Salinity Trends Research Articles

Regional hydrogeology of the Arab-D aquifer in Central and Eastern Saudi Arabia with highlighting its environmental and energy potential

The Jurassic Arab-D reservoir hosts major oil-producing zone in Eastern Saudi Arabia with production from individual wells exceeding 25000 B/D. From a water supply perspective, Saudi water authorities consider it a minor aquifer with small yields of relatively high salinity; hence, it did not receive much attention in previous studies of aquifers. The present paper describes regional hydrogeological characteristics of the Arab-D in terms of groundwater flow, salinity and temperature, and discusses geological factors controlling these characteristics. Although high groundwater salinity in the Arab-D precludes it from being a potential water supply resource, studying the hydrogeology of Arab-D provides a hydrodynamic tool to oil exploration and development project. It also sets the stage for detailed studies of Arab-D aquifer potential use for industrial effluent disposal and as new geothermal energy source. Most of groundwater flow in Arab-D occurs in the porous and permeable grainy-textured upper zones. The top limit of the groundwater flow domain in Arab-D is the overlying massive Arab-D anhydrite unit. Trends in Arab-D hydraulic head, water salinity and temperature show gravity-driven flow towards the coastal region of Eastern Arabia. Major anomalies in these trends exist near the Ghawar, Summan, Jauf and Yabrin north-south faults. These anomalies are results of fault zone architecture that consists of sealing fault core zones surrounded by conductive fault damage zones. Depth, salinity, and temperature of the Arab-D between north Ghawar and Berri fields show that it has potential uses for industrial effluent disposal and geothermal energy projects.

Deep Waters in British Columbia Mainland Fjords Show Rapid Warming and Deoxygenation From 1951 to 2020

AbstractMany complex fjord systems cross British Columbia's coastline. A 70 year (1951–2020) time series analysis of temperature, salinity, and oxygen in four such fjords between ∼54 and 50oN (Douglas Channel, Rivers Inlet, Knight Inlet and Bute Inlet) shows that changes were greatest in deep waters between the sill and the bottom. In Rivers, Knight and Bute Inlet, the deep water temperature increased by 1.2–1.3°C over 70 years, up to two times the global average for open ocean waters at corresponding depths, while salinity increased by 0.1–0.2, and oxygen decreased by 0.4–0.7 mLL−1. The most northern inlet, Douglas Channel, showed a temperature increase of 0.8°C from 1951 to 2016, while trends in oxygen and salinity were not statistically significant. An analysis of Apparent Oxygen Utilization suggests that the deep waters in Douglas Channel are more readily exchanged with the outer coast than the three other fjords.

Mineral chemistry, fluid inclusion and stable isotope studies of the Suyoc epithermal veins: Insights to Au-Cu mineralization in southern Mankayan Mineral District, Philippines

The Suyoc prospect is an epithermal vein-type mineralization located at the southern part of the Mankayan Mineral District, Northern Luzon, Philippines. The prospect’s epithermal veins are hosted in volcaniclastic rocks and conglomerate, which belong to the Late Oligocene to Early Miocene Balili Formation and the Middle to Late Miocene Suyoc Conglomerate, respectively. These veins are classified into three major types: quartz vein, quartz-sulfide vein, and quartz-carbonate vein. The quartz vein exhibits massive and cockade textures associated with pyrite + chalcopyrite. The quartz-sulfide vein consists of massive and comb quartz associated with pyrite + chalcopyrite + sphalerite. The quartz-carbonate vein has massive quartz associated with rhodochrosite and chalcopyrite + sphalerite + galena + Au/Ag ± bournonite. In addition, massive gypsum ± pyrite occurs as a minor vein-type.Fluid inclusion measurements in quartz from the three major vein-types revealed 230–250 °C formation temperatures and 1.0–3.5 wt. % NaCl equivalent salinity, which are values consistent with epithermal deposits. Quartz textures (e.g., massive, cockade, comb, crustiform) and dominance of liquid-rich fluid inclusions do not suggest that boiling is a primary mechanism of vein deposition. Possible mechanisms are inferred as meteoric water dilution based on homogenization versus salinity trend in quartz vein and presence of rhodochrosite in quartz-carbonate vein, and wall rock interaction based on FeS trend in sphalerite crystals of the quartz-carbonate vein. The presence of pyrite and chalcopyrite in the major vein-types and the FeS mole percent values (0.51 to 8.30) in quartz-carbonate vein indicate an intermediate sulfidation state. The alteration minerals illite, chlorite, pyrite and quartz indicate near-neutral pH condition. δ34S values, which vary from −1.1 to +3.9‰, suggest reduced condition when compared to the representative bulk δ34S value for the Mankayan Mineral District. The characteristics and conditions strongly indicate an intermediate sulfidation epithermal (ISE) style of mineralization. Moreover, the δDwater (−63 to −66‰) and δ18Owater (−3.9 to −1.1‰) values from the major vein-types suggest late stage formation in a magmatic-hydrothermal system similar to other ISE deposits in the Northern Luzon Segment (e.g., Victoria, Acupan and Antamok).Given these, the presence of the Suyoc ISE veins in the underexplored southern part of the Mankayan Mineral District implies potential presence of undiscovered cogenetic porphyry Cu and high sulfidation epithermal mineralization in the area.

