Impact Of Saltwater Intrusion Research Articles

Hydrogeochemical characterization and water quality evaluation for drinking and irrigation purposes of coastal aquifers of Middle Andaman

A comprehensive study to characterize the hydrogeochemistry of the region and the impact of saltwater intrusion on groundwater was conducted along the eastern coast of Middle Andaman of Andaman and Nicobar (A&N) Islands. The escalating population growth and intensified tourism activities have resulted in the over-extraction of groundwater. Seismic activities led to the opening of lineaments to the sea and the dissolution of limestone in the influence of seawater. 24 groundwater samples and 1 reference sample from sea were taken from various locations of middle Andaman. The analysis involved the determination of major cations, anions, and heavy metals using Inductively Coupled Plasma Optical Emission spectroscopy (ICP), spectrophotometry, and flame photometry. Furthermore, X-ray diffraction analysis, binary diagrams, Chloro-alkaline indices (CAI), Gibbs Plot, correlation matrix, Piper plot, Chadha’s plot and Principal Component Analysis (PCA) to the major ions data indicated rock-water interactions, strong correlations among alkali and alkaline earth metals, and interactions between seawater and carbonate minerals respectively. The water quality index indicated “very poor to unsuitable for drinking purposes” in 24% of the samples. Additionally, indices for irrigation suitability; total hardness (TH), residual sodium carbonate (RSC), and Magnesium adsorption ratio (MAR) were found to be detrimental for irrigation in 80%, 08%, and 12% of the water samples, respectively. These results highlight the importance of implementing effective water resource management techniques, such as groundwater extraction rates, adopting appropriate water treatment technologies to mitigate the adverse impacts of heavy metals, saltwater intrusion and maintain water quality for human consumption and agricultural use in the region.

Elucidating the links between N2O dynamics and changes in microbial communities following saltwater intrusions

Saltwater intrusion in estuarine ecosystems alters microbial communities as well as biogeochemical cycling processes and has become a worldwide problem. However, the impact of salinity intrusion on the dynamics of nitrous oxide (N2O) and associated microbial community are understudied. Here, we conducted field microcosms in a tidal estuary during different months (December, April and August) using dialysis bags, and microbes inside the bags encountered a change in salinity in natural setting. We then compared N2O dynamics in the microcosms with that in natural water. Regardless of incubation environment, saltwater intrusion altered the dissolved N2O depending on the initial saturation rates of N2O. While the impact of saltwater intrusion on N2O dynamics was consistent across months, the dissolved N2O was higher in summer than in winter. The N-related microbial communities following saltwater intrusion were dominated by denitrifers, with fewer nitrifiers and bacterial taxa involved in dissimilatory nitrate reduction to ammonium. While denitrification was a significant driver of N2O dynamics in the studied estuary, nitrifier-involved denitrification contributed to the additional production of N2O, evidenced by the strong associations with amoA genes and the abundance of Nitrospira. Higher N2O concentrations in the field microcosms than in natural water limited N2O consumption in the former, given the lack of an association with nosZ gene abundance. The differences in the N2O dynamics observed between the microcosms and natural water could be that the latter comprised not only indigenous microbes but also those accompanied with saltwater intrusion, and that immigrants might be functionally rich individuals and able to perform N transformation in multiple pathways. Our work provides the first quantitative assessment of in situ N2O concentrations in an estuary subjected to a saltwater intrusion. The results highlight the importance of ecosystem size and microbial connectivity in the source-sink dynamics of N2O in changing environments.

