Vulnerability to contamination by phosphorus in a zero-order basin with a high density of pigs and a history of slurry addition: extrapolation of an index

The application of phosphorus (P)-index methodology to assess the risk of water pollution from agriculture in river basins usually takes time and expends a great amount of resources. This study adapted the P-index methodology using digital mapping of key basin risk criteria for P loss in reference areas to evaluate the wider vulnerability to P loss in a zero-order basin with an intense concentration of pigs and with a history of pig slurry additions to the soil. The P content of eleven reference areas, where ten areas have received various applications of pig slurry and one area has no history of addition, was extrapolated to a zero-order basin using principal component analysis and analysis of hierarchical groupings. Estimated loss of soil and the distance between the P source and the watercourse were mapped using satellite images and in situ evaluations. The methodology of extrapolating was well correlated with a survey of P concentrations in land runoff and provides the potential to improve land management of those areas that are most vulnerable. Principal component analysis and hierarchical clustering analysis proved to be useful tools for the separation of areas with different slurry application times. Our results suggest that the P loss risk could be reduced through the adoption of soil conservation techniques such as reduced-tillage incorporating slurry and crop residue management to provide adequate soil protection, reduce the impact of raindrops and reduce erosion risk and transport of chemical pollutants to water bodies.     

Human-made disasters and economic impact for a developing economy: evidence from Brazil

Natural Hazards - This article analyzes the short-term economic impacts of the collapse of the ‘Fundão’ mining tailings dam, located in the Brazilian state of Minas Gerais. This...     

Global textures and the formation of self-bound gravitational systems

Using a Newtonian approximation we developed a quantitative criterion for the collapse of a spherical distribution of matter under an isolated texture field. In particular, we found the evolution of an overdense region is strongly determined by two parameters: the energy scale of symmetry breaking ( η ) and the initial radius of the system. Applying our collapse criterion to typical galaxy scales we verified the formation of 10¹¹‐M_⊙ objects at z ≲9 and 10¹²‐M_⊙ objects at z ≲5.     

Prospective scenarios for water quality and ecological status in Lake Sete Cidades (Portugal): The integration of mathematical modelling in decision processes

The design of alternative strategies for water and ecological quality protection at the Lake Verde of Sete Cidades should be coupled with the assessment of future trophic states. Therefore, a mathematical model was developed to make prospective scenarios to reduce the risk of environmental degradation of the lake, and a modified Psenner scheme was used to characterize P distribution in the sediments. The model was able to describe thermal stratification, nutrient cycling (P, NH₄ and NO₃), dissolved O₂, and phytoplankton dynamics in the water column and adjacent sediment layers. Internal P recycling, resulting from thermal stratification and sediment anoxia, was identified as the main cause for the increase of P concentration in the hypolimnion followed by slow transfer to the epilimnion (about 20 μg/L annual average). Cyanobacteria blooms during spring were explained by the availability of P and increased water temperature verified during this season. The most sensitive model parameter was sediment porosity. This parameter has a direct effect in dissolved O₂ and P profiles and also in phytoplankton biomass. Finally, different water quality restoration scenarios were identified and their effectiveness assessed. Without the adoption of remediation measures (scenario control), Lake Verde water quality would deteriorate with annual average concentrations of total P and phytoplankton biomass (dry matter) reaching 34 μg/L and 2 mg/L, respectively, after 10 years of simulation. The reduction of P loads (scenario PORAL) into the lake would improve water quality comparatively to the scenario control, reducing the annual average concentrations of total P from 34 μg/L to 26 μg/L and of phytoplankton from 2 mg/L down to 1.4 mg/L after 10 years of simulation. In scenario sediments, corresponding to a decrease in the organic content of the sediments, a reduction in the concentrations of total P and phytoplankton is expected in the first two years of simulation, but this effect, would be attenuated throughout the years due to organic matter sedimentation. The best strategy is obtained by combining external and internal measures for P remediation. Finally, it is recommended that the model be used to integrate the results of water quality monitoring and watershed management plans.     

The cenozoic aquifer system of the Lower Tagus Basin: a description of the hydrogeological situation in the Almada region (Portugal)

A conceptual hydrogeological model of the Mio-Pleistocene deposits in the Almada region, located in the Cenozoic aquifer system of the Lower Tagus Basin (Portugal), has been developed. Though numerous studies have been conducted on its geological features, there have not been enough hydrogeological investigations to define the origin, flow path and the groundwater quality and to understand the coexistence of overlapped interacting aquifers. Therefore, a study is presented here on the occurrences and features of groundwater resources in the Almada region based on an inventory in the field (wells, springs and boreholes), physical and chemical analyses, geologic setting, and tectonic and geomorphologic observations. This aquifer system has long been a source of concern because of the high level of extraction over the last few decades, as well as the progressive degradation of the water quality. Available groundwater resources have been affected by intensive agricultural and industrial activity, as a consequence of incorrect or non-existent hydrogeological knowledge.     