Evolution of Salinity and Water Table Level of the Phreatic Coastal Aquifer of the Emilia Romagna Region (Italy)

The coastal aquifers of the Mediterranean region are highly susceptible to seawater intrusion due to a combination of challenges such as land subsidence, high aquifer permeability, urbanization, drainage, and an unsustainable use of water during the dry summer months. The present study is focused on a statistical analysis of groundwater data to evaluate the spatial changes of water level and electrical conductivity in the coastal phreatic aquifer of the Emilia-Romagna (Northeast Italy) for the period from 2009 to 2018. Data from 35 wells distributed across the entire regional coastal area are used to establish a temporal trend, as well as correlations between salinity, water table level, and rainfall. Water table and salinity distribution maps for the entire study area are discussed regarding surface geology and water management. Most of the wells are in the beach wedge sand unit, which allows for easy connectivity between groundwater and surface water. Surface water and groundwater salinization are enhanced along the surface water bodies connected to the sea. The lowest water table level occurs in the western and northern parts of the study area, because of the semiconfined behavior of the aquifer. Only in the northernmost, close to the Po River, and in the southernmost parts of the study area does the groundwater remain fresh for the whole period considered due to river aquifer recharge. In the rest of the region, the thickness of freshwater lenses, where present, is less than 4.5 m. The existence of a water table level below sea level and high saline water at the bottom of the aquifer in most of the study area suggest that the aquifer is in unstable hydrodynamic conditions and groundwater quality is not fit for human consumption or for irrigation. This study is the first to provide a regional overview of the state of groundwater level and salinization within the coastal aquifer of the Emilia-Romagna Region; it also suggests that, overall, the salinization trend has slightly decreased from 2009 to 2018.

Post-eastern Mediterranean Transient Oxygen Decline in the Deep Waters of the Southeast Mediterranean Sea Supports Weakening of Ventilation Rates

Long-term trends in oxygen, salinity, and nutrients were followed in the Southeastern Mediterranean (SEMS) deep waters from 2002 to 2020. Results show a net decrease in oxygen since 2008 of −0.5 ± 0.1 μmol kg−1 yr−1 in the bathypelagic depths (1,200–2,000 m). Multiannual variability in oxygen levels superimposed this trend, and is likely associated with variations in thermohaline fluxes. The 2020 mean oxygen concentration of 179.5 ± 2.3 μmol kg−1 is comparable to the pre-Eastern Mediterranean Transient (EMT) mean value. The post-EMT signature is clearly demonstrated in both oxygen and salinity over the period of 2002–2013, but since 2014 it diminished, mainly due to mixing of the Aegean deep water (AegDW) mass with the overlying old Adriatic water mass. This trend reflects a switch back to the pre-EMT regime, characterized by thermohaline homogeneity of the deep water column in the SEMS. The long-term decline of deep water oxygen levels is also accompanied by a corresponding increase in dissolved inorganic nutrients, supporting aging of the deep water masses. Our results suggest that ventilation of the SEMS deep water is currently occurring at a lower, pre-EMT rate, probably as a result of moderated deep water formation in recent time.

