Footprints of human activities identified in the sedimentary sequence of submerged historical saltpans can reveal the history of the site and can indicate the relative sea level during its ...operational period. Saltpans are man-made constructions used continuously for salt production in the Mediterranean at least for the last 2000 years. The east Adriatic coast contains many such submerged remains, preserved and well-dated by historical archives. Sedimentological, microfossil and geochemical analyses of the sediments from cores drilled in the saltwork area at Brbinj, Dugi Otok, Croatia, enable the reconstruction of various past environmental conditions. The current study aims to: a) identify the anthropogenic unit in the sedimentary sequence deposited over time, b) determine its age, and c) use it as past sea-level limiting points. Basal units made of terra rossa soil materials were identified in the sedimentary records. These layers are located -120 ±7 cm below mean sea level next to the separation wall and -125 ±7 cm and -135 ±7 cm, respectively, in the inner pools, most likely representing a man-made pavement. The terra rossa layer is overlaid by a unit rich in faunal remains dominated by euryhaline foraminifera and ostracod species such as Ammonia veneta and Cyprideis torosa, representing the saltworks unit. The flooding of the saltpans by the rising sea is manifested by the deposition of an upper sedimentary unit dominated by remains of marine species. The base and the top of the saltwork unit are dated by Optically Stimulated Luminescence to 1040±50 CE and to 1390±30 CE, respectively. The study presents a new approach for obtaining footprints of human activities in ancient, submerged saltpans, by identifying and dating the indicative anthropogenic layers and using these for the reconstruction of paleo sea-level. The described method can be applied all around the Mediterranean.
In aquatic environments, microplastics (MPs) are pervasive which could have a considerable negative impact on the environment, organisms and pose a risk to human health. However, knowledge about the ...exposure and ecological risk of MPs in the coastal ecosystems of developing countries is limited. In this study, we analyzed salt samples from five commonly consumed processed and unprocessed sea salts of different commercial brands originated from 15 salt pans in Bangladesh to assess the abundance, characteristics and potential risks of MPs. The quantities of MPs in unprocessed salts (average 195 ± 56 item/kg) were higher than those in the processed salts (average 157 ± 34 item/kg). One-way analysis of variance (ANOVA) showed significant (p < 0.05) differences among the average numbers of MPs in both processed and unprocessed salts. MP levels in this study were 2–3 times higher than those reported from some other countries. Fiber-shaped and transparent MPs were dominant in both cases. MPs less than 0.5 mm in size were the most abundant in both unprocessed (58.2%) and processed (62.2%) salts. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed five types of polymers, including polyethylene terephthalate (PET−35%), polypropylene (PP−27.5%), polyethylene (PE−25%), polystyrene (PS−10%), and Nylon (2.5%) in the studied salts. The sea salts were classified as potential hazard index (PHI) levels IV to V, indicating serious MP contamination, whereas potential ecological risk factor (Ei), potential ecological risk index (RI), and pollutant load index (PLI) indicated moderate levels of pollution of MPs. Domestic and municipal wastewater effluents to Bay of Bengal and fishing activities may attributed to presence of MPs in the sea salt. These findings can be used by consumers, salt industries and policy makers to reduce MPs levels during consumption, production and policymaking.
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•First risk assessment of microplastics (MPs) in food-grade sea salt from the study area.•The average MPs in unprocessed and processed sea salt were 194.67 ±55.68 item/kg and 157.00 ±34.10 item/kg, respectively.•Fibers were mostly dominant in both unprocessed (79.24%) and processed (94.93%) sea salt samples.•FTIR confirmed that PET, PP, PE, PS and nylon polymers were present in processed sea salt.•Based on PHI values, the risk of MP pollution in Bangladeshi processed sea salt was classified as Hazard category IV to V.
While we have abundant archaeological evidence for the salting establishments that once operated in the Roman world salting fish (and meat), archaeological evidence for salt works is rarer; yet in ...antiquity salt was essential not only in food preservation but in many other production processes. The few known cases of Roman salt works investigated archaeologically (e.g., those at O Areal near Vigo or at Caunos in Turkey) offer some information on the physical infrastructure for salt production. However, the issue of ownership – whether marine salt works in the late republican and imperial periods were always a state monopoly – remains unclear. This article presents the available archaeological evidence for Roman marine salt works and argues that in the late Republic and during the first two centuries of the Empire state ownership was not the norm for marine salt pans, but rather the exception. The capillary diffusion of fish-salting workshops is a good indicator that salt could be freely acquired in the quantities needed for this activity, presumably at a fair price. This is in stark contrast compared to later historical period when salt was certainly a state monopoly.
