ABSTRACT
This chapter examines the types of water quality variables that are typically assessed and the processes that lead to their occurrence and nature in rivers, ponds and lakes. It then considers the natural processes and factors that control the spatial and temporal patterns of surface water chemistry including natural geology, seasonality and variability in surface water discharge. Humans have had large impacts upon surface water quality. The chapter will explain how changes in agricultural practices and urbanisation affect water quality, and the mitigation factors that are being used to try to reduce water pollution from these sources. The chapter also describes the causes of acid mine drainage, its impact on water quality and mitigation options that exist. The causes of acid rain, its impact on water quality and how legislation in Europe and North America has led to the reduction of acid rain are also discussed. Finally, the chapter examines the role of national and international policies and legislation in reducing water pollution and mitigating against the effects of climate change and population growth on future surface water quality.
