GDGT Distribution in a Stratified Lake and Implications for the Application of TEX86 in Paleoenvironmental Reconstructions

We investigated the relationship between distributions of GDGTs, GDGT-based proxies and environmental factors in a stratified lake in northwestern Norway. More than 90% of isoGDGTs were produced at the bottom of the oxycline, indicating a predominance of ammonia-oxidizing Group I.1a of Thaumarchaeota, supported by high crenarchaeol/caldarchaeol ratios. Dissolved oxygen content, rather than temperature, exercised a primary control on TEX86 values. In spite of low BIT value in surface sediment, the reconstructed lake surface temperature was “cold” biased. MBT values in streams and lake surface water were significantly smaller than those in the catchment soil, suggesting in situ production of brGDGTs in streams. A rapid transition of MBT vs. temperature/pH relationships occurring at the bottom of oxycline indicated the differential production of various brGDGTs with D.O. and depths. Only within the oxycline were CBT-based pH values close to in situ pH. Our results confirm earlier studies calling for caution in applying TEX86 as a surface temperature proxy, or MBT and/or CBT for reconstructing pH, in anoxic or euxinic lakes, estuaries and ocean basins. We propose that caldarchaeol/crenarchaeol ratio, an indicator of contributions from methanogenic archaea, together with the BIT and TEX86 proxies, can help reconstruct past levels of stratification

Holocene environmental changes disclosed from anoxic fjord sediments by biomarkers and their radiocarbon content

The power and validity of compound-specific radiocarbon dating was evaluated using sediments from Saanich Inlet, Canada, in age ranging from recent to 5000 yr BP. Compounds characteristic of higher plants, phytoplankton and archaea, were isolated by preparative GC and semi-preparative HPLC. For preparative HPLC a new method was designed, to be able to rapidly isolate relatively polar and high molecular weight biomarkers. After radiocarbon analysis, compound 14C ages were calibrated to produce calendar ages, for comparison with the sediment ages and the age of the total organic carbon (TOC). Phytoplanktonic and archaeal lipids showed on average age differences with the sediment of ~800 years, consistent with published DIC reservoir ages. Because the sediment ages were known, specific reservoir ages could be determined and compared with model reservoir ages. Planktonic biomarkers showed considerable variation, while crenarchaeol, from ubiquitously occurring marine archaea, showed minor variations in reservoir age. This indicates that compound specific 14C dating of crenarchaeol proves to be a promising new dating method for marine, carbonate-poor sediments, because it was relatively easy to isolate in sufficient amounts and consistent regarding reservoir effects. An increasing relative age of the terrestrial biomarker towards recent times pointed towards an ongoing aging of the soil in the fjord environs, due to the ongoing accumulation of the refractory soil organic carbon after deglaciation of the area. The results suggest that the terrigenous organic carbon pool in temperate regions may still be increasing as a long-term response to the end of the last ice-age. A 400 year sedimentary record of the anoxic Kyllaren Fjord (West Norway) was investigated using organic geochemical, geochemical and sedimentological approaches in order to reconstruct environmental changes. The results show that in the first half of the 19th century an environmental change occurred, likely caused by a change in the precipitation regime, vegetation and/or land use. In the last century a distinct increase in primary productivity is observed, likely caused by 'natural' eutrophication due to the transformation of the fjord from an open to a confined system by the building of a partially open dam in 1954, possibly combined with anthropogenic eutrophication. Decreased delta-13C values of several biomarkers point towards enhanced carbon recycling in the fjord over the last century. The results of a similar biogeochemical study on the South Norwegian Drammensfjord, covering the last millenium, show that eutrophication already started halfway the 19th century. This was concurrent with the industrialization of sawmills and papermills along the river Drammen and upstream water bodies, which could be traced by 'coniferous' biomarkers in the sediment. The concurrent disappearance of a suite of (bi)cyclobotryococcenes from the upper fjord sediments also revealed that eutrophication likely caused the demise and eventual disappearance of the alga Botryococcus braunii from the fjord. Because of the preference of this alga for oligotrophic and slightly brackish conditions, and the possibility to easily trace these specific biomarkers, it is argued that the disappearance of this alga from a sedimentary record can serve as an palaeoenvironmental indicator for early eutrophication

A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati

The equatorial Pacific Ocean atoll islands of Kiritimati and Teraina encompass great physical, chemical and biological variability within extreme lacustrine environments. Surveys of lake chemistry and sediments revealed both intra- and inter-island variability. A survey of more than 100 lakes on Kiritimati found salinities from nearly fresh to 150 ppt with the highest values occurring within the isolated, inland portions of the island away from the influence of groundwater or extreme tides. Dissolved oxygen (DO) and pH values also showed considerable variability with a less regular spatial pattern, but were both generally inversely related to salinity. Series of lakes, progressively more isolated from marine communication, present a modern analog to the chemical and morphologic evolution of presently isolated basins. Sediments on both islands consist of interbedded red and green silt, possibly degraded bacterial mat, overlying white, mineralogenic silt precipitate. Variability may be indicative of shifts in climatological parameters such as the El Niño Southern Oscillation (ENSO) or the Pacific Intertropical Convergence Zone (ITCZ)

Can fireworks-related injuries to children during festivities be prevented?