Multistage hydrothermal quartz veins record the ore-forming fluid evolution in the Meiling Cu–Zn (Au) deposit, NW China

The Meiling Cu–Zn (Au) deposit, located in the center of the southeastern Kalatag district in the eastern Tianshan, NW China, is characterized by multistage ore-bearing quartz veins. The fluid inclusion, textures, and trace element compositions of the quartz associated with three main mineralization stages—Stage I: quartz (Qtz1) + pyrite ± chalcopyrite ± sphalerite veins; Stage II: quartz (Qtz2) + pyrite + chalcopyrite + sphalerite veins; and Stage III: quartz (Qtz3) + pyrite + chalcopyrite + covellite veins—are investigated to reveal the ore-forming fluid evolution. Stockwork and breccia Qtz1 (245 °C to 348 °C) with impure surfaces have high concentrations of the trace elements Li, Ga, Ge, Sb, and Sn, indicating that Qtz1 crystallized during a fluid boiling event under relatively hydrofracturing conditions. The fluid composition, temperature, and fluid flow rate largely influenced the trace elements in Qtz2-1 (wide temperature range of 111 °C to 279 °C) and Qtz2-2 (121 °C to 218 °C), which are characterized by smoky gray and milky quartz veins, respectively. Decreasing temperature and pressure and enhanced fluid-rock reactions may have been the factors causing the precipitation of chalcopyrite and sphalerite in Stage II. Qtz3 (110 °C to 202 °C) + chalcopyrite + covellite veins in Stage III mostly show comb-like and porous textures, and Qtz3 has relatively low Li, Al, Ti, Ga, Ge, and B contents and Li/Al ratios, indicating that Qtz3 crystallized under open and oxidized conditions. The locally higher Li, Al, and Ti contents in the rims than in the cores of Qtz2-2 and Qtz3 can be attributed to rapid growth rates. The Ti contents and fluid inclusion of quartz indicate a decreasing trend of temperature and salinity during the evolution of ore-forming fluid from the early to late stages. Furthermore, the low Ti contents (<10 ppm) of quartz in the main mineralization stages generally reveal that the mineralization temperatures were less than 350 °C, as evidenced by the fluid inclusion microthermometry data (150 °C to 230 °C). The quartz data indicate that the Meiling deposit probably shows an affinity with epithermal deposits. Nevertheless, the medium- to high- temperature and salinity fluid in Stage I and high-Ti and high-Al field of epithermal deposits, as well as the complex “C”-shaped trend in the Ti vs. Al discrimination diagram, indicate that the Meiling deposit underwent potentially magmatic-hydrothermal fluid evolution and metallogenesis.

Spectral Characterization of Dissolved Organic Matter in Seawater and Sediment Pore Water from the Arctic Fjords (West Svalbard) in Summer

Fjords in the high Arctic, as aquatic critical zones at the interface of land-ocean continuum, are undergoing rapid changes due to glacier retreat and climate warming. Yet, little is known about the biogeochemical processes in the Arctic fjords. We measured the nutrients and the optical properties of dissolved organic matter (DOM) in both seawater and sediment pore water, along with the remote sensing data of the ocean surface, from three West Svalbard fjords. A cross-fjord comparison of fluorescence fingerprints together with downcore trends of salinity, Cl−, and PO43− revealed higher impact of terrestrial inputs (fluorescence index: ~1.2–1.5 in seawaters) and glaciofluvial runoffs (salinity: ~31.4 ± 2.4 psu in pore waters) to the southern fjord of Hornsund as compared to the northern fjords of Isfjorden and Van Mijenfjorden, tallying with heavier annual runoff to the southern fjord of Hornsund. Extremely high levels of protein-like fluorescence (up to ~4.5 RU) were observed at the partially sea ice-covered fjords in summer, in line with near-ubiquity ice-edge blooms observed in the Arctic. The results reflect an ongoing or post-phytoplankton bloom, which is also supported by the higher levels of chlorophyll a fluorescence at the ocean surface, the very high apparent oxygen utilization through the water column, and the nutrient drawdown at the ocean surface. Meanwhile, a characteristic elongated fluorescence fingerprint was observed in the fjords, presumably produced by ice-edge blooms in the Arctic ecosystems. Furthermore, alkalinity and the humic-like peaks showed a general downcore accumulation trend, which implies the production of humic-like DOM via a biological pathway also in the glaciomarine sediments from the Arctic fjords.

