The geochemical features of the Ter River watershed (NE Spain)

The aims of this paper is to assess the different major ion proportions which define the chemical water type in each sampling-station of the river Ter watershed. Considerations of the relative abundance on the various major ionic constituents of the river is the main subject of discussion. The results show tlÍat application of multivariate statistical techniques may help in clustering the different watershed with similar chemical properties characterized by several abiotic factors. The spatial distribution of major dissolved ions has al so been considered in addition to an approach to determining regional differences in solute levels of the river Ter during low flow conditions.Características geoquímicas d e l a cuenca del río Ter. El objetivo de este trabajo ha sido conocer las distintas proporciones de los compuestos iónicos mayoritarios que definen el carácter geoquímico de cada punto de muestreo en la cuenca del río Ter Se ha considerado la variación espacial y temporal de la composición relativa de estos compuestos. La forma de representar las distintas proporciones iónicas en diagramas de Piper y de Maucha sugerían un espectro de variación espacial característico para algunas subcuencas. La aplicación de técnicas estadísticas multivariantes (análisis discriminante) ha servido para agrupar las distintas subcuencas que presentaban las mismas características hidroquímicas. Se clasificó un total de 10 grupos de subcuencas, cuyo resultado revelaba diferencias geoquímicas entre sectores del tramo principal del río Ter y entre afluentes calcáreos poco y muy mineralizados. Algunos de los factores fisiográficos de la cuenca (litológicos y actividad humana diversa) ayudaban, también, a detenninar el carácter geoquímico de cada subcuenca. El cloruro, el sodio y el potasio eran los iones que mejor relación guardaban con la actividad antropogénica. El resto de los iones estaba mucho más relacionado con las características litológicas y no presentaba correlación significativa con los cambios de caudal

Monte Carlo study of few-bosons in a one-dimensional trap

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2023, Tutors: Bruno Juliá-Díıaz, Grigori AstrakharchikWe consider a one-dimensional system of few-bosons in a harmonic trap that interact via a contact potential. In addition, we explore a system of non-interacting bosons in the presence of an impurity. The Variational Monte Carlo method is utilised to calculate an upper bound of the ground state energy. Furthermore, we numerically obtain the one-body density matrix, which allows us to determine the occupation numbers and the impurity density profile. The occupation numbers reveal that, in the absence of any impurity, the condensation diminishes as the repulsive interaction strength among bosons increases. Finally, in the presence of an impurity, we show the existence of two distinct regimes: a miscible regime and a non-miscible one

The biometrics of attraction

El grau de simetria dels organismes es considera un indicador de la qualitat genètica individual i en alguns casos associat a l’èxit reproductor que poden tenir. En aquest treball es vol comprovar en humans, si la percepció de bellesa està associada a més simetria facial. Per tal raó, es va realitzar un taller a Can Boet (Mataró) al març del 2017 on cada participant va avaluar de forma individual fotografies de rostres de 25 noies i 25 nois segons la seva percepció de bellesa, i al mateix temps s’analitzava la simetria de tots els rostres segons una sèrie de caràcters facials bilaterals. L’objectiu d’aquest taller era comprovar si realment existia aquesta relació, i a més a més, tenint en compte l’opinió dels homes i de les dones per separat. Els resultats demostraren que tant per a homes com per a dones, els valors alts de asimetria s’associaven a una menor percepció de bellesa. No obstant, no podem afirmar que la percepció de la bellesa vagi associada a un grau més gran de simetria facial pel que fa a les noies. Cal remarcar que en humans la percepció de bellesa i la conseqüent tria de parella està fortament condicionada per factors sòcioculturals. Sembla ser que la percepció de bellesa que tenen els homes de les noies no sempre es correspon a un grau més gran de simetria, sinó que segurament es veu condicionada quan aquestes estan força maquillades. No podem dir el mateix pel que fa al col·lectiu de dones, atès que aquestes sí valoren positivament el fet que els rostres femenins siguin més simètrics, encara que aquest criteri no sigui prou significatiu en aquest treball.The degree of symmetry of organisms is considered an indicator of individual genetic quality and is associated with individual reproductive success. In this study, we aimed to test whether human perception of beauty is related to facial symmetry. To elucidate this relationship, we analysed the degree of facial symmetry by measuring 10 facial traits of 25 portraits of boys and girls. The beauty of each face was evaluated according to the opinion of men and women separately. This study was carried out during a workshop held in Can Boet, Mataró, Catalonia in March 2017. The results of the workshop demonstrated that high values of asymmetry were associated with less attractiveness according to the judgements of both men and women. However, we cannot conclude that the perception of facial symmetry has a real effect on the valuation of beauty. It is fair to say that in humans the choice of a partner is also strongly conditioned by socio-cultural factors, which also differ according to sex. In this study, men’s perception of beauty in girls’ faces did not correspond to greater symmetry. It seems that men’s perception of beauty is improved by faces wearing make-up. On the other hand, women give higher scores of attractiveness to symmetrical faces (regardless of sex), although our data were not statistically significant

