Water pollution: A view from ecology

The results of various methods typically used by governments to assess the environmental impact of potential pollutants do not give comparable results. It is argued that the cause is not the assessment techniques themselves but rather the paradigm of ecology from which they spring.     

Micellar-Enhanced Ultrafiltration and Air Stripping for Surfactant-Contaminant Separation and Surfactant Reuse

Micellar-enhanced ultrafiltration (MELT) and air stripping were evaluated for surfactant-contaminant separation and surfactant recovery. Two linear alkyl diphenyloxide disulfonate (DPDS) surfactants were evaluated with the contaminants naphthalene and trichloroethylene. A separation model developed from micellar partitioning principles showed a good correlation to batch MEUF studies, whereas flux analysis highlighted concentration polarization effects in relation to hydrophobe length. MEUF effectively concentrated the surfactant-contaminant system (93 to 99 percent retention); however, this did not result in surfactant-contaminant separation. Batch and continuous flow air stripping models were developed based upon air/water ratio, surfactant concentration, and Micellar partitioning; model predictions were validated by experimental data. Sensitivity analyses illustrated the decline in contaminant-surfactant separation with increasing surfactant concentration (e.g., TCE removal efficiency declines from 83 percent to 37 percent as C-16 DPDS concentration increases from 0 to 55 mM). This effect is greater for more hydrophobic contaminants (naphthalene vs. TCE) and surfactants with greater solubilization potential (C16-DPDS vs. C-12 DPDS). The resulting design equations can account for this effect and thus properly size air strippers to achieve the desired removal efficiency in the presence of surfactant micelles. Proper selection and design of surfactant-contaminant separation and surfactant recovery systems are integral to optimizing surfactant-enhanced subsurface remediation.     

Glacier inventory of the Gran Campo Nevado Ice Cap in the Southern Andes and glacier changes observed during recent decades

The Gran Campo Nevado (GCN) forms an isolated ice cap on the Península Muñoz Gamero (PMG) located 200 km to the south of the Southern Patagonia Icefield (SPI). We present a glacier inventory of the GCN made up by 27 drainage basins (in total 199.5 km²) and other small cirque and valley glaciers of the southern part of PMG (in total 53 km²). The glacier inventory is based on a digital elevation model (DEM) and ortho-photos. Contour lines from maps, relief information derived from Landsat TM satellite imagery from 1986 and 2002 and stereoscopic data from aerial photos were combined in a knowledge-based scheme to obtain a DEM of the area. A digital ortho-photo map based on aerial photos from 1998 and several ortho-photos based on aerial photos from 1942 and 1984 could be produced from the initial DEM. A geographical information system (GIS) served to outline the extent of the present glaciation. All major glaciers of the GCN show a significant glacier retreat during the last 60 yr. Some of the outlet glaciers lost more than 20% of their total area during this period. Overall glacier retreat amounts to 2.8% of glacier length per decade and the glacier area loss is 2.4% per decade in the period from 1942 to 2002. We hypothesise that GCN glaciers may have reacted faster and more synchronously with the observed warming trend during recent decades when compared with the SPI.     

Variazioni delle latitudini terrestri e fenomeni geofisici

Riassunto Esposti brevemente i fondamenti teorici dello spostamento dell'asse istantaneo di rotazione terrestre nella massa della Terra, ed accennato alle prove sperimentali che hanno condotto a stabilire la realtà del fenomeno, sono analizzate le variazioni delle latitudini terrestri, che comprendono una variazionepolare ed una variazionenon polare. La variazione non polare appare dovuta principalmente ad anomalie rifrazionali, aventi sede nell'atmosfera terrestre e caratteristiche locali. La variazione polare comprende due oscillazioni essenziali: una avente origine meccanica (nutazione culeriana), modificata dall'elasticità terrestre; l'altra avente origine geofisica, e dipendente da spostamenti annuali dell'asse di massimo momento d'inerzia della Terra (asse di figura). L'analisi della variazione polare mostra perturbazioni strettamente connesse con la costituzione della Terra e con fenomeni geofisici. In tutti i suoi aspetti il problema della variazione delle latitudini terrestri implica la considerazione di fenomeni geofisici aventi sede nell'atmosfera, alla superficie e all'interno della Terra.