准噶尔盆地植被与土壤盐渍化关联性变化趋势分析

准噶尔盆地作为北疆地区主要的气候单元其环境变化会影响北疆地区整体的的生态环境变化。植被作为衡量区域生态环境的重要指标直接反映了准噶尔盆地的生态状况，近年来受到全球气候变化的影响准噶尔盆地地区气候格局发生改变，盆地相比于往年降水和气温明显升高，这种改变影响了盆地的植被变化同时也会在部分地区诱发土壤盐渍化灾害。土壤盐渍化是我国西北地区常见的导致植被退化的因素，其生成原因与地形和气候因素有关。为了探究准噶尔盆地植被变化与土壤盐渍化的关联性，基于2002-2019年生长季MOD09A1遥感影像数据，利用最大值合成法、Mann-Kendall趋势分析，Hurst趋势分析法、相关性分析等方法对准噶尔盆地植被和土壤盐渍化变化趋势以及两者的关联性进行了分析。结果表明，受区域降水和气温升高的影响，近20年来准噶尔盆地生长季植被整体呈增加趋势，各季节增加区域面积占比为63.50%-90.93%，平均为77.98%。土壤盐渍化呈减少趋势，各季减少区域面积占比为46.50%-86.78%，平均为70.68%。在地形低洼、排水不畅的区域土壤盐渍化程度加重，植被因盐分胁迫导致衰退，植被减少及巨大的蒸发降水比使得该地区土壤进一步变干，湿度降低。关联性分析结果表明各季植被与土壤盐渍化的变化中呈显著负相关的区域面积占比为37.36%-57.83%，平均为51.75%。Hurst趋势预测结果表明，当前植被和土壤盐渍化两者呈显著性变化的区域未来预测与当前变化方向相同，两者呈一般性变化的区域未来预测与当前相反。研究有助于在全球气候变化背景下了解准噶尔盆地近年来生态环境变化，结果为区域生态环境的可持续发展提供参考。;As the main climate unit in Northern Xinjiang, the environmental change of Junggar basin will affect the overall ecological environment change of Northern Xinjiang. Vegetation, as an important indicator of regional ecological environment, which directly reflects the ecological situation of Junggar basin. In recent years, under the influence of global climate change, the climate pattern of Junggar basin has changed. Compared with previous years, the precipitation and temperature in the basin have increased significantly. This change affects the vegetation change in the basin, and also induces soil salinization in some areas. Soil salinization is a common factor leading to vegetation degradation in Northwest China, which is related to terrain and climate factors. In order to explore the relationship between vegetation change and soil salinization in Junggar basin, this study was based on MOD09A1 remote sensing image data during the growing season from 2002 to 2019, this study analyzed the variation trend of plant cover and soil salinization in Junggar Basin and the correlation between them by using of the methods of maximum value composite, Mann-Kendall trend analysis, Hurst trend analysis and correlation analysis. The results showed that in the last 20 years, the plant cover in Junggar Basin was increasing in the growing season due to the influence of the regional precipitation and climate warming. The proportion of the increased area in each season was 63.50%-90.93%, with an average of 77.98%. Soil salinization, however, showed a decreasing trend, with a decreased area of 46.50%-86.78% in each season and the average value was 70.68%. In the low-lying area with poor drainage, the degree of soil salinization increased, the vegetation declined due to salt stress, the decrease of vegetation and the huge ratio of evaporation and precipitation made the soil further dry and the humidity decreased. The correlation analysis indicated that the proportion of areas with significantly negative correlation between vegetation and soil salinization in each season were 37.36%-57.83%, with an average of 51.75%. And the results of Hurst trend prediction suggested that the future prediction direction of areas with significant change in aspects above are the same as the current change trend, while one with a general change is opposite to the current change direction in future direction. This study devoted to obtain the information of the ecological environment changes in Junggar Basin in recent years under the global climate change background, in order to provide references for the sustainable development of regional ecological environment.