Using the rescaled range analysis for the study of hydrological records: The river Ter as an example

Water discharges into the Ter river have a strong influence on the water chemistry and on the dynamics of benthic cornmunities. For this reason, the temporal pattems followed by monthly runoff from 1 954 to 1 988 have been studied. From a statistical point of view, discharges show a very regular seasonal cycle, but in practice, climatic events introduce a source of variability on runoffs. To determine whether the series of 420 monthly discharges fluctuates with sorne regularity or at random, a rescaled range analilsis was made. The persistence (H) of the series of discharges was measured by the equation R / S = (T / 2) . In fact, H is a measure of the existence of clear trends or periodicities in the records of persistent stocastic processes. An additional measure of the persistence was obtained by means of the relationship D = 2 - H, where D is the local fractal dimensiono For comparative reasons, a random series of the same length, mean and standard deviation was generated and analysed in the same way as the Ter discharges were. The results were H = 0.68 and D = 1 .38 and H = 0.44 and D = 1 .52, for the Ter data and for the random series respectively. These results show that the simulated series is a case of ordinary Brownian motion while the Ter discharges series has an intermediate value of persistence. Because of the value of H in the Ter series, there are periods whose values were estimated by the autocorrelation function and the periodogram of the series. The results show the existence of short fluctuations of 3, 6 and 12 months deterrnining the seasonality of the annual cycle, and large fluctuations with periods of 5.5, 8.6, 1 0.1 and 11.7 months which can be considered an expression of cycles of circa 7 and 1 1 years.Water discharges into the Ter river have a strong influence on the water chemistry and on the dynamics of benthic cornmunities. For this reason, the temporal pattems followed by monthly runoff from 1 954 to 1 988 have been studied. From a statistical point of view, discharges show a very regular seasonal cycle, but in practice, climatic events introduce a source of variability on runoffs. To determine whether the series of 420 monthly discharges fluctuates with sorne regularity or at random, a rescaled range analilsis was made. The persistence (H) of the series of discharges was measured by the equation R / S = (T / 2) . In fact, H is a measure of the existence of clear trends or periodicities in the records of persistent stocastic processes. An additional measure of the persistence was obtained by means of the relationship D = 2 - H, where D is the local fractal dimensiono For comparative reasons, a random series of the same length, mean and standard deviation was generated and analysed in the same way as the Ter discharges were. The results were H = 0.68 and D = 1 .38 and H = 0.44 and D = 1 .52, for the Ter data and for the random series respectively. These results show that the simulated series is a case of ordinary Brownian motion while the Ter discharges series has an intermediate value of persistence. Because of the value of H in the Ter series, there are periods whose values were estimated by the autocorrelation function and the periodogram of the series. The results show the existence of short fluctuations of 3, 6 and 12 months deterrnining the seasonality of the annual cycle, and large fluctuations with periods of 5.5, 8.6, 1 0.1 and 11.7 months which can be considered an expression of cycles of circa 7 and 1 1 years

Variability of DOC and nitrate responses to storms in a small Mediterranean forested catchment

International audienceSevere drought periods followed by intense rainfall often leads to major floods in Mediterranean catchments. The resulting hydrology is complex and the response of solutes in the streams is often unpredictable. This study aimed to identify the most relevant factors controlling the hydrological responses to storms of an intermittent Mediterranean stream and to link those factors with dissolved organic carbon (DOC) and nitrate during storm events. Measurements of climate, hydrology, DOC and nitrate concentrations during 26 storm events over three hydrological years were analysed. The contribution of the storm events to the total DOC and nitrate annual export was also calculated. Nitrate was mainly mobilised during high flow, while most of the DOC export occurred during baseflow. Solute concentrations peaked after drought periods and the solute export was maximal during the largest rainfalls (i.e. > 100 L m-2). One single large storm contributed some 22% of the total annual export of DOC, and about 80% of that of nitrate. Discharge was a good predictor of neither DOC nor nitrate responses, so variables other than discharge were considered. Factor Analysis was used to identify the main factors controlling the biogeochemical responses. Antecedent moisture conditions and the magnitude of the storm event were the most relevant factors and accounted for 63% of the total variance. Solute responses during high flow were highly variable. However, solute concentration changes showed a significant and moderate relationship with the factors controlling the hydrological responses (i.e. ? DOC v. the antecedent moisture conditions and ? NO3-N v. the magnitude of the storm event). Keywords: dissolved organic carbon, nitrate, Mediterranean, drought, Fuirosos catchment, storms</p

