Deep water oxygen in European lakes

A study of more than 1,500 European watersheds finds that deep water oxygen concentrations in European lakes began to decline around 1850 and quickly decreased after 1900 mainly in response to enhanced phosphorus exports from concurrent widespread urbanization, suggesting that increases in sewage pollution at the turn of the century led to enhanced biological productivity and low oxygen concentrations in many European lakes well before the general use of commercial fertilizers and the onset of climate warming. - Read at PNAS.org

Article #16-05480: “Urban point sources of nutrients were the leading cause for the historical spread of hypoxia across European lakes,” by Jean-Philippe Jenny et al.