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1. Regional and Local Stratigraphic Markers in Three Hudson River Cores Taken Near Peekskill, New York: LWB4-3

   McCann, B. ; Abbott, D. H. ; Bostick, B. C. ; Diallo, M. B. ; Abdul, B. ; Adeghe, S. ( December 2018 , American Geophysical Union, Fall Meeting 2018, abstract #B53I-2172)

   We have been studying the stratigraphy of core LWB4-3 taken in 2001 in the Hudson River near Peekskill New York along the transit path of the Peekskill meteorite. We measured magnetic susceptibility at 1 cm intervals down to 108 cm and chemical composition at 1 cm intervals down to 192 cm. The highest magnetic susceptibility occurs at 18 cm depth. This inferred Peekskill meteorite layer with high magnetic susceptibility contains locally higher concentrations of Ni and higher Ni/Cr ratios. Our identification of the high susceptibility, high Ni layer as coming from the fall of the Peekskill meteorite in 1991 is consistent with a uniform sedimentation rate in the core and the occurrence of the base of modern Pb at > 192 cm depth (below the base of the core). From previous work on cores from Central Park Lake, the base of modern Pb represents the year 1880 A.D. We also found other prominent horizons whose ages fit a linear sedimentation rate model. We found a peak in As, whose inferred age matches 1988, the year when Pb and Cu arsenide were banned as pesticides. In addition, we found a modest susceptibility peak above the Peekskill layer whose inferred age matches that of the 1996 Hudson River flood. We found a second modest susceptibility peak below the Peekskill layer whose inferred age matches that of the "Great Catskill Toilet Flush Flood" in 1980. This layer also has local maxima in Pb, Cu and Ca. The Catskills contain Devonian limestone that might be the source of excess Ca. Copper Mine brook is located on the east bank of the Hudson north of Peekskill and is a potential source of Cu during floods. Our core exhibits a distinct increase in Ca content starting at 20 cm depth and increasing towards the top of the core. This prominent increase in Ca may represent 1991 A.D, the time of the invasion of the zebra mussel. We are testing this depth range for calcium carbonate to determine if the upward calcium increase could be from the invasion of the zebra mussel, increased soil erosion or anthropogenic pollution. We found a peak in Pb at 112 cm depth whose inferred age matches that of the cessation of incinerator burning in 1938. Cs-137 and Pb-210 ages are in progress and may be available by the time of the meeting. We also saw an unusual horizon at a depth of 118 cm with a high peak of Cr. This would be approximately the year 1936, which corresponds to a large flood in the Hudson. 

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2. Regional and Local Stratigraphic Markers in Three Hudson River Cores Taken Near Peekskill, New York: Core LWB 4-5

   Abdul, B. ; Adeghe, S. ; Diallo, M. B. ; McCann, B. ; Abbott, D. H. ; Bostick, B. C. ; Chang, C. ; Block, K. A. ( December 2018 , American Geophysical Union, Fall Meeting 2018, abstract #B53I-2167)

   We have been studying the stratigraphy of core LWB 4-5 taken in 2001 in the Hudson River 1.5 km north of the transit of the Peekskill meteorite in October 1992. We measured magnetic susceptibility and elemental composition at 1 cm intervals down to 50 cm and then at 5 cm intervals down to 108 cm. Magnetic susceptibilities are unusually high (above 20 cgs units) from 12-19 cm and again at 31 cm. The level at 31 cm contains mm-sized fragments of Fe oxide. X-Ray Fluorescence spectroscopy revealed high Ni/Cr levels concentrated from 9-11 cm and again below 97 cm. We found tektite-like spheroids, dumbbells and teardrops from 8-15 cm depth. They are glasses and they contain appreciable K, consistent with an origin as true tektites but we have not identified the source. Overall, we interpret the high susceptibility, high Ni/Cr and possibly tektite bearing layer as a resulting from the fall of one of the bodies postulated to have fallen with the Peekskill meteorite in 1992. A 1992 age for the top of the Peekskill layer at 8-9 cm depth is consistent with a uniform sedimentation rate in the core and the occurrence of the base of modern Pb at 97 cm depth. From previous work on cores from Central Park Lake, the base of modern Pb represents the year 1880 A.D. We also found other prominent horizons whose ages fit a linear sedimentation rate model. We found a step change in As/Pb ratio whose inferred age matches 1988, the year when Pb and Cu arsenide were banned as pesticides. Our core exhibits peaks in Ca and Sr content and a minor susceptibility peak at 17.5 depth that may represent the 1980 "Great Catskill Toilet Flush" Hudson River flood event. The Catskills contain abundant marine limestone that could serve as a source for Ca and Sr. A prominent susceptibility peak at 37.5 cm could represent a flood in 1955. We also found a peak in Pb at 50 cm depth whose inferred age matches that of the cessation of incinerator burning in 1938. 137Cs and 210Pb ages are in progress and may be available by the time of the meeting. The high Pb and As levels in parts of LWB 4-5 are supported by examination of the coarse fraction. We found two bright orange grains, both with carbon rich coatings. One grain analyses on the X-ray analyzer of an SEM as 8%C, 70% Pb, 17%As and 2% Cu. The second grain analyzes as 10% C, 43% Pb, 1% Ca, 2% P, 27% As, 4% Fe, 2% Ni, 1% Si, and 6% Zn. All analyses are in wt.% on an oxygen free basis. 

