Sustainable Habitat Restoration: Fish, Farms, and Ecosystem Services

Biomass burning impacts biogeochemical cycling, vegetation dynamics and climate. However, interactions between fire, climate and vegetation are not well understood and therefore studies have attempted to reconstruct fire and vegetation history under different climatic conditions using sedimentary archives. Here we focus on levoglucosan, a thermal by-product of cellulose generated during biomass burning, and, therefore, a potential fire biomarker in the marine sedimentary archive. However, before levoglucosan can be applied as a biomass burning proxy in marine sediments, there is a need for studies on how levoglucosan is transported to the marine environment, how it is reflecting biomass burning on continents, as well as the fate of levoglucosan in the marine water column and during deposition in marine sediments. Here we present analyses of levoglucosan, using an improved Ultra High Pressure Liquid Chromatography-Electro Spray Ionization/High Resolution Mass Spectrometry (UHPLC-ESI/HRMS) method, in atmospheric particles, in particulate matter settling through the water column and in marine surface sediments on a longitudinal transect crossing the tropical North Atlantic Ocean at 12°N. Levoglucosan was detected in the atmosphere, although in low concentration, possibly due to the sampled particle size, the source area of the aerosols, or the short time interval of sampling by which large burning events may have been missed. In sinking particles in the tropical North Atlantic Ocean we find that levoglucosan deposition is influenced by a mineral ballast effect associated with marine biogenic particles, and that levoglucosan is not transported in association with mineral dust particles. Highest levoglucosan concentrations and seasonal differences in sinking particles were found close to continents and low concentrations and seasonal differences were found in the open ocean. Close to Africa, levoglucosan concentration is higher during winter, reflecting seasonal burning in northwestern Africa. However, close to South America levoglucosan concentrations appear to be affected by riverine transport from the Amazon River. In surface sediments close to South America, levoglucosan concentration is higher than in the middle of the Atlantic Ocean, implying that here the influence from the South American continent is important and perennial. Our study provides evidence that degradation of levoglucosan during settling in the marine water column is not substantial, but is substantial at the sediment–water interface. Nevertheless, levoglucosan was detected in all surface sediments throughout the tropical North Atlantic, indicating its presence in the marine sedimentary record, which reveals the potential for levoglucosan as a biomass burning proxy in marine sediments

The quest for optimal control of relapses in children with nephrotic syndrome

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Therapeutic drug monitoring of mycophenolate mofetil in pediatric patients: novel techniques and current opinion

Introduction: Mycophenolate mofetil (MMF) is an ester prodrug of the immunosuppressant mycophenolic acid (MPA) and is recommended and widely used for maintenance immunosuppressive therapy in solid organ and stem-cell transplantation as well as in immunological kidney diseases. MPA is a potent, reversible, noncompetitive inhibitor of the inosine monophosphate dehydrogenase (IMPDH), a crucial enzyme in the de novo purine synthesis in T- and B-lymphocytes, thereby inhibiting cell-mediated immunity and antibody formation. The use of therapeutic drug monitoring (TDM) of MMF is still controversial as outcome data of clinical trials are equivocal. Areas covered: This review covers in great depth the existing literature on TDM of MMF in the field of pediatric (kidney) transplantation. In addition, the relevance of TDM in immunological kidney diseases, in particular childhood nephrotic syndrome is highlighted. Expert opinion: TDM of MMF has the potential to optimize therapy in pediatric transplantation as well as in nephrotic syndrome. Limited sampling strategies to estimate MPA exposure increase its feasibility. Future perspectives rather encompass approaches reflecting total immunosuppressive load than single drug TDM

Aeolian transport and deposition of plant wax <i>n</i>-alkanes across the tropical North Atlantic Ocean

Long chain n-alkanes are terrestrial higher plant biomarkers analysed in marine sedimentary archives to reconstruct continental palaeoclimatic and palaeohydrological conditions. Latitudinal variation in their concentration and distribution in marine sediments relatively close to the continent has been widely studied, but little is known on the extent to which this continental signal extends to the ocean. Furthermore, no studies have examined the seasonal variation in the deposition of these biomarkers in marine sediments. Here we studied longitudinal variation in the composition of long chain n-alkanes and two other terrestrial higher plant biomarkers (long chain n-alkanols and long chain fatty acids) in atmospheric particles, as well as longitudinal and seasonal variation in long chain n-alkanes in sinking particles in the ocean at different water depths and in surface sediments, all collected along a 12°N transect across the tropical North Atlantic Ocean. The highest abundance of all three biomarker classes was closest to the African coast, as expected, because they are transported with Saharan dust and the largest part of the dust is deposited close to the source. At this proximal location, the seasonal variability in long chain n-alkane flux and the chain length distribution of the n-alkanes in sinking particles was most pronounced, due to seasonal change in the dust source or to change in vegetation composition in the source area, related to the position of the Intertropical Convergence Zone (ITCZ). In contrast, in the open ocean the seasonal variability in both the long chain n-alkane flux and chain length distribution of the n-alkanes was low. The abundance of the alkanes was also lower, as expected because of the larger source-to-sink distance. At the western part of the transect, close to South America, we found an additional source of the alkanes in the sinking particles during spring and autumn in the year 2013. The δ13C values of the alkanes in the surface sediment closest to the South American continent indicated that the isotope signal was likely derived from C3 vegetation from the Amazon, implying an input from the Amazon River, as there is no significant aeolian input from South America there since the prevailing wind direction is from the east. Finally, the concentration of the alkanes was similar in the material collected from the atmosphere, the particles collected while settling through the marine water column, and in the surface sediments, providing evidence that degradation of long chain n-alkanes from the atmosphere to settling at the sediment–water interface at deep open ocean sites is minimal

