Emerging Contaminants at a Closed and an Operating Landfill in Oklahoma

Landfills are the final depositories for a wide range of solid waste from both residential and commercial sources, and therefore have the potential to produce leachate containing many organic compounds found in consumer products such as pharmaceuticals, plasticizers, disinfectants, cleaning agents, fire retardants, flavorings, and preservatives, known as emerging contaminants (ECs). Landfill leachate was sampled from landfill cells of three different age ranges from two landfills in Central Oklahoma. Samples were collected from an old cell containing solid waste greater than 25 years old, an intermediate age cell with solid waste between 16 and 3 years old, and operating cell with solid waste less than 5 years old to investigate the chemical variability and persistence of selected ECs in landfill leachate of differing age sources. Twenty‐eight of 69 analyzed ECs were detected in one or more samples from the three leachate sources. Detected ECs ranged in concentration from 0.11 to 114 μg/L and included 4 fecal and plant sterols, 13 household\industrial, 7 hydrocarbon, and 4 pesticide compounds. Four ECs were solely detected in the oldest leachate sample, two ECs were solely detected in the intermediate leachate sample, and no ECs were solely detected in the youngest leachate sample. Eleven ECs were commonly detected in all three leachate samples and are an indication of the contents of solid waste deposited over several decades and the relative resistance of some ECs to natural attenuation processes in and near landfills.     

Source term balance in a severe storm in the Southern North Sea

This paper presents the results of a wave hindcast of a severe storm in the Southern North Sea to verify recently developed deep and shallow water source terms. The work was carried out in the framework of the ONR funded NOPP project (Tolman et al. 2013) in which deep and shallow water source terms were developed for use in third-generation wave prediction models. These deep water source terms for whitecapping, wind input and nonlinear interactions were developed, implemented and tested primarily in the WAVEWATCH III model, whereas shallow water source terms for depth-limited wave breaking and triad interactions were developed, implemented and tested primarily in the SWAN wave model. So far, the new deep-water source terms for whitecapping were not fully tested in shallow environments. Similarly, the shallow water source terms were not yet tested in large inter-mediate depth areas like the North Sea. As a first step in assessing the performance of these newly developed source terms, the source term balance and the effect of different physical settings on the prediction of wave heights and wave periods in the relatively shallow North Sea was analysed. The December 2013 storm was hindcast with a SWAN model implementation for the North Sea. Spectral wave boundary conditions were obtained from an Atlantic Ocean WAVEWATCH III model implementation and the model was driven by hourly CFSR wind fields. In the southern part of the North Sea, current and water level effects were included. The hindcast was performed with five different settings for whitecapping, viz. three Komen type whitecapping formulations, the saturation-based whitecapping by Van der Westhuysen et al. (2007) and the recently developed ST6 whitecapping as described by Zieger et al. (2015). Results of the wave hindcast were compared with buoy measurements at location K13 collected by the Dutch Ministry of Transport and Public Works. An analysis was made of the source term balance at three locations, the deep water location North Cormorant, the inter-mediate depth location K13 and at location Wielingen, a shallow water location close to the Dutch coast. The results indicate that at deep water the source terms for wind input, whitecapping and nonlinear four-wave interactions are of the same magnitude. At the inter-mediate depth location K13, bottom friction plays a significant role, whereas at the shallow water location Wielingen also depth-limited wave breaking becomes important.     

Marine debris from the Oregon Dungeness crab fishery recovered in the Northwestern Hawaiian Islands: identification and oceanic drift paths

Two Dungeness crab trap tags and floats lost off the State of Oregon, USA during the 2006-2007 fishing season were recovered 4years later in the Northwestern Hawaiian Islands (NWHI): on Lisianski Island on July 15, 2010; and on Kure Atoll on December 10, 2010. This is the first documented recovery of marine debris from Oregon fisheries in the NWHI. We simulate the oceanic drift tracks of the derelict fishing gear with the Ocean Surface Current Simulator (OSCURS) model using estimated loss dates in Oregon based on interviews with the crab trap owners and known recovery sites and dates in the NWHI. These data confirm the US Pacific Northwest as a source of marine debris deposited in the NWHI and provide enhanced understanding of the oceanic drift pathways of marine debris in the North Pacific Ocean.     

Rapid 20th century environmental change on northeastern Baffin Island,Arctic Canada inferred from a multi-proxy lacustrine record

The Arctic has a disproportionately large response to changes in radiative forcing of climate, and arctic lacustrine ecosystems respond sensitively to these changes. The goal of this research is to generate high-resolution climate records for the past two millennia using multiple proxies in order to place 20th and 21st century climate and environmental change into a long-term context. We use a ¹⁴C- and ²¹⁰Pb-dated surface core from Lake CF8 on northeastern Baffin Island, Arctic Canada to generate a high-resolution multiproxy reconstruction of climate and environmental change. Throughout the late Holocene, primary productivity in Lake CF8 was low, but increased almost 20-fold in the past 200 years. Insect (Chironomidae) assemblages also show dramatic changes since 1950 AD, with cold stenothermous chironomid taxa disappearing from the record altogether. These changes in productivity and chironomid assemblages are unprecedented in the past 5,000 years. The dramatic ecological shifts that occurred at Lake CF8 have also been observed elsewhere in the Arctic, and will likely continue at ever-increasing rates as anthropogenic inputs of green house gases continue to cause climate warming and enhanced lacustrine primary production.     

