Salinity Trends Research Articles

Correction to “Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water”

Correction to “Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water”

Beyond Phosphorus: Salinization as a driver of eutrophication symptoms in North American lakes

The acceleration of global urbanization continues to fuel concerns surrounding water quality impairments in urban lakes, particularly eutrophication. Eutrophication of freshwater environments is generally assumed to be driven by increased anthropogenic phosphorus (P) supplies which can alleviate limitations on primary production. Salinization is also recognized as a stressor on urban freshwater quality, particularly in cold temperate climate regions where salts are applied to road surfaces as de-icing agents. While the ecological damages caused by P enrichment and salinization to freshwaters are both well established, thus far, their impacts on water quality have only been considered independently. Although improvements to the management of urban stormwater and wastewater have decreased P inputs to freshwater systems in recent decades, many lakes worldwide remain eutrophic, as indicated by declining dissolved oxygen (DO) concentrations and rising dissolved inorganic P (DIP) concentrations in the hypolimnion. Our previous study of an urban freshwater lake in Ontario, Canada, showed that persistent eutrophication symptoms are linked to salinization associated with impervious land cover expansion, rather than increased external P loading. In this research, we present a multiple decade of water chemistry data analyses for several other urban lakes in Ontario, Wisconsin, and Minnesota to determine how increased lake salinization rates intersect with water temperature and morphometry to alter water column stratification, thus, increasing eutrophication symptoms. Our trend analysis shows progressive salinization (observed through significant increases in chloride or electrical conductivity) of all the lakes investigated. Calculations of lakes mixing indices over time show that, on average, lake stratification is becoming more stable with increased salinity playing a crucial role in enhancing lake stratification. Overall, salinity is becoming a stronger regulator of water density than temperature in the cold temperate urban freshwater lakes of North America. The increasing salinity trends are accompanied by increasing hypolimnion hypoxia and increasing DIP to total P (TP) ratios in all lakes, thereby demonstrating the mechanistic link between salinization and internal P loading. Rising salinity intensifies water column stratification, in turn, reducing the oxygenation of the hypolimnion and enhancing internal P loading from the sediments. These results highlight that stricter management of de-icing salt application rates should be considered to control lake eutrophication symptoms in cold climate regions.

Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water

Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water

A decade-long study on the effect of furrow and subsurface drip irrigation using unconventional water on soil salinity and the growth of pistachio trees

Furrow irrigation is the most common method of irrigating pistachio orchards in Iran. Water use efficiency using this method of irrigation is close to 35%. Ten years ago, a subsurface drip irrigation (SDI) project was initiated with highly saline and alkaline water for the first time in Iran at the Feyzabad pistachio research station, at 34̊ 54ʹ 15ʺ N, 58̊ 45ʹ 37ʺ E, located in the northeast of Iran, at an altitude of 850 meters from the sea. The water salinity and sodium adsorption ratio were 11.5 dS m-1 and 15.5 at the beginning of the project, and they reached 16.25 dS m-1 and 17.7 in 2021. The amount of SDI water consumption in the first year of the project (2012) was 1640 m3 ha-1 yr-1, and as the trees aged, water consumption reached 3000 m3 ha-1 in 2022. The amount of water utilized for furrow irrigation was about 6912 m3 ha-1 in 2022. Salt entering the soil through irrigation water differed by about 41 t ha-1 in 2022 between the two methods. After ten years of project implementation, the root development layer was more than 100 cm and less than 50 cm, respectively, for SDI and furrow. The trend of soil salinity has changed from 2012 to 2022: it went from 34.7 dS m-1 in 2012 to 110 dS m-1 in 2018, and then decreased to 65 dS m-1 in 2022 in the surface layer of the SDI method. In contrast, salinity increased almost twofold within the root development layer (60-140 cm) in the SDI. In the last two years (2021 and 2022), the height, crown width, trunk circumference, and yield of the pistachio trees were not significantly different between the two irrigation methods. However, there was a significant difference in the irrigation treatments during the two last years (2021 and 2022) in the annual growth, the average number of flower buds in the branch, and the average number of flower buds abscised. The branch vegetative growth in 2022 had decreased by almost 50% compared to 2021 in both methods. The results showed that the lowest annual growth was achieved in the SDI in 2022. Overall, the efficiency of water consumption in the SDI and furrow was equal to 0.09 and 0.06 kg m3, respectively. SDI net income was 1284 $ higher after expenses were deducted from 2012 to 2022. Therefore, due to severe climate change and excessive salinity increase in soil and water resources, a well-managed SDI can provide a more sustainable production method for salt-affected soils for pistachio orchards by reducing water consumption and salt entry into the soil.

