Salt Pans Research Articles

Stopover habitat use of coastal Pied Avocet revealed by satellite tracking and remote sensing technology

Stopover sites identification for migratory waterbirds is important in China’s coastal wetlands, which have experienced a massive loss of natural wetlands in recent decades. Taking the Pied Avocet (Recurvirostra avosetta), a common waterbird in China’s coastal zone as an example, our research focused on their stopover habitat use based on satellite tracking and remote sensing technology. Along the coast, a total of 6 critical stopover sites, duration of stay more than 14 days, were recognized during their 2022–2023 autumn and spring migrations of the 4 tagged individuals. The results showed that Pied Avocets used habitats close to the coastline and water source, at low elevation, and with sparse vegetation. They also had a certain tolerance for human interference. From the perspective of the land use and land cover type, the proportion (33.01 %) of artificial wetlands including paddy, salt pan, and mariculture has exceeded that (27.97 %) of natural wetlands such as bottomland, tidal flat, estuarine waters, and shallow water in the home ranges of the 6 stopover areas. The study emphasized that the habitat function of artificial wetland should be paid enough attention to while maintaining the natural wetland without further loss. In addition, habitat-oriented management suggestions were put forward for artificial wetlands. This study can provide data and technical support for the conservation and management of waterbirds stopovers, also having reference value for other species.

Participatory mapping of ecosystem services of coastal wetlands in Taiwan

AbstractThere is a lack of knowledge and understanding about what ecosystem services are and how to utilize them in a sustainable way. Ecosystem services are thus often underrecognized by the decision makers in charge of creating wetland management plans. Due to this, ecosystem services, which have been used by communities for a long time, are often left out of wetland's wise‐use plans. Inclusion of local communities and promotion of local knowledge are vital aspects of creating sustainable, equitable and resilient wetland management plans that are truly ‘wise’. In this research, we utilize participatory mapping methods to engage communities and create a database of the ecosystem services being used in Chigu Salt Pan Wetland and Chigu Lagoon, located along the coast of Southwestern Taiwan. We look at who are using the ecosystem services, to what degree they are being used and where exactly in the wetland system they are being extracted/utilized. This will pave the way for future researchers to better understand the value of Chigu Salt Pan Wetland and the ecosystem services they provide and promote the use of participatory methods in other locations.

Preparation of Valuable Solid Fertilizers from Bittern in Salt-Pans of Kanyakumari District, Tamil Nadu, India

Common salt, also known as sodium chloride, is widely distributed on earth, especially in the form of seawater, which is an inexhaustible source. Common salt is economical and an excellent supplier of balanced nutrients, viz., sodium, iron, calcium, potassium, magnesium, etc., and even trace elements. Today majority of the farmlands are being depleted of minerals because of unwanted agricultural practices. Therefore, the soil has to be made fertile by the addition of nutrients in the form of different fertilizers. The organic mixture is the humus fraction, which improves soil structure and texture. One of the important sources for the synthesis of such fertilizers is the bittern, which is an unavoidable toxic material being let off from solar salt pans after crystallizing common salt. As this bittern is highly corrosive and poses transportation problems, it can be transformed into solid fertilizers through various improved methods.

Different halophytes orchestrate microbial diversity in the rhizosphere of salinity-impacted soils

Investigating rhizosphere communities in saline soils is crucial for identifying the taxonomic groups that play significant roles in halophyte adaptation. However, how the microbiome is structured under different saline conditions remains unclear. This study aimed to analyze bacterial communities in the rhizospheres of halophyte species in different saline environments. Five rhizospheres were analyzed using high-throughput sequencing of the 16S rRNA gene: S1, Salicornia fruticosa from a hypersaline tidal plain; S2, Sporobolus virginicus; S3, Cyperus ligularis from a hypersaline lagoon; S4, Salicornia fruticosa and S5, Blutaparon portulacoides from an abandoned salt pan. Bacterial communities in the S4 and S5 rhizospheres were influenced by P and K content, suggesting that specific nutrients can foster unique microbial structures, potentially assisting in adaptation to saline soils. The unique ASV (Amplicon Sequence Variant), richness, diversity, and microbial core of the S1 system, along with its similarities to S2 and S3, suggest common halophyte adaptation strategies across different saline environments, aiding targeted survival efforts. Identifying keystone species such as Thermoleophilia in S1, Alphaproteobacteria in S2 and S3, multiple species in S4, and the presence of Clostridia and Bacilli in S5 shed light on the roles these bacteria play in halophyte survival. Metagenomic prediction analysis demonstrated that chemoheterotrophy and aerobic chemoheterotrophy were the main prediction functions. In summary, this study revealed the intricate microbial structures in halophyte rhizospheres, enriching our understanding of saline ecosystems.

