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Norton SA, Amirbahman A, Bacon L, Ewing HA, Novak M, Nurse A, Retelle M, Stager JC, Yates M. 2019. Chemical, biological, and trophic status of temperate lakes can be strongly influenced by the presence of late-glacial marine sediments. Lake Reserv Manage. 36:14–30. Lake Auburn, Maine, is a water supply for 60,000 people. Unusual silt/clay sediment, >4 m thick, occurs 15 cm below gyttja in deep water cores. We characterized cores taken in 2015 and 2016 (57 and 425 cm long, respectively), from 35 m. We determined 137Cs, 210Pb, and 206P/204Pb ratios to establish chronology for the cores and to link them stratigraphically. At least 1.1 m of sediment has accumulated since European settlement due to watershed erosion from land clearance and disturbance from about 1750 onward. The increased lake level from dams established in 1851 and the 1950–1960s has caused shoreline erosion. Extraction of sediment with HCl, scanning electron microscopy, and energy-dispersive spectroscopy analyses confirmed the presence of apatite (Ca5(PO4)3(OH)) for at least the upper 3.5 m of sediment. The apatite is soluble because of the circumneutral pH and relatively low Ca2+ concentrations. This modern sediment is derived from postglacial marine silt/clay sediment and represents a rarely considered internal source of P that predisposes the lake's water column to higher total P, rendering it more susceptible to episodic eutrophication from stresses including higher temperatures, more frequent high-intensity weather phenomena, and longer ice-free periods with stronger and longer stratification. This previously unrecognized source of P must be considered in water quality management, including chemical mitigation such as aluminum addition, lake level manipulation, and watershed erosion control. Similar situations likely exist in other coastal lakes in postglacial terrain that was inundated during deglaciation, and in inland lakes receiving sediment directly during deglaciation. [ABSTRACT FROM AUTHOR]

The nuisance species Didymosphenia geminata is thought to have been spread by humans across North and South America and New Zealand. This diatom is of interest for its ability to form thick benthic mats in streams, altering ecosystem properties. Little is known, however, about its historic distribution and the parameters that are associated with its growth in absence of human influence. Although it is considered to be native to Arctic regions, its status at lower latitudes is uncertain. We measured the concentration of D. geminata cells in a sediment core from Beauty Lake, WY, a record that dates back to the Late Pleistocene. From approximately 11,233–8750 years before present (ybp), a Didymosphenia maximum persisted, with peak concentrations of 3774±20 valves/mg dry sediment (9985 ybp). The period corresponded to low flux of Al, Fe, and P within the sediments, supporting the importance of low P in controlling distribution. Furthermore, we demonstrate that D. geminata arrived in Beauty Lake shortly after deglaciation of the watershed. This species arrived without the aid of human introduction, implying an inherent ability for dispersal. We also examined the sediment record of nearby Yellowstone Lake, WY for the presence of D. geminata during the same time interval, but cells were not detected. The Yellowstone caldera is composed of rhyolite, a rock rich in silica (Si) and modest amounts of P. We conclude that both watersheds were exposed to the potential colonization by D. geminata, but just as the North Island of New Zealand has not been able to support this diatom because of P concentrations exceeding a threshold, the Yellowstone watershed is not able to support it either. [ABSTRACT FROM AUTHOR]

Survey instruments have been developed to measure whether someone claims to be religious but do not address the degree to which someone is satisfied with their religious commitment. The Religious Surrender and Attendance Satisfaction Scale (RSASS) was revised to measure both a person's level of religious commitment and satisfaction with level of religious commitment. This study was conducted to determine initial validity for the satisfaction portion of the RSASS. Construct validity measures provided initial confirmation of the utility of RSASS as a measure of satisfaction with religious commitment, that can be used by nurses in practice and research.