Geological Hazard Potential at the Baltic Sea and Its Coastal Zone: Examples from the Eastern Gulf of Finland and the Kaliningrad Area - The Baltic Sea Basin - page 358

In the Russian Baltic and its coastal zone, the anthropogenic impact has been
constantly growing since the beginning of the eighteenth century, but during the last
decade this impact has drastically increased. In coastal zones (including the shallow
coastal waters), anthropogenic activity has become a major factor comparable by its
importance to the natural processes.
Field work and analytical data (side-scan survey, echo-sounding, sediment sam-
pling, gamma spectrometry for 137 Cs, ICP-AES, and ICP-MS) as well as the
investigation of archive materials have brought us to the conclusion that the sedi-
mentation processes in the Neva Bay have completely changed during the last two
centuries. Special conditions of mud accumulation have developed in the bottom
depression of 5-6 m in the western part of the Neva Bay (Spiridonov et al. 2008 ) .
Significant alteration of sedimentation was caused by anthropogenic impact, i.e.,
defense constructions in the outer part of the bay, construction of St. Petersburg
Flood Protection Facility, and hydroengineering works. The construction of a new
St. Petersburg harbor in the Neva Bay, accompanied by new land creation of around
477 ha and 12-14-m-deep ship channels for cruise fairies, started in 2006. As a
result of dredging and dumping processes, the concentration of suspended matter in
the water was extremely high in 2007 and the trace of suspension reached Vyborg
Bay (Fig. 16.10 ) . VSEGEI study of the nearshore bottom showed that a clayey layer
up to 3 cm thick had formed on the sand surface. The concentration of fine particle
in beach sands of resort areas increased up to 5-7% in 2007-2008. Sedimentation
system of the eastern Gulf of Finland was significantly disturbed.
Changes in sedimentary processes stressed the ecosystem of the Neva Bay and
caused degradation of fish spawning and feeding areas, decrease in plankton and
benthic community's productivity, and migration of marine birds and mammals
(Fedorov et al. 2008 ) . In 2006-2007, microalgal occurrence drastically decreased
in the outer Neva Bay and biomass of macrozoobenthos within the bay dimin-
ished. The ecosystem started to recover after the conclusion of the active phase
of hydrotechnical work.
Another big project of the eastern Gulf of Finland is the newly built Ust-Luga
port complex, which is planned to be one of the world's 10 biggest ports. According
to the plan, its carrying capacity of general cargo will reach 120 million tons/year
(50 million tons by 2010, www.ust-luga.ru ). The first part of the port complex was
constructed by 2008. A large quantity of sediments (mostly sands) were removed
from the coastal zone during the dredging and used for terminal construction. The
new ship channels will interrupt sediment transport and act as large sediment traps.
As a result, the natural sediment nourishment of the sandbars will be reduced. In
the late 1970s, the area of sand accretion was 2.24 km 2 , including 0.65 km 2 of the
bay-head sandbar area between the Luga River and the future port. By 2003, the
area of sand accretion had reduced up to 0.5 km 2 . The size of the whole accretion
zone decreased by about 80%, whereas the area of bay-head sandbar decreased by
about 30% to 0.42 km 2 (Sergeev et al. 2009 ) , so the bay-head sediment balance of
the Luga Bay was significantly changed.
Among other large planned projects, there are two more ports: the Primorsk oil
terminal, which is planned to be the biggest oil export port of northwestern Russia