Investigation of the Relationship Between Soil Salinity Trend, Land Use and Climatic Factors Change (Case Study: Shadegan, Khuzestan)

Background and Objective: The purpose of this study is to investigate the relationship between trend of soil salinity, land use and climatic factors in the region of Shadegan, Khuzestan. Method: In this study, using principal component analysis and 54 samples of soil, soil salinity maps were prepared for the years 1990, 2006 and 2015. In the next step, land use maps of the region for the mentioned years have been prepared using satellite images and trend changes are determined. On the other hand, changes in climatic factors (temperature and precipitation) for the period of 1990-2015 were evaluated. Findings: Results showed that, reducing precipitation and increasing temperature caused increasing soil salinity during 25 years and also agricultural land and irrigation by saline water increases the salinity of the soil. Discussion and conclusion: Locating Hoor al-Azim wetland in the western part of the region, although it has fresh, brackish and saline water, it may have negative effects on soil salinity of the area because of using in agriculture irrigation. Finally, it can be concluded that soil salinity of the land might change land use and it can cause desertification in the region.

Assessment of an ocean-ecosystem model in simulating the Indian coastal marine ecosystem dynamics

ABSTRACT This study describes an assessment of an ocean-ecosystem model in simulating marine ecosystem dynamics in the Indian coastal waters. Long-term sustained in-situ observations of temperature, salinity, chlorophyll-a and dissolved oxygen (DO) collected in the coastal waters of India, and ship-based observations are used for this assessment. The model captures observed trend of temperature, salinity and chlorophyll-a with high correlation in both eastern and western shelf waters except for salinity and DO along west and DO along east coast. The model performs very well in simulating the Indian coastal shelf ecosystem dynamics. The seasonal occurrence of prominent phytoplankton bloom in the central-east coast during pre-monsoon, south-west coast during monsoon and north-west coast during post-monsoon is realistically reproduced by the model. The model also reproduces the seasonal presence of significantly low DO content in the upwelled water at a shallow depth leading to coastal hypoxia in the south-west and central-east coast of India during summer monsoon. A fine-tuned model is useful in understanding better Indian coastal shelf ecosystem and predicting future changes in time and space, like the occurrence of coastal hypoxia or anticipating phytoplankton blooms. Such information is useful for predicting potential fishing grounds in coastal waters and fisheries management.

Weakening Atlantic overturning circulation causes South Atlantic salinity pile-up

The Atlantic Meridional Overturning Circulation (AMOC) is an active component of the Earth’s climate system1 and its response to global warming is of critical importance to society. Climate models have shown an AMOC slowdown under anthropogenic warming since the industrial revolution2–4, but this slowdown has been difficult to detect in the short observational record5–10 because of substantial interdecadal climate variability. This has led to the indirect detection of the slowdown from longer-term fingerprints11–14 such as the subpolar North Atlantic ‘warming hole’11. However, these fingerprints, which exhibit some uncertainties15, are all local indicators of AMOC slowdown around the subpolar North Atlantic. Here we show observational and modelling evidence of a remote indicator of AMOC slowdown outside the North Atlantic. Under global warming, the weakening AMOC reduces the salinity divergence and then leads to a ‘salinity pile-up’ remotely in the South Atlantic. This evidence is consistent with the AMOC slowdown under anthropogenic warming and, furthermore, suggests that this weakening has likely occurred all the way into the South Atlantic. The slowdown in the Atlantic Meridional Overturning Circulation (AMOC) is remotely detected in an increasing South Atlantic salinity trend. This salinity pile-up is caused by reduced divergence of surface salinity transport under a weakened AMOC.

