Is Kerala’s coastal groundwater getting salinized?

Possible effect of submarine groundwater discharge on the pollution of coastal water: Occurrence, source, and risks of endocrine disrupting chemicals in coastal groundwater and adjacent seawater influenced by reclaimed water irrigation

New approach in estimation of seawater intrusion footprint (SWIF) for irrigated crops using coastal groundwater

Influence of coastal groundwater salinization on the distribution and risks of heavy metals

Origins and processes of groundwater salinization and pollution in urban coastal aquifer under the influence of serious industrialization and urbanization were determined using major and trace element/ion geochemistry, microbial and environmental isotope analyses, and statistical correlation and hierarchical cluster analyses of chemical parameters. Electrical conductivities (EC) of the groundwater in the coastal aquifer ranged from 487 to 4280 µS/cm. Average groundwater EC values measured in wet and dry seasons were 1130 ± 420 µS/cm and 1096 ± 526 µS/cm, respectively. Wells with high EC values were noticed not only near the gulf coastline (1799–2801 µS/cm) but also at the further inland (1709–4280 µS/cm). Statistical evaluation of the groundwater analyses showed that EC had a relatively good correlation with Cl (r = 0.85–0.90, p < 0.01). Cl–Br ion couple also exhibited a significant correlation with a r squared value of 0.9545, suggesting that salinity of the coastal aquifer was controlled dominantly by single source. Piper diagram showed that predominant cation and anion types in the coastal groundwater exhibited shifts generally from Ca to Na, HCO3 to Cl and to less HCO3 to SO4. A significant variation observed in hydrogeochemical facies of the coastal groundwater resulted from dissolution of calcite, dolomite and gypsum, mixing with seawater, formation water and sewage effluents, and cation-exchange processes. Evaluation of Cl/Br mass ratio along with total nitrogen and microbiological contents of the groundwater samples indicated that seawater intrusion was occurring in the coastal aquifer. However, other sources such as mixing with saline formation water (paleo-seawater) and sewage effluents also contributed groundwater salinization locally at the inland. High seawater mixing ratios (2.5–5%) were obtained from wells close to the gulf coastline, while inland wells generally exhibited low mixing ratios (mean 0.36% ± 0.3). Fecal contamination in coastal groundwater was at notable levels. Varying redox environments (oxic/suboxic/anoxic) were observed in the coastal aquifer. Seasonal variation in the redox conditions controlled the Mn, Fe, and As enrichments in the coastal groundwater above their MCL values. This study also showed when employed with the other pollutant indicators, Cl/Br mass ratio could be used effectively to delineate the sources of contamination and salinization in coastal groundwater exhibiting low seawater mixing ratios.

ABSTRACTCoastal groundwater is a vital resource for coastal communities around the globe, and submarine groundwater discharge (SGD) delivers nutrients to coastal marine ecosystems. Climatic changes and anthropogenic actions alter coastal hydrology, causing seawater intrusion (SWI) globally. However, the selection of SWI and SGD study sites may be highly biased, limiting our process knowledge. Here, we analyse hydroenvironmental characteristics of coastal basins studied in 1298 publications on SGD and SWI to understand these potential biases. We find that studies are biased towards basins with gross domestic product per capita below (SWI) and above (SGD) the median of all global coastal basins. Urban coastal basins are strongly overrepresented compared to rural coastal basins, limiting our progress in understanding undisturbed natural processes. Despite the connection between anthropogenic activity and coastal groundwater issues, and the consequential overrepresentation of urban basins in coastal groundwater studies, perceptual (or conceptual) models of coastal groundwater rarely include anthropogenic influences aside from pumping (e.g., subsidence, land use change). Taking a holistic view on coastal groundwater flows, we have developed an editable perceptual model illustrating the current understanding, including both natural and anthropogenic drivers. As SGD and SWI in new areas of the globe are studied, we advocate for researchers to utilise and further edit this perceptual model to openly communicate our process understanding and study assumptions.

