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1 INTRODUCTION

The importance of control over such a dangerous

toxicant as Hg in the biosphere is difficult to

overestimate. Monitoring of water bodies and their

depositing component for pollution levels in bottom

sediments in river mouths that flow into internal

resource-significant water bodies is particularly

relevant . Such an object is the Vistula lagoon of the

Baltic Sea. The state network for controlling surface

land waters in the Kaliningrad region covers only

13points (18 sections). There has been no

hydrochemical monitoring of the water area since

1989 (the State Committee on Hydromet had

conducted before; only 15 stations had been

controlled in the estuary of the Kaliningrad Bay). In

recent decades, coastal pollution assessments of

Russian lagoon sector have been fragmented (in

duration, measurement intervals and survey areas).

They have been carried out with different goals by

various organizations (2000-2015: AtlantNIRO,

GeoHydroBalt (Kaliningrad), Environmental

Analytical Center (Moscow), CER-ENERGO (St.

Petersburg), etc.). The results of evaluations are not

widely available. Among all the methods for the

contaminant identification there are often used not

expensive, but low-sensitive ones. The variability of

pollutant concentrations in the bottom sediments of

the water bodies is poorly studied (Bogdanov 2018 a,

2018 b, Bogdanov & Vorontsov, Morozov 2004,

Environmental problems of the Kaliningrad region…

1999, 2002, etc.).

The goal is to assess the causes of the variability of

content and reliability of methods for determining Hg

in the bottom sediments in the Kaliningrad Sea Canal

(KSC) and in the river mouths flowing into the Vistula

Lagoon (Fig. 1).

Mercury in the Bottom Sediments of the Ship Channel

and River Mouths: the Vistula Lagoon

N.A. Bogdanov

Institute of Geography, Russian Acade

my of Sciences, Moscow, Russia

O.V. Bass

Immanuel Kant Baltic Federal University, Kaliningrad, Russia

A.N. Paranina & R. Paranin

Herzen State Pedagogical University, St. Petersburg, Russia

ABSTRACT: It is studied the distribution of Hg in bottom sediments of estuaries on the banks of the open water

area of the Vistula Lagoon and in the Kaliningrad Sea Canal (KSC) isolated from it. Methods for the

determination of Hg: inversive voltammetry and highly sensitive flameless atomic absorption spectrometry. It

has been established: from spring to autumn the activation of storms and surge events in the lagoon,

intensification of the water flushing regime of the channels ensure a significant Hg decrease in river mouths,

but in dynamically weakened KSC conditions - an increase in Hg (from 0.05 to 0.85 mg / kg). In KSC bays, the

safe level of Hg (0.3 mg / kg) for the period 2000-2015 was not exceeded (0.008 to 0.216 mg / kg), which

indicates a favorable ecological and epidemiological situation. Hg determinations by low-sensitivity methods

can be used only in qualitative assessments of the variability in concentrations of any dangerous toxicant.

Finding a reliable amount of Hg in river mouths requires the use of highly sensitive methods of analysis.

http://www.transnav.

the

International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 14

Number 3

September 2020

DOI:

10.12716/1001.14.03.23

698

Table – Sedimentation conditions, long-term and seasonal variability of Hg in bottom sediments in the river mouths of

Prokhladnaya, Graevka and KSC

__________________________________________________________________________________________________

Objects Sample selection: Hg, Methods Sediment Dynamic conditions of

Station year. mg / kg composition sedimentation (Fig. 2)

number months

__________________________________________________________________________________________________

Prokhladnaya 2 2000.06 0,016 AAS Fines and The open water area of the

2001.06 0,010 fine-grained sands bay: the reentering angle of

2010.05 15,0 IVA the breakwater at the village

2010.10 2,1 Ushakovo, significant surges

KSC Graeyvka 4 2000.06 0,011 AAS Fine-grained sands, Minor surges; dynamically

sub-latitude 0,023 admixture of weakened zone of circulations

area: 2010.05 0,05 IVA medium and in the bays, steamboat wave,

settlements villages 2010.10 0,85 fine-grained disturbance of bottom

particles

Izhevskoye – Izhevskoye: 7 2000.08 0,077 AAS Fines and sediments by turbulence from