Application of remote sensing for salinity based coastal land use zoning in Bangladesh

Rising soil and water salinity is a major concern for coastal areas. Salt-water shrimp aquaculture is a land use mal-adaption to the rising salinity trend, and is contributing to the salinity expansion as well as lowering land productivity in the coastal areas of Bangladesh. This paper aims to propose a salinity-based land use zoning to restrict salinity expansion and to reduce land use conflicts. An integrated salinity detection technique combing field soil samples, a geographic information system and remote sensing were used. Subsequently, two determining factors of land suitability—soil salinity and distance from saline water sources—were used to identify zones for paddy/crop, mixed use and shrimp. The study districts witnessed rising salinity between 1990 and 2016, and thereby, decreasing suitable land are for paddy/crop by 20.96% of the agricultural area. The land suitability for paddy, mixed use and shrimp zones was found to be 51.88%, 29.36% and 18.76% of the study area, respectively. The proposed zoning strategy of this paper can be used as a quick and efficient tool for baseline information for integrated coastal zone management plan.

Seasonal and Interannual Trends of Oceanographic Parameters over 40 Years in the Northern Adriatic Sea in Relation to Nutrient Loadings Using the EMODnet Chemistry Data Portal

Long-term data series (1971–2015) of physical and biogeochemical parameters were analyzed in order to assess trends and variability of oceanographic conditions in the northern Adriatic Sea (NAS), a mid-latitude shallow continental shelf strongly impacted by river discharges, human activities and climate changes. Interpolation maps and statistical models were applied to investigate seasonal and spatial variability, as well as decadal trends of temperature, salinity, chlorophyll-a and nutrients. This analysis shows that sea surface temperature increased by +0.36% year−1 over four decades. Annual mean flow of the Po River markedly changed due to the occurrence of periods of persistent drought, whereas the frequency of flow rates higher than 3000 m3 s−1 decreased between 2006 and 2015. Moreover, we observed a long-term decrease in surface phosphate concentrations in Po River water (−1.34% year−1) and in seawater (in summer −2.56% year−1) coupled, however, to a significant increase in nitrate concentration in seawater (+3.80% year−1) in almost all seasons. These changes indicate that the nutrient concentrations in the NAS have been largely modulated, in the last forty years, by the evolution of environmental management practices and of the runoff. This implies that further alteration of the marine environment must be expected as a consequence of the climate changes.

Climate change impacts on soil salinity in agricultural areas

AbstractChanges in climate patterns are dramatically influencing some agricultural areas. Arid, semi‐arid and coastal agricultural areas are especially vulnerable to climate change impacts on soil salinity. Inventorying and monitoring climate change impacts on salinity are crucial to evaluate the extent of the problem, to recognize trends and to formulate irrigation and crop management strategies that will maintain the agricultural productivity of these areas. Over the past three decades, Corwin and colleagues at the U.S. Salinity Laboratory (USSL) have developed proximal sensor and remote imagery methodologies for assessing soil salinity at multiple scales. The objective of this paper is to evaluate the impact climate change has had on selected agricultural areas experiencing weather pattern changes, with a focus on the use of proximal and satellite sensors to assess salinity development. Evidence presented in case studies for Californiaʼs San Joaquin Valley (SJV) and Minnesotaʼs Red River Valley (RRV) demonstrates the utility of these sensor approaches in assessing soil salinity changes due to changes in weather patterns. Agricultural areas are discussed where changes in weather patterns have increased root‐zone soil salinity, particularly in areas with shallow water tables (SJV and RRV), coastal areas with seawater intrusion (e.g., Bangladesh and the Gaza Strip) and water‐scarce areas potentially relying on degraded groundwater as an irrigation source (SJV and Murray‐Darling River Basin). Trends in salinization due to climate change indicate that the infrastructure and protocols to monitor soil salinity from field to regional to national to global scales are needed.Highlights Climate change will have a negative impact on agriculture, particularly in arid regions. Proximal/remote sensors are useful to assess climate change impact on soil salinity across scales. Salt‐water intrusion, shallow water tables and degraded water reuse will increase soil salinity. Infrastructure and protocols to monitor soil salinity across multiple scales are needed.