Impact of saltwater intrusion on poverty in rural households in the Mekong Delta, Vietnam

Purpose: The purpose of this study is to examine the causal relationship between saline intrusion and poverty in rural households in the Mekong Delta based on the 2018 Vietnam Household Living Standard Survey data.
 Design/Methodology/Approach: A sample of 344 rural households in the Mekong Delta is used to analyze the causal relationship between saline intrusion and poverty through income. This study employed the Ordinary Least Squares method and the oprobit model to investigate the causal relationship between saline intrusion and rural household income. Finally, this study estimates the impact of saline intrusion on poverty using different propensity score matching methods.
 Findings: 1) Saltwater intrusion has a significant negative impact on the income of rural households, making households more likely to fall into the lower income group; 2) Saltwater intrusion has a greater negative impact on the incomes of poorer households than non-poor households, while also having a negative impact on households with low education and farming; and 3) By reducing household income as well as income from farming activities, infiltration increases the risk of poverty for rural households and reduces the household's ability to escape poverty.
 Conclusion: This study demonstrates how saltwater intrusion affects household poverty by reducing income and raising the likelihood that households will fall below the Vietnamese government's designated poverty income threshold.

Effects of water salinity on cadmium availability at soil-water interface: implication for salt water intrusion.

Low-lying paddy fields in estuaries can be affected by salt water intrusion; however, it remains unclear how salt water intrusion influences the availability of heavy metals in paddy soil. In this study, batch adsorption and incubation experiments of soil were conducted with different salt water sampled along the estuary to investigate the effects of salt water intrusion on cadmium (Cd) availability. The surface complexation model (SCM) was established to assess the effects of pH on Cd adsorption behavior, which presented typical pH-dependent characteristics. The results of SCM also showed that Cd-chloro complexes became the dominant species when the ionic strength increased. The results of Cd fractions in the incubation experiments revealed a significant increase in dissolved Cd with increasing ionic strength. This may be attributed to the increased point of zero charge (pHpzc) in the presence of salt water with higher salinity, which likely formed more positive charges on soil surfaces, causing an inhibition of Cd adsorption via electrostatic repulsion. Moreover, higher concentrations of Cl- in salt water favored the formation of Cd-chloro complexes, facilitating Cd release from soil particles. This study provides mechanistic insights into the impact of salt water intrusion on Cd availability at the soil-water interface of paddy soil along the estuary.

Study to assess the impact of saltwater intrusion in Ho Chi Minh City under climate change conditions

Study to assess the impact of saltwater intrusion in Ho Chi Minh City under climate change conditions

Impact of saltwater intrusion on relation to fruit growing households in Ben Tre, Vietnam

Purpose. Saltwater intrusion affected seriously the livelihood of mangosteen growers in Ben Tre, a coastal province in the Vietnamese Mekong Delta in 2016. This study assesses how saltwater intrusion influenced the livelihood vulnerability of the mangosteen households and communities.
 Methodology / approach. This study used the United Nations’ Livelihood Vulnerability Index (LVI) and a similar index from the Intergovernmental Panel on Climate Change (LVI-IPCC) using data from 196 interviewed mangosteen growers in Cho Lach district, Ben Tre province in 2016 and 2018. A total of twenty-five (25) indicators are applied to calculate the two indices, using data as exposure to saltwater intrusion and natural hazards (5), socio-demographic factors (11), and sensitivity of health, finance, and source of water for domestic use (9).
 Results. The analysis results show that mangosteen-growing households had a medium vulnerability in 2016 and 2018 based on both indices. However, they were extremely vulnerable due to saltwater intrusion in 2016, and a high household percentage had a moderate value in the vulnerability index. They did not experience how to respond to saltwater intrusion and received a late warning on saltwater intrusion from the local authorities and media. However, mangosteen-growing households had a quick adaptive behavior to shift to new crops to improve their income in 2018.
 Originality / scientific novelty. The study provides a set of indicators to assess the vulnerability of this low-vulnerable area based on past studies as well as the actual situation of the study area in 2016 and 2018 to determine what factors influenced the main components, LVI and LVI – IPCC. These indicators represented the characteristics of the rural households in Vietnam and other Asian countries. This research also indicated how LVI and LVI – IPCC results differently and when they should be used. The analysis identified the factors influencing the LVI and LVI – IPCC by levels of saltwater intrusion in different years of 2016 and 2018, two different severe and less severe sites, adaptive and non-adaptive households, and their interaction. 
 Practical value / implications. LVI and LVI-IPCC are good indicators for local and regional assessments on how saltwater intrusion and natural hazards affect households’ and communities’ livelihood and thereby how to guide them to respond promptly in such cases.