Objective. To determine the epidemiological features and outcome of fireworks-related injuries among children 0 - 13 years old.Design. A retrospective study from the trauma registry of a children’s hospital from 2001 - 2009.Results. Fifty-five children were treated for injuries from fireworks. The mean age was 8.8 years, 78% were boys, and the largest age group was 5 - 9 years old. Firecrackers accounted for 95% of the injuries; the most commonly injured body sites were hands (44%), eyes (42%) and face (31%); 47% of the patients had more than one injury. The most common injury type was burns (67%); 25 children were admitted, mostly to the burns and ophthalmology units. The mean length of hospital stay was 3.5 days. Surgical intervention was required in 38% of the patients. Most of the fireworks accidents occurred in or around the patients’ homes. There were more fireworks-related injuries around Guy Fawkes Day (85%) than New Year’s Eve (9%).Conclusion. Consumer fireworks cause serious but preventable injuries to children, either as users or bystanders. Children and their families should be encouraged to enjoy pyrotechnical displays conducted by professionals at designated areas. All fireworks for individual private use should either be supervised by an adult or banned. Current legislation should be more strictly enforced, especially the sale to under-age children

Bacterial, Archaeal and Fungal Succession in the Forefield of a Receding Glacier

Glacier forefield chronosequences, initially composed of barren substrate after glacier retreat, are ideal locations to study primary microbial colonization and succession in a natural environment. We characterized the structure and composition of bacterial, archaeal and fungal communities in exposed rock substrates along the Damma glacier forefield in central Switzerland. Soil samples were taken along the forefield from sites ranging from fine granite sand devoid of vegetation near the glacier terminus to well-developed soils covered with vegetation. The microbial communities were studied with genetic profiling (T-RFLP) and sequencing of clone libraries. According to the T-RFLP profiles, bacteria showed a high Shannon diversity index (H) (ranging from 2.3 to 3.4) with no trend along the forefield. The major bacterial lineages were Proteobacteria, Actinobacteria, Acidobacteria, Firmicutes and Cyanobacteria. An interesting finding was that Euryarchaeota were predominantly colonizing young soils and Crenarchaeota mainly mature soils. Fungi shifted from an Ascomycota-dominated community in young soils to a more Basidiomycota-dominated community in old soils. Redundancy analysis indicated that base saturation, pH, soil C and N contents and plant coverage, all related to soil age, correlated with the microbial succession along the forefiel

Evolution of carbon fluxes during initial soil formation along the forefield of Damma glacier, Switzerland

Soil carbon (C) fluxes, soil respiration and dissolved organic carbon (DOC) leaching were explored along the young Damma glacier forefield chronosequence (7-128years) over a three-year period. To gain insight into the sources of soil CO2 effluxes, radiocarbon signatures of respired CO2 were measured and a vegetation-clipping experiment was performed. Our results showed a clear increase in soil CO2 effluxes with increasing site age from 9±1 to 160±67gCO2-Cm−2year−1, which was linked to soil C accumulation and development of vegetation cover. Seasonal variations of soil respiration were mainly driven by temperature; between 62 and 70% of annual CO2 effluxes were respired during the 4-month long summer season. Sources of soil CO2 effluxes changed along the glacier forefield. For most recently deglaciated sites, radiocarbon-based age estimates indicated ancient C to be the dominant source of soil-respired CO2. At intermediate site age (58-78years), the contribution of new plant-fixed C via rhizosphere respiration amounted up to 90%, while with further soil formation, heterotrophically respired C probably from accumulated ‘older' soil organic carbon (SOC) became increasingly important. In comparison with soil respiration, DOC leaching at 10cm depth was small, but increased similarly from 0.4±0.02 to 7.4±1.6gDOCm−2year−1 over the chronosequence. A strong rise of the ratio of SOC to secondary iron and aluminium oxides strongly suggests that increasing DOC leaching with site age results from a faster increase of the DOC source, SOC, than of the DOC sink, reactive mineral surfaces. Overall, C losses from soil by soil respiration and DOC leaching increased from 9±1 to 70±17 and further to 168±68gCm−2year−1 at the <10, 58-78, and 110-128year old sites. By comparison, total ecosystem C stocks increased from 0.2 to 1.1 and to 3.1kgCm−2 from the young to intermediate and old sites. Therefore, the ecosystem evolved from a dominance of C accumulation in the initial phase to a high throughput system. We suggest that the relatively strong increase in soil C stocks compared to C fluxes is a characteristic feature of initial soil formation on freshly exposed rock