Long-term trends of salinity in coastal wetlands: Effects of climate, extreme weather events, and sea water level

Coastal freshwater ecosystems play major roles as reservoirs of biodiversity and provide many ecosystem services and protection from extreme weather events. While they are of particular importance worldwide, they are affected by a large variety of anthropogenic threats, among which salinization has been less studied, particularly regarding large temporal and spatial data sets based on real case scenarios, while salinity can impact biodiversity and ecosystem functioning. In this study, we investigated the variations of salinity across long-term (1996–2020) and seasonal (monthly records) temporal scales and spatial (varying distance to the coastline) scales in water bodies of two typical temperate coastal wetlands situated on the Atlantic coast of France. We complemented our analyses with models of sea water levels computed at both sites across 2000–2020. Our detailed data set allowed for highlighting that salinity in ponds varied seasonally (higher during summer, due to decreased precipitation and higher temperature), but also spatially (higher closer to the seashore, which pattern increased through time). Over the long term, decreased precipitation but not increased temperature induced increasing salinity. We also highlighted contrasted long-term patterns of salinity changes on these two coastal wetlands, with one site were salinity decreased over time linked to the responses to marine flood, allowing to document the temporal dynamics of salinity following a massive intrusion of sea water. Complementarily, at both sites, water levels at high tides increased through time, a pattern which can induce additional salinization. To our knowledge, our study is the first to investigate long-term changes in salinity in coastal wetlands through natural processes (e.g. seaspray, seasonal variations) and ongoing climate perturbations (e.g. marine surges linked to extreme weather events, increased temperature and decreased precipitations).

Analysis of Water and Salt Spatio-Temporal Distribution along Irrigation Canals in Ningxia Yellow River Irrigation Area, China

The large amount of salinized soil in the Yellow River irrigation area is a threat to the sustainable development of agriculture, and in order to efficiently control the soil salinization trend, it is necessary to research water and salt variations and the distribution of soil in the area. In this study, soil salinization along two typical canals (West Main Canal and Tanglai Canal) in the Ningxia Yellow River irrigation area in China is investigated using data regarding water content, salt ions and pH from soil samples collected at 165 points along these canals. At each of these points, soil samples from various layers were collected for measurement from August 2019 to December 2020. Various methods, such as Pearson’s correlation analysis and Kriging interpolation, were employed to obtain the temporal and spatial distributions of water content, pH value and salt ions from the soil samples. It was found that the mean total salt value is 2.75 g/kg, which indicates that the soil in the study area is moderately salinized soil. The average value of soil pH is 8.5, indicating that the soil in this area is alkaline. Furthermore, it is evident that the coefficient of variation for certain soil ions, including HCO3−, Cl−, Ca2+, Na+ and K+, is greater than one, which indicates that their spatial distribution in the study area is severely uneven. Moreover, the soil salt content in the study area gradually increases from the southwest to the northeast, in the flow direction of the West Main Canal and the Tanglai Canal. The water content distribution along the two canals also exhibits notable non-uniformity, displaying a pattern higher in the north and east and less in the south and west. Moreover, the annual distribution of total salt content in the surface layer demonstrates an initial increase followed by a decrease, with the peak value typically occurring in August or September. The research results have an important significance on agriculture in the Ningxia Yellow River irrigation area.

Temperature and salinity trends in the northern limit of the Canary Current Upwelling System

Thermohaline time series are crucial for detecting and quantifying abiotic changes in the marine environment, and even more so in the present global change scenario. This is particularly relevant for the Ría the Vigo and its adjacent shelf, a highly productive ecosystem at the northern limit of the Canary Current Upwelling System (CanCUS). This study analyses a 34-year time series (1987–2020) of Conductivity-Temperature-Depth (CTD) casts, the longest series available to date in the region. Long-term trends, shifts, and seasonal variability of temperature and salinity were assessed and investigated in relation to regional meteorological variability and basin-scale atmospheric teleconnection indices. Generalized Additive Models (GAM) allowed us to determine that monthly thermohaline variability can be largely explained by regional meteo-climatic variability, mainly upwelling index and river discharge. Trends and shifts in some teleconnection patterns, especially the East Atlantic (EA) pattern, may also be related to both the shift in salinity in 2013 and its long-term decrease below 50 m depth. Despite the current global warming context, no statistically significant trend was observed for either the upwelling index or temperature. The spatial analysis of sea surface temperature trends suggests that our study area has been responding to climate change differently from other surrounding near-shore areas, as the Finisterre Cape or the southern Bay of Biscay. Overall, this study highlights the importance of long-term observations to elucidate the impact of climate change in the northern limit of the CanCUS and encourages caution when extrapolating conclusions from ecosystem studies on a regional scale.

