~ This paper not to be cited without prior reference to the author

International Council for

the Explo~ation ofthe SeaC.M. 1979/C:2

Hydrography Cttee

Ref. Marine Environmental

Quality Cttee

Investigations of Temperature, Salinity, ·Oxygen,

pH, Alkalinity and Organie Pollutants in the

Baltic Sea during BOSEX i 77

by

Gerhard Dahlmann

Horst Gaul

Günter Weichart

Deutsches:Hydrographisches Institut

Bernhard-Nocht-Strasse 78

2000 Hamburg 4Federal Republic of Germany

* BOSEX Contribution No. 25

- 2 -

ABSTRACT

From 12 to 23 September 1977 the Deutsches Hydrographisches

Institut participated with the RV "Gauss" in the research

program of BOSEX'77 (Baltic Open Sea Experiment 1977). BOSEX'77

was a joint interdisciplinary experiment, that took place in

the Baltic proper in September 1977. It was arranged by ICES/

SCOR Working Group on the study of the pollution of the Baltic,

and its purpose was to joinphysical, chemical and biological

efforts.

This paper presents the results of the physical and chemical

examinations, i.e. measurements of temperature, salinity, O2

,

pH, alkalinity, and organic pollutants (chlorinated- and

petroleum hydrocarbons).

As expected, the central stations of the BOSEX area show very

similar vertical distributions, indicating a pattern of dis­

crete horizontal layers, typical for the Baltic.

The pollutant measurements indicate this area as a compara­

tively low polluted part of the Baltic.

•

•

- 3 -'

Du 12 au 23 septembre 1977, le Deutsches Hydrographisches

Institut avait partici~e, avec le navire de recherche GAUSS,

au programme BOSEX '77 (Baltic Open Sea Experiment 1977).BOSEX '77 etait une experience commune interdisciplinaire

qui ~vait ete e~~ectuee, en septembre 1977, dans la mer

Baltique proprement dite. Cette experience avait 'ete orga­

nise par le groupe de travail ICES/SCOR pourles etudes de

la pollution dans la mer Baltique. Son objecti~ etait de

joindre des travaux de physique, chimie et biologie •

Cet article presente les resultats des etudes physiques et

chimiques, c'est-~-dire des mesures de la temperature, de la

'salinite, del'02' du pH, de l'alcalinite et des polluants

organiques (hydrocarbures chlorees et hydrocarbures de petrole).

Comme attendu, les stations centrales de la region de l'ex­

perience BOSEX rev~lent des distributions verticales pareilles,

indiquant un mod~le de couches individuelles horizo~tales qui

sont caracteristiques pour la mer Baltique.

Les mesures de polluants montrent que, dans cette region.de

la mer Baltique, la pollution est comparativement peu importante •

, .

( ,

- 4,-

METHODS

Parameters of the classical, chemical oceanography:

Water sampIes were taken by plastic Nansen bottles (Hydrobios,

Kiel) from 3 m, 10 m, 20 m, 30 m, 40 m~ 50 m, 70 m, 90 m etc.

The pH was measured by a glass eleytrode (Schott & Gen., Mainz). 0 +

at about 150. The precision (95 % confidence) was -0,01 unit.

Alkalinity was calculated from pH after addition of HGl, ac­

cording toANDERSON and ROBINSON, Industr. Eng. Chem. (Anal.)

18, 767 - 773 (19 46 ). The precision (95 % confide~ce) was

!0,02 mequivalents • dm~3.

Temperature was measured with normal hydrographic reversing

thermometers.

Salinity was determined using an inductive salinometer (Beckmann

Instruments).

Pesticides and PCBs:

Sampling:

Sampling the surface layer was done with a stainless steel

funnel, that collects 1 1 water when sinking through the sea

surface. The water sampIe corresponds to a 3,5 mm layer from tIthe surface (STADLER & SCHOMAKER, Dt. hydrogr. Z. 28, 117

(1975».