Aesthetic Outcomes of Perineal Reconstruction with the Lotus Petal Flap

The lotus petal flap can be applied for reconstruction of extensive defects in the vulvoperineal area. Studies on aesthetic outcomes are lacking. This study aimed to fill this gap. METHODS: All patients who underwent lotus petal flap reconstruction between October 2011 and December 2015 were asked permission to have their photographs used. Two questionnaires were used: (1) the Strasser score to assess the overall aesthetic results (range 0–15) and (2) the Patient and Observer Scar Assessment Scale (POSAS; range 6–60). Six plastic surgeons and 6 laymen filled in the Strasser score and the Observer scale of the POSAS. Patients filled in the Strasser score, the Patient scale of the POSAS and scored their overall satisfaction with the aesthetic results on a Likert scale (0–10). RESULTS: The photographs of 11 patients were included. The median Strasser score of all observers of 11.9 (range 0.0–75.0) indicated a mediocre aesthetic result. The median total POSAS score of 15.6 (range 6.0–41.0) indicated an aesthetically acceptable scar. Strasser and POSAS scores of the plastic surgeons and laymen did not differ significantly from the patients’ scores. The patient satisfaction score with the aesthetic result was a median of 6.0 of 10. CONCLUSIONS: The findings indicate that, overall, patients were moderately satisfied with the aesthetic results of their lotus petal flap reconstructions, as were the plastic surgeons and laymen. For clinical practice, it is important that the plastic surgeon manages expectations carefully before surgery, as it is possible that patients might experience a rather low aesthetic outcome after perineal reconstruction

Hässeldala – a key site for Last Termination climate events in northern Europe

The Last Termination (19 000–11 000 a BP) with its rapid and distinct climate shifts provides a perfect laboratory to study the nature and regional impact of climate variability. The sedimentary succession from the ancient lake at Hässeldala Port in southern Sweden with its distinct Lateglacial/early Holocene stratigraphy (&gt;14.1–9.5 cal. ka BP) is one of the few chronologically well‐constrained, multi‐proxy sites in Europe that capture a variety of local and regional climatic and environmental signals. Here we present Hässeldala's multi‐proxy records (lithology, geochemistry, pollen, diatoms, chironomids, biomarkers, hydrogen isotopes) in a refined age model and place the observed changes in lake status, catchment vegetation, summer temperatures and hydroclimate in a wider regional context. Reconstructed mean July temperatures increased between c. 14.1 and c. 13.1 cal. ka BP and subsequently declined. This latter cooling coincided with drier hydroclimatic conditions that were probably associated with a freshening of the Nordic Seas and started a few hundred years before the onset of Greenland Stadial 1 (c. 12.9 cal. ka BP). Our proxies suggest a further shift towards colder and drier conditions as late as c. 12.7 cal. ka BP, which was followed by the establishment of a stadial climate regime (c. 12.5–11.8 cal. ka BP). The onset of warmer and wetter conditions preceded the Holocene warming over Greenland by c. 200 years. Hässeldala's proxies thus highlight the complexity of environmental and hydrological responses across abrupt climate transitions in northern Europe

A radiocarbon-based assessment of the preservation characteristics of crenarchaeol and alkenones from continental margin sediments

Author Posting. © Elsevier B.V. , 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Organic Geochemistry 39 (2008): 1039-1045, doi:10.1016/j.orggeochem.2008.02.006.Crenarchaeotal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids and alkenones are two types of biomarkers derived from planktonic marine micro-organisms which are used for reconstruction of sea-surface temperatures. We determined the radiocarbon contents of the archaeal GDGT crenarchaeol and of alkenones isolated from continental margin sediments. Systematic differences were found between the two biomarkers, with higher radiocarbon contents in crenarchaeol than in the phytoplankton-derived alkenones. These differences can be explained by variable contributions of pre-aged, laterally advected material to the core sites. Crenarchaeol appears to be more efficiently degraded during transport in oxygen-replete environments than alkenones. Whether this reflects the influence of chemical structure or mode of protection (e.g., particle association) is not yet known.This work was funded by a Spinoza grant of NWO to J.S.S.D. and by NSF-grant OCE-0327405 to T.I.E.