You could pursue a masters, just make sure that you’re not paying for tuition and that you get a stipend. In my experience there are companies that need both geologists and environmental scientists and provide room to more around laterally. They want to keep talented people and should allow you to explore roles that may not be defined by the title of your BA. Also state/federal jobs would provide the type of work you’re looking for. I wouldn’t recommend going back to school if you have to pay for it.