Epilithon δ15N signatures indicate the origins of nitrogen loading and its seasonal dynamics in a volcanic Lake

摘要: Abstract The intensification of agricultural land use and urbanisation has increased nutrient loads in aquatic ecosystems. Nitrogen can alter ecosystem structure functioning, resulting algal productivity, blooms eutrophication. principal aim the present paper is to extend epilithic δ 15 N signatures a lake order evaluate potential impact anthropogenic nitrogen discharges (organic inorganic) that also reach coastal waters. Epilithic associations were collected from volcanic rocks different seasons shallow water along entire perimeter Lake Bracciano analysed for their stable isotope signatures. Furthermore, some stones moved an unpolluted site polluted one verify effect on signature association. epilithon’s provided strong evidence space-time variability inputs. differing quality was reflected high isotopic variation within lake, especially at beginning summer (1.7‰ ≤ δ N ≤ 13.3‰), while winter, when pressure lowest, less accentuated (3.1‰ ≤ δ N ≤ 7.6‰). At all sampling times, spatial found be related various human activities shore (especially tourism agriculture), seasonal sites intensity pressures (higher lower winter). Our results showed physicochemical properties did not influence signature, which contrast strongly site-specific around lake. Thus, distribution across space time used direct reduction strategies region assist monitoring effectiveness environmental protection measures.