation–precipitation relationships near the coast, and 2) for accurate analysis of spatiotemporal precipitation variability and its impacts on hydropower generation and environmental and sustainable water resource management, it is essential to calibrate satellite-based precipitation estimates with additional rain gauge data.

Identifying the Key Parameters in Mathematical Model to Simulate the Main Nutrients Transformation Process in Vietnamese Catfish (Pangasianodon Hypophthalmus) Ponds

Pangasius farming is a process of putting a large amount of material into the pond but then only harvesting a small amount of the farmed fish and discharging the rest as waste into the aquatic environment. This practice pollutes water sources and degrades the water environment in nearby rivers and canals. To address this issue, it is necessary to establish a mathematical model that can simulate the nutrient transformation processes in the pond. This study aims to set up a mathematical model to simulate the variation in the compositions of major nutrients in Pangasius ponds, determine the key parameters affecting the model, optimize the culture regime, enhance fish quality, and minimize environmental impact. The results have shown that the model’s output data after calibration is relatively close to reality and the key parameters of the model were defined.

Variable downcanyon morphology controlling the recent activity of shelf-incised submarine canyons (Alboran Sea, western Mediterranean)

This research aims to distinguish genetic sedimentary processes building canyon geomorphological patterns and the factors driving different sedimentary activities in two nearby Mediterranean shelf-incised submarine canyons (Carchuna and Motril) that exhibit different degrees of incision on the narrow margin of the northern Alboran Sea.The straight Carchuna Canyon incises the shelf up to 200 m off the coastline and exhibit steep canyon walls featuring narrow terraces, muddy sands with high contents of organic matter along the thalweg, and transported shelf benthic foraminifera in distal settings. The Motril Canyon head is wider and incises the shelf edge, ca. 2 km off the coastline. It exhibits a sinuous morphology and less steep walls, wider terraces, and higher sedimentation rates with muddy sediments along the thalweg. In both canyons, cross-section relief, width, incision, and area decrease downslope, although these parameters increase locally.The downslope variations of geomorphological parameters are attributed to enhanced erosional/depositional processes promoted by tectonically controlled abrupt changes of the axial channel orientation. The degree of shelf incision, the location of the canyon heads in relation with the local sediment sources, and the seasonally variable hydrodynamic regimes determine the different degrees of recent canyon activity. The Motril Canyon is interpreted as a mature system that reflects episodic activity, collecting fine-grained sediments from the nearby Guadalfeo River. The Carchuna Canyon exhibits a youthful developmental stage whose activity is more continuous and involves sediment trapping of littoral cells and continuous downslope sand transport.

The role of technology in the water–energy–food nexus. A case study: Kerinthos, North Euboea, Greece

The water–energy–food (WEF) nexus is a basic element of prosperity, yet it is not equally distributed on the land. Human progress has optimized the function of the WEF nexus to bridge the inequality gap. In order to understand this progress, this study compares the preindustrial and modern agricultural practices in an area in Greece. Interviews were conducted with an elderly man who lived in the 1950s, and the process was quantified in units of WEF. The same procedure was also carried out with modern farmers for modern agricultural practices. In comparing the past and present agricultural processes, it is observed that today, a farmer can feed approximately 100 times more people. This feat has been achieved as modern practices push the land with energy sources in multiple ways (fuels and fertilizers). However, energy indices such as energy ratio, net energy gain, specific energy, and energy productivity do not seem to be improved. Furthermore, farmers prefer to pump underground water for irrigation, instead of utilizing the nearby river, as was done in the past when the river provided both energy to the watermill and an abundance of water for irrigation. In addition, as the price of wheat is dependent on the stock market, even in 2023, there are risks to food security, the cultivation of wheat was not economically efficient for farmers in this area in 2023.

Seasonal variations and water chemical control mechanism of water quality in a suburban river near a coal city: a case study in the Xinbian River of Suzhou City, Anhui Province, China

Abstract To study the seasonal change rules of water quality indicators and water chemical control mechanisms in the nearby city river Xinbian River, in Suzhou City, Anhui Province, China, nine points were selected and periodically sampled for 12 months. Totally 108 water samples were collected, and basic physical–chemical indicators and routine ions (e.g., Ca2+, Mg2+, Na+, K+, SO42−, Cl−, F−, NO3−, CO32−, and HCO3−) were measured. Piper diagram, Gibbs diagram, and ion ratio method were used. The result shows that the seasonal and upstream-to-downstream variations in pH were less varied, whereas the fluctuation in dissolved oxygen was large. Four ions, namely, SO42-, F−, Cl−, and Na+ generally first decreased overall and then changed from spring to winter. The maximum contents of SO42- (406.03 mg/L), Cl− (250.22 mg/L), and Na+ (269.99 mg/L) in single water samples appeared at the S9 sampling point (Suzhou control gate) in March 2020. The dominant hydrochemical types in summer were Na–Ca–HCO3 and Na–Mg–SO4, while Na–Mg–SO4 and Na–Mg–HCO3 were the main hydrochemical types in the other seasons. The control factors of water chemical composition vary according to the season. However, rock weathering (e.g., silicate dissolution) is the dominant control factor of water chemistry in the studied river section.

