Assessment of the physicochemical characteristics of surface waterbodies in a region earmarked for shale gas exploration (Eastern Cape Karoo, South Africa)

摘要

The proposed drilling for shale gas resources in the Eastern Cape Karoo region of South Africa has triggered much debate over the potential effects of hydraulic fracturing on water resources. Herein we present results on some limnological aspects of surface waterbodies in this water-scarce region before shale gas exploration. Thirty-three waterbodies (nine dams, 13 depression wetlands and 11 rivers) were sampled in November 2014 and April 2015. Principal component analysis revealed that depression wetlands and rivers had distinct physicochemical signatures, whereas dams were highly variable in their physicochemical attributes and exhibited characteristics similar to those of either rivers or depression wetlands. Non-parametric multivariate regressions and permutational multivariate analysis of variance (MANOVA) indicated that landscape variables such as underlying geology, altitude and land use poorly explained the physicochemical characteristics of the sampled waterbodies. Waterbody type was the only factor that explained a significant amount of the variation in physicochemistry during both sampling events. These data need to be supplemented by water quality information from additional sites and over longer time periods, as well as supporting data relating to other aspects, such as algae and invertebrates, before they can be used as a baseline for the long-term monitoring of freshwater ecosystems in the region.