Phosphorus flux from wetland ditch sediments

The accumulation of phosphorus (P) in the bottom sediment of field drainage ditches poses a threat to the ecology both of the ditch water and downstream water courses. We investigated the amounts, forms and internal loading of sediment-bound P along two drainage ditches that regulate water levels in a basin fen (~ 200 ha) supporting a mixture of restored wetland and drained agricultural fields. Water levels in the Lady's Drove Rhyne are currently managed to enhance the biodiversity of the wetland (Catcott Lows Reserve — an area formerly cultivated for arable crop production); whereas, the East Ditch is managed to drain adjoining land that remains under arable and livestock production. Laboratory-based chemical fractionation schemes were used to characterise the forms and potential mobility of the sediment-bound P, whilst pore-water equilibrators were employed in situ to evaluate the diffusive flux of P through the sediment–water column, and to characterise the corresponding redox conditions. Along both ditches, sediment pore-water profiles indicated conditions ranging from weakly to very reducing conditions with increasing depth, and net fluxes of P from the sediment to overlying water. P flux values ranged from 0.33 to 1.30 mg m− 2 day− 1. Both the degree of P saturation (DPS) of the sediment and NaOH extractable (Fe/Al-bound) P correlated significantly (P < 0.05) with P flux. Both in the wetland and agricultural ditches, by far the highest values for P flux were recorded at sites closest to points of drainage water entry from the corresponding, adjoining land. Although the P flux data were obtained from only a single sampling event, this study highlights the contribution of historical as well as ongoing agricultural land use on the sustained elevated P status of ditch sediments in lowland catchments.

The early transcriptomic response to interleukin 1β and interleukin 33 in rat neonatal cardiomyocytes

In the heart, inflammatory cytokines including interleukin (IL) 1β are implicated in regulating adaptive and maladaptive changes, whereas IL33 negatively regulates cardiomyocyte hypertrophy and promotes cardioprotection. These agonists signal through a common co-receptor but, in cardiomyocytes, IL1β more potently activates mitogen-activated protein kinases and NFκB, pathways that regulate gene expression. We compared the effects of external application of IL1β and IL33 on the cardiomyocyte transcriptome. Neonatal rat cardiomyocytes were exposed to IL1β or IL33 (0.5, 1 or 2h). Transcriptomic profiles were determined using Affymetrix rat genome 230 2.0 microarrays and data were validated by quantitative PCR. IL1β induced significant changes in more RNAs than IL33 and, generally, to a greater degree. It also had a significantly greater effect in downregulating mRNAs and in regulating mRNAs associated with selected pathways. IL33 had a greater effect on a small, select group of specific transcripts. Thus, differences in intensity of intracellular signals can deliver qualitatively different responses. Quantitatively different responses in production of receptor agonists and transcription factors may contribute to qualitative differences at later times resulting in different phenotypic cellular responses.

Using reanalysis data to quantify extreme wind power generation statistics : a 33 year case study in Great Britain

With a rapidly increasing fraction of electricity generation being sourced from wind, extreme wind power generation events such as prolonged periods of low (or high) generation and ramps in generation, are a growing concern for the efficient and secure operation of national power systems. As extreme events occur infrequently, long and reliable meteorological records are required to accurately estimate their characteristics. Recent publications have begun to investigate the use of global meteorological “reanalysis” data sets for power system applications, many of which focus on long-term average statistics such as monthly-mean generation. Here we demonstrate that reanalysis data can also be used to estimate the frequency of relatively short-lived extreme events (including ramping on sub-daily time scales). Verification against 328 surface observation stations across the United Kingdom suggests that near-surface wind variability over spatiotemporal scales greater than around 300 km and 6 h can be faithfully reproduced using reanalysis, with no need for costly dynamical downscaling. A case study is presented in which a state-of-the-art, 33 year reanalysis data set (MERRA, from NASA-GMAO), is used to construct an hourly time series of nationally-aggregated wind power generation in Great Britain (GB), assuming a fixed, modern distribution of wind farms. The resultant generation estimates are highly correlated with recorded data from National Grid in the recent period, both for instantaneous hourly values and for variability over time intervals greater than around 6 h. This 33 year time series is then used to quantify the frequency with which different extreme GB-wide wind power generation events occur, as well as their seasonal and inter-annual variability. Several novel insights into the nature of extreme wind power generation events are described, including (i) that the number of prolonged low or high generation events is well approximated by a Poission-like random process, and (ii) whilst in general there is large seasonal variability, the magnitude of the most extreme ramps is similar in both summer and winter. An up-to-date version of the GB case study data as well as the underlying model are freely available for download from our website: http://www.met.reading.ac.uk/~energymet/data/Cannon2014/.