Summary, Miljøstyrelsen

Havnesedimenters indhold af miljøfremmede organiske forbindelser

Summary

The aim of the project was to describe the contamination of harbour sediment with organic pollutants and summarising the recent strategies and future needs for dredging and deposition of sediment from harbours.

The pollution of harbour sediments was investigated in industrial harbours (Fredsholmløbet, Odense Havn, Vejle Havn, Kolding Havn, and Åbenrå Havn), oil harbours (Prøvestenen and Århus Havn), a fishing harbour (Århus Fiskerihavn) and yacht harbours (Svanemøllen Lystbådehavn, Fåborg Lystbådehavn, Marselisborg Lystbådehavn, and Sønderborg Lystbådehavn). Out of a total of 113 analysed compounds only 34 compounds were found in concentrations above the detection limit. The occurrence of compounds within different groups is summarised in the following table:

Compound	Number of parameters measured	Number of parameters detected	Number of detection in sediment samples
Phthalates	11	5	2-12
Nonylphenols	1	1	12
Chlorobenzen	8	1	2
Phenol	14	1	10
PAH	18	18	9¹
PCB	7	2	1
LAS	1	1	10
Antifouling	8	6	12²
Hydrocarbons	1	1	12

^{1 In three samples one or more PAHs were below the
detection limit.
^{2 One sample under detection limit for Irgarol. Five
samples under detection limit for DBT and eight samples under detection limit for MBT
Phosphat triesters, chlorinated pesticides, pesticides and the antifouling compounds
atrazine and simazine were not found in the sediment in concentration above the detection
limit.}}

The loading of the harbours depends strongly on the individual compounds. The highest concentration was found (in descending order to the concentration) of:

Phthalates in Frederiksholmløbet, Århus Fiskerihavn, Odense Havn, Kolding Havn and Svanemøllen Lystbådehavn;

Nonylphenol in Frederiksholmsløbet and Odense Havn;

3/4-methylphenol in Vejle Havn and Kolding Havn;

Sum PAH’er in Århus Fiskerihavn, Svanemøllen Lystbådehavn, Odense Havn and Århus Havn;

LAS in Frederiksholmløbet, Åbenrå Havn, Odense Havn and Kolding Havn;

Diuron in Marselisborg Lystbådehavn, Vejle Havn and Odense Havn;

Irgarol in Marselisborg Lystbådehavn and Sønderborg Lystbådehavn;

TBT in Århus Havn and Odense Havn;

DBT in Århus Havn;

Copper in Svanemøllen Lystbådehavn, Frederiksholmløbet, Århus Fiskerihavn, Marselisborg Lystbådehavn and Odense Havn;

Total hydrocarbons in Svanemøllen Lystbådehavn, Århus Havn and Odense Havn.

The degradation products (MBT and DBT) from TBT were found in Århus Oliehavn, Frederiksholmløbet, Åbenrå Havn and Marselisborg Lystbådehavn. In addition, DBT was found in Svanemøllen Lystbådehavn, Fåborg Lystbådehavn and Sønderborg Lystbådehavn.

There was only two significant correlations between loss of ignition and the concentrations of the pollutants in the sediments. In addition, no unambiguous correlation between the concentration of the pollutants in the sediment and the application of the harbour was found.

The strategies in the Danish counties for dredging and disposal of sediments from harbours and the further needs for dredging and disposal were investigated by questionnaire. For most counties it is common to analyse for copper and other heavy metals prior to permission for dredging is given. Few counties have analysed for TBT (DBT and MBT) or hydrocarbons prior to permission for dredging. Only one county has analysed for irgarol in sediments prior to permission for dredging.

Most counties use a limit value for copper for dumping of dredged sediment. Typically, the limit value for copper concentration in the dredged sediment must not exceed a value higher than two times the background concentration. Generally, no limit for organic pollutants is established.

The amount of dredged sediment in 1998-99 was estimated at 0.8-0.9 mill. tons each year. The needs for the near future in 2000-2003 are estimated to 0.8-1.5 mill tons each year.

The majority of the dumping sites are located in areas with moderate to strong current and with no permanent sedimentation. Only very few places are in sediment accumulation areas. Nine counties have established deposits on land or basins for contaminated sediments. About 0.2 mill. tons contaminated sediment has been deposited in 1998 and about 0.4 tons in 1999. Some deposits are temporary and are used for drainage of the sediment for water after which the sediments are transported to more permanent deposits. No deposits are equipped with membranes and the majority has overflow outlet for water to the sea.