&amp;lt;p&amp;gt;The coastal zone of the Netherlands is the densely populated economic heartland of the Netherlands. This low-lying area is predominantly located below current mean sea level. Groundwater in large parts of the Dutch coastal zone is saline, having infiltrated during Holocene transgressions. This saline groundwater is now slowly moving upward, driven by artificially lowered drainage levels and resulting land subsidence. Coastal groundwater in the Netherlands is vulnerable to climate change and rising sea levels, as groundwater levels rise, fresh groundwater reserves decrease, and surface water is salinized by exfiltrating saline groundwater.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We developed a high-resolution nationwide 3D fresh-salt groundwater flow and transport model to assess effects of climate change and sea level rise on groundwater salinization in the Netherlands. The fully scripted modelling workflow includes a 3D multiple indicator kriging interpolation of all available salinity measurements, that accounted for uncertainty in both measurements and interpolation. The developed model used a parallellized version of the SEAWAT model code to allow otherwise time-consuming calculations. It links to the existing national hydrological modelling framework to allow calculation of climate change effects on surface water supply and demand and agricultural damage. We used the resulting modelling framework to calculate groundwater effects of different climate change and sea level rise scenarios up to 2100.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Results show significant effects of climate change and especially sea level rise on coastal groundwater. Significant head increase (&amp;gt; 5% of SLR) is experienced in shallow aquifers between 2 to 10 km inland, dependent on the varying hydrogeological settings along the Dutch coast. In deeper aquifers, head increase generally propagates further, to up to 15 km inland. Through the combined effects of head increase and the inward movement of saline groundwater, salt loads to surface water increase over a significantly larger zone, extending to 25 km inward. Results signify the importance of including the long-term displacement of brackish and saline groundwater when assessing coastal groundwater effects of climate change and sea level rise.&amp;lt;/p&amp;gt;

Integrated impacts of mariculture on nitrogen cycling processes in the coastal groundwater of Beihai, southern China

In many places around the globe, groundwater has been threatened by various pressures, which calls for better management strategies for groundwater sustainability. In this study, we suggest a novel framework for identifying factors critical to coastal groundwater based on results from City Blueprint (CB) assessments. By compiling the 5856 indicator results of the City Blueprint Approach (CBA) from 122 cities and analyzing the correlation between these indicators, we constructed City Blueprint networks (CBN) by using a complex network modeling approach for three groups of cities: all 122 cities, 40 coastal, and 82 non-coastal cities. These networks were then analyzed for their node centralities to identify major factors that influence coastal groundwater management. Interestingly, our analysis revealed that groundwater has various indirect but important links with the factors that are typically unexplored in the literature. We also assessed the CB of the two largest coastal cities in South Korea. By combining the results of network analysis and CB assessment of the two cities, we could identify the indicators that are potentially at risk regarding coastal groundwater. We propose the CBN as a novel approach to unveil underestimated or hidden factors related to the target system (e.g., groundwater), which allows extensive options for sustainable groundwater management.

