Geochemical records of sediments in the Eastern Gotland Basin—products of sediment dynamics in a not-so-stagnant anoxic basin?

• Published in: Applied geochemistry Vol. 13; no. 3; pp. 349 - 358
• Main Authors: Emeis, K.-C, Neumann, T, Endler, R, Struck, U, Kunzendorf, H, Christiansen, C
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.1998; Elsevier
• Subjects: Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Geochemistry; Pollution, environment geology; Soil and rock geochemistry; Northeast Atlantic; North Atlantic; Baltic Sea; ANE, Baltic Sea, Gotland Basin; accumulation; heavy metals; Atlantic Ocean; metals; industry; transport; pollution; seismic profiles; chemical analysis; drill cores; enrichment; trace-element analyses; dynamics; organic carbon; marine sediments; sulfides
• ISSN: 0883-2927; 1872-9134
• DOI: 10.1016/S0883-2927(97)00104-2

Geochemical data from 4 cores taken in the Eastern Gotland Basin of the Central Baltic Sea (68 to 243 m water depth) show that depositional conditions for heavy metals in sediments were similar at all water depths prior to anthropogenic influxes. After the onset of industrialization, the deep anoxic parts of the basin expanded at irregular intervals and the <63 μm fractions of the sediments became characterized by high organic C and heavy-metal accumulation rates. The difference between the enrichment patterns in the basin and on the slope suggests that material enriched in organic matter (and associated trace elements) and in sulphides (and associated trace elements) is preferentially deposited in the basin. The composition of the sediments in the basin therefore reflects the effects of lateral transport of the sediment, which enriches organic C in the deepest part of the basin and of anoxia in the deep water of the basin, where metal sulphides are formed. Previous estimates of the timing of the onset of industrial pollution in the Central Baltic may have been in error because these new data suggest that this began in the Eastern Gotland Basin in about 1870.