The Swedish environmental reporting system has large amounts of information regarding point source discharges. But, point sources represent only a limited part of the total discharges. Therefore contributions from diffuse sources are important to identify in relation to the spread of various substances to the environment. Ex-amples of diffuse sources include road traffic, agriculture, use of solvents, chemi-cals emitted from use-phase of products, and small industries. Here, these and simi-lar diffuse emissions to air are published in the Swedish Pollutant Release and Transfer Register (S-PRTR, with Swedish acronym UTIS). This data is derived from the air and climate reporting made to the Convention on Long-range Trans-boundary Air Pollution (CLRTAP) and UNFCCC. Data at the S-PRTR is listed for several organic pollutants, such as PAHs and heavy metals. Data on diffuse emis-sions to water is currently not provided at the S-PRTR website. Certain diffuse emissions into water are included in the international emission reporting, such as the HELCOM PLC periodical and EEA WISE SoE Emissions.

The project described herein is based on the development project "Feasibility study for possible publication of diffuse emissions at SPRTR, and is designed to:

 Publish data on emissions from diffuse sources, primarily to water, from selected sectors and substances or substance groups.

 Compare data collected for these diffuse emissions in relation to totals for data reported to E-PRTR.

 Based on the knowledge acquired during this project to propose more regu-lar procedures for collecting data regarding diffuse emissions.

Substances considered in the project include nutrients (nitrogen and phosphorus), metals (lead, cadmium, copper, mercury, nickel and zinc) and certain organic com-pounds (PAHs, PBDEs, nonylphenols, PCBs, HCHs, DDT, endosulfan, and diox-ins. There is currently no data in certain matrices for these organic pollutants.

The project has four separate subprojects:

 Diffuse emissions of metals and nutrients to water.Diffuse emissions of certain organic pollutants to water.Diffuse emissions of nonylphenols and nonylphenol ethoxylates from different product groups.Analyses of report-ed data for air and water, and comparison with diffuse emissions.Project 1 covers the following diffuse sources: atmospheric deposition on water, forest land, agriculture, other land, stormwater, local on-site wastewater treatment facilities, industrial facilities and wastewater treatment plants not included in reporting to E-PRTR. Copper is also considered as emission from antifouling boat paint. Subpro-ject 1 findings show that the most significant emission source for nitrogen and phosphorus is agricultural and forests land. Forests dominate as the source of all metals. As well, diffuse emissions of most other metal are significant from agricul-ture, deposition on water, other land and stormwater. Geographically, distribution of emissions shows that stormwater is more significant in the south (Northern Baltic, Southern Baltic, and Skagerrak and Kattegat river basin districts) than in the north (Bothnian Bay and Bothnian Sea river basin districts). This is as expected due to greater traffic volumes in the south. In future, data from water load reporting can be easily recalculated in the geo-database to match publication in the E-PRTR. Coordinating with departments producing water emission statistics is necessary, though.

Subproject 2 findings show that data for only a few organic pollutants is currently available (such as PAHs, PBDEs, nonylphenols, dioxins, DEHP, PCBs, HCH, DDT, endosulfan and chlorinated paraffins). Data for many of these substances is available only for single or a few diffuse sources (small industries and WWTPs, deposition on water, stormwater and deposition on land). Data for diffuse emis-sions of organic pollutants that is currently available are uncertain and based on few measurements.

Subproject 3 shows that it is possible to estimate nonylphenols (NPequ) emissions to air, soil and wastewater. The largest source of NPequ to wastewater is from textiles, while smaller amounts are from detergents. The data are uncertain, however, as they are based on emission factors with significant uncertainties.

Finally,subproject 4 findings show that all diffuse emissions are significant. Dif-fuse emission of nitrogen, phosphorus and metals to water is at least 10 times or more larger compared to point sources, in nearly all cases. Agricultural land domi-nates as a source in the case of phosphorus and nitrogen. Emissions of organic pollutants to water show significant gaps in the data because very few companies report emissions.

Regarding emissions of organic pollutants and metals to the air, the difference between point sources (E-PRTR) and diffuse emissions based on data from CLRTAP are in most cases not as great as for water. For copper, diffuse emissions to air from brake linings is the largest source of diffuse emission (>90%). And for PAH, diffuse emissions from the energy sector dominates, corresponding to nearly 100% of the total. Emissions of each pollutant (nearly all) is greater to water than to air for point sources, diffuse sources, and the total.

When comparing emissions from various industries, findings show that forestry industry facilities contribute approximately 90% when it comes to cadmium emis-sions to water from point sources according to E-PRTR (total 440 kg). Still, this is much lower than diffuse emissions as found in Subproject 1, 3,900 kg – indicating diffuse emissions are nearly 9 times greater. The difference for emissions to water is not very large between point sources reported to E-PRTR and those not (in the e-PRTR) – indicating that the point sources under E-PRTR include a large portion of all discharges from point sources to water.

The quality of data is sufficient to show diffuse emission levels of nutrients and metals at the S-PRTR, reported for the national, river basin district or more refined levels, since this data is based on values reported to the EU and HELCOM. Re-garding organic pollutants to water and nonylphenols from products, the data is more uncertain and is therefore not recommended to be published in the S-PRTR. For emissions to air, our conclusion is that national totals, as reported to the UNPCCC and CLRTAP can be included in the S-PRTR.