Turbulence in the presence of internal waves in the bottom boundary layer of the California inner shelf

Turbulence measurements were collected in the bottom boundary layer of the California inner shelf near Point Sal, CA, for 2 months during summer 2015. The water column at Point Sal is stratified by temperature, and internal bores propagate through the region regularly. We collected velocity, temperature, and turbulence data on the inner shelf at a 30-m deep site. We estimated the turbulent shear production (P), turbulent dissipation rate (ε), and vertical diffusive transport (T), to investigate the near-bed local turbulent kinetic energy (TKE) budget. We observed that the local TKE budget showed an approximate balance (P?≈?ε) during the observational period, and that buoyancy generally did not affect the TKE balance. On a finer resolution timescale, we explored the balance between dissipation and models for production and observed that internal waves did not affect the balance in TKE at this depth.     

Now I See: Photovisualization to Support Agricultural Climate Adaptation

To remain viable, agricultural producers will need to adapt to changing climatic conditions in coming decades. Agricultural advisers play an important role in helping producers decide to adopt appropriate adaptation practices. Photovisualizations have the potential to complement currently utilized outreach and education strategies. This research uses a focus group approach to explore (1) whether photovisualizations can aid in decision-making about climate change adaptation, and (2) what characteristics of photovisualizations are most effective at conveying spatial aspects of adaptation practices. We found that photovisualizations generate rich discussions about ecological and economic effects as well as tradeoffs associated with climate adaptation practices. To have the greatest impact, photovisualizations should be used when producers are considering implementing high-cost or high-risk projects, when practices are likely to dramatically change the visual landscape, or when a practice is unfamiliar to a producer.     

The ageing body and the homespace

Summary In this paper, findings are presented from a qualitative study of older people's lives in Newcastle upon Tyne, England, to examine the place of the body in everyday meanings and constructions of ageing. Focusing on the home, we show how notions about gendered as well as ageing bodies affect the use and meaning of space.     

How conservative is arsenic in coastal marine environments? A study in Irish coastal waters

The conservative potential of arsenic in the relatively pristine waters of Galway Bay, an estuarine system in the west of Ireland, is examined through the inter-seasonal variations in the distribution of its total, hydride and non-hydride fractions. The arsenic concentrations in Galway Bay and local fresh water sources at all seasons were lower than what is considered the natural seawater concentration of 2 μg L⁻¹ (27 nM). The effects of physical mixing, biological uptake and regeneration of arsenic on its distribution are considered. The degree of biological uptake and regeneration of the element are determined by a first order speciation between total arsenic (a small part of which should be of organic origin) and hydride arsenic (mostly of inorganic origin). The structural similarity of arsenic species to phosphate in seawater causes arsenic to be taken up by biota, which then have to detoxify it, so results are presented against phosphate to determine the degree of biological transformation of arsenic at different seasons. An in-house, batch type system of hydride generation coupled to electro-thermal atomic absorption spectrometry is used for the analysis of arsenic; this is preceded by UV-digestion prior to the measurement of total arsenic. Results show only a small association of arsenic with phosphate but a near linear, positive distribution pattern between arsenic and salinity in Galway Bay (R² ∼ 0.6), which is reproducible among seasons, indicating that in this environment the biological uptake of arsenic is likely to be a much slower process than the physical mixing of the water masses.     

Isotopic variation (δN, δC,and δS) with body size in post-larval estuarine consumers

Stable isotope analyses were conducted on fish and crabs in Apalachicola Bay, Florida (USA) to determine whether δ¹⁵N values are correlated with length within these species. Our objective was to define the smallest trophic unit of the system as a prelude to further isotopic evaluations of consumer trophic level in Apalachicola Bay. In some cases, the smallest trophic unit is the individual species; however, previous gut content analysis on organisms in this system indicated that subdivision by size class within species might be required. However, over the size ranges observed, there was no systematic change in the δ¹⁵N values of individual consumers. Analysis of the δ¹³C and δ³⁴S values of these species reveal no obvious shifts in the utilization of organic matter sources with length that could be obscuring a trend in the δ¹⁵N signal. We find no isotopic evidence for a systematic trophic level increase within the species examined over the size ranges observed in this estuary. These results indicate that species rather than size class is the best predictor of trophic habit among these Apalachicola Bay consumers.     

Molecular characterization of dissolved organic matter (DOM) along a river to ocean transect of the lower Chesapeake Bay by ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

In this study, electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) is utilized to molecularly characterize DOM as it is transported along a river to estuary to ocean transect of the lower Chesapeake Bay system. The ultrahigh resolving power (greater than 500,000) and mass accuracy of FTICR-MS allow for the resolution of the thousands of components in a single DOM sample, and can therefore elucidate the molecular-level changes that occur during DOM transformation from a terrestrial location to the marine environment. An important feature of FTICR-MS is that its sensitivity allows for direct analysis of low salinity samples without employing the traditional concentration approaches involving C₁₈ extraction or ultrafiltration. To evaluate the advantages of using direct analysis, a C₁₈ extract of riverine water is compared to its whole, unfractionated water, and it was determined that the C₁₈ extraction is selective in that it eliminates two major series of compounds. One group is aliphatic amines/amides that are not adsorbed to the C₁₈ disk because they exist as positive ions prior to extraction. The second group is tannin-like compounds with higher oxygen contents and a more polar quality that also allow them not to be adsorbed to the C₁₈ disk. This direct approach could not be used for brackish/saline waters, so the C₁₈ method is resorted to for those samples. Along the subject transect, a significant difference is observed in the molecular composition of DOM, as determined from assigned molecular formulas. The DOM tends to become more aliphatic and contain lower abundances of oxygen-rich molecules as one progresses from inshore to the offshore. A considerable amount of molecular formula overlap does exist between samples from sites along the transect. This can be explained as either the presence of refractory material that persists throughout the transect, due to its resistance to degradation, or that the assigned molecular formulas are the same but the chemical structures are different. ESI-FTICR-MS is a powerful technique for the investigation of DOM and has the ability to detect compositional variations along the river to ocean transect. Visualization tools such as two dimensional and three dimensional van Krevelen diagrams greatly assist in highlighting the shift from the more aromatic, terrestrial DOM to the more aliphatic, marine DOM.     

Stumbling upon history: collective memory and the urban landscape

Notable historical events are most commonly commemorated by state-sanctioned monumental structures designed as collective memorials. In contrast, this essay attends to Gunter Demnig’s Stumbling Stones, a countermemorial to the Holocaust, set in the vernacular landscape of cities throughout Europe. As participants in a trip sponsored by the German government, bringing American Jews to the capital city of Berlin, we reflect upon our experiences as we question the narrative differences between monumental memorials and countermemorials. This ethnographic study moves the reader through the crowded boulevards of Germany’s capital city, past historical sites and into museums where we share space and commune with the voices of the past that have come to define individual and collective memory in Berlin.