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Summary Having briefly set forth the theoretical principles of the displacement of the istantaneous axis of rotation of the Earth in the interior of the same, and made reference to the experimental tests that have shown the reality of the phenomenon, the variations of the terrestrial latitudes, which include apolar and anon polar variation, are analyzed. The non polar variation seems to have its origin mainly in refractional anomalies, that have their place in the atmosphere and local characteristics. The polar variation includes two fundamental oscillations: one having mechanical origin (Eulerian nutation), modified by the elasticity of the Earth, and another having geophysical origin and depending on annual displacements of the axis of the maximum momentum of inertia of the Earth (axis of figure). The analysis of the polar motion shows perturbations hightly connected with the constitution of the Earth and with geophysical phenomena. In all its appearances the problem of the variation of the terrestrial latitudes implies the consideration of geophysical phenomena occurring in the atmosphere, at the surface, and in the interior of the Earth.

     

Use of molecular approaches in hydrogeological studies: the case of carbonate aquifers in southern Italy

Waterborne pathogens represent a significant health risk in both developed and developing countries with sensitive sub-populations including children, the elderly, neonates, and immune-compromised people, who are particularly susceptible to enteric infections. Annually, approximately 1.8 billion people utilize a faecally contaminated water source, and waterborne diseases are resulting in up to 2.1 million human mortalities globally. Although groundwater has traditionally been considered less susceptible to contamination by enteric pathogens than surface water due to natural attenuation by overlying strata, the degree of microbial removal attributable to soils and aquifers can vary significantly depending on several factors. Thus, accurate assessment of the variable presence and concentration of microbial contaminants, and the relative importance of potentially causative factors affecting contaminant ingress, is critical in order to develop effective source (well) and resource (aquifer) protection strategies. “Traditional” and molecular microbiological study designs, when coupled with hydrogeological, hydrochemical, isotopic, and geophysical methods, have proven useful for analysis of numerous aspects of subsurface microbial dynamics. Accordingly, this overview paper presents the principal microbial techniques currently being employed (1) to predict and identify sources of faecal contamination in groundwater, (2) to elucidate the dynamics of contaminant migration, and (3) to refine knowledge about the hydrogeological characteristics and behaviours of aquifer systems affected by microbial contamination with an emphasis on carbonate aquifers, which represent an important global water supply. Previous investigations carried out in carbonate aquifers in southern Italy are discussed.     

Genetic variability of the blue and red shrimp Aristeus antennatus in the Western Mediterranean Sea inferred by DNA microsatellite loci

Genetic variation at eight microsatellite loci was studied in nine populations of the blue and red shrimp Aristeus antennatus to investigate whether distinct stocks are present in the Western Mediterranean Sea. A high level of gene flow and no evidence of genetic partitioning were discovered. No significant variation was found (F_ST = 0.00673, P-value = 0.067) even when shrimps from exploited and those from deep-water unexploited grounds were compared. No evidence of reduction or expansion of population size in the recent past was found, as indicated by the bottleneck and interlocus g-tests. Our results are consistent with previous studies using mitochondrial gene methods and allozymes, indicating that, for this species, extensive pelagic larval dispersal and adult migration are probably responsible for the genetic homogeneity observed. In particular, due to a different bathymetric distribution of males and females, reported to be associated with different water masses and hence with possible differential dispersal capacity between sexes, the hypothesis of sex-biased dispersal was tested. Mean values of corrected assignment indices and mean relatedness values were higher for males, suggesting that females are the more widely dispersing sex. Molecular assessment of A. antennatus from the Western Mediterranean provides data of biological and evolutionary interest for the successful management of such a highly valuable fishery resource.