A COMPARATIVE ASSESSMENT OF WATER QUALITY IN FOUR EXPERIMENTAL LAKES CREATED ON IRISH CUTAWAY PEATLAND

摘要

Of the 80,000 hectares of cutaway peatland emerging in Ireland over the next 25 years, 15,000-20,000 will be developed into shallow conservation lakes. This study focused on four experimental lakes created on contrasting areas of cutaway, which were sampled over a 34-month period for various physico-chemical and biological parameters. The purpose of the research was to elucidate the primary factors impacting water quality in cutaway lakes, so that future cutaway lakes can be designed for optimal water quality. Results indicated that variations in the depth and composition of the residual peat layer, the degree to which mineral subsoils were exposed and the presence of a hard-water influent were the principal factors determining water chemistry. Lakes with an inorganic influence had low levels of colour, dissolved nutrients and low primary productivity and high values of pH, dissolved ions and phytoplankton species diversity. Conversely, the study lake underlain by entirely peaty sediments, with no hard-water inflow, exhibited a very low pH and low phytoplankton species diversity but an unexpectedly high rate of primary productivity, sustained by moderately high phosphorus concentrations. The results highlighted the desirability of introducing some inorganic influence when creating future lakes on cutaway peatland.