**1.3 Significant diffuse sources of pollution including land use**

Water pollution, such as sewage or industrial effluent pollution, is normally easier to monitor because it generally occurs from a single source, but diffuse water pollution results from multiple sources [15]. Diffuse water pollution is a widespread problem and it is important to know the extent to which different sources of diffuse pollution have an impact on water quality [16], agriculture being one of the main sources of diffuse pollution. Various activities contribute to diffuse pollution indicating agriculture, forestry, mining, construction, and urban life, and the local climate, geology, and other natural phenomena that can influence the size and extent of the problem. In agriculture, diffuse pollutants include sludge from soil erosion, nutrients from fertilizer application, or non-compliance with pesticide handling and chemical application legislation—Directive 2009/128/EC [17].

As in the case of point sources of significant pollution, the main categories are represented by:

• human agglomerations without wastewater collection systems and compliant landfills;


Eutrophication is the enrichment of water with nutrients such as nitrate or phosphate, causing an accelerated development of algae and higher plants, which leads to unwanted disturbance of the balance of organisms in the water but also to water quality in general [18]. Thus, habitat disturbances occur for fish and invertebrate species, the development of toxic algae with an impact on the fishing industry, and the flourishing of recreational waters lead to the closure of the navigation or recreational use area with an impact on the tourism and leisure industry [19]. Loss of nutrients or agrochemicals in soil and water in addition to affecting the environment is also an agricultural financial loss. In addition, groundwater is endangered due to leakage or percolation of nutrients and pesticides from the land surface. Diffuse agricultural pollution is mainly associated with soil particles, pesticides, and other potentially toxic chemicals, including veterinary medicines, nutrients, pathogens, bacteria from animal waste, and manure spread on the ground [20].
