measurements of water quality were taken from a river downstream from an abandoned chemical dumpsite. concentrations of a certain chemical were obtained from 9 measurements taken at the surface of the water, 9 measurements taken at mid-depth of the water, and 9 measurements taken at the bottom of the water. what type of study was conducted, and what is the response variable of the study? responses an experiment was conducted, and the response variable is the concentration of the chemical.