Research on the regulation of Three Gorges Reservoir in response to saltwater intrusion in the Yangtze River Estuary

With the changes of economic society and human activities to the natural environment, the impact of saltwater intrusion becomes more frequent and the degree of harm becomes more serious. The Yangtze River Estuary is a densely populated and economically developed area in China, but in terms of water resources utilization, the Yangtze River Estuary is often suffering from saltwater intrustion in dry season. As the backbone of the cascade reservoirs in the Yangtze River Basin, the scientific operation of the Three Gorges Reservoir plays an active role in reducing the saltwater intrusion in the Yangtze River Estuary. Therefore, based on the analysis of the characteristics of Yangtze River Estuary, this paper sums up the variations of saltwater intrusion and discusses the main dynamic factors of saltwater intrusion. In addition, it explores the internal relationship between the upstream water volume and the saltwater intrusion. It takes the allocation of the fresh water resources by the water resources regulation of the Three Gorges Reservoir as a main discussing point. In the end, this paper focuses on the countermeasures and effect of emergency water replenishment on the saltwater intrusion in the Yangtze River Estuary.

Assessing the adaptive capacity of farmers under the impact of saltwater intrusion in the Vietnamese Mekong Delta

Saltwater intrusion is one of the main problems in the coastal provinces in the Mekong Delta (including the Tra Vinh province), and it is becoming more severe with climate change and rising sea levels. In the face of this problem, a strategic plan has been developed for the Vietnamese Mekong Delta that suggests adapting to increasing salinity levels. However, the farmers’ capacity to implement the changes is unclear. The objective of this study was to assess farmers’ adaptive capacities towards saline intrusion in the Tra Vinh province in order to provide appropriate adaptation options, using the MOTA (Motivation-Ability) approach. This study surveyed 187 farmers regarding their perception, motivation, and ability in different saline environments in the study area, including three regions: seawater areas (region 1), brackish water areas (region 2), and freshwater areas (region 3). The results showed that farmers have quite high perceptions of salinity intrusion, especially farmers who live in areas affected by it. Regarding the level of saltwater intrusion, the farmers’ motivation in all three regions had a negative score, which indicates their motivation for adapting to increased salinity was quite low. Additionally, the farmers’ adaptive capacities in all three regions were moderate, with lowest capacities in educational level and rate of participation in non-agricultural organizations. The study results may be useful for managers and policy-makers in proposing appropriate and feasible options for implementing an adaptation plan to ensure sustainable livelihoods for local farmers.

Assessing the impact of saltwater intrusion on agricultural land in Nghe An’s coastal areas in the context of climate change

Climate change is occurring increasingly complex and unpredictable, therefore the phenomenon of saltwater intrusion at coastal areas is also increasingly serious. The saltwater intrusion threatens the production and life of people in Nghe An’s coastal areas. Our study used MIKE11, MIKE 21 and ArcGIS software to assess the effects of saltwaters intrusion on agricultural land. The results indicate that the agricultural lands in Nghe An’s coastal areas are at high hazards of saltwater intrusion. Cua Lo town is the most affected by the saltwater intrusion, typically with land for cultivation of perennial trees (BHK), paddy land (LUC, LUK), land for production forests (RST), and land for aquaculture (TSL) are at high risk from the base (with more than 90 % of the total land area).