Ecology of testate amoebae (thecamoebians) in subtropical Florida lakes

Fifty-seven surface sediment samples from 35 Florida lakes were collected to study testate amoebae. Seven genera, 17 species, and 28 strains were identified in the 46 sediment samples from 31 lakes that contained testate rhizopods. Seven species accounted for ≥90% of the individuals in all samples. Sediment total phosphorus (TPsed), organic matter (OM), and total carbon:total nitrogen ratio (TC:TN) were measured to assess the effect of these variables on thecamoebian assemblages. OM content was the only sediment variable that influenced presence/absence of thecamoebians. Samples with <5% OM contained no thecamoebians. Lakes with multiple surface sediment samples showed high Morisita–Horn similarity values (0.74–0.99), indicating that all sites at which samples were collected in a lake provided representative thecamoebian assemblages. No relationship was observed between thecamoebian diversity indices and sediment variables. Lake trophic state and pH were examined to explore potential water column influences on thecamoebian communities. Highest thecamoebian diversity indices were found in mesotrophic to eutrophic lakes with pH near 8.0. These results suggest that water column conditions have a greater influence on thecamoebian assemblages than do sediment variables. We used multivariate analysis to evaluate the relations between water quality variables and testate rhizopod assemblages. Canonical correspondence analysis (CCA) showed that alkalinity and pH are the water column variables that most influence the relative abundance of species. Thecamoebians thus hold promise as bioindicators of acidification in Florida lakes. Thecamoebian remains in lake sediment cores should be useful to infer past anthropogenic shifts in lake pH.     

Spitzer IRAC infrared colours of submillimetre-bright galaxies

High-redshift submillimetre-bright galaxies identified by blank field surveys at millimetre and submillimetre wavelengths appear in the region of the Infra Red Array Camera (IRAC) colour–colour diagrams previously identified as the domain of luminous active galactic nuclei (AGNs). Our analysis using a set of empirical and theoretical dusty starburst spectral energy distribution (SED) models shows that power-law continuum sources associated with hot dust heated by young (≲100 Myr old), extreme starbursts at z > 2 also occupy the same general area as AGNs in the IRAC colour–colour plots. A detailed comparison of the IRAC colours and SEDs demonstrates that the two populations are distinct from each other, with submillimetre-bright galaxies having a systematically flatter IRAC spectrum (≳1 mag bluer in the observed [4.5]–[8.0] colour). Only about 20 per cent of the objects overlap in the colour–colour plots, and this low fraction suggests that submillimetre galaxies powered by a dust-obscured AGN are not common. The red infrared colours of the submillimetre galaxies are distinct from those of the ubiquitous foreground IRAC sources, and we propose a set of infrared colour selection criteria for identifying SMG counterparts that can be used even in the absence of radio or Multiband Imaging Photometer for Spitzer (MIPS) 24 μm data.     

Moraine pebbles and boulders yield indistinguishable Be ages: A case study from Colorado, USA

Cosmogenic exposure dating of moraines during the last two decades has vastly improved knowledge on the timing of glaciation worldwide. Due to a variety of geologic complications, such as moraine degradation, snow cover, bedrock erosion and isotopic inheritance, samples from multiple large boulders (>1–2 m) often lead to the most accurate moraine age assignments. However, in many cases, large boulders are not available on moraines of interest. Here, I test the suitability of pebble collections from moraine crest surfaces as a sample type for exposure dating. Twenty-two ¹⁰Be ages from two Pleistocene lateral moraine crests in Pine Creek valley in the upper Arkansas River basin, Colorado, were calculated from both pebble and boulder samples. Ten ¹⁰Be ages from a single-crested Bull Lake lateral moraine range between 3 and 72 ka, with no statistical difference between pebble (n = 5) and boulder (n = 5) ages. The lack of a cluster of ¹⁰Be ages suggests that moraine degradation has led to anomalously young exposure ages. Twelve ¹⁰Be ages from a single-crested Pinedale lateral moraine have a bimodal age distribution; one mode is 22.0 ± 1.4 ka (three boulders, two pebble collections), the other is 15.2 ± 0.9 ka (two boulders, five pebble collections). The interpretation of the two age modes is that two glacier maxima of similar extent were attained during the late Pleistocene. Regardless of moraine age interpretations, that ¹⁰Be ages from pebble collections and boulders are indistinguishable on moraines of two different ages, and in two different age modes of the Pinedale moraine, suggests that pebble collections from moraine crests may serve as a suitable sample type in some settings.     

Land cover effects on runoff patterns in eastern Piedmont (USA) watersheds

Physiography and land cover determine the hydrologic response of watersheds to climatic events. However, vast differences in climate regimes and variation of landscape attributes among watersheds (including size) have prevented the establishment of general relationships between land cover and runoff patterns across broad scales. This paper addresses these difficulties by using power spectral analysis to characterize area‐normalized runoff patterns and then compare these patterns with landscape features among watersheds within the same physiographic region. We assembled long‐term precipitation and runoff data for 87 watersheds (first to seventh order) within the eastern Piedmont (USA) that contained a wide variety of land cover types, collected environmental data for each watershed, and compared the datasets using a variety of statistical measures. The effect of land cover on runoff patterns was confirmed. Urban‐dominated watersheds were flashier and had less hydrologic memory compared with forest‐dominated watersheds, whereas watersheds with high wetland coverage had greater hydrologic memory. We also detected a 10–15% urban threshold above which urban coverage became the dominant control on runoff patterns. When spectral properties of runoff were compared across stream orders, a threshold after the third order was detected at which watershed processes became dominant over precipitation regime in determining runoff patterns. Finally, we present a matrix that characterizes the hydrologic signatures of rivers based on precipitation versus landscape effects and low‐frequency versus high‐frequency events. The concepts and methods presented can be generally applied to all river systems to characterize multiscale patterns of watershed runoff. Copyright © 2013 John Wiley & Sons, Ltd.