Impact of agromeliorative measures on the agrophysical properties of the soil

In irrigated agriculture of the Turkestan region, due to improper implementation of agroreclamation measures and worn-out drainage systems, the level of mineralized groundwater increases, which leads to secondary salinization of soils, which negatively affects soil fertility and cotton yields. The introduction into production of modern integrated agro-reclamation technologies to improve the agro-reclamation conditions of soils, based on the rational use of irrigated land, is currently an urgent problem. The scientific and practical significance of the conducted research lies in the effective application of intensive agro-reclamation complex measures for the prevention of soil salinization processes in the Turkestan region in order to optimize the agrophysical properties of soils. Research methods – Experimental studies were carried out at the Agricultural Experimental Station of Cotton Growing and Melon Growing. All the methodological requirements for the method of laying field experiments according to the method of the Union, adopted in irrigation conditions for field and vegetation experiments with cotton, have been met. In the scientific work, studies were conducted to determine the yield of the domestic zoned cotton variety «Maktaaral-4017». In the results of the research work, it was found (var. 4) that when carrying out measures for deep loosening of the soil by 55 cm and laser planning of the soil, the volume mass of the soil (density) improves, i.e. in spring, the volume mass of the soil, on average in a layer of 0-30 cm, was 1.30 g/cm3, which improved by 0.008 g/cm3 compared to the control. Salinization trends are increasing in the soil conditions of the Turkestan region from year to year. Therefore, in the prevention of negative factors negatively affecting the land, reducing the salt content in saline lands and improving the conditions of gray soil, as well as in increasing the yield of cotton, these effective methods of intensive agro-reclamation are the value and practical significance of research work.

Changes in Salinity, Mangrove Community Ecology, and Organic Blue Carbon Stock in Response to Cyclones at Indian Sundarbans.

Climate change-induced frequent cyclones are pumping saline seawater into the Sundarbans. Fani, Amphan, Bulbul, and Yaas were the major cyclones that hit the region during 2019-2021. This study represents the changes in the soil parameters, mangrove biodiversity and zonation due to the cyclone surges in the Indian Sundarbans between 2017 and 2021. Increasing tidal water salinity (parts per thousand) trends in both pre-monsoon (21 to 33) and post-monsoon (14 to 19) seasons have been observed between 2017 and 2021. A 46% reduction in the soil organic blue carbon pool is observed due to a 31% increase in soil salinity. Soil organic blue carbon has been calculated by both wet digestion and the elemental analyzer method, which are linearly correlated with each other. A reduction in the available nitrogen (30%) and available phosphorous (33%) in the mangrove soil has also been observed. Salinity-sensitive mangroves, such as Xylocarpus granatum, Xylocarpus moluccensis, Rhizophora mucronata, Bruguiera gymnorrhiza, and Bruguiera cylindrica, have seen local extinction in the sampled population. An increasing trend in relative density of salinity resilient, Avicennia marina, Suaeda maritima, Aegiceras corniculatum and a decreasing trend of true mangrove (Ceriops decandra) has been observed, in response to salinity rise in surface water as well as soil. As is evident from Hierarchical Cluster Analysis (HCA) and the Abundance/Frequency ratio (A/F), the mangrove zonation observed in response to tidal gradient has also changed, becoming more homogeneous with a dominance of A. marina. These findings indicate that cyclone, climate change-induced sea level rise can adversely impact Sustainable Development Goal 13 (climate action), by decreasing organic soil blue carbon sink and Sustainable Development Goal 14 (life below water), by local extinction of salinity sensitive mangroves.

Overexpression of the Purple Perilla (Perilla frutescens (L.)) FAD3a Gene Enhances Salt Tolerance in Soybean.