Dynamics of plant communities and the impact of saltwater intrusion on the floodplains of Kakadu National Park

The distribution of vegetation communities on floodplains within Kakadu National Park, in tropical northern Australia, is related to micro-topography and, therefore, water depth and duration of flooding. Floodplains of the Kakadu Region, because of their proximity to the coast, are most vulnerable to the impacts of climate change, with saltwater intrusion, as a result of sea-level rise, being a serious risk. Our main objectives were to determine the variability of the distribution of plant communities on the floodplains and understand the potential risk of increased saltwater intrusion to these communities. We present data on the natural salinity-tolerance range of selected floodplain plants and discuss the likely effects of saltwater intrusion on floodplain plant distributions and productivity. The results of change analysis using high spatial-resolution satellite data showed the importance of the variation of water availability in determining patterns of plant communities. Hydrodynamic modelling suggests that sea level rises will result in 40% of the floodplain transformed into saline habitats by 2070. The most obvious effect of this would be the conversion of the freshwater vegetation to salt-tolerant mangroves and other salt-marsh plants, with a concomitant change in animals and their use of these areas.

Impact of salinity and pH on phytoplankton communities in a tropical freshwater system: An investigation with pigment analysis by HPLC

An in vitro study was carried out to understand the effects of salinity shock and variation in pH on phytoplankton communities in a tropical freshwater system of the Godavari River (a major peninsular river in India). The distributions of, and variations in, phytoplankton communities were assessed by quantitative determination of their class specific marker pigments, using HPLC. Subtle changes in salinity of the freshwater by one practical salinity unit (PSU) completely removed green algae from the system and allowed the cyanobacteria to come into dominance. The cyanobacteria were found to tolerate higher osmotic stress until the salinity reached a PSU of 16. The higher salinity tolerance range of the cyanobacteria was attributed to the enhanced synthesis of zeaxanthin as protective xanthophylls against the osmotic stress. However, the effects of changing pH were not as dramatic as salinity where the green algae and the cyanobacteria from the same freshwater system showed a considerable acclimation towards the fluctuating pH. These findings are environmentally relevant to understand the likely impact of salt water intrusion and pH variation on phytoplankton communities in a tropical freshwater system.

Accelerated microbial organic matter mineralization following salt-water intrusion into tidal freshwater marsh soils

The impact of salt-water intrusion on microbial organic carbon (C) mineralization in tidal freshwater marsh (TFM) soils was investigated in a year-long laboratory experiment in which intact soils were exposed to a simulated tidal cycle of freshwater or dilute salt-water. Gas fluxes [carbon dioxide (CO2) and methane (CH4)], rates of microbial processes (sulfate reduction and methanogenesis), and porewater and solid phase biogeochemistry were measured throughout the experiment. Flux rates of CO2 and, surprisingly, CH4 increased significantly following salt-water intrusion, and remained elevated relative to freshwater cores for 6 and 5 months, respectively. Following salt-water intrusion, rates of sulfate reduction increased significantly and remained higher than rates in the freshwater controls throughout the experiment. Rates of acetoclastic methanogenesis were higher than rates of hydrogenotrophic methanogenesis, but the rates did not differ by salinity treatment. Soil organic C content decreased significantly in soils experiencing salt-water intrusion. Estimates of total organic C mineralized in freshwater and salt-water amended soils over the 1-year experiment using gas flux measurements (18.2 and 24.9 mol C m−2, respectively) were similar to estimates obtained from microbial rates (37.8 and 56.2 mol C m−2, respectively), and to losses in soil organic C content (0 and 44.1 mol C m−2, respectively). These findings indicate that salt-water intrusion stimulates microbial decomposition, accelerates the loss of organic C from TFM soils, and may put TFMs at risk of permanent inundation.

