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Arsenic research in chemical weapons dumping areain the Baltic Sea final report

Responsible executive:dr. K. Jokšas

Customer: Environmental protection agencyExecute: Nature research centerContract No.: SUT-4-25/4F12-135

March 2014, Vilnius

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CONTENTS

INTRODUCTION.....................................................................................................................................3

1. DETERMINATION OF ARSENIC IN THE BALTIC SEA BOTTOM SEDIMENT .....................5

1.1. SAMPLE COLLECTION...........................................................................................................5

1.2. METHOD AND ANALYSIS DESCRIPTION..........................................................................7

1.2.1. Instrumentation....................................................................................................................7

1.2.2. Determination of total arsenic ............................................................................................. 7

1.2.3. Determination of inorganic arsenic .....................................................................................8

2. INTERLABORATORY COMPARISON .........................................................................................9

3. RESULTS AND DISCUSSION ......................................................................................................10

CONCLUSIONS .....................................................................................................................................15

SUMMARY ............................................................................................................................................16

References ...............................................................................................................................................17

APPENDIX .............................................................................................................................................18

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INTRODUCTION

Chemical weapons together with nuclear and bacteriological weapons are classified by the UnitedNations as weapons of mass destruction. About 55 000 tons of chemical weapons were dumped in theBaltic sea after the World War II: significant amounts of sulfur mustard, phosgene, Adamsite(diphenylaminechloroarsine), Clark I (diphenylarsine chloride), Clark II (diphenylarsine cyanide) andarsine oil [1]. The warfare agents were officially discarded overboard into two basins – the BornholmBasin and the Gotland Basin, but there are some evidences, that the warfare agents are also present inthe other locations of the sea sediment. Research by Poland’s Military University of Technology hasfound traces of mustard gas on the sea bed just a few hundred metres off the Polish coast, in the Gulf ofGdansk, although no known dumping zone is located in the gulf of Gdansk or near.

Chemical warfare agents were stored in aircraft bombs, artillery shells, encasements containersand wooden encasements. During the dumping operation the munitions were cast overboard eitherloose or packed in wooden chests. The chests were often seen drifting around before sinking to thebottom, some of them were even washed ashore. There is also a possibility that such chemicalweapons, packed in wooden crates, sank not in the desired location [2].

Stored chemicals can be released into the sea water because of corrosion of the munitions and theintensity of the leakage is not determined yet. It is clear though that the corrosion of the munitions hasbeen steadily advancing. Before 1992 most of the munitions, caught by the fishermen, was only partlycorroded, but since 1992 nearly all munitions is either empty or very heavily corroded [3].

The chemical warfare agents dumped in the sea pose three main threats [2]. Firstly, agents can bewashed ashore causing danger to the people. Such incidents were reported on Polish beaches, mainlybetween 1952 and 1955. The possibility that chemical munitions can now be washed ashore from thedumping areas is extremely unlikely. The Bornholm and Gotland basins are characterized by stablestratification, with only slight bottom currents except during exceptional periods of flushing to thebasins. In addition, the dumped material would need to be moved upwards from a depth below 100 min order to be washed ashore [4].

The second danger is related to the human activity in the dumpsites. Fisherman can trawl lumpsof viscous mustard gas from the sea floor with their nets. Over the period 1995 – 2002 about 3 – 11such incidents were reported each year. It shows that chemical weapons are still a great risk for thecrews of fishing vessels operating in this part of the Baltic [2].

The third is the threat to the marine environment. Large scale leaking would lead to the fatalconsequences. The probability of such an occurrence is getting bigger since the corrosion of thecontainers is increasing. Besides, human activity, related to the bottom sediment (installation ofhydrotechnical structures, trawling, installation of gas pipes, etc.) can also affect the stability of thecorroded munitions. It is still difficult to evaluate the real impact of chemical warfare agents to the seaecosystem. Most of the chemical warfare agents degrade in the presence of water by hydrolysis afterthey are adsorbed onto the bottom sediments. There is also a possibility of bioaccumulation of arseniccompounds in marine organisms [2].

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Clark I [(C6H5)2AsCl] and Clark II [(C6H5)2AsCN] are expected to adsorb onto sediments andreact only very slowly with water. Both degrade eventually to form tetra-phenyldiarsine oxide, which isitself toxic and is hydrolysed very slowly. Similarly, adamsite [NH(C6H4)2AsCl] is practicallyinsoluble in water, adsorbs onto sediments, and hydrolyses very slowly forming phenarsazinic oxide.Thus, the chemical munitions Clark I, Clark II and adamsite, together with toxic reaction products, canbe preserved for a long time on the sea bed. Clark I, Clark II and adamsite are expected to spread veryslowly from the chemical munitions source and only contaminate local sediments. Thus, elevatedarsenic concentrations in the sediments can indicate a leakage of chemicals from the munitions [5, 6].

Determination of the total arsenic concentration in the bottom sediment can help to indicatewhether there is a leakage of toxic substances, but for more precise and informative analysis theamount of inorganic and organic arsenic compounds should be also evaluated. Arsenic is mainlypresent in inorganic forms in the environment and these forms are generally more toxic than theorganic forms. Knowing the distribution of organic and inorganic arsenic species can help to evaluatetoxic effects to the water organisms and to the whole sea ecosystem [7, 8].

Aim of the research – to determine arsenic (total, inorganic, organic) concentration in thebottom sediment from a chemical munitions dumpsite in the Baltic Sea and other areas and, accordingto the information obtained, evaluate the spread of the dumped chemical warfare agents containingarsenic.

Goals of the research:1. To perform optimization of the arsenic determination method and to participate in the international

interlaboratory comparison:

To select and, according to the recommendations of the Buying organization, to optimize themethod for arsenic determination;

To take part in the international interlaboratory comparison for intercalibration of the chosenanalysis method and verification of the results obtained;

Optimise (if there is a need) the analysis method according to the results of interlaboratorycomparison.

