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2 Polish Geological Institute Special Papers

2 2008

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Development of the Southern Coastal zone of the Eastern Gulf of Finland (from lebyazhye to the St. Petersburg flood protective dam)

Suslov G. A., Ryabchuk D. V., Nesterova E. N., Fedorova E. K.

Polish Geological Institute Special Papers

2008

Vol. 23

109-116

In July–September 2004 and April 2005, the specialists of the Department of Marine and Environmental Geology of All-Russian Geological Institute (VSEGEI) conducted field studies of the coastal zone of the Gulf of Finland from thesouthern alignment of the St. Petersburg Flood Protective Dam to Lebyazhye. The basic purpose of the studies is the analysis of coastal zone dynamics. Along the southern coast of the Gulf of Finland from Lebyazhye to the Dam, three different coastal dynamics zones were identified: (1) flat accumulative shore with aquatic plants, (2) erosion zone and (3) zone of modern sand accumulation. Along-shore sand drift in the eastern direction was also determined. Alongside with routine observations, the comparative analysis of space photography images of the study area, carried out during last 20 years, allowed finding out that as a result of intense eastward sand transfer, as mush as 80 metres of sand accumulative bodies have been eroded since 1982 near the village of Izhora. To the west of a small river, a 230-metres long sand split has been formed since 1982.

A new map of the Neva Bay bottom sediments and technogenic objects under the result of side-scan sonar profiling

Spiridonov M. A., Ryabchuk D. V., Kropachev Y. A., Nesterova E. N., Zhamoida V. A., Vallius H., Kotilainen A.

Polish Geological Institute Special Papers

2008

Vol. 23

95-107

In summer 2004, Department of Marine and Environmental Geology of VSEGEI carried out investigations of the Neva Bay bottom surface east of the St. Petersburg Flood Protective Dam using a side-scan sonar system. The main aim of this experimental work was the creation of a new “factographical” map of bottom sediments and different types of technogenic objects. State geological surveys of the Neva Bay bottom were carried out by VSEGEI in 1987–1989. Besides, geoenvironmental investigations were conducted here in 1993–1995 and 2000–2002. As a result, a set of maps of bottom sediments based on hundreds of sampling stations (both cores and grab-sampler) were compiled. Side-scan investigations of 2004 allowed more exact recognition of the bottom sediment distribution. Furthermore, in some places new data permit to suppose that the sedimentary conditions have changed here during the last decades as a result of high technogenic load, including Flood Protective Dam influence. In summer 2004 there were a joint expedition of the VSEGEI and the Geological Survey of Finland (GTK). Altogether 10 sampling stations from the mud accumulation areas were sampled with a use of Niemisto corer. Cores were sliced in 1 cm samples and analyzed in chemistry laboratory of GTK (Finland) – gamma spectrometry for 137Cs, ICP-AES and ICP-MS, whereupon important results about heavy metals concentration and distribution were received.