Variability of Sea-Ice Extent in Baffin Bay over the Last Millennium

Comparison of an ice core glaciochemical time-series developed from thePenny Ice Cap (PIC), Baffin Island and monthly sea-ice extent reveals astatisticallysignificant inverse relationship between changes in Baffin Bay spring sea-iceextent andPenny Ice Cap sea-salt concentrations for the period 1901–1990 AD.Empiricalorthogonal function analysis demonstrates the joint behavior between changesin PICsea-salt concentrations, sea-ice extent, and changes in North Atlanticatmosphericcirculation. Our results suggest that sea-salt concentrations in snowpreserved on thePIC reflect local to regional springtime sea-ice coverage. The PIC sea-saltrecord/sea-ice relationship is further supported by decadal and century scalecomparisonwith other paleoclimate records of eastern Arctic climate change over the last700 years. Our sea-salt record suggests that, while the turn of the century wascharacterized bygenerally milder sea-ice conditions in Baffin Bay, the last few decades ofsea-ice extentlie within Little Ice Age variability and correspond to instrumental recordsof lowertemperatures in the Eastern Canadian Arctic over the past three decades.     

Bioremediation of Chlorinated Pesticides in Field‐Contaminated Soils and Suitability of Tenax Solid‐Phase Extraction as a Predictor of Its Effectiveness

Bioremediation is intensively studied today as a treatment method for soil contaminated with chlorinated pesticides, chemicals counted among persistent organic pollutants. In the presented work, results of desorption kinetics study using consecutive Tenax TA solid phase extraction (SPE) were tested as predictors of 3‐wk anaerobic soil bioremediation effectiveness for chlorinated pesticides γ‐HCH, DDT, and methoxychlor. Field‐contaminated samples were used in these experiments, and conditions of bioremediation tests were based on previous research. Amounts of pesticides removed during bioremediation (43–98% of initial concentrations) were in most cases much larger (average ratio 1.37) than rapidly desorbing fractions estimated in SPE using two‐compartment model of desorption kinetics. The scatter of results was also considerable (standard deviation 0.45). However, there was a statistically significant correlation between amounts removed and rapidly desorbing fractions (R² = 0.64), indicating a relationship between degradability and desorbability. Nonetheless, determination of rapidly desorbing fractions was considered rather a poor indicator of soil bioremediation efficiency for chlorinated pesticides. The total amounts of pesticides desorbed by Tenax in 72 h performed better in this respect (R² = 0.73, fraction removed/desorbed = 1.10 ± 0.20, average ± standard deviation). Disappearance of DDT during bioremediation was accompanied by DDD formation but this was considerably lower than results expected from stoichiometry.     

Holocene floristic diversity and richness in northeast Norway revealed by sedimentary ancient DNA (sedaDNA) and pollen

We present a Holocene record of floristic diversity and environmental change for the central Varanger Peninsula, Finnmark, based on ancient DNA extracted from the sediments of a small lake (sedaDNA). The record covers the period c. 10 700 to 3300 cal. a BP and is complemented by pollen data. Measures of species richness, sample evenness and beta diversity were calculated based on sedaDNA sampling intervals and 1000‐year time windows. We identified 101 vascular plant and 17 bryophyte taxa, a high proportion (86%) of which are still growing within the region today. The high species richness (>60 taxa) observed in the Early Holocene, including representatives from all important plant functional groups, shows that modern shrub‐tundra communities, and much of their species complement, were in place as early as c. 10 700 cal. a BP. We infer that postglacial colonization of the area occurred prior to the full Holocene, during the Pleistocene‐Holocene transition, Younger Dryas stadial or earlier. Abundant DNA of the extra‐limital aquatic plant Callitriche hermaphroditica suggests it expanded its range northward between c. 10 200 and 9600 cal. a BP, when summers were warmer than present. High values of Pinus DNA occur throughout the record, but we cannot say with certainty if they represent prior local presence; however, pollen influx values >500 grains cm^?2 a^?1 between c. 8000 and 7300 cal. a BP strongly suggest the presence of pine woodland during this period. As the site lies beyond the modern tree limit of pine, it is likely that this expansion also reflects a response to warmer Early Holocene summers.     

