Assessment of the Quality of Raw Water for Salt Production in Pangarengan, Sampang, East Java

Seawater is the primary raw material for the production of sea salt. Seawater quality dramatically affects to salt production. The purpose of this study was to evaluate the seawater’s quality as a raw material for salt production in Pangarengan, Sampang, East Java, Indonesia. The assessment of water quality in this study includes physical and chemical characteristics. The location of this research was in the salt fields that close to settlements with high anthropogenic activity. Sampling points were the seawater inlet (P1), reservoir plot/bozem (P2), and evaporation plot (P3). Assessment of temperature, pH, salinity and water saturation using in-situ measurements. Determination of heavy metal parameters (Mercury, Cadmium, Lead, and Arsenic) using UV spectrometry. The physical characteristics of the highest water temperatures were in evaporated plot (40°C), while the water temperatures in the seawater entrance and reservoir ponds were respectively 33.5 °C and 36 °C. pH, one of the chemicals parameter, at the seawater entrance, reservoir plot, and evaporated plot were 8.2, 7.7, and 9. The salinity of the three points is more than 33 ‰, and the raw water saturation in the evaporated pool is 24° Be. Analysis of heavy metals in this study showed levels below seawater quality standards for consumption purposes.


Introduction
Salt fields are generally located in coastal areas to facilitate the flow of water as a raw material into the plots.However, coastal areas are often places where various types of waste are disposed of, making them vulnerable to pollution [1].Therefore, salt farms must be located on the coast with clean, unpolluted sea waters, free of garbage, and slightly suspended solids, far from ports, industrial zones, agriculture, settlements, and major cities.Thus, pre-production of salt needs to pay attention to salt land management so that the salt produced is free of pollutants [2].
The quality of the sea salt will depend on the quality of the seawater, the manufacturing process, and the technology used [3].The salt produced from sea water, which is pumped into salt production plots, is highly prone to heavy metal contamination.Salt containing heavy metals such as Lead (Pb), Cadmium, Mercury, and Arsenic will pose a risk to human health if ingested [4].The presence of heavy metals in marine water can be directly ingested by marine organisms and subsequently build-up in their tissues.This build-up can spread throughout the food chain and pose a risk to marine life and human health.[5].In addition, other studies have shown that low-level concentrations of Pb and Cd, as well as Hg and As, can have adverse effects on human health.The presence of heavy metals in food 1298 (2024) 012026 IOP Publishing doi:10.1088/1755-1315/1298/1/012026 2 can lead to a variety of health issues, including damage to the central nervous system, brain injury, paralysis, delayed growth, renal impairment, bone weakness, DNA alteration, and cancer [6].
Salt field samples from Sandpit in Karachi, Pakistan that receive untreated effluent through Lyari River show health risk assessment (HRA) index 2 to 6 times higher than non-carcinogenically relevant THQ (Target Hazard Quotient) (TQ) (As), (Pb), (Al), (Hg), and (Cr).The hazard index similarly indicates that salt is at least 20 times more hazardous than other materials, with a hazard index value of 20.29.The carcinogenic rate (CR) index of heavy metals Cd, As, Cr and Ni is also higher than the CR reference value of 1 × 10 −4 [7].
Pangarengan Village, Sampang Regency is one of the salt centers on Madura Island which uses the evaporation method in producing salt.The salt fields in Pangarengan Village are currently up to 5 km from the shoreline and are in a residential area.Land adjacent to human activities allows for a decrease in the quality of seawater as a source of raw material for the production of consumption salt.Based on the condition of the salt field in Pangarengan Village, Sampang Regency, determining the quality of salt requires testing the quality of raw water that is free from heavy metal contamination.The purpose of this study was to evaluate the seawater's quality as a raw material for salt production in Pangarengan, Sampang, East Java, Indonesia.This study examined the physical and chemical properties of water, including its temperature, pH, salinity and water saturation, as well as the presence of heavy metals such as mercury, cadmium, lead, and arsenic.Water chemistry generally influences the toxicity of environmental pollutants, particularly metals.

Method 2.1. Time and place of research
This study conducted purposive sampling by taking samples from the salt fields farthest from the seashore and located around the settlements of Pangarengan Village, Sampang Regency, East Java, Indonesia (Figure 1).Sampling points were seawater inlet (P1), reservoir plot (P2), and evaporated plot (P3).

Research methods 2.2.1. Tools and materials
This research uses the tools and materials listed in Table 1.Heavy metal analysis 2.2.2.Temperature, salinity, pH and saturation Assessment of temperature, salinity, pH and the degree of water saturation using in situ measurements.Assessment of temperature using a thermometer, measuring salinity using a refractometer, pH data using a pH meter, and the degree of saturation of a water sample using baume meter (Figure 2).

