This book contains a collection of papers from the special issue on DOM in Freshwater Ecosystems: Nature, Origins and Ecological Significance, published in Vol. 164, Issue 1 (164-1), 2023. of the journal Biogeochemistry. Nutrient flux to fresh waters is increasing globally wherever there is sustained economic development, generating extensive and undesirable impacts on freshwater ecosystems. Dissolved Organic Matter (DOM) is a key component...