Vzmorye downward the 0,136 fine-grained sands, screw propellers;

mouth of the 2001.06 0,133 admixture of black, predominant transfer of

river Grayevka, cheesy oily-clayey matter, energy and pollutants

ship passage, slimes of H

2S odor eastward the mouth of the

moorings river Pregolya

village 8 2000.08 0,023

Vzmorye: 0,096

along the coast, 2015.11 0,008-

moorings, ship (6 samples) 0,136

channel 0,015-

0,216

Background [4] 2000.06 0,023 The upper river courses of Deyma and Pregolya beyond large

industrial facilities and residential areas

Target safe level of concentration 0,3 Recommendations and indicative estimates of environmental

Minimally hazardous concentration with and hygienic hazard to humans and ecosystems: Dutch lists of

toxicological risks (urgent remediation) 10 pollutants, bottom sediments [1, 8]

__________________________________________________________________________________________________

AAS – atomic absorption spectrometry using the "cold steam" technique, modified scheme of the Zeeman effect and

spectrometers "IMGRE-900" (2000-2001), "SA-915 +" (2015), detection limit (DL) Hg = 0.001 mg / kg; IVA –inversion

voltammetry, DL = 0.01 mg / kg

2 OBJECTS AND METHODS

Bottom sediments: layer 0-0.1 m; sands, admixtures of

gravel, silt, pelite; dark-colored sludge with H

2S odor;

the mouths of the main rivers (Mamonovka,

Prokhladnaya, Pregolya, Grayevka, Nelma,

Primorskaya); KSC sections (stations No. 7, 8); survey

time - ice-free periods of 2000, 2001, 2010 and 2015

(Fig. 1, table).

The definitions of Hg are made by accredited

laboratories using metrically certified, but different in

accuracy methods: highly sensitive non-flame AAS

(2000-2001 and 2015), IVA (2010). The approximate

diagnosis of the ecological and hygienic danger of Hg

accumulation is compared with the background

content and threshold levels of hazardous

concentrations (table) (Bessonov & Yanin 2005,

Bogdanov & Vorontsov, Morozov 2004, SP 11-102-97

Engineering … 1997).

3 DISCUSSION OF RESULTS

3.1 Major sources of mercury and migration factors

Sources of Hg: solid, liquid, gaseous wastes and spills

of Hg-containing substances at industrial, transport,

agricultural, residential facilities; emissions from fuel

combustion plants; transboundary pollutants

transfers and others. Secondary contamination is

associated with the resuspension of contaminated

bottom sediments by floating craft (table) (Bessonov

& Yanin 2005, Bogdanov 2018 a, 2018 b, Bogdanov &

Vorontsov, Morozov 2004, Environmental problems…

1999, 2002, Volokh & Yanin 2005).

Conditions and factors of accumulation-scattering Hg.

The main ones, besides the existing Hg sources and

their functioning characteristics, include

hydrometeorological and lithodynamic conditions:

wind conditions, surge events, coastal dynamics of

water and sediment, size and sorption capacity of

bottom sediments and suspensions; seasonal

fluctuations in the river water content, etc. (Fig. 2,

table).

699

Figure 1. Scheme for sampling sediments: estuaries and KSC

(Kaliningrad Sea Canal)

The water content of the rivers increases and the

coastal dynamics intensifies in the autumn-winter

period. Self-cleaning conditions for studied objects

becomes favorable. The maximum marks of water

level in the bay fall at September-February (> 80% of

occurrence; up to +180 cm 3-4.12. 1999 with W and

SW winds and –136 cm 20.10. 1989, E and NE winds)

[4, 5, 6]. The energy potential of hydro- and litho-

dynamic processes off the banks and in the mouths of

rivers in the open waters of the lagoon is higher by

several orders than in the KSC. In its sub latitudinal

section dynamically stagnant zones of weak water

circulations, sediment and accumulation of pollutants

are characteristic (the mouth of the Grayevka river,

the bay near the villages of Izhevskoye, Vzmorye and

others, Fig. 2).