Identifying geomorphic domains using hierarchically clustered drainage area‐slope scaling

AbstractArea‐slope scaling is an important tool for analysing geomorphic processes. In this study, we used hierarchical clustering to sort the area‐slope scaling data for both the numerical landscape created using the LandLab model and real landscapes. Random forest analysis was used to explore the effect of hierarchical clustering. We aimed to illustrate the heterogeneous features of area‐slope clustering and their influencing factors and to test whether they can be used to distinguish geomorphic domains. Our results showed that hierarchical clustering can easily detect the heterogeneous features of area‐slope scaling constrained by tectonic uplift and fluvial erodibility but not those constrained by the diffusion coefficient. The slope gradients over the inflection/transition zone of the colluvial and fluvial domains play a key role in identifying area‐slope scaling from different geomorphic domains. Case studies show that area‐slope scaling of clusters would be affected by different lithology and distance away from the trunk channel. In the high erosion circumstance, the fluvial process caused by tectonics leads to increasing slope gradients over whole geomorphic domains, as well as to retreating inflection between the colluvial and fluvial process domains. In low erosion circumstances or steady state, the fluvial process caused by nearby rivers cannot effectively change the slope gradients but can retreat the inflection. The real landscapes suggest that basins should be carefully selected for area‐slope scaling analysis to ensure that they are representative of the entire study area. Before geomorphological research, more basins of a specific research region need to be selected to conduct hierarchical clustering to select representative basins. Our study could be helpful in the identification of area‐slope domains, the extraction of geomorphic metrics and geomorphic process research.

Evaluating heavy metal contamination and ecological risks in rivers surrounding Banyuroto Landfill in Indonesia

This study, carried out between May and June 2023, aimed to assess the influence of landfill leachate on environmental conditions, specifically regarding the pollution of river water near the Banyuroto landfill. The parameter of the difference heavy metals in this study are Mercury (Hg), Cadmium (Cd), Lead (Pb), Chromium (Cr), Manganese (Mn), Copper (Cu), and Iron (Fe). The potential ecological risk index is investigated due to the harm to the nearby river ecology. The sampling was conducted at eight discrete locations in close proximity to the dump. The levels of heavy metals were quantified using Atomic Absorption Spectroscopy (AAS). Furthermore, the Potential Ecological Risk (PER) technique was utilized to assess the potential environmental dangers that these metals may pose. The findings unveiled disparate concentrations of heavy metals across the various locations where point 5 of the sampling become most polluted area due to increased anthropogenic activities. The Mercury (Hg) concentrations ranged from 0.014 to 0.032 mg/kg, whereas the Cadmium (Cd) and Chromium (Cr) levels exhibited minimal variation in the below Limit of Detection (LOD). Lead (Pb) exhibited LOD readings, suggesting their minimum presence. The concentrations of Manganese (Mn) and Copper (Cu) were relatively low, whereas Iron (Fe) exhibited the greatest levels, ranging from 0.2405 to 1.2209 mg/l. The maximum potential ecological risk values were calculated and ranked from highest to lowest as follows: Hg (262.19) &gt; Fe (20.35) &gt; Cr (0.374) &gt; Cd (0.245) &gt; Cu (0.297) &gt; Mn (0.100). Remarkably, the possible environmental hazards associated with all heavy metal characteristics constantly remained below the threshold of 40 except the maximum concentration of the total of Heavy Metals. This indicates that their concentrations present a substantial ecological danger in some situations.

Hydrochemical stratigraphic analysis of the filling of the Meirama mine shaft I: monitoring and filling

The application of an old open-pit lignite mine as an auxiliary reservoir for the supply of the city of La Coruña has involved a detailed analysis of the chemical quality of the vertical profile. The study has shown that a stratified lake is formed where the shape of the filling (first with groundwater and later surface waters from the nearby rivers were added) has influenced the formation of the lake profile. The Meirama mine is an open-pit brown lignite mine located in NW Spain. Exploitation ended in March 2008, leaving a pit of approximately 146 hm3 with a maximum depth of 205 m. The rehabilitation of the pit consisted of the creation of a lake that will serve as an auxiliary water reservoir for the city of La Coruña. The filling process lasted approximately 8 years (March 2008–May 2016) with subterranean and surface contributions from the environment. The formation of an invariant chemocline and a seasonal thermocline was observed. Therefore, in this work, (the first of a series of two articles), an analysis of the evolution of various physicochemical parameters, elements, and compounds at certain heights (the surface, the first 2 m (2 mbs), at 59 masl, and at the bottom (2 masl)). In this first article, the physicochemical parameters of pH, dissolved oxygen, temperature, and some metallic elements (iron and manganese) are analysed. From the analyzed parameters it can be seen the creation of a surface thermocline and a chemocline at a depth of 59 masl with the beginning of the formation of anoxic conditions of the bottom of the pit through the consumption of oxygen.