Secondary Metabolites of Halobacillus sp.: Antimicrobial and Antioxidant Activity, Biological Compatibility, and Gas Chromatography-Mass Spectrometry (GC-MS) Analysis.

Background The rise of infectious diseases and the emergence of resistant pathogens pose significant challenges to human health. In response to this global threat, researchers are exploring novel sources of bioactive compounds for effective antimicrobial therapies. One avenue of investigation is the study of halophilic bacteria and their secondary metabolites. These bacteria thrive under extreme conditions and produce valuable bioactive metabolites, which have the potential for therapeutic applications. Methods In this study, the potent bacterial cultures obtained from the Payanur salt pan, Tamil Nadu, were analyzed for the antimicrobial activity of their metabolites. The secondary metabolites were obtained from the halophilic bacteria by culturing the bacteria in 8% NaCl. The resultant secondary metabolites produced were extracted using ethyl acetate and their antimicrobial property was studied using the well diffusion method. The minimum inhibitory concentration (MIC) of these metabolites against five clinical pathogens, namely, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans was determined. Their antioxidant property was studied using the DPPH(2,2-diphenyl-1-picrylhydrazyl) method and biological compatibility was determined by hemolytic assay of the secondary metabolites. Results The potent halophilic bacteria isolated from salt pan bacteria were phenotypically and genotypically identified as Halobacillus sp.The secondary metabolites extracted from these bacteria yielded 110 mg of crude metabolites. The antimicrobial activity of crude metabolites shows a moderate zone of inhibition of 14 mm for P. aeruginosa, 13 mm for E. coli and C. albicans, and 11 mm for S. aureus. The minimum inhibitory concentration was 128 µg/mL for E. coli, P. aeruginosa, and C. albicans,which was found to bethe best growth inhibition concentration. The DPPH scavenging activity shows a higher activity till the concentration of 64 µg/mL.The hemolytic activity of 25% is obtained at 128 µg/mLand below 64µg/mL, there is no hemolytic activity. The gas chromatography-mass spectrometry (GC-MS) analysis of the secondary metabolites shows the presence of 17 compounds. Among them, there were fourmajor compounds: (i) cyclo(L-prolyl-L-valine) (probability of 95.63%), (ii) pyrrolo[1,2-a]pyrazine- 1,4-dione,hexahydro-3-(2-methylpropl) (probability of 94.45%), (iii) 2,5-piperazinedione,3,6-bis(2-methylpropyl)(probability of 71.94%) and (iv) pyrrolo[1,2-a]pyrazine-1,4-dione,hexahydro-3-(phenylmethyl)(probability of 88.01%). Conclusion In conclusion, the isolated bacterium is confirmed to be Halobacillus sp.and the secondary metabolites produced by this bacterium could be the potential source for the development of novel antimicrobial and antioxidant compounds that are highly biologically compatible. Further research mayhelpto developnovel compounds in the pharmaceutical industry.

“Architecture, construction system and functioning of the roman saltworks of O Areal (Vigo-Galicia-Spain). A reference in the investigation of salt production in the roman world”

These Roman saltworks are located in the city of Vigo, in the northwest of the Iberian Peninsula, and they were part of a large industrial complex, dedicated to the production of sauces and salted fish. To this day, they are the best-preserved solar evaporation marine saltworks evidences in the Roman world, making it possible to know the entire production cycleBased on ceramic contexts and C14 data, we have concluded a period of use around the 1st-3rd c. AD, which falls completely within what is known as the Warm Roman Period.The architecture of the salt complex is articulated through different types of ponds, of various dimensions and construction characteristics. They use different materials for their construction: stone, ceramics, silt, clay, wood or sand. Its characteristics and dimensions are in accordance with its function within the salt production cycle: decanters, evaporators and crystallizers. Other architectural elements complete the ensemble and help to understand its functioning in detail.Knowledge of the architecture, constructive techniques and morphology of these saltworks has made it possible to identify others even when excavated on small surfaces, thanks to the archaeological indicators that the study of these salt pans allows us to define.