Figure 2. Hydro- and lithodynamics of the estuary of the

Kaliningrad Bay [4]. Wave energy fluxes, T / s: 1, 2 and 3 are

transverse to the bay, En = 1-500, 501-1000 and 1001-1496,

respectively; 4, 5, 6 and 7 –paralic zone , E

= 0.01-1.1; 1.2-10;

11-50 and 51-104 respectively; 8 – the resultant wind value

direction of 242° and of 62% frequency during sampling

period has corresponded to the average long-term

parameters (weather station "Kaliningrad"); 9 – the

predominant transfer of water, suspensions and pollutants,

10, 11 and 12 – suspended substances, mg / l: 12-50, 51-100

and 101-231, respectively; 13 – bottom features, 14-15 –

sampling points, 16 – ledges of bank erosion.

3.2 Seasonal dynamics of mercury concentrations in

sediments

These are the seasonal features of coastal dynamics of

the receiving reservoir, fluctuations in the water

content and washing mode of the watercourses which

control the variability of Hg concentrations in the

bottom sediments.

During autumn-winter activity of surge events and

wind-cut occurrence in the estuaries of rivers that

flow into the open water area of the lagoon, alluvium

is cleared of pollutants. In our situation - from Hg.

Seasonal self-cleaning, period from May till October

2010, estuaries, mg / kg: Primorskaya from 53 to 0.53

(100 times), Pregolya from 62 to 5.7 (11 times),

Prokhladnaya 15 to 2, 1 (7 times), Nelma from 10.1 to

1.6 (6 times) Mamonovka from 8.1 to 3.9 (2 times). In

the estuary of the river Grayevka, open to surge from

S and SW winds, while KSC water area isolated from

the sea gulf and dynamically weakened, the amount

of Hg from spring to autumn 2010 increased ~ 17fold

(from 0.05 to 0.85 mg / kg). Episodic increases in Hg

emissions are also not excluded, according to the

differences in the values of its concentrations in the

mouth of the river Grayevka in 2000-2001 and in 2010.

In the alluvium of the river estuaries background

and signal levels of hazardous accumulation with excess

concentrations are recorded everywhere, which is

probably due to significant differences in the accuracy

and correctness of metal definitions. So, in June 2000

(AAS method) and May 2010 (SVM method) at the

mouth of the r. Prokhladnaya concentrations differed

1000 times (0.016 and 15 mg / kg, respectively).

Obviously, the reason for such variability lies not in

the «hurricane» increase in Hg emissions, but in the

accuracy of measurement methods (table).

3.3 Dangerous levels of concentration

In the bottom sediments of the bays of the sub

latitudinal part of the KSC, the excess of hazardous

levels of Hg concentration was not recorded either in

2000–2001 or in 2015 (conditions for an active mode of

navigation, tendencies of pollutant accumulation).

Moreover, Hg content was comparable among

themselves for different years of control that shows

the adequacy of the determination methods and the

absence of significant long-term changes in the

processes of entry – concentration – scattering of the

metal as well as a fairly favorable ecological and

epidemiological situation on Hg.

4 CONCLUSIONS

Regarding the variability of Hg content in the

alluvium of the river estuaries in the Vistula Lagoon

basin, one can identify the main reasons: openness /

isolation of the receiving water area; seasonality of

hydrometeorological, wave-energy and surge-surging

phenomena; water content and washing mode of river

courses. Autumn-winter activation of these natural

factors causes self-purification of alluvium in the

mouths of rivers on the open shores of Lagoon. The

dynamically weakened conditions in the areas

isolated from it, with a significant accumulation of

700

sources of pollutants and fine-grained bottom

sediments (<0.1 mm), contribute to Hg accumulation.

However, its amount in the sediments of the KSC for

the period 2000-2015 did not change significantly and

was below the dangerous environmental and hygienic

levels of Hg concentration.

Hg determinations by low-sensitivity methods can

be used only in qualitative assessments of the

variability of concentrations of a hazardous toxin.

The final elucidation of the causes of this kind of

variability and reliability of Hg amount in bottom

sediments requires additional studies of the

functioning the sources and conditions of Hg

accumulation with the use of highly sensitive

methods of analysis.

ACKNOWLEDGEMENTS

The work was performed under the theme of the State task

No. 0148-2019-0005, No. АААА-А19-119021990091-4.

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