....HYPOX kickoff: Site introduction
Black Sea/Istanbul Strait (Bosphorus) Area
Namık Çağatay (ITU-EMCOL)
Gaute Lavik (MPG)
....HYPOX kickoff: Site introduction
Part 1: Paleooceanography &
Paleoclimatology (WP4)
Namık Çağatay (ITU-EMCOL)
....HYPOX kickoff: Site introduction
Part 1: Paleooceanography &
Paleoclimatology (WP4)
Outline
A. Black Sea: General Oceanography
B. Istanbul (Bosphorus) Strait: Hydrography & watermass exchange
C. Black Sea shelf and slope near Bosphorus outlet
area: Bathymetry, site productivity, O2 and other
related parameters
D. Paleoceanography, paleoclimate, and anoxia history
DNE
DN
DANUBE
ES
TE
DON
PER
R
Black Sea
?
DNE
DN
DANUBE
ES
TE
DON
PER
R
Black Sea
¾ Large, enclosed unoxic basin, covering 432,000
km2;
?
max.depth: 2250 m.
¾ Anoxia below 100-150 m since ~8 ka BP due to sharp density
stratification, weak vertical circulation and organic matter degradation.
¾ Sensitive to climate chages
¾ Positive water balance
¾ Severe environmental degradation in the last 30-40 yrs, mainly because of
riverine input of contaminants and nutrients. Signs of recent recovery.
Oceanographic features
Hydrology & water budget
¾Cyclonic rim current
¾ Positive water balance
¾ Salinity SW: 17-18‰, BW: 22.5‰ ¾ River input: 352 km3/yr
¾ Pycnocline,halocline, oxycline at
¾ Precipitation: 300 km3/yr
-100 to -150 m
¾ Evaporation: 353 km3/yr
¾ Suboxic zone (~30 m thick),
located at halocline
Özsoy and Ünlüata (1997)
Upper layer circulation
Oğuz et al. (1993)
Introduction to Bosphorus area
Bosphorus
area
Introduction to Bosphorus area
Interest in the Bosphorus area because of:
¾Mediterranean inflow: the major factor in local
ventilation of deep waters
¾Active surface layer circulation with rim current
transporting major Black Sea riverine inputs
¾ Evidence of the latest marine connection
(Noah’s Flood Hypothesis) and resulting
anoxia
Bosphorus
area
....HYPOX kickoff: Site introduction
Main scientific questions
¾What is the role of the Mediterranean
water in the ventilation of the deep Black
Sea basin? Has this role changed with
time?
¾How fast was the last marine
transgression? Catastrophic vs. gradual?
¾How fast did the anoxia evolve?
¾Did the anoxic/oxic interface change
during decadal to millenial time scales
Istanbul Strait
(Bosphorus)
Black Sea
¾Fault-controlled river
valley
¾Length: 31 km
¾Width:
0.7-3.5 km
¾Sill depth:-35 m in S
-58 m in N
¾Two-layer flow
through the strait
Sea of Marmara
Water exchange through the Bosphorus (mean annual volume fluxes)
Based on steady state mass and salt balances
Outflow to Marmara (surface) :
Inflow to Black Sea (undercurrent) :
605 km3
305 km3
Ünlüata et al. (1990)
Özsoy and Ünlüata (1997)
Salinity distribution along the
Bosphorus channel
(a) “normal” Two-layer
exchange
Extraordinary events of a few days
duration:
(b) lower layer flow blocked at
the northern sill
This occurs in spring-summer at high
Black Sea outflow
(c) upper layer blocked,
resulting three-layers
This occurs during autumn and winter
when surface flow reverses
(Özsoy et al., 1997)
Salinity and Temperature
cross-sections along a
transect from Bosphorus
to deep water
Özsoy et al. (1993)
Salinity
June 1988
Temperature
14.5°C
June 1988
8°C
Boundary mixing processes driven by Mediterranean inflow from Istanbul Strait
Özsoy et al (1993),
Özsoy and Ünlüata (1993)
....HYPOX kickoff: Site introduction
M15L15
Productivity, O2 and related parameters
2
5
8
T(degC)
11
14
17
20
23
26 14
19
S(psu)
24
29
34
39
0
0
0
DO(mg/l)
8
12
16
0
20
20
40
40
60
60
60
80
80
80
20
40
D(m)
D(m)
4
100
Ýstanbul BoðazýKaradeniz çýkýþý
100
100
May 2003
Courtesy Hüsne altınok
M15L15
Productivity, nutrient profiles
H2S (µM)
Si (µM)
10
0.0
050
%0.1 LD
100
In Situ PP
Chl-a
FPL
PP
POC
Fluo
Rel. Fluo.