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3. Data report: calibration of XRF scanning CaCO3 estimates for the upper 30 m along the Site U1543 splice, International Ocean Discovery Program Expedition 383

   https://doi.org/10.14379/iodp.proc.383.201.2023  

   Kasuya, T. ; Iwasaki, S. ; Okazaki, Y. ( June 2023 , Proceedings of the International Ocean Discovery Program Expedition reports)

   To estimate the calcium carbonate (CaCO3) content in the Site U1543 sediment core samples retrieved during International Ocean Discovery Program (IODP) Expedition 383 at high downcore resolution, the X-ray fluorescence (XRF) scanning Ca data, at a spacing of every 10 mm downcore, were calibrated using a total of 118 coulometry-based discrete CaCO3 analyses from the upper 30 meters composite depth (mcd) along the splice. To remove the volume measurement problems of XRF and estimating CaCO3 contents quantitatively, first, raw XRF peak areas were scaled to reduce the effect resulting from the differences in efficiency at absorbing X-rays. Then, the scaled XRF scanning data were normalized to adjust the variability of the amount of XRF peak areas due to porosity and calibrated to properly estimate CaCO3 content. Based on the quality assessment, the calibrated XRF CaCO3 estimates are within ±4.50 wt% of the discrete measurements (1 standard deviation). This data report presents a discrete CaCO3 measurement data set, a normalized median-scaled XRF data set, and XRF CaCO3 estimates on the core depth below seafloor, Method A (CSF-A), and core composite depth below seafloor, Method A (CCSF-A), depth scales. 

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4. Data report: X-ray fluorescence studies of Site U1457 sediments, Laxmi Basin, Arabian Sea

   https://doi.org/10.14379/iodp.proc.355.203.2018  

   Lyle, M. ; Kulhanek, D.K. ; Bowen, M.G. ; Hahn, A. ( December 2018 , Proceedings of the International Ocean Discovery Program)

   null (Ed.)

   Bulk sediment chemistry was measured at 2 cm resolution along cores from International Ocean Discovery Program (IODP) Site U1457 using the X-ray fluorescence (XRF) core scanner at the IODP Gulf Coast Repository. The Pleistocene splice section assembled from Holes U1457A and U1457B was scanned in its entirety, and nearly continuous sediment bulk chemistry profiles were constructed to a depth of 125 m core composite depth below seafloor (CCSF). Some sections of Hole U1457C were also scanned: (1) an upper Miocene hemipelagic section and (2) a 30 m lower Paleocene section directly overlying basalt. In the Pleistocene spliced sections, 2 cm spacing represents a sampling resolution of 150–300 y, whereas in the upper Miocene section this spacing represents about 500 y between samples. We report data and acquisition conditions for major and many minor elements. We find large variability in CaCO3 content in the Pleistocene section, from around 14 to 89 wt%. We used discrete shipboard CaCO3 measurements to calibrate the XRF Ca data. CaCO3 has cyclic variability and correlates with light sediment colors. Variation in aluminosilicate elements is largely caused by changes in dilution by CaCO3. The lower part of the spliced section, presumably representing distal Indus Fan deposits, has a distinctive but more uniform composition than the upper part. 

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5. Long‐term variability and density dependence in Hudson River Dreissena populations

   https://doi.org/10.1111/fwb.13444  

   Strayer, David L. ; Fischer, David T. ; Hamilton, Stephen K. ; Malcom, Heather M. ; Pace, Michael L. ; Solomon, Christopher T. ( December 2019 , Freshwater Biology)

   We used a 27‐year record ofDreissenapopulations in the freshwater tidal Hudson River to describe interannual variation in population density, body size, and body condition; estimate long‐term variation in recruitment, survivorship, and shell growth; and assess possible controls on the populations.

   Dreissenapopulations in the Hudson have been highly variable, with interannual ranges ofc.100‐fold in abundance and biomass, and 7‐fold in mean body mass. This large interannual variation arises from both long‐term trends and 2–5‐year cycles.

   Long‐term trends include the 2008 appearance of the quagga mussel (Dreissenarostriformis), which still forms a small part (<10%) of the dreissenid community, and a decline in zebra mussel body size. The decline in body size was caused by a long‐term decline in adult survivorship rather than a decline in rates of shell growth. We could detect no long‐term trends in adult abundance or spread ofDreissenaonto soft sediments in the Hudson.

   We observed persistent, strong cycles in adult abundance and body size. These were driven by the appearance and decay of eight dominant year classes over the 27 years of our study, and were a result of temporal variation in recruitment rather than temporal variation in survivorship. The observed strongly irregular recruitment appears to arise from strong adult–larval interactions, and is consistent with previous simulation model results showing that interactions between adults and larvae can drive persistent cycling.

   We found evidence that negative density dependence affects recruitment, somatic growth, and body condition ofDreissenain the Hudson. Warm summers may also cause high adult mortality.

   We put our results into the context of a conceptual model ofDreissenapopulation dynamics, and argue that neither the dynamics nor the controls of populations of these important invaders is known satisfactorily.

    

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