Edinburgh Sept RIVER RHINE AS A SOURCE OF MICROPOLLUTANTS IN THE CANAL SEDIMENTS OF THE CITY OF DELFT (THE NETHERLANDS) Peter Kelderman *, Yang Xuedong *, Qu Wenchuan * and Wim Drossaert ** * International Institute for Infrastructural, Hydraulic and Environmental Engineering ( **

OUTLINE OF PRESENTATION Sediment quality problems in The Netherlands Quality assessment inner/outer city Delft sediments Statistical evaluation of the Delft data River Rhine characteristics Statistical comparison Delft /river Rhine data Conclusions

Edinburgh Sept PROBLEM DESCRIPTION The Netherlands, at the mouths of a number of international rivers, serves as a “sedimentation basin” of polluted sediments. Some 30 million m 3 of dredged materials have to be processed each year. Of this, ca. 30% is polluted and has to be stored and/or processed. Also municipalities such as Delft pay high cost for the sludge storage and treatment.

Edinburgh Sept THE NETHERLANDS IN EUROPE River Rhine, Meuse and Scheldt Delft

Edinburgh Sept Sediment quality assessment in The Netherlands Class 1 : unpolluted ……… class 4 : heavily polluted Heavy metals and organic micropollutants Overall sediment quality class based on “worst case”

| | = 1 km

Edinburgh Sept In inner city, 95% in sediment class 3+4 (  ) SEDIMENT QUALITY AT 200 STATIONS IN DELFT In outer city only 45% in class 3+4 Main pollutants: Cu, PAHs, Zn Rijn-Schie canal probably largest supplier of pollution

Edinburgh Sept INNER CITY AND RIJN-SCHIE CANAL 5 inlet points with RS canal Pumping station P.S. continuously draws in water from RS canal Thus accumulation of polluted sludge in the inner city canals.  River Rhine (20 km’s)

Edinburgh Sept % of Pb, Zn and Cu from Rijn-Schie canal MASS BUDGET HEAVY METALS INNER CITY Internal HM sources: run-off, combined sewer overflows Virtually no effluent discharges onto RS canal --> river Rhine ?? kg/yr

Edinburgh Sept SHIPPING TRAFFIC RIJN-SCHIE CANAL High suspended solids loads due to high ships’ velocities: 85% SS reduction for ship speeds < 1.5 m/sec. bottom current

Edinburgh Sept STATISTICAL TESTS ON 200 SEDIMENT STATIONS LINEAR CORRELATION between the sediment parameters FACTOR ANALYSIS for finding independent sets of variables (Factors) responsible for variance in sediment data; for this the VARIMAX rotation method was used. CLUSTER ANALYSIS for finding spatial groups belonging together (K-means clustering technique).

Edinburgh Sept Very good correlations for Cd-Zn; Hg-Cu; Cu-Zn.. --> common sources? Metals-PAHs also well correlated CORRELATION BETWEEN PARAMETERS r-values In red: p<0.001

FACTOR ANALYSIS Factor 1: Zn +Cd +As + PAHs (42.6% of variance) Factor 2: Hg + Cu + Pb (16.6% of variance) Factor 3: particle size distribution (9.8% of variance) In total three factors (out of the original 10) explain ca. 70% of the variance in the Delft sediment data:

Edinburgh Sept stations --> 7 spatial clusters Cluster 1 and 2 (low pollution) mainly in outer city ( ) Cluster 4 (“intermediate pollution”) mainly in inner city CLUSTER ANALYSIS 182 SEDIMENT STATIONS Cluster 3 (“high pollution”) also in inner city (local pollution?) Other clusters less consistent.

Mean plot of clusters

Edinburgh Sept DETAILED STATISTICAL ANALYSIS AT 3 STATIONS Station 1 and 9: probably pollution from Rijn-Schie canal Station 10: mainly local pollution? Compare with river Rhine data: are there relationships??

Edinburgh Sept RIVER RHINE Switzerland, Germany, France, Netherlands 60 million people in river Rhine catchment Highest pollution in 1970’s; large water quality improvement over last decades.

Edinburgh Sept WATER QUALITY IMPROVEMENT RIVER RHINE Heavy metals loads at Dutch-German border

Edinburgh Sept Pollution levels at stations 1 and 9 comparable to river Rhine; station 10 much higher pollution levels HEAVY METAL CONTENTS RIVER RHINE/ DELFT

Edinburgh Sept CLUSTER ANALYSIS Virtually all data of stations 1 and 9, together with all river Rhine data, belong to cluster 2 81% of data station 10 in cluster 3.

Edinburgh Sept CONCLUSIONS River Rhine still largest supplier of heavy metal pollution into city of Delft. Large reduction of polluted sediment inputs by creating less turbulent water conditions --> reduce ships’ velocities in main shipping canal. Gradual improvements may be expected. However, diffuse sources will remain problem!