2. To determine arsenic content (total, inorganic, organic) in the Baltic bottom sediment samples froma chemical munitions dumpsite and other areas (the predictable amount of the samples is 170 units).

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1. DETERMINATION OF ARSENIC IN THE BALTIC SEA BOTTOM SEDIMENT

1.1. SAMPLE COLLECTION

Sediment samples were collected from the sampling stations in Lithuanian territorial waters andfrom other stations, located in the Baltic Sea. Sampling locations in Lithuanian aquatory are illustratedin Fig. 1 and 2.

Fig.1. Sediment sampling stations in Gotland deep and in Lithuanian EEZ. Date: 2013-04-26-27.

21 stations were sampled in Lithuanian territory. 9 of them are located in Gotland deep chemicalmunitions dumpsite, 2 of them lies in Lithuanian EEZ (Fig.1). Seven samples were collected fromsediment sampling stations near Lithuanian coastline (Fig.2). Other samples were collected from thebottom sediments at three locations across the coastal area of Lithuania (Fig.2). More detailedinformation about the location of sediment sampling stations is presented in Table 1.

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Fig.2. Sediment sampling stations near Lithuanian coastline. Date: 2013-08-21-22 and 2013-11-22.

Table 1.Coordinates of the sediment sampling stations

No. StationCoordinates

Longitude Latitude1. 65 55°52,9᾽N 20°20,5᾽E2. 66 56°00,0᾽N 19°39,0᾽E3. CHEMSEA1 56°00,0᾽N 19°14,9᾽E4. ChG1 56°01,2᾽N 19°08,8᾽E5. ChG2 56°02,1᾽N 19°14,6᾽E6. CHEMSEA2 55°59,0᾽N 19°14,2᾽E7. CHEMSEA5 55°58,8᾽N 19°11,1᾽E8. ChG5 55°57,3᾽N 19°14,5᾽E9. CHEMSEA3 55°56,2᾽N 19°10,4᾽E10. CHEMSEA4 55°55,1᾽N 19°07,6᾽E11. CHEMSEA6 55°56,2᾽N 19°14,4᾽E12. ChG14 55°43,1᾽N 21°03,7᾽E13. ChG13 55°44,1᾽N 21°03,0᾽E14. ChG10 55°45,9᾽N 20°53,5᾽E15. CHEMSEA7 55°49,0᾽N 20°39,0᾽E16. CHEMSEA8 55°41,6᾽N 20°36,2᾽E17. 20A 55°39,0᾽N 20°50,0᾽E18. N-6 55°24,3᾽N 20°42,4᾽E19. N-3 55°28,0᾽N 20°32,0᾽E20. ChG12 55°45,7᾽N 21°03,0᾽E21. ChG11 55°45,0᾽N 20°58,4᾽E

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1.2. METHOD AND ANALYSIS DESCRIPTION

1.2.1. Instrumentation

The measurements of concentrations of total and inorganic arsenic in bottom sediments wereperformed using Atomic Absorption Spectrometer Shimadzu AA-680 combined with Hydride VaporGenerator Shimadzu HVG-1 (HG-AAS).

Aqueous-phase chemical generation of volatile hydrides is performed by sample derivatizationwith sodium borohydride in acidic media. Acid catalyses hydrolysis reaction of borane reagent(NaBH4). Arsenic in aqueous solution reacts with hydrolyzed borane, forming the volatile species ofinterest (arsine). Sample, 0,5 % NaBH4 and 5 mol/l hydrochloric acid solutions are fed into themanifold by the pump, mixed and sent to the reaction coil. The gaseous hydride is transferred into aheated measuring cell by means of a carrier gas (argon) stream. Air – acetylene flame is used to heatthe absorption cell, where hydride is pyrolyzed. The absorption at 193,7 nm (arsenic line) serves as ameasure of arsenic concentration. Methods limit of detection is 100 ng/g.

1.2.2. Determination of total arsenic

Total arsenic measurement was performed according to LST EN 16206 Annex C:Alternative digestion procedure with the same digestion efficiency to ensure completemineralization of all organic and inorganic arsenic species for HGAAS measurement: dry ashingwith magnesium oxide and magnesium nitrate as ashing reagents.

Sediment samples for determination of total arsenic were mineralized by dry digestion. 2 g ofbottom sediment, homogenized and dried to remove hygroscopic humidity, was weighed in a quartzdish, 3 g of magnesium oxide and 20 ml of 10 % magnesium nitrate solution were added and mixed.The mixture was dried at 100 °C and ashed at 575 °C overnight.

The ash were dissolved with 50 ml 6 mol/l hydrochloric acid, solution was heated and filteredinto a 100 ml flask. The crucible, funnel and filter paper were rinsed thoroughly with hot water until 90ml filtrate is collected. The solution was cooled and the flask was filled to 100 ml. After that solutionwas ready for the pre-reduction procedure. The acid concentration of the test solution was 3 mol/l HCl.

Arsenic (V) was reduced to arsenic (III): 2,5 ml of 20 % potassium iodide/20 % L-ascorbic acidsolution was added to the test solutions, the flask was filled with 3 mol/l hydrochloric acid and mixedthoroughly. For a blank sample only 3 g of magnesium oxide and 20 ml of 10 % magnesium nitratesolution were added to the quartz dish and further procedures were performed identically as with thesediment samples. Measurements on HG-AAS were carried out 30 minutes after the samples wereprepared.

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1.2.3. Determination of inorganic arsenic

Inorganic arsenic measurement was performed according to EN 16278:2012. Animalfeeding stuffs – Determination of inorganic arsenic by hydride generation atomic absorptionspectrometry (HG-AAS) after microwave extraction and separation by solid phase extraction(SPE).

