Acidic deposition effects on upland organic soils and their drainage water
The work presented in this thesis investigates the effects of precipitation chemistry on the chemical characteristics of upland organic soils in the UK and their associated drainage waters. It also describes effects on a number of microbially-mediated processes and concludes with a study on methods for the amelioration of peat acidification. Data presented in chapters 3, 5 and 6 have recently been published or accepted for publication (Sanger et al. 1993 a. 1993 b and 1993 c). The first chapter describes the nature of soil acidity and reviews the relevant literature on the effects of acidic deposition, with particular emphasis on upland organic soils and their drainage waters. Chapter 2 describes a field survey carried out in the UK which investigates relationships between the exchangeable and total element chemistry of peat and precipitation chemistry. The results showed that peat collected from areas receiving high concentrations of H+, NH4+, SO42- andNO3- in precipitation were characterised by high extractable NH4+ and total P. and low extractable NO3-, base saturation and exchangeable Ca2+ and Mg2+. TheNH4+ concentration in precipitation was strongly related to a number of soil chemical parameters and the results suggest that future changesin NH4+ inputsto peatscould significantlyeffect soil and drainage water chemistry. The results also show that (1) processes involved in the cycling of N and P may have been altered by precipitation chemistry (2) exchangeable Ca2+ and Mg2+ have been displaced by NH4+ and H+ in areas with high acidic deposition. Peat from areas with a high marine input in precipitation contained high concentrations of exchangeable N+ and K+. Laboratory simulation studies (chapter 3 and 4) using intact peat monoliths were carried out to complement the regional survey described in chapter 2. They were set up to examine element fluxes from peats in relation to precipitation chemistry.