Interactions Between Soils and Laboratory Simulated Electrolyte Solution

To study the impact of salt water intrusion on two types of soils from west coast region of India were investigated in the laboratory. The key characteristics evaluated included Atterberg limits, compaction characteristics, hydraulic conductivity and chemical characteristics of selected soils. The sea at this coast receives effluent from different points and hence the characteristics change with time and locality. Therefore, to maintain uniform composition, 0.5 N sodium chloride solution (NaCl) was prepared in the laboratory and batch tests were used to determine the immediate effect on soils. Soil specimens were prepared by mixing the soils with 0.5 N NaCl in the increments of 0, 5, 10 and 20% by weight to vary the degree of contamination. Experimental results of soils mixed with 0.5 N NaCl showed that the maximum dry density increases and the optimum moisture content (OMC) decreases with increasing sodium chloride concentration. The study also revealed that the hydraulic conductivity of the soils tested increases with increase in sodium chloride concentration. The Atterberg limits of contaminated specimens show a remarkable change when compared with uncontaminated specimens.

Land Use Change and Environmental Hazard in the Coastal Areas: The Case of Laizhou Gulf, China

Research on land use or land cover changes in the coastal areas of China has received little attention. The Laizhou Gulf, located in Shandong Province of China, was investigated to assess land use change dynamics by using Landsat™ satellite images of two periods, 1988 and 2002; ground-based information; and geographical information systems. The land uses were grouped into six categories: cropland, forestland, grassland, urban and/or built-up land, water, and barren land. The results indicated that land use since 1988 has changed significantly. The total area of cropland rapidly decreased from 2249.9 km2 in 1988 to 2223.5 km2 in 2002, decreasing by 26.4 km2; water area decreased from 433.5 km2 in 1988 to 414.8 km2 in 2002, decreasing by 18.7 km2; and barren land area decreased from 128.3 km2 in 1988 to 93.6 km2 in 2002, decreasing by 34.7 km2. Concurrently, continuous increases of other land use types occurred between 1988 and 2002: grassland increased by 13.6 km2 from 99.7 km2 to 113.3 km2, and urban and/or built-up land increased by 94.9 km2 from 824.4 km2 to 919.3 km2. These alterations were natural and human induced. These factors expose coastal areas of Laizhou Gulf to environmental hazard, namely, saltwater intrusion. Manmade interventions and actions, such as construction of coastal structures and exploitation of aquifers without adequate knowledge of the hydrology setting and an adequate management program, worsen this natural hazard. Uncontrolled human activity induces environmental damage to the overall coastal plains. The impact of saltwater intrusion on land use changes in the area is also discussed.

PROFILE: "Low-Salt" Shrimp Aquaculture in Thailand: Goodbye Coastline, Hello Khon Kaen!

/ Intensive shrimp culture has been confined to relatively narrow bands of land along the seashores of tropical developing nations due to the need for large volumes of saltwater for water exchange during the culture period. Recent developments in Thailand suggest, however, that this close association could soon be a thing of the past. Large numbers of Thai farmers are adopting low-salinity culture systems that rely upon sea or salt pan water that is trucked inland. This development greatly increases the potential for establishing shrimp cultivation much further from the coast than previously believed possible. The migration of intensive shrimp farming into freshwater environments, however, raises serious concerns over the disposal of pond effluents and the impact of saltwater intrusion on surrounding agricultural activities. In the absence of effective government regulation of the expansion and operation of the shrimp culture industry, supporting local nongovernmental organizations (NGOs) and community initiatives may be the only means of minimizing the negative impacts of shrimp farming on rural communities.KEY WORDS: Aquaculture; Shrimp; Salinity; Thailand

Intrusion indices ‐ a measure of groundwater quality

Abstract The Intrusion Index is the arithmetic mean of three indices ‐chloride, sulfate, and nitrate ‐ that define the impact of human activities on groundwater quality in Florida and presumably elsewhere. The Intrusion Index and the component indices are arranged on a scale of 0–100 (0–59 is good, 60–69 is fair, and 70–100 is poor) in analogy with the Trophic State Index. The Chloride Index should reflect the impact of salt water intrusion. The Sulfate Index can reflect the impact of excessive pumping and contamination of the surficial aquifer by deep aquifer water, and the Nitrate Index can reflect the impact of agricultural activities, among others.