The samples were treated with diluted hydrochloric acid and hydrogen peroxide solution usingmicrowave assisted heating – inorganic arsenic species were extracted and As(III) is oxidized toAs(V). The microwave reaction system Anton Paar Multiwave 3000 was used for digestion of sedimentsamples. Teflon vessels were washed with hot 10% nitrogen acid (HNO3) and rinsed with redistilledwater three times. Approximately 0.2g of dried, well homogenized and ground (to particle size of lessthan 0.5 mm) sample was weighed into PTFE microwave oven vessel. 10 ml of the extraction solution(volume fraction of 3% H2O2 in 0,055 mol/l HCl) was added. After vessels were closed, inserted intoceramic vessels and fitted into the rotor body, the rotor was put in the oven chamber and the programpresented in Table 2 was started.

Table 2Applied microwave program

Samples were allowed to cool at a room temperature. The supernatant was then transferred tocentrifuge containers and centrifuged for 10 min at 4000 rpm. The centrifuged supernatant was mixedwith 3 ml 40 mol/l ammonium carbonate buffer solution. If necessary, diluted acetic acid or dilutedsodium hydroxide should be added to achieve pH of the solution 6,5 ± 1.The inorganic As is selectively separated from other arsenic compounds using solid phase extraction(SPE). Supelclean™ LC-SAX SPE (Sigma Aldrich) cartridges with strong anion exchange stationaryphase were used for this procedure. The SPE tubes were conditioned with 2 ml methanol and 2 ml SPEequilibration solution (equal volumes of 40 mmol/l ammonium carbonate solution mixed with 3%H2O2 in 0.055 mol/l HCl). After loading the centrifuged buffered sample solution into the column,washing with 3 ml 0,5 mol/l acetic acid was performed. The retained As (V) on the SPE cartridge iseluted with 1,25 ml of 0,4 mol/l hydrochloric acid. The SPE cartridges were let to run dry usingvacuum (50 kPa) for 5 min.

Prior to the determination pre-reductions of test solutions were carried out. The eluate was mixedwith 7 ml potassium iodide/ascorbic acid solution in hydrochloric acid (1,25 g of KI and 1,25 g of L-ascorbic acid dissolved in 2,6 mol/l hydrochloric acid) and was left to stand at room temperature for 60min. After the incubation 6 ml of 2,6 mol/l hydrochloric acid was added, the solution was mixed andleft for another 60 min at a room temperature. Blank samples were treated in the same way. 10 ml ofwater was added, the samples were transferred to 50 ml volumetric flasks and filled to volume.

Measurements on HG-AAS were carried out 30 min after the preparation of samples wascompleted.

Step Temperature Time1 90°C 25 min.2 Cooling 10 min.

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2. INTERLABORATORY COMPARISON

In the first phase of the interlaboratory comparison (ILC) process we received three sedimentsamples with the unknown concentration of arsenic. The determined concentrations of total, inorganicand organic arsenic are presented in Table 3.

Table 3Concentrations of total, inorganic and organic arsenic in the three unknown samples

(First phase of the interlaboratory comparison process)Sample No. Total arsenic

concentration, mg/kgInorganic As

concentration, mg/kgOrganic As

concentration, mg/kgX1 6.2 6.1 0.1X2 50.0 49.6 0.4X3 117.4 116.4 1.0

In the second phase of ILC process five unknown sediment samples were sent to our laboratory.They were analyzed identically to the first portion. Results of the analysis are presented in Table 4.

Table 4Concentrations of total, inorganic and organic arsenic in the three unknown samples

(Second phase of the interlaboratory comparison process)Sample No. Total arsenic

concentration, mg/kgInorganic As

concentration, mg/kgOrganic As

concentration, mg/kgX1 6.3 5.1 1.2X2 41.4 40.4 1.0X3 21.5 20.7 0.8X4 3.7 3.3 0.4X5 4.2 3.8 0.4

The evaluation of interlaboratory comparison is not presented here – the results of otherparticipating laboratories are unknown to us. The evaluation will be accomplished by the organizers ofthe project “CHEMSEA”.

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3. RESULTS AND DISCUSSION

Bottom sediment samples were collected in the territorial waters of Lithuania and in the otherlocations of the Baltic Sea. Information about the sediments from Lithuanian aquatory and the resultsof analysis are presented in Fig.1, Fig.2 and Table 5. Table 6 shows concentrations of arsenic (total,inorganic and organic), found in the sediment from other territories of the Baltic Sea.

In the south-eastern part of the Baltic Sea bottom water velocities can vary from 0 to 40 cm/s [9].Weak and mean velocity currents prevail in sampling stations, located in Lithuanian territorial waters.Dominant current velocity in surface water layer (0 – 10 m) in the sampling stations is 3 – 8 cm/s. Thebiggest current speed (12 cm/s) was measured in CHEMSEA 5 station. Current velocity in the deeperlayers (10 – 30 m) ranges from 1 to 13 m/s, similar current speed (1 – 12 cm/s) is measured in thetransitory dynamic zone (30 – 45 m). The weakest current speed prevails in the near-bottom layer.Currents were directed to north-east (2 - 68°) in station 65, hereupon to south-west (182-262°) instation 66. East-south (90-192°) direction of the currents is dominating in stations CHEMSEA3,CHEMSEA4 and CHEMSEA6. In the other sixteen stations, north direction of the currents isdominating.

Table 5Characteristics of the sediment samples collected in Lithuanian territorial waters

No. Code ofthe

sample

Station Depth Type of thesediment

Samplingdate

Total As,mg/kg

InorganicAs,

mg/kg

OrganicAs,

mg/kg1. Dugn.