The present baseline research infers that the salts present in the sea may contain microplastics (MPs), as the seawater is contaminated due to a number of anthropogenic activities. Herein, 25 types ...of sea salt samples were collected from salt pans located in the Tuticorin coastal region. The MPs present in the samples were separated and identified by various methods such as handpicking, visual classification, and micro-Fourier transform infrared spectroscopy (μ-FT-IR) and atomic force microscopy (AFM). The MPs that measured less than 100 μm formed the major part of the salts, accounting to 60% of the MPs among the total pollutants. The MPs that were found in abundance in the sea salts were polypropylene, followed by polyethylene, nylon, and cellulose. This study was conducted in salt pan areas and demarcated the percentage of MPs present in sea salts. Table salt, which is a prime edible commodity, was found to be contaminated with MPs through polluted seawater, which poses a threat to public health.
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•The present attempt was carried out to Preliminary study on Microplastics pollution in commercial marine sea salt along Tuticorin Coast, Gulf of Mannar, SE coast of India.•Various types of microplastics was identified, including nylon (NY) cellulose (CL), polyethylene (PE), polypropylene (PP) and some microplastics or nonplastic particles, were also unidentified.•A microplastic was measuring less than 100 μm represented the major part of the particles, computing for 60% of the total microplastics.•The possible anthropogenic sources of the microplastics in the salt pans are from city people dumped plastic waste via buckle channel.
We studied the abundance of microplastics from commercial table salts and table salts from salt pans at Marakkanam and Parangipettai, Tamil Nadu, India. Microplastic abundance in the salts collected ...from salt pans had a range of 3.67 ± 1.54 to 21.33 ± 1.53 nos./10 g of salt which were higher than the microplastics retrieved from the commercial salts which ranged from 4.67 ± 1.15 to 16.33 ± 1.53 nos./10 g of salt. All the microplastics retrieved were fibers which were secondary in origin. Black, red, blue, green, white, brown, and colorless microplastics were observed in the samples. FT-IR results showed that 4 types of polymers, namely, Nylon, Polypropylene (PP), Low Density Polyethylene (LDPE), and Polyethylene Terephthalate (PET) were present in the samples. Domestic and municipal wastewater discharges into the estuaries may contribute to microplastics in the table salts. Our study proves that table salts (processed and unprocessed) are prone to microplastic contamination.
•Microplastics are known to enter the human body via table salts.•Processed and unprocessed table salts are prone to contain microplastics.•Groundwater as an alternative to seawater yields lesser microplastic contamination in table salts.
Perennial halophytes dominate coastal ecosystems, but little is known about how the biotic and abiotic factors alter their microbial community. This study compares the bacterial diversity associated ...with the rhizosphere, with respect to adjacent soil, for the halophyte Arthrocnemum macrostachyum in high salt marshes in Southern Spain, in dry and wet seasons (July and October, respectively) using metagenomics coupled with High-Throughput Sequencing. The read-based analysis revealed that seven phyla (Proteobacteria, Actinobacteria, Bacteroidetes, Gemmatimonadetes, Chloroflexi, Firmicutes and Acidobacteria) accounted for the 90% of the diversity and 94% of the abundance and that, seasonal and spatial variations in soil salinity were the main determinants of the bacterial community diversity in these marshes, compared to the apparent no effect of the plant. However, at A. macrostachyum flowering stage, the bacterial community associated with the rhizosphere was comparatively more diverse than that inhabiting adjacent bulk soil, suggesting a more intensive plant-microbe interaction during this period.
•Mediterranean salty marshes host a diverse community of bacteria.•Salinity strongly structures its bacterial communities in the soil.•Wet conditions in October homogenize the communities.•In summer, the halophyte A. macrostachyum could be also important factor for structuring the bacterial community.
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The Salar de Olaroz is one of the main Li operations in Argentina. In order to identify sources and to understand the dynamics of Li in this salt pan, chemical and isotopic analysis ...(δ7Li and 87Sr/86Sr) of brines, thermal and river waters, as well as ignimbrites and sediments that outcrop in the basin were performed. The Li concentrations in shallow brines (i.e., ∼0.6 m below surface) range from 260 to 890 mg L−1 (average = 841 mg L−1, n = 16), while in deep brines (i.e, 200–450 m b.s.) concentrations are higher (average = 993 mg L−1, n = 16) and range from 690 to 1490 approximately. δ7Li values range from +5.9 to +7.2 ‰ and from +8.1 to +10.2 ‰ in shallow and deep brines respectively, while δ7Li values of the regional rocks and sediments vary between -13.8 and +0.5‰. The 87Sr/86Sr values indicate that the chemical composition of brines in Olaroz is the result of mixing between solutes that are originated from bedrock weathering by shallow meteoric water and water that has a hydrothermal contribution. Due to evaporation, Li concentrations in shallow brines increase by two or three orders of magnitude when compared with the values determined in the main tributaries and in the discharge of thermal waters. This process does not produce measurable isotopic fractionation of Li, thus the isotopic signature of shallow brines and halite crystals in contact with these waters are similar. As brine density increases, water descends through layers of silt and as the brine ages at depth, the formation of secondary minerals enhance the preferential adsorption of 6Li onto clay minerals and Fe (hydr)oxides resulting in higher δ7Li values in deep brines. Nevertheless, Li concentrations remain nearly constant or slightly increase with depth, which suggests that the removal of this element from the water due to adsorption is offset by Li contributions derived from processes that do not produce any isotopic fractionation. Two processes may account for this in the study system: 1) the mixing with ancient Li-rich fluids trapped in the deeper evaporitic layers that preserved the isotopic signature of their contemporaneous brines; and 2) the release of loosely- bound Li from the exchangeable sites of smectites that compose the clastic fraction of the salt flat sediments as they acquire a more crystalline nature over time. Consequently, it is expected that sediments accumulated below the salt crust may provide an important additional reservoir of Li to the brine, but further experimental studies will be necessary to investigate the mechanisms that control the partition of Li between the aqueous and solid phases and its isotopic fractionation in extremely arid and saline environments.