Artificial wetlands providing space gain for the suitable habitat of coastal Pied Avocet

A large number of artificial wetlands have replaced natural wetlands along waterbird migration routes to supply breeding, resting and feeding grounds for waterbirds. Effective identification of potential artificial wetlands that could serve as suitable habitats for waterbirds can provide important reference for field investigation and waterbird conservation. In this study, the habitat suitability of the Pied Avocet in the Yellow River Delta (YRD), China was simulated with the optimized MaxEnt model based on its occurrence records and environmental variables. The results showed that the MaxEnt model could well predict the habitat suitability of the Pied Avocet (Recurvirostra avosetta) in the YRD. The suitable habitats were distributed in the specific areas of the coastal zone, and artificial wetlands such as salt pans and mariculture ponds were the main components in the high-suitability area. The top three environmental factors affecting habitat selection were the land use and land cover (LULC), distance to the coastline and normalized difference vegetation index (NDVI). This paper emphasizes the role of artificial wetlands in providing suitable habitat for waterbirds. In order to better protect the habitat of waterbirds and alleviate human-bird conflict in the YRD, some targeted suggestions were put forward for the management gap of artificial wetlands. This study has strong practical significance for the protection and habitat management of waterbirds in the YRD. The methodology we employed is transferable to other wetlands, where efficient management is inhibited due to a lack of comprehensive field investigations.

The astrobiological potential of the Makgadikgadi Basin, Botswana: Field analogue for planetary exploration

Terrestrial analogue sites have been crucial for studying Martian geology and mineralogy, integrating the direct evidence available from Mars through remote sensing and in situ measurements carried out by the instruments on board robotic missions. Studying readily available and accessible terrestrial analogues of Martian fossil or extant environments is considered the most efficient way to answer crucial scientific questions. These analogues offer opportunities to collect a range of geological and microbiological data. The Makgadikgadi Basin (MKB) in Botswana is one of such environments hosting a system of salt pans presenting striking similarities with Mars playa deposits. The MKB presents layered mounds, relict fan deltas with inverted channels, polygonal structures and evaporitic crusts harboring communities of extremophiles. The present-day MKB is predominantly fed by groundwater and local precipitations in an overall arid to semi-arid climate, characterized by high UV radiation and salinity, deposition of evaporitic minerals and authigenic clays. The shallow subsurface of the MKB pans is covered by diagenetic features (duricrusts) including silcretes and calcretes. These pans can serve as test beds for the physical and chemical characteristics of playa deposits on Mars and help improve our understanding of the conditions that might support life outside our planet.

Schoemansdal: Van Voortrekkervoorpos tot volksfeesterrein

In 1856 A.H. Potgieter and Louis Trichardt had already selected a site for a town at the foot of the Soutpansberg. This town, however, was only built in 1848 after Potgieter's party had left Ohrigstad because of his desire to live beyond the British sphere of influence and the need for a northern route to communicate with Inhambane. At first called Oude Dorp, the name of the town was later changed to Soutpansbergdorp and in 1855 to Schoemansdal. It was an attractive town and flourished because of hunting, the ivory trade, agriculture and the salt pan near it. Itinerant and ivory traders provided the necessities of life, and constituted the community's main link with the outside world. The arrival of the Rev. Van Warmelo in 1864 and the teacher Van Boeschoten in 1866 added much to the spiritual and social welfare of the community. The town was eventually evacuated in 1867 because of the Transvaal government's irresolute attitude towards the struggle of the inhabitants with the Venda. Only in 1898 was a new town, Louis Trichardt, founded near by.