The Bølling‐age Blomvåg Beds,western Norway: implications for the Older Dryas glacial re‐advance and the age of the deglaciation

Blomvåg, on the western coast of Norway north of Bergen, is a classical site in Norwegian Quaternary science. Foreshore marine sediments, named the Blomvåg Beds and now dated to the Bølling‐Allerød from 14.8 to 13.3 cal. ka BP, contain the richest Lateglacial bone fauna in Norway, numerous mollusc shells, driftwood, and flint that some archaeologists consider as the oldest traces of humans in Norway. The main theme of this paper is that the Blomvåg Beds are overlain by a compact diamicton, named the Ulvøy Diamicton, which was interpreted previously as a basal till deposited during a glacial re‐advance into the ocean during the Older Dryas (c. 14 cal. ka BP). Sediment sections of the Blomvåg Beds and the Ulvøy Diamicton were exposed in ditches in a cemetery that was constructed in 1941–42 and have subsequently not been accessible. A number of radiocarbon and cosmogenic ¹⁰Be exposure ages demonstrate that the diamicton is not likely to be a till because minimum deglaciation ages (14.8–14.5 cal. ka BP) from the vicinity pre‐date the Ulvøy Diamicton. We now consider that sea ice and icebergs formed the Ulvøy Diamicton during the Younger Dryas. The Scandinavian Ice Sheet margin was located on the outermost coastal islands between at least c. 18.5 and 14.8 cal. ka BP; however, no ice‐marginal deposits have been found offshore from this long period. The Older Dryas ice margin in this area was located slightly inside the Younger Dryas margin, whereas farther south it was located slightly beyond the Younger Dryas margin.     

Real-time precise point positioning augmented with high-resolution numerical weather prediction model

GPS Solutions - The tropospheric delay is one of the major error sources in precise point positioning (PPP), affecting the accuracy and precision of estimated coordinates and convergence time,...     

Evaluation of a Novel Control Method on Biofilm Parameters in an Aerated Submerged Fixed‐bed Biofilm Reactor

One of the critical technological parameter in operation of aerated submerged fixed‐bed biofilm reactor (ASFBBR) is the control over process of biofilm detachment. Both, an excessive growth of biomass with its accumulation in the bioreactor and an exceeded biofilm detachment rate, cause serious operational and technological problems. The studies presented in this paper demonstrate that in an ASFBBR reactor with a PVC bed carrier media, an effective way to maintain a proper shear stress acting on the biofilm and causing its detachment could be an internal recirculation of wastewater instead of backwashing with wastewater or air flushing. In case of polishing of oil‐refinery wastewater with average COD loading rate equal to 9 g COD/(m² day), the minimum value of the hydraulic loading rate in such reactor is 1.9 m³/(m² h), at which there was no excessive growth of biofilms. Despite a significant decrease of the biofilms thickness and amount of biomass in the reactor, there was no significant decline in the efficiency of pollutant removal from oil‐refinery wastewater, which made it possible to obtain the quality of effluent at the outlet of the bioreactor significantly below the water permits and standards.     

Optimum stochastic modeling for GNSS tropospheric delay estimation in real-time

GPS Solutions - In GNSS data processing, the station height, receiver clock and tropospheric delay (ZTD) are highly correlated to each other. Although the zenith hydrostatic delay of the...     

The assessment of environmental pollution caused by mining and metallurgy wastes from highly polluted post-industrial regions in Southern Poland

Stored metallurgy and mining wastes contain relatively high amounts of potentially toxic elements. To monitor the distribution of contaminants originating from dumps, the chemical and physical properties of the wastes must be characterised. In this study, the chemical properties of wastes deposited in two different locations in Southern Poland (Szklary and Zloty Stok) were evaluated. Heaps located in Zloty Stok contain wastes from gold mineralisation comprising arsenic while wastes in Szklary originate from a factory that produced an iron-nickel alloy. In Szklary the total concentrations of Ca, Mg, Fe, Zn, Mn, Cr, Co, Cu, Ni, Tl, Ag, Cd and Pb were determined, while in Zloty Stok also As is an important contaminant. To assess the risk of contamination of the surrounding environment and to select the proper method for removing the contaminants, information on the distribution of elements between operationally defined phases must be obtained. For this purpose, a six-step sequential extraction was used. The mobility of most elements in the wastes from Szklary and Zloty Stok was relatively low; however, the large amount of As, 40–180 mg L^?1, that could be released to environment in case of Zloty Stok was high. The results of fractionation studies indicated that Ag, Cd, Tl, Co, Cu, Cr, Pb, Zn and Mn may be released into environment under low pH and low redox potential conditions, which can be induced by bacterial activity.