Because the surface film proved to be an accumulator for

chlorinated hydrocarbons and other pollutants subsurface

sampIers have to pass through the surface in a closed po­

sition in order to avoid contamination. We used two types

of sampIers, one is a 20 1 stainless steel cylinder (STADLER &

SCHOMAKER, Dt. hydrogr. Z. ~, 81 (1976», the other consists

of a 10 1 standard Duran 50 reaction vessel with a 100 mm

"

~

-------------------

- 5 -

wide flat ground flange fixed by ,a stainless steel protective

basket to the hydrographie wire (STADLER & SCHOMAKER, Dt. hy­

drogr. Z. JQ. 20 (1977».

The glass sampIer is more appropriate for several reasons:

The smoother surface (mostly glass), the better accessibility

for cleaning proeedure (100 mm wide easydemountable flange)

and the possibility to extract directly from the sampling

vessel (minimized losses by adsorption).

All water sampIes were immediately extracted with hexane by

shaking for half an hour. When the phases had separated two

hours later the hexane phase was collected on board and stored

until further treatment in the land based laboratory.

Analyses:

The extracts were dried with sodium sulfate, concentrated to

2 ml and sprayed on thin layer plates coated with silica gel,

together with a standard for calibration purposes. The plate

was developed in acetone und hexane. According to the

standard the plate was cut in four different zones, which

were eluted separately.

These four fractions were brought to dryness on a rotary

~ evaporator rinsed with hexane and finally brought to a

volume of 0,2 ml.

From this volume aliquots were taken for gas chromatography

on paeked eolumns of different polarity (STADLER & ZIEBARTH,

Dt. hydrogr. Z. 28, 263 (1975». Calibration was done once

a day.

A compound was considered to be identified when the retention

'time on both columns was correct within 2 % and the substance

appeared in the corresponding zone of the thin layer chro­

matogram.

- 6 -

Because some of the values for DDT and its metabolites proved

to have been unsufficiently separated from PCBs the DDT data

are omitted.

Petroleum hydrocarbons:

Sampling:

The sampling and handling procedure aboard were exactly the

same as described for pesticide and PCB analyses except for

the investigation of the surface layer: Surface sampies were

collected with a stainless steel wire screen (STADLER & ttSCHOMAKER, Dt. hydrogr. Z. 22, 61 (1977». After collection

the sampie was extracted with 300 ml spectroquality CCl4

.All samples were stored in the dark until further treatment

in the land based laboratory.

Analyses:

The analyses were carried out according to the "guide of

operational procedures for the IGOSS pilot project", IOC,

Manuals and Guides No. 7:

The extracts were dried with sodium sulfate and evaporated

to 5 ml.

The surface samples were analysed by IR-spectroscopy, after

a "clean up" by column chromatography (column packed with

Florisil and A1 2 0 3 ) to retain "polar" material.

The subsurface sampies were analysed by UV-Fluorescence with

the extracts excited at 310 nm and measured at 360 nm.

Specific quantitative data cannot be obtained by spectros­

co~c methods because of some generaldifficulties:

1) The detected material is unknown and variable in com­

position.

•

•

--------- - ---------- ---

- 7 -

2) Tbe spectroscopic investigation allows to summarize mole­

cular properties that are common to all hydrocarbons, but

does not allow any conclusions for a specific substance.

Thcrefore all concentrations of petroleum hydrocarbons in this

paper are given in uni ts of an arbi trari'ly, chosen Ekofisk crudei < ,,-

oil, even thoughthe detected material may in part be of bio-

genic origin.

Procedural blanks were determined by carrying all solvents

through the entire analyses •

RESULTS AND DISeUSSION'

According to the BOSEX program, the RV "Gauss" carried out

4 stations per day, situated in 7 km distance around the cen­

tral station (see Fig. 1). One station was chosen f~r inter­

calibration purposes with the RV "Argos". Subsequently an

additional station was darried out in the Bornholm Deep,

followed by a number of monitoring stations in the Lübecker

Bucht and Kieler Bucht.

Parameters of the classical chemical oceanography:

SampIes for salinity, O2 , pH and alkalinity were taken from

8 tu 10 different depths. All vertical profiles (see Fig. 2

and J) show no stratification to about JO m to 40 m depth.