Nuos. 1065 47 Mud silty –

coarse grained2013-04-26 3.5 ± 0.3 3.5 ± 0.3 0.0 ± 0.3

2. Dugn.Nuos. 11

66 57 Sand fine 2013-04-26 2.2 ± 0.3 2.1 ± 0.1 0.1 ± 0.3

3. As 26 CHEMSEA1 87 Mud silty –coarse grained

2013-04-27 4.2 ± 0.2 4.1 ± 0.2 0.1 ± 0.2

4. As 14 ChG2 117 Mud silty –coarse grained

2013-04-27 15.9 ± 0.5 9.6 ± 0.2 6.3 ± 0.5


2013-04-27 14.2 ± 0.3 9.9 ± 0.2 4.3 ± 0.3


2013-04-27 6.9 ± 0.4 6.7 ± 0.4 0.2 ± 0.4


2013-04-27 8.3 ± 0.7 8.1 ± 0.3 0.2 ± 0.7


2013-04-27 7.2 ± 0.5 6.3 ± 0.3 0.9 ± 0.5


2013-04-27 9.8 ± 0.2 9.0 ± 0.2 0.8 ± 0.2


2013-04-27 4.0 ± 0.2 4.0 ± 0.1 0.0 ± 0.2

11. As 3 CHEMSEA6 78 Sand silty 2013-04-27 0.5 ± 0.2 0.3 ± 0.1 0.2 ± 0.212. As 49 ChG14 16 Sand fine 2013-08-21 2.6 ± 0.3 0.9 ± 0.2 1.7 ± 0.313. As 47 ChG13 15 Sand fine 2013-08-21 2.2 ± 0.2 0.6 ± 0.2 1.6 ± 0.2

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Table 5 (continued)No. Code of

thesample


Samplingdate

TotalAs,mg/kg

InorganicAs,mg/kg

OrganicAs,mg/k

g14. As 50 ChG10 34 Sand fine 2013-08-21 1.8 ± 0.3 1.2 ± 0.1 0.6 ± 0.315. As 48 CHEMSEA7 40 Coarse-grained

silt2013-08-21 2.6 ± 0.3 0.7 ± 0.1 1.9 ± 0.3

16. As 46 CHEMSEA8 48 Sand silty 2013-08-21 1.5 ± 0.2 0.9 ± 0.2 0.6 ± 0.217. As 37 20A 43 Sand fine 2013-08-21 1.2 ± 0.2 0.8 ± 0.1 0.4 ± 0.218. As 40 N-6 36 Sand fine 2013-08-22 1.4 ± 0.3 0.9 ± 0.2 0.5 ± 0.319. As 42 N-3 42 Medium-grained

sand2013-08-22 1.4 ± 0.1 1.1 ± 0.1 0.3 ± 0.1

20. As 32 ChG12 11 Sand fine 2013-11-22 2.5 ± 0.2 1.0 ± 0.3 1.5 ± 0.321. As 41 ChG11 27 Sand silty 2013-11-22 1.7 ± 0.1 0.9 ± 0.2 0.8 ± 0.2

Arsenic data are plotted in Fig. 3.

Fig.3. Concentrations of inorganic and organic As in Baltic Sea bottom sediment

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Concentration of total arsenic ranged from 0.5 mg/kg to 15.9 mg/kg in the sediment samples fromLithuanian aquatory (see Table 5 and Fig.3). As expected, the lowest concentrations of total arsenicwere measured in the sediments from Lithuanian coastal zone. Total arsenic concentration in thesesamples ranged from 1.2 to 2.6 mg/kg.

Samples from the more distant stations (St. 65 and 66) exhibited slightly higher arsenic content:2.2 – 3.5 mg/kg. It is affected due prevailing of fine grained bottom sediments. The highestconcentrations of total arsenic were found in the samples from chemical munitions dumpsite (east ofthe Gotland deep). The maximum arsenic concentrations were measured in the sediment from ChG2station: it varied from 14.2 to 15.9 mg/kg. Slightly lower arsenic concentrations were determined insediments from other stations in Gotland deep: 9.8 mg/kg (CHEMSEA3), 8.3 mg/kg (CHEMSEA5),7.2 mg/kg (ChG5). It is surprising that one of the samples from the same zone exhibited the lowestconcentration of arsenic: 0.5 mg/kg. Sample was collected from CHEMSEA 6, which is located at theeast-south part of the chemical munitions dumpsite area, at the very edge of it.

Table 6 shows concentrations of arsenic (total, inorganic and organic), found in the sedimentfrom various parts of the Baltic Sea. Coordinates of the stations, depth and type of the sediment are notpresented: only codes of the samples were revealed to us in order to keep the confidentiality.

Table 6Concentrations of total, inorganic and organic arsenic in the bottom sediments collected

from the Baltic SeaNo. Code of the sample Total As,

mg/kgInorganic As,

mg/kgOrganic As,

mg/kg

1. 1 ROV Feb 13 18.6 ± 0.5 12.5 ± 0.3 6.1 ± 0.52. 10 ROV Feb 13 15.8 ± 0.6 10.9 ± 0.3 4.8 ± 0.63. 8 Apr 13 ROV LEPA (As) 15.9 ± 0.3 11.4 ± 0.1 4.5 ± 0.34. ROV 5 LEPA (As) 17.9 ± 0.4 9.9 ± 0.1 8.1 ± 0.45. 2R3RS 13.6 ± 0.9 10.1 ± 0.3 3.6 ± 0.96. 15 Apr 13 BOX LEPA 18.3 ± 1.1 9.9 ± 0.5 8.3 ± 1.17. 4 Apr 13 ROV LEPA 23.5 ± 0.4 10.6 ± 0.1 12.9 ± 0.48. 11 Apr 13 ROV LEPA (As) 16.8 ± 0.2 11.0 ± 0.2 5.8 ± 0.29. 33 ROV Feb13 + 40m 16.0 ± 0.1 8.49 ± 0.2 7.6 ± 0.2