PON
PON (µM)
PP (µM)
30
8
40
50
200
150
S, ppt
Chl-a (µg L-1)
%1 LD
150
S
40
0
σt
22
0
16
250 T
%T
POC (µM)
0.2 1.0
0
200
%T
0.0 0.3
0.0
150
PO4
NO3
NH4
Si
0
0.0
DO
100
Depth(m)
%1 LD
% 0.1 LD
50
Depth(m)
400
0
025
5
0
200
Western Black Sea - Rim Current Region
7.Oct.1999, St.M15L15, 42°15'N 29°15'E
PO4,NO3+2,
T,°C - Sigma-t DO (µM)
NH4(µM)
PP(mgC m-3d-1)
Yeşim Çoban (1997)
Bathymetry
Shelf edge
Flood et al. (2009); Di Ioro and Yuce (1999) and Nato-Saclant
Paleooceanogrpahy
Plaeoclimatology
Shelf fan delta
Courtesy D. Di Ioro and after Di Ioro and Yuce (1999) and Nato-Saclant
Paleooceanogrpahy
Paleoclimatology
Shelf fan delta
Courtesy D. Di Ioro and after Di Ioro and Yuce (1999) and Nato-Saclant
Ryan et al. (2005)
Ryan et al. (2005)
Aksu et al., 2002
Ryan et al. (2005)
Courtesy of W.B.F. Ryan
(younger than 8.4 ka)
Erosion surface α1
Erosion surface α
marine
Neoeuxine
(between 12 and 9.4 ka)
Courtesy of W.B.F. Ryan
Stratigraphic evidence of Anoxia
2000-2700 a BP
Anoxia
7800-8000 a BP
9400 a BP: Lake/Marine transition
Deep basin stratigraphy
Paleoclimatic and Paleoceanographic evolution
Sapropel and anoxia
Bahr et al. (2007)
Paleoclimatic and Paleoceanographic evolution
Sapropel and anoxia
Bahr et al. (2007)
(Courtesy of WFB Ryan)
(Courtesy of WFB Ryan)
Time lag between marine reconnection at 9400 a BP and anoxia in the basin at 8000 a BP
(Courtesy of WFB Ryan)
Sedimentary record
of Late Maunder
Minimum (1645-1715)
West Black Sea
East Black Sea
Güngör and Çağatay (2005)
Sedimentary record
of Late Maunder
Minimum (1645-1715)
East Black Sea
West Black Sea
High carbonate accumulation during cold periods
Güngör and Çağatay (2005)
....HYPOX kickoff: Site introduction
Aim of the WP4 work at the site
¾ Assess the history with respect to basin structure, water
level, water flux, and sedimentation.
¾ Obtain long term, HR sedimentary records of anoxia
using inorganic geochemical proxies.
¾ Analyze past and recent structure of benthic
communities sensitive to oxygen concentrations
¾ Study paleoclimate of the systems and their relation to
oxygen depletion.
¾ Obtain time-series data on oxygen and related
parameters over the Bosphorus area, using
observatories with suitable sensors.
These are the objectives listed under WP4 and WP6
....HYPOX kickoff: Site introduction
Suggested key parameters
•
•
•
•
•
•
•
•
HR profiles of redox sensitive elements (İTU)
Pyrite framboid size (water column vs diagenetic)
TOC/TIC (İTU)
Biomarkers
Isotopic signatures
Analysis of benthic fauna (IBSS)
Dating of sediments by AMS C-14 and radionuclides
Time series O2 and related parameters (WP6)
....HYPOX kickoff: Site introduction
Part 2: Biogeochemical processes (WP6)
Gaute Lavik (MPG)
Water exchange between the Mediterrainan and the Black Sea
Mediterranean Sea
Marmara Sea
Bosporus Strait (32m deep
water
* > 3000 km³ of Mediterranean
enters the Black Sea per year
*This import of saline Mediterranean waters
maintains the pycnocline
*The warm an saline Mediterranean water injects
oxygen into the rim current at and below the pycnocline
(sulphidic)
* How does this effect the biogeochemical cycling?