The increasingly serious trend of soil salinization inhibits the normal growth and development of soybeans, leading to reduced yields and a serious threat to global crop production. Microsomal ω-3 fatty acid desaturase encoded by the FAD3 gene is a plant enzyme that plays a significant role in α-linolenic acid synthesis via regulating the membrane fluidity to better accommodate various abiotic stresses. In this study, PfFAD3a was isolated from perilla and overexpressed in soybeans driven by CaMV P35S, and the salt tolerance of transgenic plants was then evaluated. The results showed that overexpression of PfFAD3a increased the expression of PfFAD3a in both the leaves and seeds of transgenic soybean plants, and α-linolenic acid content also significantly increased; hence, it was shown to significantly enhance the salt tolerance of transgenic plants. Physiological and biochemical analysis showed that overexpression of PfFAD3a increased the relative chlorophyll content and PSII maximum photochemical efficiency of transgenic soybean plants under salt stress; meanwhile, a decreased accumulation of MDA, H2O2, and O2•-, increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbic acid peroxidase (APX), as well as the production of proline and soluble sugar. In summary, the overexpression of PfFAD3a may enhance the salt tolerance in transgenic soybean plants through enhanced membrane fluidity and through the antioxidant capacity induced by C18:3.

Excess chloride and impervious surfaces reduce over-winter quality of stream algal assemblages

Winter road salt use leads to the salinization of freshwater habitats. Freshwater organisms experience negative effects due to increased chloride ions, including algae in periphyton biofilms. This study examines the effects of road salt on algal assemblage composition, lipid production, and enzyme activity. Five streams throughout Erie County, New York, US were sampled monthly from October 2018 to March 2019. Chloride concentrations in all streams averaged 203.6 Cl- mg/L throughout the winter and had a highly significant relationship (rs = 0.82) with developed land use. Algal biodiversity scores decreased with elevated salinity (rs = 0.11). Algae exhibited the greatest total lipids in January (2.92 mg/m2) and the lowest in March (1.03 mg/m2). Similar trends were observed with ω3 and ω6 compounds. Overall desaturase Δ6 activity trended with stream Cl- concentrations, mainly along ω6 pathways, suggesting an inflammatory stress response. Algal assemblages exhibited evidence of chronic salt exposure through impaired taxonomic composition and patterns of lipid production that followed trends in stream water salinity. These effects suggest road salt applications have negative effects on stream primary producers with consequences for higher trophic levels.

Assessment of soil salinity by geo-spatial technology in Ballia district of Uttar Pradesh

Soils vary in their characteristics from one place to another place due to interactions of soil forming and processes. Assessment of spatial and temporal variation of characteristics is needed for any mean or use it's crucial to take into account the diverse spatial differences in soil properties, which has long in this context. Geographic information system (GIS) technology has enormous potential in the field of soil's assessment for upgrading soil statistic systems for an accurate and cost-effective means of understanding changes in the landscape. The future agricultural monitoring of the nutritional quality of the soil in diverse regions and villages is crucial. In this paper assessment of spatial variation of soil salinity using GIS techniques around the Ballia District of Uttar Pradesh is presented from the year 1994 to 2019. Normalized Difference Salinity Index (NDSI) was used. It showed increasing trend in salinity from 1994 to 2019 for each block. Using Landsat (TM/OLI) imageries with a 30 m spatial resolution, the spatial distribution of salinity from 1994 to 2019 was determined and low negative NDSI value was observed from - 0.143 to -0.117 in the southeast part of Ballia which can be an important explanation for soil degradation due to increasing soil salinity.

Climate change effects on soil salinity in rainfed maize areas: a case study from South Africa

Abstract In maize fields, few studies have been conducted to identify the temporal trend of soil salinity and formulate optimal irrigation plans under climate change. Therefore, the main goals of this study were to predict changes in soil salinity over 2022–2050 and to formulate an optimal supplemental irrigation plan preventing soil salinity in a South African rainfed maize field. The study used the Global Climate Model (GCM) MPI-ESM1-2-LR to obtain future climate data for the study area from 2022 to 2050 and applied the HYDRUS-1D model to project the effects of these future climate data on soil salinity over the same period and to identify the best irrigation plan under climate change. Two key findings were revealed: first, the combined use of GCMs (i.e., MPI-ESM1-2-LR model) and soil-water models (i.e., HYDRUS-1D) was a powerful tool to identify soil salinity trends and formulate optimal irrigation plan under climate change. Second, in addition to rainfall amount, supplying a limited supplemental irrigation amount equal to 8% of the actual evapotranspiration of maize at the mid-season stage of maize growth can significantly reduce soil salinity (<1.7 dS m−1) and enhance soil moisture under climate change by 2050. These findings will be useful for preventing soil salinity in rainfed maize fields.