10. 26 Apr 13 ROV LEPA 15.2 ± 0.6 11.1 ± 0.2 4.1 ± 0.611. 4 Mar 12 LEPA 20.4 ± 0.5 9.6 ± 0.2 10.8 ± 0.512. ROV3 20.2 ± 0.3 11.6 ± 0.4 8.6 ± 0.413. 10 GT Apr 12 7.7 ± 0.7 6.5 ± 0.4 1.2 ± 0.714. 8 GT Apr 12 7.1 ± 0.9 6.1 ± 0.2 1.0 ± 0.915. 6 GT Apr 12 13.8 ± 0.9 12.0 ± 0.1 1.8 ± 0.916. 6 R3 RS 2.4 ± 0.1 2.1 ± 0.1 0.3 ± 0.117. 2 R4 RS 10.7 ± 0.3 11.9 ± 0.4 0.6 ± 0.418. 5 GD Apr12 20.4 ± 0.2 11.7 ± 0.2 8.7 ± 0.2

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Table 6 (continued)No. Code of the sample Total As,

mg/kgInorganic As,

mg/kgOrganic As,

mg/kg19. 4R3RS 2.5 ± 0.3 2.0 ± 0.1 0.5 ± 0.320. 1GD Apr12 19.6 ± 0.2 11.8 ± 0.6 7.8 ± 0.621. ROV 7 As, 150g 23.2 ± 0.3 11.2 ± 0.4 11.9 ± 0.422. 18 Apr 13 ROV 17.4 ± 0.7 12.4 ± 0.3 5.0 ± 0.723. 2 Apr 13 ROV 23.4 ± 0.4 12.2 ± 0.2 11.1 ± 0.424. 2 Mar 12 13.1 ± 0.5 11.5 ± 0.3 1.6 ± 0.525. 20 Apr 13 BOX 19.4 ± 0.2 11.6 ± 0.1 7.8 ± 0.226. 26 Apr 13 BOX 15.8 ± 0.3 11.9 ± 0.5 3.9 ± 0.527. 6 Apr 13 ROV 21.5 ± 0.2 10.4 ± 0.3 11.0 ± 0.328. 23 Apr 13 BOX 18.8 ± 0.5 11.5 ± 0.2 7.3 ± 0.529. 11 Mar 12 14.0 ± 0.7 9.7 ± 0.4 4.3 ± 0.730. 9 Mar 12 4.3 ± 0.5 3.5 ± 0.1 0.8 ± 0.531. 7 Apr 13 BOX 16.6 ± 0.8 11.1 ± 0.1 5.5 ± 0.832. 31 ROV Feb 13 + 50 m 14.6 ± 0.5 11.1 ± 0.2 3.6 ± 0.533. 8 Mar 12 1.9 ± 0.1 1.2 ± 0.3 0.6 ± 0.334. 1 Sep 12, 150 g 17.4 ± 0.2 11.6 ± 0.9 5.8 ± 0.935. WH349/B09/1, 150g 7.6 ± 0.8 7.0 ± 0.1 0.6 ± 0.836. WH349/B13/3, 150g 16.3 ± 0.4 10.9 ± 0.4 5.3 ± 0.437. 12 GT Apr 12 V2 20.5 ± 0.3 10.0 ± 0.3 10.5 ± 0.338. WH349/B13/1, 150g 5.9 ± 0.1 5.5 ± 0.3 0.4 ± 0.339. 4 Sep 12, 150g 2.1 ± 0.1 1.7 ± 0.1 0.3 ± 0.140. ROV 10 LEPA 15.5 ± 0.8 11.3 ± 0.4 4.3 ± 0.841. ROV 26, 60g 17.0 ± 0.1 9.1 ± 0.2 7.9 ± 0.242. ROV 1, 100g 18.8 ± 0.1 0.8 ± 0.1 18.0 ± 0.143. 25 Feb 13 4.8 ± 0.4 4.6 ± 0.3 0.2 ± 0.444. 27 Feb 13 BOX 23.1 ± 0.6 9.0 ± 0.4 14.1 ± 0.645. 13 ROV Feb

13 + 200 m19.1 ± 0.1 7.9 ± 0.5 11.1 ± 0.5

46. 30 ROV Feb 13 14.9 ± 0.9 9.2 ± 0.2 5.7 ± 0.947. 4 ROV Feb 13 13.9 ± 0.4 7.7 ± 0.6 6.1 ± 0.648. 12 ROV Feb 13 17.1 ± 0.2 7.9 ± 0.4 9.2 ± 0.449. 17 Feb 13 BOX 17.5 ± 0.2 9.1 ± 0.1 8.4 ± 0.250. 27 ROV Feb 13 + 40m 24.5 ± 0.8 10.1 ±0.4 14.4 ± 0.851. 9 ROV Feb 13 14.7± 0.6 8.6 ± 0.4 6.0 ± 0.6

It is obvious that sediment samples from various aquatories have elevated arsenic content incomparison with thus taken from Lithuanian territorial waters. We can see from the Table 6 thatcontent of total arsenic is in the range of 2.1 – 24.5 mg/kg, but concentration of arsenic is higher than13 mg/kg in the most of the stations from the Baltic Sea.

It is also clear from Tables 5 and 6 and Fig.3 that arsenic is mainly present in the inorganic formin the samples examined.

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However, as discussed below, the obtained data, even from the chemical munitions dumpsiteregion, are relatively low if compared to the other investigations of the sediments in the Baltic andNorth Seas (see Table 7).

