Determination of strontium isotopic composition in natural waters: examples of application in subsurface waters of the coastal zone of Bragantina region, Pará

摘要

Analytical procedures used for determining the concentrations and isotope composition of strontium in subsurface waters, by mass spectrometry, are described. Sampling was performed in coastal plateaus, salt marsh and mangrove environments in the coastal region of Pará. Coastal plateau waters have d87Sr between 1.51 and 6.26?‰ and Sr concentration bellow 58 ppb. Salt marsh waters show d87Sr between 0.55 and 0.90?‰ and Sr concentration between 93 and 114 ppm, while mangrove waters have d87Sr?‰ around zero and Sr concentration above 15 ppm. Differences in the 87Sr/86Sr ratio in these subsurface waters are detected, as well as seasonal variations in the coastal pleteau waters.