Characterization of the quality and physiological status of Penaeus vannamei in salt pans at various salinities

Characterization of the quality and physiological status of Penaeus vannamei in salt pans at various salinities

Antioxidant potential of pigments produced by halophilic archaea isolated from salt pans of India

Antioxidant potential of pigments produced by halophilic archaea isolated from salt pans of India

Ecological Studies of Saurashtra Coast and Neighbouring Islands II. Beyt Island

The plant ecology Beyt island, a narrow crooked strip of sand rock to the east of Okhamandal point and about 3 km to the north of the mainland of Okhamandal situated 22°35' : 72°21' in the Gulf of Cutch is presented in this paper. Based on the types of situations and edaphic features the vegetation of the island has been distinguished into 3 main categories : (1) Strand, (2) Salt pans, slacks and mud formations and (3) Inland mixed scrub forest. Main features of thewvegetation and analysis of soils are described under the'above mentioned heads. The flora is a mixture of coastal and inland types. Further, the affinity of the flora with the adjacent lands of Cutch and Okhamandal to Diu coastal area has been studied. A list of the plants occurring in the island is enumerated.

Solid-Liquid Phase Equilibria of a Quaternary Sulfate-Type System Containing Lithium, Rubidium, and Magnesium at 298.2 K.

The aim of this study was to obtain the relationship between ion interactions and the crystallization patterns of salt species in the lithium-rubidium-magnesium sulfate system at 298.2 K. The phase equilibria of the aqueous quaternary system Li+, Rb+, Mg2+//SO42--H2O were studied by the isothermal dissolution method at T = 298.2 K and p = 94.77 kPa. The density, refractive index, and composition of equilibrium solution were determined, on the basis of which solid-liquid phase diagrams and density/refractive index vs composition diagrams were drawn. The phase diagram consists of four quaternary invariant points and six crystallization regions, corresponding to the crystallization areas of single salts Rb2SO4, Li2SO4·H2O, and MgSO4·7H2O, as well as double salts 3Li2SO4·Rb2SO4·2H2O, Li2SO4·Rb2SO4, and Rb2SO4·MgSO4·6H2O. Notably, rubidium-containing double salts occupy more than 50% of the entire phase diagram area. The results indicate that the interactions between Li+ and Rb+ with coexisting Mg2+ and SO42- are complex, leading to the formation and precipitation of various lithium- and rubidium-bearing double salts, which hinder the effective concentrations of lithium and rubidium during the solar evaporation process in salt pans. Additionally, a multitemperature comparison of the solid-liquid phase diagrams at 273.2, 298.2, and 308.2 K reveals that temperature is also a significant factor influencing the solid-phase types and crystallization areas. For instance, the crystallization form of the double salt 3Li2SO4·Rb2SO4·2H2O changes to 3Li2SO4·Rb2SO4 at 308.2 K and the crystallization area of Li2SO4·Rb2SO4 gradually decreases, while the crystallization area of Rb2SO4·MgSO4·6H2O generally exhibits an increasing trend.

Tracking annual changes of coastal aquaculture ponds in China during 1986–2021

The rapid expansion of coastal aquaculture ponds has made outstanding contributions to global food security and economic development in coastal areas, but this expansion inevitably has a significant impact on coastal ecosystems. Strengthening the spatiotemporal monitoring of aquaculture ponds is crucial for optimizing coastal land use and efficiently managing aquaculture ponds. However, aquaculture pond data on national scale and interannual variability are lacking. Here, we utilized Landsat times series images from 1986 to 2021 to generate annual maps of aquaculture ponds in China's coastal areas and investigated its spatiotemporal characteristics. We find that the overall accuracy of our aquaculture ponds classification was over 90% each year. Aquaculture ponds were concentrated in Bohai Bay, the Jiangsu Coastal Plain, and the Pearl River Delta in China's coastal areas. The time series of aquaculture ponds change could be divided into three stages: rapid growth (1986–2000), stable growth (2001–2016), and a slow decline (2017–2021). The spatial evolution of aquaculture ponds was characterized by (1) continuous seaward expansion, (2) continuous inland and seaward expansion, (3) continuous inland expansion, (4) continuous expansion and then shrinkage, and (5) rapid shrinkage. Moreover, the main aquaculture ponds classification errors were salt pans, reservoirs, abandoned ponds, port facilities, lakes, and pit ponds. Our study demonstrated a new method for applying satellite remote sensing for coastal ecosystem management, and our maps and findings can be used to optimize the development and sustainability of coastal aquaculture ponds.