PDF HTML阅读 XML下载 导出引用 引用提醒 浑河河水及其沿岸地下水污染特征 DOI: 10.5846/stxb201306171723 作者: 作者单位: 沈阳地质矿产研究所,沈阳地质矿产研究所,沈阳地质矿产研究所 作者简介: 通讯作者: 中图分类号: P641；X523 基金项目: 中国地质调查局地质调查资助项目（1212010913004） Contamination characteristics in surface water and coastal groundwater of Hunhe River Author: Affiliation: Shenyang Institute of Geology Mineral Resources,Shenyang Institute of Geology Mineral Resources,Shenyang Institute of Geology Mineral Resources Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选择沈阳地区重要河流浑河及其沿岸地下水进行定量分析，研究并探讨了包括无机物和有机物在内的水质综合污染特征。结果表明，浑河河水中氨氮、硝氮、亚硝氮和酚超过了地表水环境质量标准，最大超标倍数分别为15.8、1.5、82.4和1.8倍，检测出的11种卤代烃、氯苯和六六六等有机物均未超标。浑河沿岸地下水中氨氮、硝氮、亚硝氮、化学需氧量、酚和铅超过地下水质量标准，超标率分别为31.6%、10.5%、26.3%、36.8%、47.4%和26.8%，检测出的4种卤代烃和六六六等有机物均未超标。河水及其沿岸地下水中的污染物，尤其是有机污染物种类和浓度高值基本出现在城西的谟家-大祝断面之间。浑河水质主要受城市工业废水、居民生活污水排放的影响，沿岸地下水的污染来源包括工业生产或农村居民生活造成的地表污染物垂直入渗式的点源污染、浑河水侧向渗透补给式的线源污染以及农药化肥使用产生的面源污染，而有机污染物主要通过点源污染地下水。浑河各区段的使用功能、包气带岩性及沿岸水源地开采井布局等因素都为受污染的河水对沿岸几百米范围内的浅层地下水的补给提供了条件，造成浅层地下水的污染，对当地生态系统及人类健康构成潜在威胁。 Abstract:The pollution characteristics of Hunhe River and its costal groundwater were investigated which included inorganic and organic index. The results indicate that concentrations of ammonia, nitrate, nitrite and phenol in Hunhe River exceeded the National Environmental Quality Standard for Surface Water, and the maximum exceed multiple was 15.8, 1.5, 82.4 and 1.8, respectively. Ammonia, nitrate, nitrite, COD, Pb and phenol in coastal groundwater of Hunhe River exceeded the Environmental Quality Standard for Groundwater and the exceed ratio were 31.6%, 10.5%, 26.3%, 36.8%, 47.4% and 26.8%, respectively. But organic matters which were detected in the river and coastal groundwater such as chlorobenzene and benzex didn't exceed the standard. The pollutants especially organic pollutants were various and high-concentration from Mo jia-Da zhu section. The surface water quality was mainly affected by the city industrial wastewater and domestic sewage. The pollution in coastal groundwater was due to point source pollution vertical infiltrating caused by industrial production or rural residents activities, line source pollution by lateral infiltration recharged from river and non-point source pollution owing to the use of pesticide and fertilizer. Thereinto, organic pollution of groundwater was mainly on account of point source pollution. Some factors such as river using function, vadose zone lithology and layout of exploitation well along the river made pollutant transportation from the polluted river to shallow coastal groundwater within a few hundred meters which poses a great potential threat to ecosystem and local population. 参考文献 相似文献 引证文献

Coastal aquifers in Terengganu, Malaysia, face increasing challenges in groundwater quality and availability, necessitating a comprehensive assessment of their vulnerability. This study investigated groundwater vulnerability and susceptibility in the coastal region of Terengganu, Malaysia, where coastal aquifers face threats to groundwater quality and availability. A comprehensive groundwater vulnerability assessment was conducted using the TRUST Index. This index-based approach considers the lithology, river proximity, well usage, distance to the seashore, and well type. Field investigations were undertaken to obtain real-time measurements of well behavior. This included conducting constant-rate pumping tests on four private wells to gauge hydraulic conductivity. Consequently, flow rates were meticulously monitored throughout these tests, and water level measurements and physicochemical assessments were conducted over a 120-minute duration. Following this, the data was analyzed utilizing AQTESOLV software to determine the hydraulic conductivity, transmissivity, and storativity of the aquifer. The data from MW4, MW16, and MW20 collectively indicate favorable hydraulic characteristics, suggesting water movement within the aquifer, ranging from 4.02 m3/day to 11.39 m3/day. In contrast, MW7 displays an unexpectedly high discharge rate of 19.77 m3/day, suggesting a highly permeable and efficient water-transmitting unconfined aquifer with limited water storage capacity. The vulnerability assessment classified the wells as Low, Moderate, and High vulnerability. Wells MW1, MW6, MW7, and MW20 were categorized as low vulnerability, indicating relatively secure groundwater quality and availability. Wells MW2, MW3, MW8, MW9, MW12, MW13, and MW14 were classified as moderately vulnerable, suggesting a moderate level of potential risk. Meanwhile, wells MW4, MW5, MW10, MW11, MW15, MW16, MW17, MW18, and MW19 were labeled as highly vulnerable, signifying a higher susceptibility to threats. The correlation matrix revealed insightful connections between hydrological and water quality parameters. The distance from the seashore is inversely correlated with salinity and specific conductance, signifying a reduced seawater water impact farther inland. Note that wells near rivers exhibit higher salinity, likely due to potential saltwater intrusion, emphasizing the importance of understanding these relationships in coastal aquifer systems. This study comprehensively assesses coastal groundwater vulnerability, behavior, and water quality. Its unique contributions lie in the meticulous hydraulic characterization and identification of unconventional well behavior. These findings emphasize the importance of considering temporal variations, local influences, and tailored management strategies for sustainable coastal groundwater resource utilization.