Below the layer the temperature decreases rapidly to about

J oe to 4 oe, followed by a slight increase to 4 oe to 5 oe

in about 90 m depth. The pH decreases continuously from about

8,25 to 7,J and remains almost~constant below 80 m depth.

The concentration of oxygen decreases from about 7 cmJ/dmJ in

the surface layer to 1,5 to 2,1 cmJ/dmJ ?elow 90 m. There is

a remarkable phenomenon, which was found in all the series~,

,from the BOSEX aren. Just below the surface layer in 40 m to

50 m depth the oxygen concentration increases slightly to about

- 8 -

7,5 to 8 cm3/dm3 . A probable explanation may be an exchange

(shear) o~ the sur~ace layer by the preceeding storm.

The limits of the different layers can also be seen in the

vertical profiles o~ salinity and alka\nity by slight bends

01' their curves.

These observations indicate the strong vertical stability of

the water masses in the Baltic proper even aft~r the stormy

weather conditions mentioned above.

Pesticides and PCBs:

Tab. 1 shows the results of the pesticide- and PCB-analyses.

Because the BOSEX area is remote from intense shipping and

obviously not directly influenced by industrial 01' municipal

waste waters, we have reason to assurne, that the distribution

of the pollutants is homogeneous within the different water

layers in this area.

At the surface thc concentrations of chlorinated hydrocarbons

vary considerably due to the patchiness of surface films, as

can be seen from the standard deviation.

Thc 10 m layer is much more homogeneous with standard devia­

tions weIl within the range of confidence o~ the methods used.

The subsurface sampies below 60 m show a by far greater va­

riability, the reason for this is not yet understood.

The concentrations in the BOSEX area are of the same magnitude

as have been observed in West~n Baltic and German Bight in

1975.

Petroleum hydrocarbons:

The results of the petroleum hydrocarbon measurements are

shown in Tab. 2. These data indicate the whole BOSEX area

•

•

- 9 ~

as relatively low polluted. It is therefore convenient to com­

pare these data with the results from other stations in the

Baltic, especially in those areas with intense shipping.

Fig. 1 shows the con~entrations of petroleum hydrocarbons in

the surface layer determined during the BOSEX cruise and also

another cruise in the Baltic in 1978. It can clearly be seen,

that there are low concentrations in the open sea, whereas in

the bights of Kiel and Eckernförde and on the main shipping

routes (Fehmarn Belt) these concentrations are high.

Despite of the disadvantages of the methods used for petroleum

hydrocarbon analyses (no differentiation between hydrocarbons

of natural origin and oil pollution, arbitrarily chosen stan­

dard etc.) the comparison of the data indicates that the

Western Baltic especially in areas with intense shipping

traffic is significantly pollutedby petroleum hydrocarbons.

Table 1

Results of' Pesticide and PCBs Analyses

Station Position }:PCB Lindane Dieldrin o<.-BHC (pg/l)

Surf'ace 7 56°09,0' N 18°43,0' E 2.5,9 3, 1 - 4,9

(0 - J mm) 9 56°00,2' N 18°43,0' E 21,7 2,4 2,2

13 56°0.5,0' N 18°36,5' E 54,9 4,0 - .10,4

34,2 3, 1 5,7 X *18, 1 0,8 4,0 +

**s -

.53 26 70 s ~

Subsurface 7 56°09,0' N 18°43,0' E 11 ,8 2,6 0,06 6,0

(10 m) 10,3 2,6 0,10 6,3 ...56°00,2' 18°43,0' 8,7 4,4

09 N E 3,3 0,07

10,6 2,3 0,06 4,8

13 56°0.5,0' N 18°36,.5' E 5,8 2,6 0,08 2,0

9,4 2,7 0,07 4,7 X

2,3 0,3 0,02 1,7 +8 -

24 11 29 36 s ~

X * = average value

s :t ** = standard deviation

Table 1 (cont.)