Use of Stable Isotopes (δ13C and δ15N) to Infer Post-Breeding Dispersal Strategies in Iberian Populations of the Kentish Plover.

Beaches are among the habitats most frequented by migratory birds for breeding and/or wintering. However, threats such as human pressure and sea level rise can reduce the availability of these habitats for different species. The presence of alternative areas, such as salt pans and brackish habitats, is essential for many migratory shorebird populations. This study addresses the post-breeding dispersal of the Kentish plover (Charadrius alexandrinus) in the Iberian Peninsula by analysing C and N isotopes in feathers. The study was conducted at six locations along the Iberian coast, which were categorized into three areas: the NW Atlantic coast, the Atlantic coast of Andalusia, and the Mediterranean coast. Although linear mixed models did not reveal any significant effects of sex or coastal area on isotopic levels, the variability in the data suggests different habitat-use strategies in the post-reproductive period. Isotopic levels in birds from the northwest of the Iberian Peninsula exhibit greater fidelity to a single habitat type, while those from the Mediterranean coast and the Atlantic coast of Andalusia show greater variability, indicating different individual dispersal strategies. The lack of alternative habitats for the northwest Iberian population, the reduction in available habitat due to rising sea levels, and human pressure together pose a serious threat to the survival of this species, already with an unfavourable conservation status.

Groundwater Contamination in Arid Coastal Areas: Qatar as a Case Study.

The Arab region is located in an arid environment and suffers from water scarcity and poor water quality which are expected to become more severe in coming years due to global warming. In this study, the groundwater quality of 205 wells in Qatar was investigated. The physical parameters of pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, inorganic carbon (IC), and organic carbon (OC) were determined. The study characterized the concentrations of major anions of Cl, F, Br, NO3, PO4, and SO4, and major cations of Ca, K, Mg, and Na. Importantly, metals and metalloids including V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Pb, and U were determined. The results revealed that the groundwater of all wells is not drinkable due to high salinity (average TDS 4598 mg/L and salinity 0.4%, respectively). Additionally, average concentrations of major anions Cl, SO4, and F were 1472, 1064, and 1.9 mg/L, respectively, and all exceed the World Health Organization (WHO) guidelines for drinking water. However, NO3 concentration in 11 out of 205 wells was above the WHO guidelines of 50 mg/L due to intensive agriculture and fertilizer applications. Major cations of Ca, K, Mg, and Na were higher than WHO guidelines with average concentrations of 345, 63, 127, and 923 mg/L, respectively. All trace metals were much lower than the WHO guidelines for drinking water; however, the vanadium (V) average concentration in groundwater of all wells was 31 μg/L, which is five times higher than the Dutch guidelines (whereas the WHO has no guidelines for V). The groundwater of Qatar is dominated by Ca and Mg sulfates in Sabkha environments and dominated by NaCl in the coastal zones from evaporate environments consisting of coastal salt flats, salt pans, estuaries, and lagoons supersaturated by salts and the influence of sea water intrusion.

Spaceborne Radars for Mapping Surface and Subsurface Salt Pan Configuration: A Case Study of the Pozuelos Salt Flat in Northern Argentina

Spaceborne Radars for Mapping Surface and Subsurface Salt Pan Configuration: A Case Study of the Pozuelos Salt Flat in Northern Argentina

The tale of an endemic shrimp’s exceptional osmoregulation and the ancient Athalassic mangrove oasis

