D10: Impact of Contaminants - Hydromod

More documents

Recommendations

Info

Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas EUROLAKES D10: Impact of Contaminants FP5_Contract No.: EVK1-CT1999-00004 Version: 4.0 Date: 25/07/01 File: D10-vers.4.0.doc Page 58 of 136 9 LEVEL OF POLLUTION IN WATER AND SEDIMENT In the [ENVIRONMENTAL ATLAS BERLIN] it is said that there is a continual accumulation of pollutants in water bottom soils, such as heavy metals and chlorinated hydrocarbons. In the material cycle of waters sediments form a natural buffer and filter system. The waters are subject to strong variations of current, substance input, substance transport and sedimentation. In addition to the water sample analyses practised for years, sediment analyses is increasingly important in evaluating qualities of the total ecosystem of a water body. In comparison to water analyses and independent of current inputs, sediment tests reflect the long term quality situation. For this reason, sediment tests are a better basis for fundamental comparisons with other flowing waters. The suspended and precipitate substances stored on the water bottom form a reservoir for many pollutants and trace substances of low solubility and low degree of degradability. According to their chemical persistence and the physical-chemical and biochemical characteristics the substances are conserved in sediments over longer periods of time. Even after sedimentation, portions of fixed substances can be remobilised and re-enter the material cycle of water. Analyses of sediment samples from different depths give a chronological record of inputs in waters and can also allow conclusions to be drawn regarding sources of contamination. Also mineral suspension and precipitation substances are able to store heavy metal ions on their outer surface and they can also be bound in water organisms. The heavy metals can be taken up by higher organisms through the food chain, or they sink to the bottom as sediment, depending on the flow velocity of water. Various pesticides and PCB have the characteristic of being stored adsorptively on suspended matter or in plant organisms. After attaining into the sediment this substances and by ingestion of the organisms they reach the food chain. Eels have a high fat content and eat bottom organisms and bury themselves in sediment. That way, the intake of pesticides and PCB not only takes place through nutrients. They also ingest them through the skin and accumulate them in the body fat [ENVIRONMENTAL ATLAS BERLIN]. 9.1 TRANSPORT AND ACTION OF TRANSPORT IN WATER [FENT 1998] refers that several processes are responsible for the destiny of chemicals in water bodies, like disposition, dilution in the water, volatility in the atmosphere, sedimentation, abiotic chemical conversation (hydrolysis, photolysis, oxidative and reductive processes), biotic conversations(microbial reduction, metabolism) and bioaccumulation. He continues that chemicals having a high vapour pressure and a low water solubility are given to the atmosphere very fast. If substances have a low water solubility and a low vapour pressure they prefer to adhere at particles and sediment. Figure 9-1 shows the apply of contaminants to their volatility in a simplified version.
Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas EUROLAKES D10: Impact of Contaminants FP5_Contract No.: EVK1-CT1999-00004 Version: 4.0 Date: 25/07/01 File: D10-vers.4.0.doc Figure 9-1: Organic contaminants [FENT 1998] Page 59 of 136 Chemicals normally spread in water more or less by solubility, adsorption at particles and the accumulation in organisms. The compounds can be deposited from the atmosphere to the water[FENT 1998]. From here they can reach the soil by disposals. These relations are shown in Figure 9-2. As adsorbents particles play an important part in waters. Through sorption to particles and sediments contaminants can be eliminated from the water body. The adsorption abilities of the particles to the ground or sediment are responsible for their rate of mobilisation and migration in and out of the ground in a significant way [FENT 1998]. input Infiltration of groundwater Air/Water-exchange ATMOSPHERE Deposition Transport Transformation WATER SEDIMENT Photolyse Sedimentation Sediment-Waterexchange Figure 9-2: Transport- and transformation processes of contaminants in stagnant waters, modified according to [FENT1998]. dish
Page 1 and 2:
Integrated Water Resource Managemen
Page 3 and 4:
Page 5 and 6:
Page 7 and 8: Integrated Water Resource Managemen
Page 57: Integrated Water Resource Managemen
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
show all

D10: Impact of Contaminants - Hydromod

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?