The dataset contains dissolved greenhouse and nutrient data collected from seven UK estuaries: the Clyde, Clywd, Conwy, Dart, Forth, Tamar and Tay, for the LOCATE project. Sampling was conducted from July 2017 to April 2018 on a quarterly basis, and was coordinated to occur on falling tides and to target specific salinities of interest: 1, 2, 5, 10, 15, 25 psu. Data were obtained via collection of gas and water samples in situ, and concentrations were derived via subsequent sample processing and analysis.