Probing clustering features around Cl 0024+17

I present a spatial analysis of the galaxy distribution around the cluster Cl 0024+17. The basic aim is to find the scales where galaxies present a significant deviation from an inhomogeneous Poisson statistical process. Using the generalization of the Ripley, Besag, and the pair correlation functions for non-stationary point patterns, I estimate these transition scales for a set of 1000 Monte Carlo realizations of the Cl 0024+17 field, corrected for completeness up to the outskirts. The results point out the presence of at least two physical scales in this field at 31.4^″ and 112.9^″. The second one is statistically consistent with the dark matter ring radius (75^″) previously identified by Jee [Jee, M.J., 2007. ApJ 661, 728]. However, morphology and anisotropy tests point out that a clump at 120^″ NW from the cluster center could be the responsible for the second transition scale. These results do not indicate the existence of a galaxy counterpart of the dark matter ring, but the methodology developed to study the galaxy field as a spatial point pattern provides a good statistical evaluation of the physical scales around the cluster. I briefly discuss the usefulness of this approach to probe features in galaxy distribution and N-body dark matter simulation data.     

Dark energy and flatness from observational H(z)+WMAP constraint

We analyse the dark energy problem using observational H(z) data plus the curvature constraint given by WMAP. After a non-parametric statistical study covering the most probable range of Ω _m0 and H ₀ from different combination of data, we investigate the possibility of having the dark energy EoS parameter ω _x ≠−1. In order to keep strict flatness (1% of deviation from Ω=1), our results point out this is the case for 0.20≲Ω _m0≲0.23 and H ₀≈67 km/s/Mpc, with ω _x ≈−0.55. However, if we admit a 10% deviation from the flatness condition, ω _x may have any value in the range [−1.2,−0.5] for 0.20≲Ω _m0≲0.35 and 67≲H ₀≲74 km/s/Mpc.     

A Modeling Approach to Assess the Key Factors in the Evolution of Coastal Systems: the Ebro North Hemidelta Case

One-Line shoreline evolution models have been used as a tool to understand and forecast long-term coastal evolution. However, in some coastal environments, where the influence of the wind is important, the limitations of existing models preclude its direct application to characterize its effect on sediment transport processes. To fill this knowledge gap, we have developed a shoreline evolution model that includes the effect of wind on longshore sediment transport and accounts for beach-dune sedimentary exchange due to aeolian transport. The model produces quantitative estimates of sediment transport and exchanges rates alongshore, easing the assessment of the role of different forcing agents in coastline evolution. The model was applied to the Ebro north hemidelta coast. The results are used to discuss the relative importance of the wind interaction in the evolution of different coastline stretches. Aeolian sand transport at Riumar Beach could cause coastal erosion. At the rectilinear coast, aeolian exchange does not seem to influence the shoreline evolution but the wind-current interaction does. The model provides valuable data when considering the approach to be taken regarding conservation measures. Alongshore aeolian sediment transport can be useful when designing and placing aeolian sediment traps. Conservation of the Ebro north hemidelta coast needs to focus on increasing the river sediment supply. The application herein presented can be regarded as a first step in understanding wave and wind coupling effects in shoreline evolution.     

The Two-Component Virial Theorem and the Physical Properties of Stellar Systems

Using eigenmode expansion of the Mark III and SFI surveys of cosmological radial velocities, a goodness-of-fit analysis is applied on a mode-by-mode basis. This differential analysis complements the Bayesian maximum likelihood analysis that finds the most probable model given the data. Analyzing the surveys with their corresponding most likely models from the CMB-like family of models, as well as with the currently popular LambdaCDM model, reveals a systematic inconsistency of the data with these "best" models. There is a systematic trend of the cumulative chi(2) to increase with the mode number (where the modes are sorted by decreasing order of the eigenvalues). This corresponds to a decrease of the chi(2) with the variance associated with a mode and hence with its effective scale. It follows that the differential analysis finds that on small (large) scales the global analysis of all the modes "puts" less (more) power than actually required by the data. This observed trend might indicate one of the following: (1) the theoretical model (i.e., power spectrum) or the error model (or both) have an excess of power on large scales, (2) velocity bias, or (3) the velocity data suffers from systematic errors that have not yet been corrected.