Image processing tools in the study of environmental contamination by microplastics: reliability and perspectives

Environmental Science and Pollution Research - Microplastic pollution is one of the greatest environmental concerns for contemporary times and the future. In the last years, the number of...     

Effects of Fish Stocking on Ecosystem Services: An Overview and Case Study Using the Stockholm Archipelago

In this article, we focus on documented and possible effects of fish stocking in terms of ecosystem services. The increasing use of fish stocking between 1970 and 2000 in the semiurban setting of Stockholm archipelago, Sweden, is used as case study. The objective is to analyze this management practice from an ecosystem perspective, accounting for both the ecological and social context of releasing fish. The results show that enhancements of four native species (Salmo S. trutta, Salmo salar, Stizostedion lucioperca, and Anguilla anguilla) have dominated over new introductions of one nonnative species. (Oncorhynchus mykiss). The major objective has been to increase fish catches for local resource users. Involved stakeholders include three management agencies, one hydropower company, and several local sport fishing associations. Documented effects focus on recapture and production rates. However, our analysis suggests that additional positive or negative effects on biodiversity, food web dynamics, mobile links, or ecological information may also result, with possible consequences for the long-term provision of food, game, and aesthetic values. We conclude that a more adaptive and cooperative management approach could benefit from a deeper analysis of where, when, and what species is released, by whom, which stakeholders that use the fish and those ecosystem services the fish generate, and of the role of formal and informal institutions for monitoring and evaluating the success of releasing fish.     

Matrix effect in case of purification of oily waters by membrane separation combined with pre-ozonation

In the present study, oil in water emulsions (c_oil?=?100 ppm; d_{oil droplets}?<?2 μm) was purified with ozonation followed by microfiltration using polyethersulfone (PES) membrane (d_pore?=?0.2 μm). The effects of pre-ozonation on membrane microfiltration were investigated in detail both in case of ultrapure and model groundwater matrices, applying different durations (0, 5, 10, and 20 min) of pre-ozonation. Simultaneously, the effects of added inorganic water components on the combined method were investigated. Size distribution of oil droplets, zeta potentials, fluxes, and purification efficiencies were measured and fouling mechanisms were described in all cases. It was found that the matrix significantly affected the size distribution and adherence ability of oil droplets onto the membrane surface, therefore fouling mechanisms also were strongly dependent on the matrix. In case of low salt concentration, the total resistance was caused mainly by reversible resistance, which could be significantly reduced (eliminated) by pre-ozonation. In case of model groundwater matrix, nearly twice higher total resistance was measured, and irreversible resistance was dominant, because of the higher adhesion ability of the oil droplets onto the membrane surface. In this case, pre-ozonation resulted in much lower irreversible, but higher reversible resistance. Increased duration of pre-ozonation raised the total resistance and reduced the elimination efficiency (due to fragmented oil droplets and water soluble oxidation by-products) in both cases, therefore short pre-ozonation can be recommended both from economic and performance aspects.     

Effective Transboundary Aquifer Areas: An Approach for Transboundary Groundwater Management

The natural complexity, heterogeneity, and extent of transboundary aquifers around the world, have led to controversy over which method or criteria should be used to identify and delineate their boundaries. Currently, there is no standard methodology that aquifer‐sharing countries can use to delineate the area of a transboundary aquifer. In the case of Mexico and Texas, Mexico uses administrative boundaries, whereas Texas uses geological boundaries. This paper proposes a method for delineation and prioritization of aquifers (or aquifer areas) called effective transboundary aquifer areas (ETAAs), which uses a combination of physical criteria (geological boundaries, topography, and hydrography) and the location and density of active water wells in the borderland between Mexico and Texas. This method identifies the area of priority (productivity area) in the aquifer using pumping patterns or hot spots regardless of the aquifer’s surficial geological limits, therefore offering a more effective, local and practical management option at the transboundary level. Different geological features or pumping patterns will have different sizes and locations of ETAAs within the same aquifer. In West Texas, which is dominated by bolsons, the method produces limited options for ETAAs, whereas in South Texas in the easternmost border the identified ETAAs are more significant.     

Remediation of drinking water contaminated with arsenic by the electro-removal process using different metal electrodes

The purification of water by the electro-removal process using different metal electrodes is widely used in different spheres of science and industry. The comparative characteristics under galvanostatic conditions of zinc (Zn), brass (Cu-Zn), copper (Cu) and iron (Fe) anodes for arsenic (As) removal from water by the electro-removal process in laboratory scale experiments were determined at current densities of 1.5, 3 and 12 mA cm(-2) for 60 min, from a solution containing different concentrations of As(v) (from 70 to 130 microg L(-1)). The results at these different current densities indicated that rapid arsenic removal was achieved at higher current densities (12 mA cm(-2)), with the chemical precipitation of arsenate complexes. The removal of As was relatively efficient, with the following tendency (at 1.5 mA cm(-2)): Fe (>93%) congruent with Zn (>93%) > Cu-Zn (>73%) >Cu (>67%), these efficiencies were relatively independent of the removal rate for all the initial arsenic concentrations investigated. This behaviour is attributed to the electrochemical intrinsic properties of the most active metals, and to the chemical precipitation reactions following the electrochemical process, iron being the most attractive metal for arsenic removal for practical applications.     