Existing methods for the extraction of priority metallic pollutants as Ag, Cd, Cu, Ni and Zn from saline waters present limited efficacy due to the high complexity of the water matrix, which affects ...metals speciation. There is a lack of reagents for the efficient extraction of the metal chlorocomplexes formed at the natural pH of saline waters, requiring tedious and reagent consuming processes. To develop a simple method for the efficient micro-extraction of metallic chlorocomplexes in saline waters, two task specific ionic liquids (TSILs) are proposed. The TSILs methyltrioctilammonium hexylsulfanyl acetate (N1888C6SAc) and methyltrioctilphosphonium hexylsulfanyl acetate (P1888C6SAc) have been supported on a solvent bar micro-extraction (SBME) device and applied to the micro-extraction of Ag, Cd, Cu, Ni and Zn from seawater, as well as inland and marshland salt-pan waters. The extraction efficacy was related with the formation of negatively charged chlorocomplexes, being higher for Cd, Ag and Zn than for Cu and Ni. Concluding, the proposed methodology can be considered as a valuable and simple tool for the selective extraction of metals from saline and hypersaline natural waters.
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•N1888C6SAc and P1888C6SAc extracted metal chlorocomplexes from saline waters.•Metals forming negatively charged chlorocomplexes (Cd, Ag Zn) are better extracted.•Increasing salinity, metal chlorocomplexes are extracted by ionic exchange.
Abstract
Salt pans are commonly found in coastal marshes and play a vital role in the marsh plant zonation. However, the correlation between these hypersaline zones and the marsh hydrological ...conditions have barely been characterized. This study numerically investigates the effects of evaporation rate, tidal amplitude, and marsh platform slope on salt pan formation, and found that salt pans can hardly grow in the intertidal zone due to regular tidal flushing, while tend to form in the lower supratidal zone, where evaporation is sustained. The accumulated salts create an upward salinity gradient that trigger downward unstable flow. The decreases of potential evaporation rate, tidal amplitude and/or marsh platform slope strengthen the hydraulic connection between the marsh surface and the underlying watertable, the key to sustaining evaporation, and therefore result in thickener and wider salt pans. These findings offer a deeper insight into the marsh eco-hydrology and guidance for their degradation prevention.
Salt is included in a variety of foodstuffs consumed by humans and since salt is contaminated with microplastics (MPs) causes health risk for humans. MPs can absorb pollutants that may transfer ...through organisms after the ingestion of MPs and affect the health of the human body by constantly taking the contaminated salt through food. Therefore, studies are needed to analyze the presence of MPs in salt pans. The present study was undertaken to investigate the spatiotemporal variations in the occurrence, distribution, and characterization of microplastics in water, sediment, and salt from salt pans of the Thoothukudi coastal region (October 2020–September 2021). Samples were collected from three sampling sites, viz., Tharuvaikulam (station 1), Thoothukudi (station 2), and Pazhayakayal (station 3) for analysis of the MPs throughout the year as they vary with season by Nile red staining method. The maximum occurrence of MPs in the salt was recorded as 52 MPs/kg during the monsoon season, in sediments it was 45 MPs/kg post southwest monsoon season, and in surface water samples it was 42 MPs/liter post southwest monsoon season at station 1. The dominant size of MPs for all the three samples was <0.5 mm post southwest monsoon season. White color with irregular-shaped MPs was found to be dominant throughout the study. The predominant composition of the extracted MPs was characterized by Fourier transform infrared spectroscopy and identified as polyethylene and polypropylene in all the samples.
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•Spatiotemporal variations of MPs were analyzed in the salt pans.•The dominant size recorded was — <0.5 mm, shape — fragment and irregular, color — white, and polymer — PE & PP.•High level of MPs was found in salt during monsoon season at Station 1 due to wind velocity and anthropogenic activity.•The outcome of this study creates awareness among people to reduce MPs pollution.