Variation of Salinity in both Surface and Bottom Layers in Jiaozhou Bay

Based on the investigation data on Jiaozhou Bay in May and October 1979, the vertical distribution and seasonal variation of salinity in the surface and bottom waters from the inner waters to the outer waters of Jiaozhou Bay were studied, and the seasonal distribution, variation range and horizontal distribution trend of the salinity in surface and bottom layers were determined. The results showed that from May to October, in the waters of Jiaozhou Bay mouth, the inner waters of the bay mouth and the outer waters of the bay mouth, the seasonal change of salinity in both surface and bottom layers from low to high was: autumn and spring. In Jiaozhou Bay, from the inner water area to the outer water area, in May and October, the variation ranges of salinity in surface and bottom layers were basically the same. When the salinity content in surface was relatively low, that of the corresponding bottom layer was relatively low; when the salinity content in surface was relatively high, that of the corresponding bottom layer was relatively high. It showed that the salinity was fully transported to every part of the ocean through horizontal current transport and vertical eddy mixing. In Jiaozhou Bay, from the waters inside the bay mouth to the waters of the bay mouth, the horizontal distribution trends of salinity in the surface and bottom were opposite in May and the consistent in October. In May and October, the horizontal distribution trends of salinity in surface and bottom from the bay mouth to the outside of the bay mouth were consistent. Therefore, from May to October, in the inner waters of Jiaozhou Bay mouth, bay mouth waters and the outer waters of bay mouth, the seasonal variation mechanism of salinity in surface and bottom: both high and low salinity were transported by horizontal currents from the outer water area of the bay mouth to the water area of the bay mouth, and then to the inner water area of the bay mouth, which determined the seasonal variation mechanism of salinity in surface and bottom.

Erosion of the Subsurface Salinity Maximum of the Loop Current Eddies From Glider Observations and a Numerical Model

AbstractThe erosion of the subsurface salinity maximum, signature of the Caribbean Subtropical UnderWater (SUW), within the Loop Current Eddy (LCE) Poseidon (August 2016 to July 2017) in the Gulf of Mexico (GoM) and the formation of the Gulf Common Water (GCW) during its journey westward, was observed using glider data. Most of the dilution of the SUW high‐salinity core within Poseidon occurs during late autumn and winter associated with Northern winds and mixed‐layer deepening. The physical processes that contribute to salt dilution of the SUW inside the LCEs' core are investigated using a numerical regional model. The analysis of the salt budget in a long‐lasting numerical LCE and a composite analysis of sixteen LCEs reveal that the salinity trend is mostly explained by the vertical salinity diffusion. Cold and dry Northern winds during the first winter drive strong negative net heat fluxes that trigger turbulent flux of salt into the LCEs' thermostad and dilution of the SUW high‐salinity core below. The vertical salinity diffusion continues homogenizing the salinity in the upper ocean until the vertical gradient of salinity is negligible. As a result, SUW is transformed to precursor of GCW that is ultimately diffused to surrounding waters in the western GoM. Although the contribution of advection to the salinity trend above the isopycnal of 1,026 kg m−3 is of second order, below is the most important process driving loss of salinity, presumably due to, eddy‐eddy interactions during LCEs' westward propagation and eddy pumping (upwelling) during the LCEs' decaying phase along the western slope.

Near-Surface Salinity Reveals the Oceanic Sources of Moisture for Australian Precipitation through Atmospheric Moisture Transport

AbstractThe long-term trend of sea surface salinity (SSS) reveals an intensification of the global hydrological cycle due to human-induced climate change. This study demonstrates that SSS variability can also be used as a measure of terrestrial precipitation on interseasonal to interannual time scales, and to locate the source of moisture. Seasonal composites during El Niño–Southern Oscillation/Indian Ocean dipole (ENSO/IOD) events are used to understand the variations of moisture transport and precipitation over Australia, and their association with SSS variability. As ENSO/IOD events evolve, patterns of positive or negative SSS anomaly emerge in the Indo-Pacific warm pool region and are accompanied by atmospheric moisture transport anomalies toward Australia. During co-occurring La Niña and negative IOD events, salty anomalies around the Maritime Continent (north of Australia) indicate freshwater export and are associated with a significant moisture transport that converges over Australia to create anomalous wet conditions. In contrast, during co-occurring El Niño and positive IOD events, a moisture transport divergence anomaly over Australia results in anomalous dry conditions. The relationship between SSS and atmospheric moisture transport also holds for pure ENSO/IOD events but varies in magnitude and spatial pattern. The significant pattern correlation between the moisture flux divergence and SSS anomaly during the ENSO/IOD events highlights the associated ocean–atmosphere coupling. A case study of the extreme hydroclimatic events of Australia (e.g., the 2010/11 Brisbane flood) demonstrates that the changes in SSS occur before the peak of ENSO/IOD events. This raises the prospect that tracking of SSS variability could aid the prediction of Australian rainfall.

