2 research outputs found
Predicting River Macroinvertebrate Communities Distributional Shifts under Future Global Change Scenarios in the Spanish Mediterranean Area
Several studies on global change over the next century predict increases in mean air temperatures of between 1°C to 5°C that would affect not only water temperature but also river flow. Climate is the predominant environmental driver of thermal and flow regimes of freshwater ecosystems, determining survival, growth, metabolism, phenology and behaviour as well as biotic interactions of aquatic fauna. Thus, these changes would also have consequences for species phenology, their distribution range, and the composition and dynamics of communities. These effects are expected to be especially severe in the Mediterranean basin due its particular climate conditions, seriously threatening Southern European ecosystems. In addition, species with restricted distributions and narrow ecological requirements, such as those living in the headwaters of rivers, will be severely affected. The study area corresponds to the Spanish Mediterranean and Balearic Islands, delimited by the Köppen climate boundary. With the application of the MEDPACS (MEDiterranean Prediction And Classification System) predictive approach, the macroinvertebrate community was predicted for current conditions and compared with three posible scenarios of watertemperature increase and its associated water flow reductions. The results indicate that the aquatic macroinvertebrate communities will undergo a drastic impact, with reductions in taxa richness for each scenario in relation to simulated current conditions, accompanied by changes in the taxa distribution pattern. Accordingly, the distribution area of most of the taxa (65.96%) inhabiting the mid-high elevations would contract and rise in altitude. Thus, families containing a great number of generalist species will move upstream to colonize new zones with lower water temperatures. By contrast, more vulnerable taxa will undergo reductions in their distribution area.This work was funded by GUADALMED-II (REN2001-3438-C07-06/HID), a project of excellence from “Junta de Andalucía” (RNM-02654/FEDER), the Spanish “Ministerio de Ciencia e Innovación” (CGL2007-61856/BOS), projects and a collaboration agreement between the “Spanish Ministerio de Medio Ambiente, Medio Rural y Marino” and the University of Granada (21.812-0062/8511)
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Doping liquid argon with xenon in ProtoDUNE Single-Phase: effects on scintillation light
Abstract
Doping of liquid argon TPCs (LArTPCs) with a small
concentration of xenon is a technique for light-shifting and
facilitates the detection of the liquid argon scintillation
light. In this paper, we present the results of the first doping
test ever performed in a kiloton-scale LArTPC. From February to May
2020, we carried out this special run in the single-phase DUNE Far
Detector prototype (ProtoDUNE-SP) at CERN, featuring 720 t of total
liquid argon mass with 410 t of fiducial mass. A 5.4 ppm nitrogen
contamination was present during the xenon doping campaign. The goal
of the run was to measure the light and charge response of the
detector to the addition of xenon, up to a concentration of
18.8 ppm. The main purpose was to test the possibility for
reduction of non-uniformities in light collection, caused by
deployment of photon detectors only within the anode planes. Light
collection was analysed as a function of the xenon concentration, by
using the pre-existing photon detection system (PDS) of ProtoDUNE-SP
and an additional smaller set-up installed specifically for this
run. In this paper we first summarize our current understanding of
the argon-xenon energy transfer process and the impact of the
presence of nitrogen in argon with and without xenon dopant. We then
describe the key elements of ProtoDUNE-SP and the injection method
deployed. Two dedicated photon detectors were able to collect the
light produced by xenon and the total light. The ratio of these
components was measured to be about 0.65 as 18.8 ppm of xenon were
injected. We performed studies of the collection efficiency as a
function of the distance between tracks and light detectors,
demonstrating enhanced uniformity of response for the anode-mounted
PDS. We also show that xenon doping can substantially recover light
losses due to contamination of the liquid argon by nitrogen.</jats:p