Table 7Recent investigations of arsenic in Baltic and North Sea sediments

Year Sampling station Total As (mg/kg) Reference1996 - 1997 North sea (Dutch coast) 11 – 29 [12]

1996 Baltic proper 7 – 23 [13]1988 Gulf of Finland 4 – 28 [10,14]2002 Skagerrak 43 – 49 [6]

1997 - 2001 Skagerrak (munitions dumpsite) 9 – 200 [11]2002 Skagerrak (munitions dumpsite) 75 – 480 [6]

1997 - 2001 Bornholm depth 18 – 150 [11]1997 - 2002 Gotland (Liepaja dumpsite) 18 – 28 [11]

According to various sediments of the Baltic and North Seas investigations, concentrations oftotal arsenic range from 4 mg/kg to 49 mg/kg (not in the munitions dumpsites) [6,10,12,13,14]. Higherarsenic concentrations are usually found in the sediments collected from chemical munitionsdumpsites: total arsenic varied from 9 to 480 mg/kg in the samples from the dumpsite in Skagerrak[6,11], from 18 to 150 mg/kg in Bornholm [11]. Relatively low arsenic content was found in Liepajachemical weapons dumpsite: total arsenic concentrations ranged from 18 to 28 mg/kg [11].

The measured arsenic concentration in sediments from different locations of the Baltic Sea isslightly lower, but in the similar range as in Liepaja dumpsite: the maximum obtained arsenic valuewas 24.5 mg/kg. Even lower concentrations were found in the Lithuanian sector (max. 15.9).

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CONCLUSIONS

1. Optimization of the arsenic determination method was performed, the laboratory participated at theinternational interlaboratory comparison:The method for arsenic determination was selected and optimized according to therecommendations of the Buying organization; Intercalibration of the chosen analysis method and verification of the results obtained wasfulfilled through the participating at the international interlaboratory comparison;The analysis method was optimized according to the results of interlaboratory comparison.

2. Concentrations of total, inorganic and organic arsenic in the bottom sediment from chemicalmunitions dumpsite region in Gotland deep (Lithuanian part) and other Baltic sea areas weredetermined.

3. The determined concentration of total arsenic is in range from 0.5 to 15.9 mg/kg in the sedimentcollected from Gotland deep (Lithuanian part). Slightly greater concentrations of total arsenic werefound in Polish aquatory (2.1 – 24.5 mg/kg). Extremely low concentrations of total arsenic weremeasured in the sediment from the Lithuanian coastal area (1.2 – 2.6 mg/kg).

4. Inorganic arsenic is the prevailing species of total arsenic in the investigated bottom sediments.5. According to the results obtained it can be concluded that the spread of the chemical warfare agents,

containing arsenic, is not big in Lithuanian territorial waters. Relatively low arsenic concentrationswere found even in the chemical munitions dumpsite. It can indicate that relatively low amounts ofchemical munitions are dumped in Lithuanian territory or that the buried munitions are not heavilycorroded. Besides, toxic materials have only little chances to approach the Lithuanian coastline sincethe near-bottom currents are directed to north basically. It is confirmed by investigation of thesediment from Lithuanian coastal area.

6. Greater concentrations of arsenic were determined in the sediment collected from other samplingstations of the Baltic Sea. It can be assumed that the arsenic contamination have spread further inother aquatories than in Lithuanian territorial waters. The reason for that could be the bigger amountof the munitions, buried in the sampling territory (or near) or the deeper corrosion of the munitions.It is impossible to present more accurate estimation since we have no information about the samplecollection stations.

16

SUMMARY

About 55 000 tons of chemical weapons were dumped in the Baltic sea after the World War II.Significant part of chemical weapons materials form arsenic containing compounds: Adamsite, Klark I,Klark II, arsine oil. It is known that arsenic containing compounds are expected to adsorb onto thebottom sediments. Thus, determined arsenic concentration in the bottom sediment can provideinformation about contamination of the sea with the chemical warfare agents. Elevated arsenicconcentrations in the sediments can indicate a leakage of chemicals from the containers. It is alsouseful to determine which part of total arsenic exists in inorganic compounds. Since the inorganic formof arsenic is more toxic, knowing it’s concentration in the sediment would help to evaluate the effect ofthe chemical warfare agents to the sea ecosystem.

Total, inorganic and organic arsenic concentrations in Baltic bottom sediments from Lithuanianterritorial water and from other locations of the Baltic Sea were determined during this investigation.

Total arsenic concentration was relatively low (ranged from 1.2 to 2.6 mg/kg) in the sedimentsfrom Lithuanian coastal zone. Concentration of total arsenic in the samples from chemical munitionsdumpsite (east of the Gotland deep) ranged from 0.5 to 15.9 mg/kg. Greater concentrations of totalarsenic were found in the samples collected from various unknown aquatories (ranged from 2.1 to 24.5mg/kg). In the samples investigated inorganic arsenic was the dominating arsenic species.

17

References

1. Politz F. Zeitbombe Ostsee — Das Giftgas-Erbe auf dem Meerersgrund. Berlin: Chr. Links Verlag— LinksDruck GmbH; 1994. 134 pp (in German);

2. Glasby, G.P., 1997. Disposal of chemical weapons in the Baltic Sea. The Science of the TotalEnvironment 206, 267 – 273;

3. Sanderson H, Fauser P. Historical and qualitative analysis of the state and impact ofdumpedchemical warfare agents in the Bornholm Basin from 1948–2008. Internal. Report DMU-75-00061B. National Environmental Research Institute; 2008. 25 pp

4. Voipio, A. (Ed.), 1981. The Baltic Sea. Elsevier Scientific, Netherlands5. Duursma, E.K. (Ed.), 1999. Dumped chemical weapons in the sea. Options. Drukkerij van

Denderen BV, Netherlands.6. Tørnes, J.A., Voie, Ø.A., Ljønes, M., Opstad, A.M., Bjerkeseth, L.H., Hussain F., 2002.

Investigation and risk assessment of ships loaded with chemical ammunition scuttled in Skagerrak.TA-1907/2002.

