With down the drain chemicals, high concern has been revealed particularly for freshwater habitats (rivers and lakes) and for transitional waters (Table 5.3). High concern has also been detected for several cropland – ecosystem service combinations. These findings can be explained by the importance of those habitats for the provision of certain ecosystem services (e.g. cropland – food; rivers – freshwater) and their potentially short distance from the point of discharge, leading to a high level of exposure. Medium concern has been found for a number of habitat x ecosystem service combinations. It is only in habitats at longer distances from the source (i.e. shelf) and overall lower importance for the delivery of an ecosystem service that increased concern became less frequent. Combinations of medium or high concern were found for all (four) categories of ecosystem services without any clear focus on one of those groups.
Within a certain ecosystem service, medium or high concern has often been found for various habitats (e.g. genetic resources in terrestrial, freshwater and marine habitats). As a consequence, the number and diversity of involved SPU is usually high. For some ecosystem services in this case study, only negligible or low concern has been found over all considered habitats. On one hand this can be explained by the ‘robustness’ of the SPUs providing a certain service; on the other hand, the expected level of exposure has to be taken into account. To give an example, terrestrial plants are involved in erosion regulation in crop- and grassland habitats. However, the potential impact of sewage sludge or sewage for irrigation is not considered to be strong enough to significantly impair this service, i.e. the plant cover will most probably not be destroyed.
Table 5.3: Down the drain chemicals – ecosystem services of concern with examples of SPUs involved in the delivery of potentially threatened services.
Black: high concern; dark grey: medium concern; light grey: low concern; white: negligible concern