curriculum in natural environmental science, vol. 2, 2010NEAR

Institute of Water Supply and Environmental ProtectionCracow University of TechnologyKrakow, ul. Warszawska 24, 31-155 Poland

Reservoirs as a trap for pollutants

Ewa Szalinska

Krakow University of Technology, Krakow, Poland

Outline:

• Reservoirs as traps for sediments• Consequences of sediments trapping• Risk related to the contaminated sediments

• Case study: Czorsztyn Reservoir

Reservoirs as traps for sediments• “The ultimate destiny of all reservoirs is to be filled

with sediment” (Linsley et al. 1992)

Source: www.usace.army.mil

• Trap efficiency – around 80-90%

Sediment as sink for contaminants

Sediment properties:• fine fraction• clays • organic C• cation exchange

capacity• pH

Processes :

• adsorption

• absorption

• ion-exchange

• Co-precipitation

• complexation

• chelation

Consequences of sediments trapping

• Loss of the reservoir volume• Accumulation of sediment-associated

contaminants• Major contaminants of sediments:

– Nutrients – Bulk Organics – Halogenated Hydrocarbons or Persistent Organics– Polycyclic Aromatic Hydrocarbons (PAHs)– Metals

Risk related to the contaminated sediments

• Possibly toxic for the invertebrates and fish• Sediment-associated contaminants can be

bioaccumulated• Direct exposure for humans• Impaired human uses

Source: McDonald & Ingersoll 2002

Case study: Czorsztyn Reservoir

Photo: T. Zabrzewski

Localization

Map source: http://www.zzw-niedzica.com.pl/; Photos: E. Szalinska

Monometallic contamination in the sampling area

300 local tanneries

Cr as a tanning agent

Map source: http://www.zzw-niedzica.com.pl/; Photo: E. Szalinska

Temporal distribution of Cr in the upper Dunajec River sediments (2000-01)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Nov-00 Dec-00 Jan-01 Mar-01 May-01 Oct-01 Nov-01

Cr

[mg

/g d

ry w

.]

Sampling site 1 Sampling site 2

Source: Szalinska et al. 2003

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Sampling site 1 Sampling site 2 Sampling site 3 Sampling site 4

Cr

[mg/

g dr

y w

.]Spatial distribution of Cr in the upper

Dunajec River sediments (2000-01)

Source: Szalinska et al. 2003

Conceptual schema of Cr transport in the Dunajec-Czorsztyn system

After Dominik et al. 2007

River Reservoir

dissolved Cr

particulate Cr(III)

Cr(III) adsorption

coagulationsedim

entation

settling aggregates

HMWC

LMWC

aggr

egat

ion

colloids

Cr(VI)

precipitation poly-Cr(OH)3

Source: Wachałowicz, unpublish.

Spatial distribution of Cr in the Czorsztyn Reservoir sediments (2006)

0,1300,012

0,120

1 %

13,8 %

Chromium Organic matter

Source: Wachałowicz, unpublish.

Spatial distribution of Cr and organic matter in the Czorsztyn Reservoir sediments (2006)

Source: Szalinska et al., in prep.

Budget of Cr for the Czorsztyn Reservoir

• Lack of precise data about Cr discharges;• Cr load estimated on the basis of WWTP data and

water sampling results;• Suspended matter as a vector in the Cr transport

(93 Kt/yr)• Total Cr load calculate with use of partition

coefficient Kd (84 t/yr)

Further reading:• Benett & Rhoton 2007. Reservoir Sedimentation and Environmental

Degradation. Assessing Trends in Sediment-Associated Trace Elements in Grenada Lake, Mississippi. J Environ Qual. 36:815-825

• Dominik et al. 2007. Speciation and environmental fate of chromium in rivers contaminated with tannery effluents. Engineering in Life Sciences, 7(2):155-169.

• MacDonald & Ingersoll 2002. A guidance manual to support the assessment of contaminated sediments in freshwater ecosystems. EPA-905-B02-001-A.

• Metre & Mahler 2004. Contaminant trends in reservoir sediment cores as records of influent stream quality. Environ. Sci. Technol., 38:2978-2986

• Pye (ed) 1994. Sediment transport and depositional Processes. Blackwell Scientific Publications

• Sundborg A. 1992. Lake and reservoir sedimentation. Prediction and interpretation. Geogr. Ann. 74A:93-100

• Szalinska et al. 2003. Fate of tannery chromium contamination in a stream: Temporal and spatial evolution of chromium(III) and chromium(VI). J. Physics IV, 107:1275-1278