Action 869 Anavissos, Greece 17-19 September 28 N/P limitation and interactions between N and P in surface water Nutrient ratios in inland watersof the Balkansand possible controlling factors Nikos Skoulikidis INSTITUTE OF INLAND WATERS
Major Balkan Rivers 83% of the total Balkan river runoff (85 km3/a) Geological zones Ecoregions (Illes) Climatic Zones
The geological background zone 1 Zone 1 acid silicate rock basins zone 2 Zone 2 mainly acid and mafic silicate rock basins Zone 3 carbonate basins zone 3
Hydrological characteristics Maximum Precipitation >55 mm (SW Montenegro) >3 mm (Dinarides) 24 mm (Pindos) Precipitation 25-5 mm less Specific discharge 18.3-34.6 L s-1 km-2 Specific discharge 4 14.9 L s-1 km-2 Evros Kamtchia Axios Pinios Strymon Aliakmonas Evrotas Nestos Sperchios Alfeios Acheloos Aoos Drin Neretva 4 35 3 25 2 15 1 5 Arachthos l/sec*km2 Eιδική παροχή Specific discharge
8 7 6 5 4 3 2 1 Nutrient concentrations in major Balkan Rivers DIN, N-NH4*1, TP*1 Aoos Acheloos Neretva Alfeios Aliakmon Sperchios Arachthos Evrotas Nestos Strymon Vjose Pinios Axios Kamchia Evros Drin 83% of the total Balkan river runoff N-NH4*1 TP*1 DIN Zones 3 (+ 2) Zones 1 + 2
Nitrate levels in major Balkan Rivers Good/Moderate boundary (.6 mg/l) Bulk Prec. Agric. Bulk Prec. "pristine" upper [C] good stat European average Krathis MCNC-high MCNC-low headwaters Small medium R Anapodaris Evrotas Alfeios Sperchios Acheloos Arachthos Pinios Aliakmon Axios Strymon Nestos Arda Tundja Evros Vjose Aoos Kamchia Drin Neretva 5 4 3 2 1 N-NO3 (mg/l)
Ammonium levels in major Balkan Rivers Good/Moderate boundary (6 µg/l) Bulk Prec. Agric. Bulk Prec. "pristine" upper [C] good stat European average Krathis MCNC-high MCNC-low headwaters Small medium R Anapodaris Evrotas Alfeios Sperchios Acheloos Arachthos Pinios Aliakmon Axios Strymon Nestos Arda Tundja Evros Vjose Aoos Kamchia Drin Neretva 8 7 6 5 4 3 2 1 N-NH4 (µg/l)
TP levels in major Balkan Rivers Good/Moderate boundary (165 µg/l) Bulk Prec. Agric. Bulk Prec. "pristine" upper [C] good stat European average Krathis MCNC-high MCNC-low headwaters Small medium R Anapodaris Evrotas Alfeios Sperchios Acheloos Arachthos Pinios Aliakmon Axios Strymon Nestos Arda Tundja Evros Vjose Aoos Kamchia Drin Neretva 9 8 7 6 5 4 3 2 1 TP (µg/l)
3,17 14 12 1 8 6 4 2 N/P ratios in major Balkan Rivers DIN (mg/l*1), P-PO4 (µg/l*5), N/P (molar) Axios Kamchia Drin Aliakmon Tundja Arda Nestos Pinios Evros Strymon Krathis Acheloos Vjose (Aoos) Neretva Evrotas Anapodaris Extreme P pollution P-PO4*5 DIN*1 N/P
Spatial N/P ratio variability N/P (molar) zone 2 zone 1 Zone 1 Zone 2 13 3 Drin Zone 3 96 Vjosa 12 Aoos N /P r a tio (m o la r ) 1 8 6 4 2 N/P % carbonates Redfield ratio zone 3 Arachthos Sperchios Alfeios zone 1 zone 2 zone 3 Eurotas
2 18 16 14 12 1 8 6 4 2 Seasonal variation of N/P ratio DIN*1 P-PO4*1 N/P Axios Enhanced N-leaching Selective P-pollution Enhanced N-leaching N/P (molar) JUL-98 AUG-98 SEP-97 OCT-97 NOV-97 DEC-97 JAN-98 FEB-98 MAR-98 APR-98 MAY-98 JUN-98
..5 1. 1.5 2. 2.5 3. 3.5 198 1981 1982 1983 1984 1985 1986 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 TP (mg/l) Axios Kamchia*1 Evros Strymon Nestos*1 Neretva 1 2 3 4 5 6 7 8 9 198 1981 1982 1983 1984 1985 1986 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 N-NO3 (mg/l) Axios Kamchia Evros Strymon Nestos Neretva 1 2 3 4 5 6 198 1982 1984 1986 1988 199 1992 1994 1996 1998 2 22 24 DIN/TP (molar) Axios Kamchia Evros Strymon Inter-annual N/P ratio trends Can not be drawn!