7. F.R. S. Bentlin, F.A. Duarte et al. Arsenic Determination in Marine Sediment Using Ultrasoundfor Sample Preparation. ANALYTICAL SCIENCES SEPTEMBER 2007, VOL. 23, 1097 - 1101

8. L. Ebdon, P. L. Cornelis, R. H. Crews, O. F. X. Donard, and P. Quevauviller, “Trace ElementSpeciation for Environment, Food and Health”, 2001, Chap. 5, RSC, Cambridge

9. Emelyanov, E.M., 2002. Geology of the Gdansk basin. Baltic Sea, Kaliningrad10. Vallius, H., Lehto, O., 1998. The distribution of some heavy metals and arsenic in recent sediments

from the eastern Gulf of Finland. Applied Geochemistry 13, 369-37711. Paka, V., Spiridonov, M., 2002. An overview of the research of dumped chemical weapons made

by the R/V ‘‘Professor Shtokman’’ in the Gotland, Bornholm and Skagerrak dump sites during1997-2001. HELCOMMONAS 4/2002, Document 3/5/NF.

12. De Boer, J., van der Zande, T.E., Pieters, H., Ariese, F., Schipper, C.A., van Brummelen, T.,Vethaak, A.D., 2001. Organic contaminants and trace metals in flounder liver and sediment fromthe Amsterdam and Rotterdam harbours and off the Dutch coast. Journal of EnvironmentalMonitoring 3, 386 – 393

13. Borg, H., Jonsson, P., 1996. Large-scale metal distribution in Baltic Sea sediments. MarinePollution Bulletin 32 (1), 8 – 21

14. Leivuori, M., 1998. Heavy metal contamination in surface sediments in the Gulf of Finland andcomparison with the Gulf of Bothnia. Chemosphere 36 (1), 43 – 59.

18

APPENDIX

19

SEDIMENTS TEST REPORT

Concentrations of total, inorganic and organic arsenic in the three unknown samples(First phase of the interlaboratory comparison process)

Sample No. Total arsenicconcentration, mg/kg

Inorganic Asconcentration, mg/kg

Organic Asconcentration, mg/kg

X1 6.2 6.1 0.1X2 50.0 49.6 0.4X3 117.4 116.4 1.0

Concentrations of total, inorganic and organic arsenic in the three unknown samples(Second phase of the interlaboratory comparison process)

Sample No. Total arsenicconcentration, mg/kg

Inorganic Asconcentration, mg/kg

Organic Asconcentration, mg/kg

X1 6.3 5.1 1.2X2 41.4 40.4 1.0X3 21.5 20.7 0.8X4 3.7 3.3 0.4X5 4.2 3.8 0.4

Nature Research CenterDr. K. JokšasProject manager

20

SEDIMENTS TEST REPORTConcentrations of total, inorganic and organic arsenic in the bottom sediments

collected from the Baltic seaNo. Code of the sample Total As,

mg/kgInorganic As,

mg/kgOrganic As,

mg/kg

1. 1 ROV Feb 13 18.6 ± 0.5 12.5 ± 0.3 6.1 ± 0.52. 10 ROV Feb 13 15.8 ± 0.6 10.9 ± 0.3 4.8 ± 0.63. 8 Apr 13 ROV LEPA (As) 15.9 ± 0.3 11.4 ± 0.1 4.5 ± 0.34. ROV 5 LEPA (As) 17.9 ± 0.4 9.9 ± 0.1 8.1 ± 0.45. 2R3RS 13.6 ± 0.9 10.1 ± 0.3 3.6 ± 0.96. 15 Apr 13 BOX LEPA 18.3 ± 1.1 9.9 ± 0.5 8.3 ± 1.17. 4 Apr 13 ROV LEPA 23.5 ± 0.4 10.6 ± 0.1 12.9 ± 0.48. 11 Apr 13 ROV LEPA (As) 16.8 ± 0.2 11.0 ± 0.2 5.8 ± 0.29. 33 ROV Feb13 + 40m 16.0 ± 0.1 8.49 ± 0.2 7.6 ± 0.2

10. 26 Apr 13 ROV LEPA 15.2 ± 0.6 11.1 ± 0.2 4.1 ± 0.611. 4 Mar 12 LEPA 20.4 ± 0.5 9.6 ± 0.2 10.8 ± 0.512. ROV3 20.2 ± 0.3 11.6 ± 0.4 8.6 ± 0.413. 10 GT Apr 12 7.7 ± 0.7 6.5 ± 0.4 1.2 ± 0.714. 8 GT Apr 12 7.1 ± 0.9 6.1 ± 0.2 1.0 ± 0.915. 6 GT Apr 12 13.8 ± 0.9 12.0 ± 0.1 1.8 ± 0.916. 6 R3 RS 2.4 ± 0.1 2.1 ± 0.1 0.3 ± 0.117. 2 R4 RS 10.7 ± 0.3 11.9 ± 0.4 0.6 ± 0.418. 5 GD Apr12 20.4 ± 0.2 11.7 ± 0.2 8.7 ± 0.219. 4R3RS 2.5 ± 0.3 2.0 ± 0.1 0.5 ± 0.320. 1GD Apr12 19.6 ± 0.2 11.8 ± 0.6 7.8 ± 0.621. ROV 7 As, 150g 23.2 ± 0.3 11.2 ± 0.4 11.9 ± 0.422. 18 Apr 13 ROV 17.4 ± 0.7 12.4 ± 0.3 5.0 ± 0.723. 2 Apr 13 ROV 23.4 ± 0.4 12.2 ± 0.2 11.1 ± 0.424. 2 Mar 12 13.1 ± 0.5 11.5 ± 0.3 1.6 ± 0.525. 20 Apr 13 BOX 19.4 ± 0.2 11.6 ± 0.1 7.8 ± 0.226. 26 Apr 13 BOX 15.8 ± 0.3 11.9 ± 0.5 3.9 ± 0.527. 6 Apr 13 ROV 21.5 ± 0.2 10.4 ± 0.3 11.0 ± 0.328. 23 Apr 13 BOX 18.8 ± 0.5 11.5 ± 0.2 7.3 ± 0.529. 11 Mar 12 14.0 ± 0.7 9.7 ± 0.4 4.3 ± 0.730. 9 Mar 12 4.3 ± 0.5 3.5 ± 0.1 0.8 ± 0.531. 7 Apr 13 BOX 16.6 ± 0.8 11.1 ± 0.1 5.5 ± 0.832. 31 ROV Feb 13 + 50 m 14.6 ± 0.5 11.1 ± 0.2 3.6 ± 0.5

