0000000000365087
AUTHOR
Glen George
The Impact of the Changing Climate on the Supply and Recycling of Nitrate
A high proportion of the nitrogen found in lakes and rivers is present in the form of nitrate. The concentration of nitrate in many surface waters has increased over the last forty years (OECD, 1982; Roberts and Marsh, 1987; Johnes and Burt, 1993). The main source of nitrate is diffuse drainage from agricultural land (Vinten and Smith, 1993) but point sources can be important in populated areas (Jarvey et al., 1998). In 1991, the European Union introduced the Nitrates Directive (91.676) to protect waters from pollution by nitrate leached from agricultural land.
The Impact of the Changing Climate on the Thermal Characteristics of Lakes
Meteorological forcing at the air-water interface is the main determinant of the heat balance of most lakes (Edinger et al., 1968; Sweers, 1976). Year-to-year changes in the weather therefore have a major effect on the thermal characteristics of lakes. However, lakes that differ with respect to their morphometry respond differently to these changes (Gorham, 1964), with deeper lakes integrating the effects of meteorological forcing over longer periods of time. Other important factors that can influence the thermal characteristics of lakes include hydraulic residence time, optical properties and landscape setting (e.g. Salonen et al., 1984; Fee et al., 1996; Livingstone et al., 1999). These f…