Comparison of organic and palynological proxies for biomass burning and vegetation in a lacustrine sediment record (Lake Allom, Fraser Island, Australia)

Continental fire and vegetation history have been studied in sedimentary archives using palynological proxies (i.e. charcoal abundance and the pollen assemblage) and organic proxies (i.e. the anhydrosugars levoglucosan and it isomers, and plant-wax n-alkanes), but rarely in concert. Here, we compared palynological and organic proxies to reconstruct fire and vegetation history in a sediment core from Lake Allom on Fraser Island, Australia, covering the last 5.4 kyrs. We found that anhydrosugar and microscopic charcoal accumulation rates had similar trends, while trends in macroscopic charcoal accumulation rates were different. This was attributed to the short distance over which macroscopic charcoal is transported compared to microscopic charcoal and anhydrosugars. Furthermore, differences in fire regime and combusted types of vegetation may also explain the differences in levoglucosan and charcoal accumulation rates in lacustrine sediments. Moreover, we found that the ratios between anhydrosugars seem to be governed by combustion conditions, or by type of burned vegetation. Long chain n-alkane accumulation rates and stable isotope compositions showed similar patterns to the pollen assemblage throughout the last 5.4 kyrs, with both representing the local vegetation history. Collectively, our results showed that in the period between 5.4 and 4 ka, biomass burning was low on Fraser Island, while at 4 ka, fire occurrence started to increase, slightly earlier than changes in vegetation and hydrology. Therefore, we suggest that increased fire activity on Fraser Island around 4 ka might have been caused by human-lit biomass burning, since aboriginals settled on Fraser Island around this time

Relationships between low-temperature fires, climate and vegetation during three late glacials and interglacials of the last 430&amp;thinsp;kyr in northeastern Siberia reconstructed from monosaccharide anhydrides in Lake El'gygytgyn sediments

© Author(s) 2020. Landscapes in high northern latitudes are assumed to be highly sensitive to future global change, but the rates and long-term trajectories of changes are rather uncertain. In the boreal zone, fires are an important factor in climate-vegetation interactions and biogeochemical cycles. Fire regimes are characterized by small, frequent, lowintensity fires within summergreen boreal forests dominated by larch, whereas evergreen boreal forests dominated by spruce and pine burn large areas less frequently but at higher intensities. Here, we explore the potential of the monosaccharide anhydrides (MA) levoglucosan, mannosan and galactosan to serve as proxies of low-intensity biomass burning in glacial-to-interglacial lake sediments from the high northern latitudes. We use sediments from Lake El'gygytgyn (cores PG 1351 and ICDP 5011-1), located in the far northeast of Russia, and study glacial and interglacial samples of the last 430 kyr (marine isotope stages 5e, 6, 7e, 8, 11c and 12) that had different climate and biome configurations. Combined with pollen and non-pollen palynomorph records from the same samples, we assess how far the modern relationships between fire, climate and vegetation persisted during the past, on orbital to centennial timescales. We find that MAs attached to particulates were well-preserved in up to 430 kyr old sediments with higher influxes from low-intensity biomass burning in interglacials compared to glacials. MA influxes significantly increase when summergreen boreal forest spreads closer to the lake, whereas they decrease when tundra-steppe environments and, especially, Sphagnum peatlands spread. This suggests that lowtemperature fires are a typical characteristic of Siberian larch forests also on long timescales. The results also suggest that low-intensity fires would be reduced by vegetation shifts towards very dry environments due to reduced biomass availability, as well as by shifts towards peatlands, which limits fuel dryness. In addition, we observed very low MA ratios, which we interpret as high contributions of galactosan and mannosan from biomass sources other than those currently monitored, such as the moss-lichen mats in the understorey of the summergreen boreal forest. Overall, sedimentary MAs can provide a powerful proxy for fire regime reconstructions and extend our knowledge of long-term natural fire-climate-vegetation feedbacks in the high northern latitudes