Results of' Pesticide and POBs Analyses

Station Position ~PCB Lindane Dieldrin ot-BHC (pg/l)

60 m 7 56°09,0' N 18°43,0' E 4,2 1,3 0,°9 4,2

85 m 7 3,1 2,5 0,°9 6,5

110 m 9 .56°00,2' N 18°43,0' E 6,3 2,6 0,17 0,5

107 m 9 18,6 2,8 0, 11 5,4

56°05,0' 18°36,5' 2,4~

95 m 13 N E 0,7 0,°3 0,8 ~

6,9 2,0 0,10 *

x * = average value+s - ** = standard deviation

6,7

97

0,°5

50

2,7

77

+s - **

Table 2

Results of the Petroleum Hydrocarbon Analyses

Subsurface (pg/l)

Station PositionSurface

SamplerDepth Sampier Depth

(pgfm2 ) (~) (m)

56°9 ' 18°43' * 85 1.047 N E 133 SET 13 1.23 SET>< 56°0.2' 18°43' * 0.80I'il (lj 9 N E 117 K 13 1.07 SET 110enG>

56°9.9' 19°2.8'O$.l 12 N E 33 K 13 1.28I:Q (lj

13 56°5 ' N 18°36.5' E 100 K 13 1.02

average values 88 1. 17 0.92

subtracted average solvent blank 75 0.08

1 54°49' N 9°50' E 633 K 6 1.90 K 16 1. 76

2 54°43 ' N 10°8' E 183 K .'8 1.53 K 18 1.56

4a 54°36' N 10°27' E 100 K 6 1. 81 K 13 1. 69

5 54°26 ' N 10°43' E 117 K 16 1. 92 ....7a 54°34.9' N 11°13.9' E 717 K 10 2.71 K ·25 3.22

/'IJ

8 54°26 ' N 11°27' E 516 K 8 1. 71 K 18 1. 31

9a 54° 15' N 11°18' E 217 K 8 1.90 K 18 2.42

10 54°7 ' N 11 0 4! E 142 K 8 1. 72 K 18 2.08

13a 54°55' N 13° E 67 K 10 1.96 K 35 1. 39

17 54°40' N 15°10' E 142 K 10 1. 88 K 56 1.99

20 54°29 ' N 9°57' E 342 K 10 2.49

25 54°27 • N 10°'6' E 158 K 7 1. 69 K 14 2.85

28 55°19.4' N 15°49.9' E 67 K 10 1.95 K 80 1. 56

29 55° N 14° E K 10 1.54 K 40 2.24

subtracted average solvent blank 183 0.17

* K*SET =stainless steel sampier = glass sampler~e

Fig.

•~1'10000ll0

Hydrocarbon concentrations at the surface

Ilr.

...

.-

- 14 -

•

•

--I:=-

mequival . dm- 3

TEMPERATURESALINITY

5 10 oe ,%0 15o

o

1

80

100m

120

1,0 1,5

ALKALINITY --t:>

pH - VALUE -~I:=-

o 7.+'O....&.-."--"'-~7_5"---'---Io.-..l'--8""'-O~.........~8-L5--1-.&..-....I-_i i\ I

20 I i:r:: 40 I II-- pH .-----. ''''. 02~50 ~~

j80 ~.

19R \120 +--r--'--r----r--r--,---r-r----r--r-

2 " 6 8 cm3'dm- 3

OXYGEN CONCENTRATION C'=

o20

:r:: 40I--

& 50Cl

Fig. 2 Depth profiles of station no. 5(17 September, 111.00 h)

•- .

- 15 -,

TEMFERATURE c:::=-

SALINITY c::=-

O 5 70°C, %0 150 i i I

20 i i iS! j j T

2:: 40 \ ~-------r" \th 60

\ .""'.""'. ALKALINITYCl

~80 \ \. \

\ , \

100• m120

1,0 1,5 mequival " dm- 3ALKALINITY C!-

pH-VALUE c:::-

O 70 7,5 8,0 8,5\ i

20 I iI i

40 / \~ /

.

'"0- 60 ~.. . °2~

J

80 !(100m

1200 2 4- . 6 8 cm3'dm~3

OXYGEN CONCENTRATION c:::-

F ig. J : Depth profiles 01' station no. 7(18 September, 8. 00 h)