21


33. 8 Mar 12 1.9 ± 0.1 1.2 ± 0.3 0.6 ± 0.334. 1 Sep 12, 150 g 17.4 ± 0.2 11.6 ± 0.9 5.8 ± 0.935. WH349/B09/1, 150g 7.6 ± 0.8 7.0 ± 0.1 0.6 ± 0.836. WH349/B13/3, 150g 16.3 ± 0.4 10.9 ± 0.4 5.3 ± 0.437. 12 GT Apr 12 V2 20.5 ± 0.3 10.0 ± 0.3 10.5 ± 0.338. WH349/B13/1, 150g 5.9 ± 0.1 5.5 ± 0.3 0.4 ± 0.339. 4 Sep 12, 150g 2.1 ± 0.1 1.7 ± 0.1 0.3 ± 0.140. ROV 10 LEPA 15.5 ± 0.8 11.3 ± 0.4 4.3 ± 0.841. ROV 26, 60g 17.0 ± 0.1 9.1 ± 0.2 7.9 ± 0.242. ROV 1, 100g 18.8 ± 0.1 0.8 ± 0.1 18.0 ± 0.143. 25 Feb 13 4.8 ± 0.4 4.6 ± 0.3 0.2 ± 0.444. 27 Feb 13 BOX 23.1 ± 0.6 9.0 ± 0.4 14.1 ± 0.645. 13 ROV Feb 13 + 200 m 19.1 ± 0.1 7.9 ± 0.5 11.1 ± 0.546. 30 ROV Feb 13 14.9 ± 0.9 9.2 ± 0.2 5.7 ± 0.947. 4 ROV Feb 13 13.9 ± 0.4 7.7 ± 0.6 6.1 ± 0.648. 12 ROV Feb 13 17.1 ± 0.2 7.9 ± 0.4 9.2 ± 0.449. 17 Feb 13 BOX 17.5 ± 0.2 9.1 ± 0.1 8.4 ± 0.250. 27 ROV Feb 13 + 40m 24.5 ± 0.8 10.1 ±0.4 14.4 ± 0.851. 9 ROV Feb 13 14.7± 0.6 8.6 ± 0.4 6.0 ± 0.6

22

SEDIMENTS TEST REPORT

Characteristics of the sediment samples collected in Lithuanian territorial watersNo. Code of

thesample


Samplingdate

TotalAs,

mg/kg

InorganicAs,

mg/kg

OrganicAs,

mg/kg1. Dugn.

Nuos. 1065 47 Mud silty –

coarse grained2013-04-26 3.5 ± 0.3 3.5 ± 0.3 0.0 ± 0.3

2. Dugn.Nuos. 11

66 57 Sand fine 2013-04-26 2.2 ± 0.3 2.1 ± 0.1 0.1 ± 0.3


2013-04-27 4.2 ± 0.2 4.1 ± 0.2 0.1 ± 0.2


2013-04-27 15.9 ±0.5

9.6 ± 0.2 6.3 ± 0.5


2013-04-27 14.2 ±0.3

9.9 ± 0.2 4.3 ± 0.3


2013-04-27 6.9 ± 0.4 6.7 ± 0.4 0.2 ± 0.4


2013-04-27 8.3 ± 0.7 8.1 ± 0.3 0.2 ± 0.7


2013-04-27 7.2 ± 0.5 6.3 ± 0.3 0.9 ± 0.5


2013-04-27 9.8 ± 0.2 9.0 ± 0.2 0.8 ± 0.2


2013-04-27 4.0 ± 0.2 4.0 ± 0.1 0.0 ± 0.2

11. As 3 CHEMSEA6 78 Sand silty 2013-04-27 0.5 ± 0.2 0.3 ± 0.1 0.2 ± 0.212. As 49 ChG14 16 Sand fine 2013-08-21 2.6 ± 0.3 0.9 ± 0.2 1.7 ± 0.313. As 47 ChG13 15 Sand fine 2013-08-21 2.2 ± 0.2 0.6 ± 0.2 1.6 ± 0.214. As 50 ChG10 34 Sand fine 2013-08-21 1.8 ± 0.3 1.2 ± 0.1 0.6 ± 0.315. As 48 CHEMSEA7 40 Coarse-grained

silt2013-08-21 2.6 ± 0.3 0.7 ± 0.1 1.9 ± 0.3

16. As 46 CHEMSEA8 48 Sand silty 2013-08-21 1.5 ± 0.2 0.9 ± 0.2 0.6 ± 0.217. As 37 20A 43 Sand fine 2013-08-21 1.2 ± 0.2 0.8 ± 0.1 0.4 ± 0.218. As 40 N-6 36 Sand fine 2013-08-22 1.4 ± 0.3 0.9 ± 0.2 0.5 ± 0.319. As 42 N-3 42 Medium-

grained sand2013-08-22 1.4 ± 0.1 1.1 ± 0.1 0.3 ± 0.1

20. As 32 ChG12 11 Sand fine 2013-11-22 2.5 ± 0.2 1.0 ± 0.3 1.5 ± 0.321. As 41 ChG11 27 Sand silty 2013-11-22 1.7 ± 0.1 0.9 ± 0.2 0.8 ± 0.2


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