Hydro-ecological relations in the Delta Waters
Hydro-ecological relations in the Delta Waters Hydro-ecological relations in the Delta Waters
4 THE QURLITY OF LAKE BED Bhm BIVER BED SEDIXENTS IN TIE SEDU4ENTATION AREAS The series of events, described above, has produced diffesences in the quality of lake beds and river beds in the sedimentation areas (Salomons, et al, 1981; Beeft*, et al, 1982). The situation regarding cadmium levels is illustrated in Figure 5. A regression analysis has been used in order to compare the meamred c~ncentrations in the varioue samples. Roft.rd.m "'.,.rr., U L R",". a full rirclc represents CO m#/kg cadm~um. Figure 5 Cadmium ooncentrationa in river bed sediments converted KO an equivalent 50Z-16 v* top lager (1986 levels). A relationship has been established between the measured concentration ad the propartioq of fines less than 16 urn in the sediment. It was
tracefore possible to convert the absolute measlured concentrations to an equivalent concentration that would be expected in a standard river bed with 550 ~f the grain fraction less than 16 um. The separation of the Eastmrn Scbeldt and Lake Erevelingen from the water flowing in the rivers Rhine ad Meuse has resulted in remaining extremely low on cent rations in these areas. The values found in the Eastern ScheldC are thought to approximate to natural hackground levels. The concentration in Lake Orevelingen is known ta be aamedhat higher. Unlike the Eastern Scheldt, this lake becm stagnant after its closnre. .As a consequence, there is less interaction between the water in the lake a d the bed deposits (resuspenaioe) in Lake CreveUngen than in the Eastern Scheldt. This explains why the concentration of contaminants in this lake still approaches the pre-1965 values. The lake beds and river beds in the s,e4imentatlon areas in the northern part of the Delta are hewily polluted. In the eastern part (Nieuwe MerwBde/&met) high contamination levels have been detected, affectiqg a layer at least 2 metres thick. Zhis material was deposited between 1970 and 1975. As an equilibrium has now developed between the hydraulic and morphalugtcal precesses, it is unlikely tKat this la~rer will be coveted by new se&ments in the future. The central section of the Delta (Hollands Diep) hag a thick layer of less polluted river sediment that was deposited in the years aftek 1975. However, more contaminated material from the 1970-1975 period is contaised below this layer. Underneath these layers can be fonnd estuarine sediments from *he period before 1970. l'he different layers referred to above can be qlearly dlvting=ished fro= core samples taken from the area (Fig. 6). It is reesgnized that the quality of the tap layer of sediment will improve as the quality of the surface water iaproves.
- Page 1 and 2: Netherlands organkation fw applied
- Page 4 and 5: TNO Commlitee on Hydrological Resea
- Page 6 and 7: 2 RIVER WATER AM) THE QPALITH OF TB
- Page 8: B.J.M. Baptist BIJkswaterstaat. Tid
- Page 11 and 12: This approach will put to use what
- Page 13 and 14: Estuaries that have not been influe
- Page 15 and 16: 2 CHIWGES XN TEE DELTA The Delta ar
- Page 17 and 18: area decltned cnnside~ably, leadins
- Page 19 and 20: Plan, then it is apparent tbt the s
- Page 21: Tiddl flats df the Eastem Seheldt v
- Page 25 and 26: Figsrlre 7 Changes in the cadrnrum
- Page 27 and 28: prevention measures are desirable h
- Page 29 and 30: elationships between different spec
- Page 31 and 32: Bio-essay Weriments with polluted s
- Page 33 and 34: considerable thought to drawing up
- Page 35 and 36: ShLOUONS, W. and BYSINK, W.D., 1981
- Page 37 and 38: are taken. The first year after the
- Page 39 and 40: The Hollands DiepJnaringpllet is pa
- Page 41 and 42: In 1976 the determination of chlozo
- Page 43 and 44: , 0.66 m 0,s - 0.02 1989 I 0.86 - 0
- Page 45 and 46: Table 3 Eutrophication of the Volke
- Page 47 and 48: Laks Volkarek ---- Lake Zoom 0.40 0
- Page 49 and 50: 4 WAGBEET MEdSIIRaS TO PEEVBT OR LT
- Page 51 and 52: Table 5 gives estimtes of the phosp
- Page 53 and 54: In principle, two states of equilib
- Page 55 and 56: Zooplankton (Alma affinis) Pike (Es
- Page 58 and 59: EUTROPHICATION OF ESTUAAIES AND BRA
- Page 60 and 61: The average discharge of Xhine and
- Page 62 and 63: and only l-2% cows frm the aive Sch
- Page 64 and 65: highest trophic potential: nutrient
- Page 66 and 67: period 1980-19$3 in an increase of
- Page 68 and 69: model calculations reveal that a ni
- Page 70 and 71: Table 3 PreUmInary carbon budget of
4 THE QURLITY OF LAKE BED Bhm BIVER BED SEDIXENTS IN TIE<br />
SEDU4ENTATION AREAS<br />
The series of events, described above, has produced diffesences <strong>in</strong> <strong>the</strong><br />
quality of lake beds and river beds <strong>in</strong> <strong>the</strong> sedimentation areas<br />
(Salomons, et al, 1981; Beeft*, et al, 1982). The situation regard<strong>in</strong>g<br />
cadmium levels is illustrated <strong>in</strong> Figure 5. A regression analysis has<br />
been used <strong>in</strong> order to compare <strong>the</strong> meamred c~ncentrations <strong>in</strong> <strong>the</strong><br />
varioue samples.<br />
Roft.rd.m<br />
"'.,.rr.,<br />
U L<br />
R",".<br />
a full rirclc represents<br />
CO m#/kg cadm~um.<br />
Figure 5 Cadmium ooncentrationa <strong>in</strong> river bed sediments converted KO<br />
an equivalent 50Z-16 v* top lager (1986 levels).<br />
A <strong>relations</strong>hip has been established between <strong>the</strong> measured concentration<br />
ad <strong>the</strong> propartioq of f<strong>in</strong>es less than 16 urn <strong>in</strong> <strong>the</strong> sediment. It was
Change language