Coastal groundwater is extremely vulnerable to saltwater contamination. This study was conducted to investigate the potential contamination of saltwater into coastal groundwater temporally. Data was obtained from PT000017 monitoring well from 2006 to 2012. Nine parameters of water quality were involved for data analyses. Two main diagrams used for data analyses are piper diagram and hydrochemical facies evolution diagram (HFE-D). All parameters were plotted to produce a piper diagram that determine the water type between different seasons. During wet season, groundwater samples are located in domain III that represent mixed Ca-Na-HCO3 water type; 2007 groundwater sample was located in domain I, represent Ca-HCO3 water type and during 2008 groundwater sample was located in domain II, represent Na-Cl water type. During dry season, groundwater samples are located in domain II that represent mixed Ca-Na-HCO3 water type meanwhile, 2009 and 2011 groundwater samples are located in domain I, represent Ca-HCO3 water type. Subsequently, HFE-D diagram was produced to determine the evolution process of salinization or freshening of coastal groundwater. In this study, all of groundwater samples were in freshening stage except during dry season 2007 groundwater sample was in the phase of saltwater intrusion.

Generally unseen and infrequently measured, submarine groundwater discharge (SGD) can transport potentially large loads of nutrients and other land-based contaminants to coastal ecosystems. To examine this linkage we employed algal bioassays, benthic community analysis, and geochemical methods to examine water quality and community parameters of nearshore reefs adjacent to a variety of potential, land-based nutrient sources on Maui. Three common reef algae, Acanthophora spicifera, Hypnea musciformis, and Ulva spp. were collected and/or deployed at six locations with SGD. Algal tissue nitrogen (N) parameters (δ15N, N %, and C:N) were compared with nutrient and δ15N-nitrate values of coastal groundwater and nearshore surface water at all locations. Benthic community composition was estimated for ten 10-m transects per location. Reefs adjacent to sugarcane farms had the greatest abundance of macroalgae, low species diversity, and the highest concentrations of N in algal tissues, coastal groundwater, and marine surface waters compared to locations with low anthropogenic impact. Based on δ15N values of algal tissues, we estimate ca. 0.31 km2 of Kahului Bay is impacted by effluent injected underground at the Kahului Wastewater Reclamation Facility (WRF); this region is barren of corals and almost entirely dominated by colonial zoanthids. Significant correlations among parameters of algal tissue N with adjacent surface and coastal groundwater N indicate that these bioassays provided a useful measure of nutrient source and loading. A conceptual model that uses Ulva spp. tissue δ15N and N % to identify potential N source(s) and relative N loading is proposed for Hawaiʻi. These results indicate that SGD can be a significant transport pathway for land-based nutrients with important biogeochemical and ecological implications in tropical, oceanic islands.