Sample preparation
Destruction aims to remove/separate other ion content, with the initial treatment it is expected that errors during analysis can be minimized.The initial treatment method used is the destruction method, namely by breaking the bonds of metal elements with other components in the matrix so that these elements are in a free state [8].Destruction of water samples was carried out by taking 5 ml of seawater samples then adding 250 ml aquadest, 30 ml of nitric acid (HNO 3 ) and 10 ml of sulfuric acid (H 2 SO 4 ), and stirring.Heating for 3 hours in a fume cupboard until the solution becomes clear and cooled.Add 10 ml of 30% H 2 O 2 (hydrogen peroxide), and filter using Whatmen No. 42.

Standard solution
Mercury (Hg) Take 0.068 g of Mercury II Chloride solution (HgCl 2 ) each as much as 0; 0.3; 0.6; 0.9; 1.2 ml and add distilled water at each concentration up to 10 ml.Each sample was taken as much as 1 ml and added 2 ml of silver nanoparticles, then stirring was carried out.Make observations using UV-Vis Spectrophotometry with waves of 280-700 nm and make a calibration curve [9].
Cadmium (Cd) Take each Cd solution as much as 0.1; 0.3; 0.5; 0.7; 0.9 ml and add distilled water at each concentration up to 10 ml.Each sample was taken as much as 1 ml and added 0.1 N Sodium Hydroxide (NaOH) 5 ml, stirred for 15 minutes.Make observations using UV-Vis Spectrophotometry with waves of 250-300 nm and create a calibration curve [10].
Lead (Pb) Take each Pb solution 0; 0.5; 1; 1.5; 2; 2.5; 3 ml and add 5 ml of 0.05 M Sodium Hydroxide (NaOH), 5 ml of 0.005% Ditizon and 5 ml of 10% KCN, then add distilled water up to 50 ml and let stand for 5 minutes.Each sample was taken as much as 1 ml and made observations using UV-Vis Spectrophotometry with waves of 460-570 nm and made a calibration curve [11].
Arsenic (As) Take each As solution as much as 1; 2; 3; 5; 6 ml and add aquadest to each sample up to 25 ml.Take 1 ml of each sample and add 3 ml of Sodium Hyprobromite (NaOBr), 15 ml of Aquadest, 0.5 ml of NH 4 -H 2 SO 4 , and 1 ml of hydrozine sulfate.Stir for 75 minutes prior to observation using UV-Vis Spectrophotometry with 845 waves and create a calibration curve [12] Observation of water samples Mercury (Hg) Take 1 ml of water sample and add distilled water at each concentration up to 10 ml.Each sample was taken as much as 1 ml and added 2 ml of silver nanoparticles, then stirring was carried out.Make observations using UV-Vis Spectrophotometry with a wave of 280-700 nm [9].
Cadmium (Cd) Take 1 ml of water sample and add distilled water at each concentration up to 10 ml.Each sample was taken as much as 1 ml and added 0.1 N Sodium Hydroxide (NaOH) 5 ml, stirred for 15 minutes.Make observations using UV-Vis Spectrophotometry with a wave of 250-300 nm [10].
Lead (Pb) Take 1 ml of water sample and add 5 ml of 0.05 M Sodium Hydroxide (NaOH), 5 ml of 0.005% Ditizon and 5 ml of 10% KCN, then add distilled water up to 50 ml and let stand for 5 minutes.Each sample was taken as much as 1 ml and observed using UV-Vis Spectrophotometry with a wave of 460-570 nm [11].
Arsenic (As) Take 1 ml of water sample and add distilled water to each sample up to 25 ml.Take 1 ml of each sample and add 3 ml of Sodium Hyprobromite (NaOBr), 15 ml of Aquadest, 0.5 ml of NH 4 -H 2 SO 4 , and 1 ml of hydrozine sulfate.Stir for 75 minutes before observing using UV-Vis Spectrophotometry with a wave of 845 [12].

