Stratigraphy of total metals in PIRLA sediment cores

Abstract

Sediment cores from 30 low-alkalinity lakes in northern New England (NE), New York (NY), the northern Great Lakes States (NGLS) of Minnesota, Michigan, and Wisconsin, and Florida (FL) have been dated by 21~ and analyzed for water and organic content, eight major elements (A1, Ti, Fe, Mn, Ca, Mg, Na, K) plus four trace metals (Pb, Zn, Cu, and V). Variations in the percentages of major elements through time are dominated by long-term independent variations in the abundance of SiO2, FeO, and to a lesser extent Ca and A1. Additional variations are caused by varying proportions of inorganic matter. Major variations in chemistry are generally unrelated to documented disturbances in the watersheds; most disturbances are minor fires or selective logging.Accelerated accumulation of Pb from atmospheric sources into sediment first occurs in sediment dated between 1800 and 1850 in NY and NE, slightly later in the NGLS region, and about 1900 in FL. Modem accumulation rates in all areas are comparable (ca. 1 to 4 #g cm -2 yr-1). Accumulation rates of Pb in some lakes have declined significantly from 1975 to 1985. Atmospheric deposition of anthropogenic Zn and Cu is also indicated by generally increasing accumulation rates in sediment cores, but the record is not as clear nor are chemical profiles in all lakes parallel to the trends in atmospheric emissions inferred on the basis of fossil fuel consumption, smelting, and other industrial activities. Inter-lake variations in profiles of Cu and Zn are large. Vanadium accumulation rates increase by the 1940s in NY and NE, but not until the 1950s in the NGLS region. This timing correlates with regional trends in the combustion of fuel oil, a major source of atmospheric V.Acidification of some of the lakes is suggested by decreases in the concentration and accumulation rates of Mn, Ca, and Zn in recent sediment, relative to other elements of catchment origin. The decreases generally occur slightly before the onset of acidification as indicated by diatoms. Increased sediment accumulation rates for Fe may indicate the acidification of watershed soils. The use of the accumulation rate of TiO2 as an indicator of rates of erosion and for normalization of trace metal accumulation rates is in question for lakes where the flux of TiO2 from the atmosphere varies and is a significant fraction of the total flux of TiO2 to the sediment.

Deconstruction of Historic Mercury Accumulation in Lake Sediments, Northeastern United States

“…The cores retrieved in the early 1980s and reported by Lorey and Driscoll (1999) were dated by alpha analysis for 210 Pb (Eakins and Morrison, 1978) at the University of Maine (Norton et al, 1992). The cores in Kamman and Engstrom (2002) (1978).…”

“…Sediment from cores retrieved in the early 1980s (Norton et al, 1992) was not analyzed for Hg until 1998 (Lorey and Driscoll, 1999). Intervals dried at 40-60°C were used for total Hg.…”

Environmental geochemistry of core sediments from Serthalaikkadu creek, East coast of India

“…In addition, higher ratios of K/Na, Al/(Na ? Ca) and Al/Si at 35-47.5 cm depth in C1 than C2 indicate domination of clay minerals in the sediments which could be due to major out flow related to heavy precipitation and it is also supported by the lower values (see normalized pattern) in C1 (Norton et al 1992). The Al-normalized pattern for the trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn) almost indicates similar distribution pattern as major elements in the down core profiles (Figs.…”

Anthropocene environmental change in an internationally important oligotrophic catchment on the Atlantic seaboard of western Europe

“…Geochemical accumulation rates were also calculated based on the product of chemical concentration (mg g À1 ) and SAR (g cm À2 yr À1 ) data while enrichment factor (EF)s were employed to distinguish between natural and anthropogenic sources of geochemical elements (Binford, 1990). The EF method is calculated on element concentrations, with Al used as a passive tracer element to reflect the natural contribution of geochemical inputs (EF function = (M/Al) sample/(M/Al) basal core sample (where M is the metal studied)) (Binford, 1990;Norton et al, 1992). Stable C and N isotopic measurements and C:N ratios were used to determine the source(s) of organic matter (Cerling, 1999;Wolfe et al, 2001;Meyers, 2003), based on procedures described in Lohse et al (2000), Talbot (2001) and Wolfe et al (2001).…”