Salinity and stable isotope dataset for Guayas estuary waters.

The Guayas estuary is an ecologically and economically vital, large estuarine system located on the western coast of South America. A suite of ∼400 water samples was collected and analyzed to enable investigation of the sources of water types within this estuary, as well as environmental processes active within various portions of it. These samples were obtained at sites distributed across the major areas of the inner and outer portions of the estuary at the ends of consecutive dry (December/January) and rainy (May) seasons. At each site, Van Dorn bottles were lowered into the water from a boat (or bridge) and then triggered when they reached specified depths. When the Van Dorn bottles were brought back aboard the boat, aliquots of water from them were promptly sealed in glass containers for later analysis. These were transported to onshore laboratories where their salinities, and their oxygen (δO) and hydrogen (δH) isotopic compositions were measured. Established analytical procedures and standards were employed to obtain a robust set of resultant data. The samples, analyses, and data presented here support the associated research article, "Stable isotope evidence for the origins of waters in the Guayas estuary and Gulf of Guayaquil" [1], to which readers are referred for interpretation.