Meteorological drought is a natural phenomenon caused mainly by a prolonged precipitation deficiency, that may propagate to the surface and groundwater systems leading to the manifestation of hydrological drought events. The impacts of drought are often less visible in the subsurface due to sparse observational records while the response of groundwater to weather variability depends on antecedent groundwater levels and hydraulic and storage properties of the aquifer system. Although groundwater is often the only resilient water resource in arid and semi-arid areas, a notable decline in groundwater levels can be difficult to manage.There is increasing evidence that coastal groundwater, which serves as the main water source for various needs (urban water supply, agriculture, etc.), is at even greater risk in semi-arid areas where the quality and quantity of fresh water stored in aquifers is threatened by seawater intrusion. It is important to note that, in these islands, periods of low recharge coincide with peak water consumption, which in turn leads to overexploitation of the aquifers to meet the increased water demands.To that end, the present study focuses on the assessment of the complex relationship between drought conditions and coastal groundwater, emphasizing on its multidimensional nature which involves the consideration of several factors, such as pumping regimes, land use, water demands, subsurface heterogeneity, geomorphology of the study area and hydraulic connection to the sea. The principal goal is to identify critical features through a comprehensive modeling approach using distributed numerical modelling and easily accessible data and tools, providing the means for informed water management, especially in ungauged coastal aquifers.The study analysed the case of a coastal aquifer located in the Greek island Kalymnos in the Aegean Sea for a period of 73 years (1950-2022). The primary source of groundwater in the study area is a calcareous unconfined coastal aquifer. A transient three-dimensional variable-density flow and salt transport numerical model was developed using SEAWAT code. Time-varying recharge input, was simulated with the ZOODRM model, a distributed recharge model. The pumping regimes were calculated based on both urban and agricultural water demands. Three drought indices for various timescales were employed for assessing drought evolution throughout the study period. That is, the Reconnaissance Drought Index (RDI) indicating the meteorological conditions, the Effective RDI (eRDI) and the Agricultural Standardized Precipitation Index (aSPI). The last two were utilised for identifying the agricultural drought conditions. The MH-data software was used for managing the meteorological input data (precipitation and potential evapotranspiration) that were obtained from the ERA5-Land database and the DrinC software was used for the drought analysis.The outcomes of the study identified significant correlations between the freshwater volume and the drought indices, indicating the response of the aquifer to meteorological and agricultural drought. The time-varying pumping and recharge, along with the corresponding meteorological and agricultural drought conditions, also provide insights on water availability and potential water depletion during drought episodes. The proposed workflow may serve as an effective and cost-efficient strategy that may be utilized in areas with limited field data.

Coastal settlements are experiencing the effects of climate change‐induced sea‐level rise, including a significant but often poorly‐characterized impact on groundwater. The shallow water tables present in the built coastal environment contribute to an increased risk from natural hazards such as groundwater flooding and saltwater intrusion. Historical urban development was accompanied by impacts on shallow groundwater, and in the future subsurface environments, including underground infrastructure, will face additional pressure. This article reviews processes of the coastal groundwater zone and simulation tools used to evaluate possible impacts of sea‐level rise. The benefits and limitations of the two main methods to assess coastal groundwater rise and contribution to flooding are discussed using studies and investigations up to 2021. The review addresses challenges associated with the simulation tools to evaluate changes in urban hydrogeology due to sea‐level rise. The models reviewed do not specifically estimate groundwater contribution to land‐surface flooding. We highlight a critical need for methodology comparisons between spatial interpolation and numerical tools that will guide future work. An adequate validation of assessment methods is required and will be supported by improved coastal groundwater monitoring networks focused on water quality, saltwater intrusion, and continuous groundwater levels records. From current monitoring practices, evidence for groundwater rise with rising sea level is not widely observed at present. New monitoring sites are recommended near the coastline and tidally influenced surface water bodies, to better evaluate the rise of the water table and impacts on infrastructure.

This study was performed to understand the chemical properties of coastal groundwaters of Korea and to evaluate salinization and desalinization using the chemical compositions of groundwaters, ionic ratios and base cation exchange. Salinization and desalinization frequently occurs in coastal and reclaimed regions, respectively. The reclaimed regions are mainly distributed in western coastal areas, but those are hardly distributed in southern coastal area. Thus, in the western coastal areas, the chemical compositions of groundwaters were mainly affected by salinization by seawater encroachment and desalinization by recharge of fresh water. 33 ~ 37% of the total groundwater samples were affected by seawater, and 6 ~ 15% of the total brackish and saline groundwater samples observed desalinization. However, in the southern coastal areas, the chemical compositions of groundwaters were mainly influenced by salinization (approximately 30 ~ 34%). Also, desalinization processes were observed in some southern groundwater samples (approximately 2 ~ 4%). While the desalinization in the western coastal groundwater was mainly observed in reclaimed regions, desalinization in the southern coastal groundwater was not observed in only reclaimed region. This study shows that desalinization can be one of main factors controlling the chemical compositions of groundwaters in the coastal areas including reclaimed regions and base cation exchange is good tool to identify desalinization.