Evidence of fine‐grained sediment transport and deposition in Sheboygan River, Wisconsin, based on sediment core chemical tracer profiles

Abstract

Fine‐grained sediment transport and deposition is observed in nine dated sediment cores obtained from the Sheboygan River. The sediment cores were dated by 137Cs and 210Pb methods. Sediment dating was supported by a polychlorinated biphenyl (PCB) analysis and U.S. Army Corps of Engineers (USACE) hydrographic surveys from 1976 to 2002. Plots of 137Cs activity versus depth show distinct peaks related to peak Sheboygan River discharges in the years 1966, 1975, 1979, and 1989. These peaks result from the scouring of sediments during storm discharges and the increased deposition of the fine‐grained fraction of particles, including colloidal clay particles (associated with 137Cs and, to some extent, PCBs), in place of the scoured sediments. Core SR1a, upstream of the Pennsylvania Avenue Bridge, and cores SR5‐SR8, farther downstream, show continuous sedimentation (1.2–11.8 cm/yr) since the late 1950s, whereas net sediment accumulation virtually ceased after 1988 at the intermediate sites of cores SR1–SR4. The maximum PCB concentration (161 ppm) occurs in 1969 in core SR4.

Sedimentary records of non-Aroclor and Aroclor PCB mixtures in the Great Lakes

“…The high level of ΣPCBs from 1940 to 1980 for the IHSC core is probably due to the constant utilization of Aroclor 1248 in high volume by the local industries until the production was banned. The local use of Aroclors has been previously observed in the sedimentary records (Bzdusek et al, 2005; Li et al, 2005). …”

PCB Congeners and Dechlorination in Sediments of Sheboygan River, Wisconsin, Determined by Matrix Factorization

“…It should be noted that samples SR1a-7 to SR1a-13 had higher amounts of sand and less organic matter, as measured by loss on ignition (2-5%), than other samples (45), perhaps enhancing downward migration. PCB congener profiles for core SR4 samples are shown in Plots of PCB congener versus concentration for various samples from core SR7 are shown in Figure 5.…”

“…Dating Analysis. Results of the dating analysis are described in Bzdusek et al (45). In short, core SR1a, upstream of the Pennsylvania Avenue Bridge, and cores SR5- Aroclors 1248 and 1254.…”

Record of anthropogenic impact on the Western Irish Sea mud belt

“…The presence of undisturbed shell horizons and bioturbation (see Figure 4) validated the undisturbed nature of the core, except at the edges with vibrocores successfully used previously for comparable studies (Santschi et al, 2001;Chillrud et al, 2003;Bzdusek et al, 2005;Jaeger et al, 2009;Nitsche et al, 2010) .…”

“…The vessel monitoring system (VMS) automatically collects positional information from fishing vessels. The system has been installed on all fishing vessels >24 m since January 2000 according to European Commission legislation, and on vessels >18 and >15 m since 2004and 2005, respectively (Gerritsen and Lordan, 2011. Gerritsen and Lordan (2011) and Gerritsen et al (2013) provide further information on VMS methods of analysis and processing.…”