The Black Sea rim current: Carrying the Mediterranian water east
M72/4 st.5
M72/4 st.4
Central Black Sea Basin: “Diffusion” constrains N-Loss
Station M74/5-5
0
Oxygen µM
100 200 300
0
Turbidity
Nitrate (µM)
2
4
0.04 0.05 0.06
40
6
40
30
15
14
29
15
14
30
15
29
15
N2 ( NH4+ NO2)
N2 ( NH4+ NO2)
60
N2 ( NH4)
Oxygen*10
60
80
80
Suboxic
100
120
100
0
3
6
9
Sulfide (µM)
0
2
4
Ammonium (µM)
120
0
5 10 15 20 25
-1
nM * d
Depth (m)
Depth (m)
N2 ( NH4)
The Black Sea rim current: Mixing up the stratification
-1
75
0
nannoM * d
Nitrate (µM)
µM Oxygen
50 100 1500 1 2 3 4 5 6 0 5 10 15 20 25 30
29
15
30
15
29
15
30
15
Turbidity (HaartT)
0,03
0,06
0,09
75
N2 NH4+NO2
N2 NH4+NO2
N2 NH4
N2 NH4
100
125
125
Suboxic
150
175
150
0
3
6 9 12 0
µM Sulfide
3
6
9
NH4
175
0
2
4
6
µM Total Mn
µM Diss. MnOx
µM Part. MnOx
8
Depth (m)
Depth (m)
100
What is the effect of the Bosporus ventilation on nutrient cycling?
Intended study sites in Hypox
How to make a high resolutions profile: The IOW/MPI Pump CTD
A small free falling Pump CTD
is currently under development
at the MPI. This system can be
operated from small vessels.
Photo: G. Lavik, MPI Bremen
Lab based micro sensors and MIMS measuring the pump water
Photo: G. Lavik, MPI Bremen
Fast responding micro sensors mounted on the Rosette
Photo: Volker Meyer, MPI
Additional slides on technological aspects
.
Photo: Volker Meyer, MPI
Oxygen respiration measurements with Optodes
Oxygen respiration measutments with Optodes (Arabian Sea)
BWS 2
670m
BWS 1
672m
290m
80m
642m
150m
Measuring respiration and sub micor-molar Oxygen by STOX
O
O
2
O
O
2
2
2
O
2
O
2
( Revsbech et al., 2008)
Measuring respiration and sub micor-molar Oxygen by STOX
O
O
2
O
O
2
2
2
O
2
O
2
A new oxygen µ-sensor:
Æcontains a second cathode, which
removes O2 when polarized
Æallows in situ calibration
Ædetection limit: ~10µM
( Revsbech et al., 2008)
STOX sensor
(Switchable Trace amount of OXygen):
Determination of ultra-low [O2] in OMZs by STOX sensors
ÆO2 consumption rate
in the core of the
OMZ:
R= 2.04 to -2.23 µM d-1
ÆSuccessfull application in the Benguela upwelling region
(19°1.22'S, 12°13.92'E; 90m): R= -0.252 ± 0.052 µM d-1
(M. Jensen, unpublished results)
( Revsbech et al., 2008)
First measurements
with STOX sensor in
OMZ off Peru
(14°14.21’S,
76°36.12’W; 60m).
18O -Tracer
2
O2 /N2
incubations
Sampling Æ Degasing Æ Refilling Æ Adjusting [O2]
(Labelling) Æ Incubation Æ IRMS/MIMS
degased
water from
inc. depth
18
He
O2
0, 6, 12, 24,
48h
µ-sensor
to check
[18O2]
18O
2
(organic
label)
HgCl2
18O
consumption Æ
MIMS
2
Results from the Benguela upwelling
19°1.22'S, 12°13.92'E; 90m:
[18O2]initial (µM)
respiration rate
(µM d-1)
~2.6
-0.222
± 0.076
~5.2
-0.499
± 0.184
~10.4
-0.969
± 0.334
ƒ Results in good agreement with STOX data:
Æ(-0.252 ± 0.052 µM d-1 – [O2]initial ~3.5 µM)
ƒ Rates dencrease with dencreasing initial [18O2] :
Æ affinity of respiring bacteria significantly reduced
Bottom water layer (BBL)
primary
production
organic matter
O2
Water
CTD
Rosette
NO3-
BBL
mineralization
Sediment
nutrients, CO2
N2, CH4, H2S
???
Corer
BottomWaterSampler
NO3-
Bottom water sampler
Sample
ADV Profiler