Estuaries Environmental Monitoring Associated with Solar Salt Production in the Brazilian Semiarid

HIGHLIGHTS

• Solar saltwork production does not affect water quality.

• Salinity is not affected by salt production.

• The ions present in the estuary are not affected by salt production.

• The estuary is oligotrophic and is not affected by salt production.

Abstract

The salt is indispensable for several industrial sectors, and its production is associated with some natural conditions. These conditions result in productive areas often close to the estuary. Thus, the objective was to evaluate the estuaries environmental monitoring associated with solar salt production in the Brazilian semiarid. The study was developed in the area of influence of a solar saltwork, in the Conchas’ river estuary, RN, where the quality of the water in the estuary was monitored for the non-productive and productive periods of the saltwork for 3 years. Thus, a collection site was established immediately in front of the saltwork discharge channel, and samples were collected monthly, at 30 cm depth, always during high tides, totaling 36 samples. For this, the following parameters were evaluated: salinity, pH, calcium, magnesium, dissolved oxygen, chlorophyll a and rainfall. Salinity was measured in the field with the aid of a portable refractometer. During the operational phase, the average salinity remained above 30.00, characterizing the environment as saline. The calcium and magnesium ions showed an average concentration of 440.00 mg/L and 1280.00 mg/L respectively, values that were according to the limits historically observed for a saline estuary in the analyzed region. The pH and dissolved oxygen were not influenced by the production period (7.93 and above 6.00mg/ L, respectively), while the concentration of chlorophyll a characterized the area as oligotrophic. The functioning of the analyzed solar saltwork did not cause significant changes in the water quality parameters of the estuary.

Keywords:
chlorophyll a; pH; rainfall; salinity