Author/Authors :
S. Vaalgamaa، نويسنده , , D.J. Conley، نويسنده ,
Abstract :
Historical sediment nutrient concentrations and heavy metal distributions were studied in four estuaries in the Gulf of Finland, Baltic Sea to
examine the response of these estuaries to temporal changes in human activities. Cores were collected using a 1-m Mackereth corer and dated
using 210Pb and 137Cs. The cores were analyzed for total carbon (TC), total nitrogen (TN), total phosphorus (TP), organic phosphorus (OP),
inorganic phosphorus (IP), biogenic silica (BSi), loss-on-ignition (LOI), Cu, Zn, Al, Fe, Mn, K, Ca, Mg and Na. Principal component analysis
(PCA) was used to summarize the trends in the chemical variables and to compare the trends at the different sites. Applying the 1986 137Cs date
as a reference point, 210Pb chronologies were constructed for the sites using either the CRS model or a composite model (using both CIC and
CRS). Significant increases were observed in sedimentation rates, TP and TN concentrations in all of the cores. Copper showed clear increases
from 1850 towards present at all sites. Furthermore, redundancy analysis (RDA) was used to correlate environmental variables (catchment land
use, catchment size, estuary surface area, depth and lake percentage) to sediment geochemistry. Based on redundancy analysis (RDA), the percentage
of agriculture in the catchment was the most important factor affecting the sediment accumulation rate. Urban land-use types and industry
correlate well with sediment Cu and Ca concentrations. Forest areas were related to high sediment BSi concentrations. Catchment land
use was the most significant factor affecting sediment geochemical composition and sediment accumulation rates in these coastal embayments.
Our results demonstrate that the coastal estuaries of the Gulf of Finland respond to the increased nutrient loading with the increased sedimentation
and nutrient accumulation rates
Keywords :
Baltic Sea , coastal sediments , nutrients , Heavy metals , Sediment chronology