The hyperarid mangrove in the Middle East is characterised by the absence of rivers or freshwater inputs and is one of the most extreme settings of this ecosystem on Earth. Endemic to Qatar’s hyperarid mangroves, a Palaemon shrimp is uniquely confined to a sole mangrove site in the Arabian Gulf. Within these mangrove channels, we unveiled brine groundwater sources exceeding 70 ppt salinity, contrasting the local marine standard of 42 ppt. Concurrently, a mysid species typically linked to salt pans and groundwater coexists. Stable isotopic analysis implied the existence of a predator–prey dynamic between this mysid species and the studied shrimp. Then, investigating the endemic shrimp’s adaptation to extreme salinity, we conducted osmolarity experiments and phylogenetic studies. Our findings demonstrate that this shrimp transitions from hypo- to hyper-osmoregulation, tolerating salinities from 18 to 68 ppt—an unprecedented osmoregulatory capacity among caridean shrimps. This speciation pattern likely arises from the species osmolarity adaptation, as suggested for other Palaemon congeners. Phylogenetic analysis of the studied Palaemon, along with the mangrove’s geological history, suggests a profound evolutionary interplay between the ecosystem and the shrimp since the Eocene. This study proposes the hyperarid mangrove enclave as an Athalassic mangrove oasis—a distinctive, isolated ecosystem within the desert landscape.

Impact of lead and zinc heavy metal pollution on the growth and phytoremediation potential of Sulla carnosa in Sebkha el Kalbia, Tunisia.

Heavy metal pollution from human and natural activities poses significant environmental and health concerns for wildlife and humans, with lead and zinc being particularly threatening. This study focuses on Sebkha el Kalbia in Tunisia, highlighting the challenges faced by local communities in addressing heavy metal pollution. The area is prone to contamination through rivers and streams that transport pollutants from industrial zones and rural areas into the salt pan. The recent establishment of an industrial zone has worsened pollution levels, calling for strict regulatory measures and clean technologies to limit heavy metal pollution and protect human health and the environment. The study assesses the impact of lead and zinc pollution on the growth of Sulla carnosa and its potential for phytoremediation. Soil and plant samples from contaminated areas were analyzed, revealing high levels of heavy metal contamination. The growth parameters of Sulla carnosa, such as plant height, weight, and enzymatic activity, were examined, showing a significant reduction in plant growth when exposed to high metal concentrations. Specifically, in the presence of 100ppm of lead (Pb), net photosynthetic assimilation (An) decreased by 52%, while the amount of Pb increased by 78%. At 800ppm of Pb, An decreased by 87%, and the amount of Pb increased by over 800%. Furthermore, the relationship between net photosynthetic assimilation and lead (Pb) content remained significant but negative. At high doses (800ppm), the biomass produced decreases by 64%, while the amount of Zn increases 2.7 times. These results suggest that at low doses, zinc is not toxic. These findings highlight Sulla carnosa as a potential candidate for phytoremediation with preferential metal accumulation in the roots and improved enzymatic activity, underscoring the urgency of addressing heavy metal pollution in Sebkha el Kalbia.

Estimation of the Ecosystem Service Value of the Yellow River Delta-Laizhou Bay Coastal Zone Considering Regional Differences and Social Development.

With economic and societal development, the ecological environment of the Yellow River Delta-Laizhou Bay coastal zone has been seriously damaged. Exploring the changes in land use and ecosystem service value (ESV) is essential to ecological construction of the region. The random forest classification method was used for land cover interpretation of the four periods of remote sensing images in the study area from 1990 to 2020. Newly calculated regional difference coefficients and social development coefficients were used to construct a dynamic ESV assessment model and to study its changes from overall and sea‒land gradient perspectives. The results showed that construction land, salt pans, aquaculture ponds, and inland water masses expanded rapidly, while cropland, tidal flats, and shallow waters shrank sharply over the past 30 years. The ESV in the study area has continued to decrease from 34.47 billion yuan in 1990 to 25.23 billion yuan in 2020, a total decrease of 9.23 billion yuan. This is mostly due to the encroachment of construction land, salt pans, and aquaculture ponds, and the flow of ecosystem services from high-value land cover types (tidal flats, herbaceous wetlands, and cropland) to medium- and low-value land cover types. Moreover, the land cover transfer and ESVs exhibited a decreasing trend from sea to land, with significant sea-land gradient differences. Land conversion is most common in the 0-15 km coastal zone, mainly from natural wetlands to artificial wetlands, where the ESV also decreases rapidly. Considering the regional differences and social development in this paper, the ESV of small-scale areas can be reasonably evaluated to explore the characteristics and causes of changes in land use and ESVs, which can provide an important reference for ecological protection and land use management in the region.