Effects of riparian vegetation removal on nutrient retention in a Mediterranean stream

We examined the effects of riparian vegetation removal on algal dynamics and stream nutrient retention efficiency by comparing NH4-N and PO4-P uptake lengths from a logged and an unlogged reach in Riera Major, a forested Mediterranean stream in northeastern Spain. From June to September 1995, we executed 6 short-term additions of N (as NH4Cl) and P (as Na2HPO4) in a 200-m section to measure nutrient uptake lengths. The study site included 2 clearly differentiated reaches in terms of canopy cover by riparian trees: the first 100 m were completely logged (i.e., the logged reach) and the remaining 100 m were left intact (i.e., the shaded reach). Trees were removed from the banks of the logged reach in the winter previous to our sampling. In the shaded reach, riparian vegetation was dominated by alders (Alnus glutinosa). The study was conducted during summer and fall months when differences in light availability between the 2 reaches were greatest because of forest canopy conditions. Algal biomass and % of stream surface covered by algae were higher in the logged than in the shaded reach, indicating that logging had a stimulatory effect on algae in the stream. Overall, nutrient retention efficiency was higher (i.e., shorter uptake lengths) in the logged than in the shaded reach, especially for PO4-P. Despite a greater increase in PO4-P retention efficiency relative to that of NH4-N following logging, retention efficiency for NH4-N was higher than for PO4-P in both study reaches. The PO4-P mass-transfer coefficient was correlated with primary production in both study reaches, indicating that algal activity plays an important role in controlling PO4-P dynamics in this stream. In contrast, the NH4-N mass-transfer coefficient showed a positive relation-ship only with % of algal coverage in the logged reach, and was not correlated with any algal-related parameter in the shaded reach. The lack of correlation with algal production suggests that mechanisms other than algal activity (i.e., microbial heterotrophic processes or abiotic mechanisms) may also influence NH4-N retention in this stream. Overall, this study shows that logging disturbances in small shaded streams may alter in-stream ecological features that lead to changes in stream nutrient retention efficiency. Moreover, it emphasizes that alteration of the tight linkage between the stream channel and the adjacent riparian zone may directly and indirectly impact biogeochemical processes with implications for stream ecosystem functioning

Green light: gross primary production influences seasonal stream N export by controlling fine-scale N dynamics

Monitoring nutrient concentrations at fine-scale temporal resolution contributes to a better understanding of nutrient cycling in stream ecosystems. However, the mechanisms underlying fine-scale nutrient dynamics and its implications for budget catchment fluxes are still poorly understood. To gain understanding on patterns and controls of fine-scale stream nitrogen (N) 18 dynamics and to assess how they affect hydrological N fluxes, we explored diel variation in stream nitrate (NO3-) concentration along a headwater stream with increasing riparian area and channel width. At the down-stream site, the highest day-night variations occurred in early-spring when stream NO3- concentrations were 13% higher at night than during day time. Such day-night variations were strongly related to daily light inputs (R2=0.74) and gross primary production (GPP) (R2=0.74), and they showed an excellent fit with day-night NO3- variations predicted from GPP (R2=0.85). These results suggest that diel fluctuations in stream NO3- concentration were mainly driven by photoautotrophic N uptake. Terrestrial influences were discarded because no simultaneous diel variations in stream discharge, riparian groundwater level, or riparian solute concentration were observed. In contrast to the down-stream site, no diel variations in NO3- concentration occurred at the up-stream site likely because water temperature was colder (10 vs. 12 ºC) and light availability was lower (4 vs. 9 mol m-2 d-1). Although daily GPP was between 10-100 folds lower than daily respiration, photoautotrophic N uptake contributed to a 10% reduction in spring NO3- loads at the down-stream site. Our study clearly shows that the activity of photoautotrophs can substantially change over time and along the stream continuum in response to key environmental drivers such as light and temperature, and further that its capacity to regulate diel and seasonal N fluxes can be important even in low productivity streams.Financial supported was provided by the Spanish Government through the projects MONTES-Consolider (CSD2008- 00040-MONTES) and MEDFORESTREAM (CGL2011-30590).Peer reviewe