Zooplankton community size structure across lakes within a semi-arid landscape: the effect of temperature and salinity

AbstractBody size is a master trait controlling biological communities and ecosystem functioning. Mean population size not only depends on the size of individuals, but also on the size distribution of individuals within the population. Mean community size is additionally influenced by the composition of species (larger- or smaller-sized species). Shallow lakes within semi-arid landscapes are prone to experience large changes in temperature and salinity, which affect the zooplankton size structure. Higher temperatures are expected to result in smaller average body size, while the effect of salinity appears to depend on the range under study. Here we analyze zooplankton body size patterns across shallow lakes from the semi-arid central region of Argentina. All community size descriptors point to decreasing size and a narrow size range at higher temperatures. On the other hand, the maximum average community body size occurred at intermediate (~30 gL−1) salinity levels. The combined effect of both variables resulted in a bell-shaped pattern, with maximum community body size toward lower temperatures and intermediate salinities. Based on future temperature scenarios, one may anticipate an overall decrease in community body size. But such prediction is strongly conditioned by regional and local trends in salinity.

Assessment of the Sea Surface Salinity Simulation and Projection Surrounding the Asian Waters in the CMIP6 Models

Sea surface salinity (SSS) is a crucial indicator that is used to monitor the hydrological cycle in the ocean system. In this study, we evaluated the simulation skill of the Coupled Model Intercomparison Project Phase 6 (CMIP6) models in reproducing the SSS in the Asian Marginal Seas (AMSs). The results show that the AMSs’ SSS simulated by most CMIP6 models is generally in good agreement with the observations in terms of spatial patterns and seasonal variability. However, these models tend to overestimate the SSS in the Eastern Arabian Sea and the Bay of Bengal by up to 1.3 psu, while they underestimate the SSS in the Bohai Sea, the Yellow Sea, the Southern South China Sea, and the Indonesian Seas, with the bias exceeding −1.5 psu. Additionally, the seasonal variations in the Sea of Okhotsk, the Bay of Bengal, and the Arabian Sea exhibit large biases with phase shift or reversal in some CMIP6 models. Notably, the observed magnitudes in the AMSs are significantly higher than the global average of 0.2 psu, ranging from 0.22 to 1.19 psu. Furthermore, we calculated the projected trends in sea surface salinity under different future scenarios by using the CMIP6 models. The results reveal relatively larger SSS freshening trends in the second half of the 21st century compared to the first half. Specifically, the freshening trends for the Shared Socio-Economic Pathway (SSP) of low- (global radiative forcing of 2.6 W/m2 by the year 2100), medium- (global radiative forcing of 4.5 W/m2 by 2100), and high-end (8.5 W/m2 by 2100) pathways are 0.05–0.21, 0.12–0.39, and 0.28–0.78 psu/century, respectively. The most rapid freshening trends of SSS are observed in the East China Seas and the Indonesian Seas, which are over two times greater than the global mean. On the other hand, the SSS freshening trends in the Arabian Sea are slightly lower than the global mean SSS freshening trend.

Geochemical Equilibrium Modelling of the Aqueous Speciation of Select Trace Elements in the Great Lakes

The behaviour and fate of trace elements in surface waters are greatly affected by their chemical form in solution, but the aqueous speciation of dissolved trace elements in the North American Great Lakes has received relatively little attention. Here, we present results from geochemical equilibrium modelling with 2021 surface water quality data to examine the spatiotemporal dynamics of trace element speciation in the Great Lakes. The relative abundance of aqueous trace element species appeared consistent with variability in solution chemistry and followed basin-wide trends in pH, alkalinity, salinity, and nutrient levels. The speciation of alkali metals was dominated by free monovalent cations, and that of oxyanion-forming elements by oxoacids, whereas significant fractions (>1%) of other aqueous complexes were also evident for rare earth elements (e.g., Ce and Gd as carbonates), alkaline earth metals (e.g., Sr as sulfates), or transition metals (e.g., Zn as phosphates). Spatially, differences in the relative abundance of aqueous trace element species were <2 orders of magnitude, with the highest variation (~50-fold) occurring for select chloride-complexes, resulting from upstream-to-downstream salinity increases in the basin. Finally, simulations of various future water quality scenarios (e.g., decreasing P levels, increasing temperature and salinity) suggest that the speciation of most trace elements is robust temporally as well. This study demonstrates how considering aqueous speciation may help improve the understanding of trace element dynamics and support water quality management in the Great Lakes.