Crop Halophytism: An Environmentally Sustainable Solution for Global Food Security.

This work analyzes the current trends in land salinization and its impact on the global food security. It is argued that reliance on salt-excluding crops is counterproductive and environmentally unsustainable. New breeding paradigms are required to incorporate halophytic traits that were present in wild relatives but lost during domestication.

Assessment of Spatial and Temporal Trend of Groundwater Salinity in Jaffna Peninsula and Its Link to Paddy Land Abandonment

Salinization is an explicit global threat faced by coastal low lands. The increased seawater ingression into groundwater due to various climatic and anthropogenic factors affects functioning of ecosystems, biodiversity and the sustainability of coastal agriculture. This study was undertaken to investigate the changes in groundwater salinity in Jaffna Peninsula over a 20-year period and its relationship with paddy land abandonment. Permanently abandoned paddy areas were mapped using historical Landsat images, while groundwater salinity changes in 63 agricultural wells for the period 1999 to 2019 were analysed. The trend in salinity, including proximity to the coast, was examined. The results showed that approximately 8178 ha (43% of total paddy land) of paddy lands had been permanently abandoned while the groundwater salinity had increased by 1.6-fold over the last two decades. An increasing salinity trend with decreasing distance from the coast was observed. Presently, nearly 59% of the wells showed salinity levels that were unsuitable for crop irrigation. The results underline the need for urgent and effective management of groundwater resources in order to maintain the sustainability of the existing paddy lands and ensure availability of potable water for consumption along the coastal low land areas of Jaffna Peninsula.

Monthly physicochemical variation of tropical island groundwater of Pulau Bidong, south China sea

The groundwater of Pulau Bidong, Terengganu, Malaysia was investigated to monitor the quality of freshwater source. Groundwater samples were collected from five sampling stations from June 2016 to October 2016. Physical parameters such as temperature, specific conductivity, dissolved oxygen (DO), pH, salinity, and DO saturation were measured in-situ by using handheld device. Meanwhile, total suspended solid (TSS), total dissolved solid (TDS), nitrate (NO3−), nitrite (NO2−), ammonium (NH4+) and phosphate (PO43−) were also analysed. The inorganic nutrients of NO3−, NO2−, NH4+, and PO43− were ranged from 0.000 to 4.310 mg/L, 0.000–0.190 mg/L, 0.000–0.807 mg/L and 0.003–0.028 mg/L, respectively. The monthly trends of specific conductivity, DO, salinity, DO saturation, NH4, NO3 and NO2 demonstrated significant variation in June (the lowest rainfall) compared to other months. Correlation matrix revealed that temperature was associated with the specific conductivity, and NH4+ strongly correlated with DO, NO3− and NO2−. Nevertheless, there is a strong negative correlation between physicochemical parameters and monthly rainfall distribution. The physicochemical parameters were within the recommended safe limits suggested by the World Health Organization (WHO) and National Drinking Water Quality Standard (NDWQS) except for pH. Nevertheless, pH of water does not directly impact on the human health. Environmetrics analysis demonstrated that NO3− and PO43− significantly influenced the groundwater quality spatially. Furthermore, the temporal variation of groundwater quality was affected by pH and salinity. Overall, the groundwater sources from Pulau Bidong are considered safe to be used as drinking water. Notably, future studies are required for long-term monitoring to ensure the good quality of groundwaters from Pulau Bidong.