N/P ratios in small/medium Greek Rivers N /P (m o la r) 35 3 25 2 15 1 5 N/P in spring 32 4.9 6.7 zone 1 zone 2 zone 3 N / P r a t i o ( m o l a r ) 15 1 5 y =,491x + 1,481 R 2 =,2617 2 4 6 8 1 % carbonates
8 7 6 5 4 3 2 1 Nutrient ratios in reference sites Zone 1 Zone 2 Zone 2 Zone3 Zone 3 Zone 1 N/P (molar) Fonias Tsivdogianni Arkoudoremma Prasinada Diavoloremma Poroia Vourkopotamos Ag. Germanos1 Ag. Germanos2 Gorgopotamos Nestorio a Nestorio b Pisoderi Pramoritsa Koromilia Vourino Venetikos Lala Platanistos Kastanies Dimosaris Miloi M. Peristeri Kalaritikos Matsouki Chaliki Melisourgou Anilio Aoos Stefani1 Stefani2 Athamania Krania Dipotama Negades Aroanas Acherondas
N/P (molar) 8 7 6 5 4 3 2 1 N/P ratios in reference sites 9.1 Median values Redfield ratio 31.9 67.1 zone1 zone2 zone3 D IN, P -P O 4 (m g /L ) 4.5 4 3.5 3 2.5 2 1.5 1.5 "pristine" forested basins "pristine" not forested basins DON > 8% DOP > 9%! DIN*1 P-PO4*1 N/P
N/P ratios in Acheloos River(zone 3) 2 18 16 N /P (m olar) 14 12 1 8 6 4 2 A1 river drilings wells springs drainage canals irrigation canals rain Σ1 N /P (m olar) 45 4 35 3 25 2 15 Possible impact of upstream reservoir Redfield ratio 23 42 Σ2 1 5 12 A1 Σ1 Σ2
N/P ratios in Evrotas River (zone 3) 3.5 3. N /P (m o la r ) 2.5 2. Evrotas main stem 1.5 Oinus trib. 1. 5 N-limited 54 5 26 3 37 38 39 5 52 9 1 11 12
N /P (m o la r ) 5, 4,5 4, 3,5 3, 2,5 2, 1,5 1, 5 N/Pratios in Evrotas River(zone 3) Evrotas - tributaries N-limited N-limited 1 2 3 6 7 14 15 16 18 19 2 21 23 24 25 27 29 31 34 42 44 46 47 There are indications that unpolluted stream sites and/or silicate geologymay favour N-limited photosynthesis
Factors controlling N/P ratio variations P-retention and N-leaching/mineralization in river sediments cause a downstream N/P increase The pristine Krathis-river µg/l 25 2 15 1 TinN P-PO4*1 TinN/P-PO4 WATER N-increase due to leaching/mineralization P-decrease due to adsorption River mouth 5 headwaters upstream midway downstream % 12 1 8 6 SEDIMENT suspended sediments (annual) suspended sediments (flood) surface sediments core sediments River mouth 4 2 N-release P-retention AFDM OC TN *1 TP *1
N/P ratios in major Greek Lakes Most of the lakes are eutrophic. The lakes show lower nutrient levels than major rivers (1-fold lowerdin and 4-fold lowersrplevels). P-storage in sediments may partly explain the generally low concentrations of SRP. CV-DIN: 81% - CV-P: 42% D IN, P - P O 4 (µ g /L ), N /P (m o la r ) 45 4 35 3 25 2 15 1 5 DIN P-PO4 N/P N-limited V o lv i K o r o n ia M ik P r e s p a K a s to r ia T r ic h o n is V is to n is D o ir a n i Ilik i Data: Min. of Agricultural Development and Food A m v r a k ia M e g P r e s p a C h im a d itid a P e tr o n Io a n n in a Z a z a r i L y s im a c h ia V e g o r itis
Conclusions The majority of running waters in the Balkans are marked by P-limited photosynthesis. Rivers in zone 3 (W. Greece) show maximum N/P ratios, followed by zone 2 (central Greece) rivers. There are indications that carbonate geology cause increased N/P ratios in rivers: prevalence of carbonate rocks/sediments may favour P- retention and thus high N/P ratios (P-adsorption on calcite and Feoxides). P-pollution (e.g. Axios), undisturbed conditions and/or silicate geology may favour N-limited photosynthesis. In Greek lakes, photosynthesis is controlled by the N-inputs. More than the half of the examined lakes reveal low DIN and thus photosynthesis is N-limited.