Groundwater level dynamic simulation and soil salinization prediction of the closed hydrogeological unit in the arid irrigation area

Abstract Aiming at problems such as inaccurate simulation of groundwater level in closed hydrogeological units, difficult quantitative prediction of soil salinization degree, and unclear water and salt migration, a three-dimensional simulation model of groundwater was established, and the development trend of groundwater level and soil salinization was predicted. The groundwater level simulation results are consistent with the changing trend of the observational data and the simulation model can be used to predict groundwater levels in closed hydrogeological units. When climate scenarios and human activity change are set as future scenarios, the average groundwater buried depth will continue to decrease in the next 10 years, the area with a groundwater buried depth of 0–5 m will exceed 50%, and even the groundwater will overflow to the surface. The change of soil salt content is predicted quantitatively and the salinization degree will develop from ‘saline–alkali soil’ and ‘mild saline–alkali soil’ to ‘medium saline–alkali soil’. The process of water and salt migration in three key hydrologic zones, namely ‘irrigation infiltration’, ‘solute migration’, and ‘water and salt accumulation’, is revealed in the closed hydrogeological unit. The research results can provide new ideas for the improvement of soil and water environment problems.

Understanding the cause of sea level rise along coastal zone for 2005–2021

Understanding the coastal sea level budget (SLB) is essential to revealing the causes of sea level rise and predicting future sea level change. Here we present the coastal SLB based on multiple sets of sea level observations, including satellite altimetry, satellite gravimetry, and Argo floats over 2005 to 2021. The coastal zone is defined within 500 km from the coast and covered by all Argo products. We find that sea level observations enable a closure for the coastal SLB for 2005-2015. However, since 2016, the coastal SLB shows a substantially larger discrepancy, consistent with the global mean SLB. The coastal SLB is unclosed for 2005-2021, with a mean sea level rise of 4.06 ± 0.27 mm yr−1, a 0.74 ± 0.21 mm yr−1 rate for ocean mass, and a 2.27 ± 0.53 mm yr−1 for the steric component. Systematic Argo buoy salinity drift after 2016 is the main cause for the non-closure of coastal SLB over 2005-2021. Ignoring the suddenly unrealistic coastal salinity trends, the global coastal SLB from 2005 to 2021 is closed with a residual trend of 0.46 ± 0.63 mm yr−1. Our results confirm that the coastal 500 km range does not need to be deliberately masked and ignored in global SLB research.

Current Status and Development Trend of Soil Salinity Monitoring Research in China

Soil salinization is a resource and ecological problem that currently exists on a large scale in all countries of the world. This problem is seriously restricting the development of agricultural production, the sustainable use of land resources, and the stability of the ecological environment. Salinized soils in China are characterized by extensive land area, complex saline species, and prominent salinization problems. Therefore, strengthening the management and utilization of salinized soils, monitoring and identifying accurate salinization information, and mastering the degree of regional salinization are important goals that researchers have been trying to explore and overcome. Based on a large amount of soil salinization research, this paper reviews the developmental history of saline soil management research in China, discusses the research progress of soil salinization monitoring, and summarizes the main modeling methods for remote sensing monitoring of saline soils. Additionally, this paper also proposes and analyzes the limitations of China’s soil salinity monitoring research and its future development trend, taking into account the real needs and frontier hotspots of the country in related research. This is of great practical significance to comprehensively grasp the current situation of salinization research, further clarify and sort out research ideas of salinization monitoring, enrich the remote sensing monitoring methods of saline soils, and solve practical problems of soil salinization in China.

The Salinity Budget of the Ross Sea Continental Shelf, Antarctica

AbstractToward understanding the trend and variability in the bottom water salinity in the Ross Sea, this study focuses on the seasonality of the salinity budget over the Ross Sea continental shelf, using a new coupled regional ocean‐sea ice‐ice shelf model. Owing to the sea ice production, the upstream advection, and the glacial melting, the Ross Sea continental shelf is characterized by the relatively saltier water on the western shelf than on the eastern shelf, with the saltiest water in the Terra Nova Bay Polynya. During the early freezing season (March–April), there is remarkable sea ice production over the broad continental shelf, which makes a significant contribution to the production of High Salinity Shelf Water (HSSW). The brine rejection in the polynyas leads to the salinification and deepening of the mixed layer, yet the upstream advection acts to decrease the salinity below the mixed layer until the deep convection is fully developed throughout the water column. The seasonal cycle of the salinity budget in the Ross Sea continental shelf is largely determined by the formation/melting of sea ice, the intrusion of modified Circumpolar Deep Water, and the outflow of HSSW, while the contribution of the Ross Ice Shelf melting is relatively small.