Data analysis
Analysis of metal content in this study uses the following formula [13]: Seawater saturation (°Be) [17] >2 0

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The physical characteristics of the highest water temperatures were in evaporated plot (40°C), while the water temperatures in the seawater entrance and reservoir ponds were respectively 33.5 °C and 36 °C.pH, one of the chemicals parameter, at the seawater entrance, reservoir plot, and evaporated plot were 8.2, 7.7, and 9.The salinity of the three points is more than 33 ‰, and the raw water saturation in the evaporated pool is 24° Be.The parameters of water as a raw material show the results of water quality suitable for salt production based on parameters of land suitability for salt ponds [14][15][16][17] and seawater quality standards based on Government Regulation of the Republic of Indonesia No 22 of 2021 about Implementation and Protection of Environmental Management Attachment VIII concerning quality standards sea water.A different thing is shown in the water saturation parameter at the water inlet of less than 2°Be which shows a low concentration.The degree of water saturation increases from the holding pond to the evaporation pond (P3) and is ready to enter the crystallization compartment.Salt ions have the potential to alter the mobility and toxic effects of heavy metals within estuarine wetland ecosystems [18].Environmental parameters such as temperature, pH, DO, and salinity also influence metal concentrations and behavior along estuaries [19].In addition, a rise in temperature will impede the absorption of heavy metal compounds by particulates, causing them to settle to the bottom.The rise in salinity results in a decrease in the concentration of toxic metals as a result of desalination.Salinity has a big role in the process of decaying heavy metals Cd and Pb when mixing in estuaries.The increase in salinity causes the concentration of Pb and Cd to decrease.The presence of high levels of carbonate in water can lead to a decrease in its solubility due to the formation of carbonatehydroxide bonds with particles in the water due to an increase in pH [20].pH is one of the essential chemical determinants of water quality.By knowing the degree of acidity (pH) of the water, the type and rate of reaction of some materials in the water can be controlled.The high or low pH of water is influenced by the compounds contained in the water.Pond water has an ideal pH between 7.5-8.5.Generally, changes in water pH are influenced by soil properties [15].
This study utilizes a calibration curve in heavy metal analysis to compare the concentration of an unknown substance in a sample to a collection of standard samples with known concentrations.The standard curve uses the absorbance spectrum data of a standard solution that has been prepared with certain concentrations.The absorbance spectrum for the standard solution is presented in Table 3 and in Figure 3 below.
Table 3.The absorbance spectrum of the standard solution Mercury (  The calibration curves for the four heavy metals above show a value of R 2 > 0.9, so the equation for each calibration curve can be used in the analysis of heavy metal content.The results of the analysis of heavy metal content in raw water for salt production in Pangarengan Village, Sampang Regency are shown in Table 4. Sea waters close to land generally have high metal content.This condition indicates that anthropogenic activity contributes to metal richness in the waters [20].Heavy metals can contaminate at every stage of sea salt production.The quality standard for heavy metal contamination in raw water for salt production uses 1 st class quality standards, namely water whose designation can be used as raw water for drinking water, and/or other uses that require the quality of water to be the same as that used.Based on the national water quality standard PPRI No 22 of 2021, it shows that raw water for salt production in Pangarengan Village, Sampang Regency is still below the set quality standards, namely 0.001 mg/l (Hg), 0.1 mg/l (Cd), 0.03 mg/l (Pb), and 0.05 mg/l (As).The results of the analysis showed that the raw water at the research location was free of mercury with a negative value of the metal concentration indicated on the calibration curve.
Even though the sampling location is in an anthropogenic area, it has not been polluted by heavy metals.This condition is due to the location of this salt land which is not adjacent to mining or industry which can increase the concentration of heavy metal pollutants [10].Industrialization and rapid economic development have created serious problems regarding heavy metal contamination in the soil and large amounts of these pollutants are discharged through streams and other routes into the coastal and estuarine environment [5].The disposal of waste from tin mining, battery industry waste disposal, shipping, and port operations can lead to an increase in the presence of heavy metals, such as copper, chromium, and manganese, in marine waters.This wastewater is discharged into river waters and transported to sea waters [2].

Conclusion
1.The physical characteristics of the highest water temperatures were in evaporated plot (40°C), while the water temperatures in the seawater entrance and reservoir ponds were respectively 33.5 °C and 36 °C.pH, one of the chemicals parameter, at the seawater entrance, reservoir plot, and evaporated plot were 8.2, 7.7, and 9.The salinity of the three points is more than 33 ‰, and the raw water saturation in the evaporated pool is 24° Be.The parameters of water as a raw material show the results of water quality suitable for salt production based on parameters of land suitability for salt fields.
2. Even though the sampling location is in an anthropogenic area, it has not been contaminated with any heavy metals.The results of the analysis of heavy metals show that all sampling locations are still below the PPRI 1 st class standard water quality standard No 22 of 2021.
3. It is necessary to compare the same research using Atomic Absorption Spectrophotometry (AAS).

Table 1 .
Tools and materials

Table 4 .
The result of analysis of heavy metal content