Polychlorinated biphenyls in polysulfide sealants--occurrence and emission from a landfill station

Approximately 80,000 kg polysulfide sealant containing 10,000-18,000 kg polychlorinated biphenyls (PCB) was deposited at a Swedish municipal landfill station during 1965-1973. Investigations during 1994 showed that soil layers underneath the landfill had concentration of PCB not alarmingly high. The concentration of PCB congeners in ground water samples was elevated 4-750 times compared to a reference sample. Based on samples of ground water, leachate water, and flux chambers measuring evaporation of PCB from the landfill surface, the emission of PCB was estimated to be 1 g sigmaPCB/yr. This very low rate was attributed to the high sorptive capacity of the sealant. Compared to a reference site, the evaporation flux was elevated for the most volatile congeners, but factors 20-1400 lower than from another landfill which was contaminated with PCB in paper-pulp fibres.     

Spatial analysis of extreme precipitation in Sweden 1961-2000

Extreme daily precipitation in Sweden for the years 1961-2000 is analyzed with respect to spatial scale, regional variations and associated weather types. Correlograms based on a lag distance of 30 km estimated the spatial scale of variation of the annual mean precipitation, the 99th percentile of daily precipitation and the average of annual maximum daily precipitation to 100 km, 60-100 km and 40-70 km, respectively. Regions of correlation with respect to precipitation at 82 stations during days of extreme events are identified through Maximum-Likelihood Factor Analysis. Eleven factors are found to provide the optimum factor solution. Weather types for the days of extreme events are determined by an objective classification scheme, based on daily sea level pressure, which is modified by subjective inclusion of fronts. In total, 63% of the extreme events occurred during cyclonic weather types, 32% during frontal, 3% during directional and 2% during anticyclonic types. The frequency of the weather types during extreme events varied between the regions however.     

Perinatal outcomes and genomic characteristics of fetal copy number variants: An individual record linkage study of 713 pregnancies

Objective

To determine the perinatal outcomes of fetuses diagnosed with a pathogenic copy number variant (CNV) or variant of uncertain significance (VUS); and to characterize these variants in terms of testing indication, genomic location, size, and inheritance.

Methods

Retrospective study of singleton pregnancies with a pathogenic CNV or VUS from a single laboratory during 2012–2018. Probabilistic record linkage between the prenatal diagnosis dataset and perinatal outcome data for births from 20 weeks gestation was performed. If no birth record was found, this implied a pregnancy loss <20 weeks.

Results

We included 6945 prenatal microarray results; a pathogenic CNV was detected in 230 (3.3%, 95% CI: 2.9%–3.8%) and a VUS in 483 (7.0%, 95% CI: 6.4%–7.6%). Of pregnancies with a pathogenic CNV, 20.0% (95% CI: 15.3%–25.6%) had a live birth, 3.0% (95% CI: 1.5%–6.2%) had a perinatal death (stillbirth or neonatal death), and 77% (95% CI: 71.1%–81.9%) had no birth record. Of those with a VUS, 64.4% (95% CI: 60.0%–68.5%) had a live birth, 1.8% (95% CI: 1.0%–3.5%) had a perinatal death, and no birth record was found for 33.7% (95% CI: 29.7%–38.1%). Most pathogenic CNVs (61.1%) were <7 Mb in size. The most common microdeletion syndromes were DiGeorge, Wolf-Hirschhorn, and Cri-du-chat syndromes.

Conclusion

This study provides an overview of perinatal outcomes and frequency of recurrent CNVs observed in the prenatal microarray era.     

Assessing equity and sustainability of water allocation in Colombia

Based on the national database of 28,104 water rights (concessions) granted in Colombia, this paper presents an analysis of how the principles of equity and sustainability are reflected in water allocation. Concessions appear to be an exclusionary mechanism since only a minority of small water users have concessions and the distribution of water volumes among those who have them is extremely inequitable. The 2009 Gini coefficient calculated for water concessions granted for agriculture was 0.90 compared with the rural land Gini of 0.88 (both indicators grouping holdings under the same entity). More than half of the Colombian departments have a higher Gini coefficient for water than for land, suggesting that water rights are at least as unequally distributed as land, in one of the most inequitable countries in Latin America. Water allocated to domestic, agriculture and hydropower use indicates a lack of consistency of water allocation criteria across regions. The volumetric and administrative attributes of water allocation in Colombia do not account for environmental flows or the concerns of marginalised groups of society that have limited access to the mechanism. Water allocation as a technical task, with limited transparency and secluded from public scrutiny, does not contribute to the solution of increasing water-related conflicts.     

Assessing human-induced pressures on coastal areas with publicly available data

The assessment of human-induced pressures on the coastal area is essential to target management plans effectively, and moreover is required by the EU Water Framework Directive. A simple and cost-effective assessment of human-induced pressures on the coastal zone is applied using two methodologies: a qualitative visual assessment which uses satellite images; and a quantitative assessment based on governmental census data. These methods are applied to defined areas (23 areas) of four Italian regions: Liguria, Tuscany, Latium and Sardinia. The results show a high agreement (83%) between these two methods, in which only four of the 23 areas are classified differently. These differences may mainly be ascribed to the qualitative or quantitative properties of the methods, and to the different geographical units adopted. These characteristics however provide complementary information, which suggests that the application of both proposed methods confirms reliability and allows fine-tuning of the assessment. The pressure assessment proposed is simple, time and cost-effective, and repeatable over time and space. It therefore can be applied in different contexts to respond to legislative requirements or to target management plans and remedial actions effectively.