Physicochemical Properties of Composite Materials Based on Thermoplastic Yam Starch and Polylactic Acid Improved with the Addition of Epoxidized Sesame Oil

Journal of Polymers and the Environment - Biodegradable materials provide a primary function in preserving and protecting food products, helping to extend shelf life. The present work aims to...     

Application of indicator kriging to the complementary use of bioindicators at three trophic levels

The use of biological indicators is widespread in environmental monitoring, although it has long been recognised that each bioindicator is generally associated with a range of potential limitations and shortcomings. To circumvent this problem, this study adopted the complementary use of bioindicators representing different trophic levels and providing different type of information, in an innovative approach to integrate knowledge and to estimate the overall health state of ecosystems. The approach is illustrated using mercury contamination in primary producers (mosses), primary consumers (domestic pigeons and red-legged partridges) and top predators (Bonelli's eagles) in southern Portugal. Indicator kriging geostatistics was used to identify the areas where mercury concentration was higher than the median for each species, and to produce an index that combines mercury contamination across trophic levels. Spatial patterns of mercury contamination were consistent across species. The combined index provided a new level of information useful in incorporating measures of overall environmental contamination into pollution studies.     

Evaluation of Cu potential bioavailability changes upon coastal sediment resuspension: an example on how to improve the assessment of sediment dredging environmental risks

Purpose  

Metal bioavailability-based sediment quality analysis, inferred from geochemical partitioning data, may contribute to improve sediment management policies. This is important because decision-making processes should not give similar priorities to sediments offering contrasting environmental risks associated to metal bioavailability. However, current uses of Sediment Quality Guidelines (SQGs) as interpretive tools to support decisions about dredging-related activities have not considered the changes in metal bioavailability upon sediment resuspension.     

Impact of chemical oxidation on soil quality

Oxidation treatment helps to reduce the polycyclic aromatic hydrocarbon (PAH) load in contaminated soils but it may also have an effect on the soil quality. The impact of permanganate and Fenton oxidation on soil quality is investigated. Soil quality is restricted here to the potential for plant growth. Soil samples were collected from an agricultural field (S1) and a former coking plant (S4). Agricultural soil was spiked with phenanthrene (PHE) and pyrene (PYR) at two concentrations (S2: 700 mg PHE kg⁻¹, S3: 700 mg PHE kg⁻¹ and 2100 mg PYR kg⁻¹). Soils were treated with both oxidation processes, and analyzed for PAHs and a set of agronomic parameters. A plant germination and growth test was run with rye-grass on treated soils. Results showed that both treatments produced the expected reduction of PAH concentration (from 64% to 97%). Besides, a significant loss of organic C and N, and strong changes in available nutrients were observed. Permanganate treatment increased the specific surface area and the cation exchange capacity in relation to manganese dioxide precipitation, and produced a rise in pH. Fenton oxidation decreased soil pH and increased the water retention capacity. Plant growth was negatively affected by permanganate, related to lower soil permeability and aeration. Both treatments had an effect on soil properties but Fenton oxidation appeared to be more compatible with revegetation.     

Health risk assessment through consumption of vegetables rich in heavy metals: the case study of the surrounding villages from Panasqueira mine,Central Portugal

Panasqueira mine is a tin–tungsten mineralization hosted by metasediments with quartz veins rich in ferberite. The mineralization also comprises wolframite, cassiterite, chalcopyrite, several sulfides, carbonates and silver sulfosalts. The mining and beneficiation processes produce arsenic-rich mine wastes laid up in huge tailings (Barroca Grande and Rio tailings). The contents of As, Cd, Cr, Cu, Pb and Zn were estimated in rhizosphere soils, irrigation waters, road dusts and in potatoes, cabbages, lettuces and beans, collected on local gardens of four neighborhood Panasqueira mine villages: S. Francisco de Assis (SFA) and Barroca suffering the influence of tailings; Unhais-o-Velho and Casegas considered as non-polluted areas. The mean concentrations of metals in rhizosphere soils and vegetables exceed the reference guidelines values and seem to be linked to the sulfides. The rhizosphere ecological risks were ranked in the order of Cd > As > Cu > Pb > Zn > Cr and SFA > Barroca > Casegas > Unhais-o-Velho. Metal concentrations, in vegetables, were found in the order of lettuce > cabbage > potatoes and SFA > Barroca > Casegas > Unhais-o-Velho. For cabbages and lettuces, the tendency of contamination is roots > leaves and for potatoes is roots > leaves > tubers. The risk for residents, due to ingesting of metals/metalloid, by consuming vegetables grown around the sampling area, was calculated and the result indicates that the inhabitants of these villages are probably exposed to some potential health risks through the intake of heavy metals and metalloids via consuming their vegetables.     

<Emphasis Type="Italic">Mesorhizobium</Emphasis> bacterial strains isolated from the legume <Emphasis Type="Italic">Lotus corniculatus</Emphasis> are an alternative source for the production of polyhydroxyalkanoates (PHAs) to obtain bioplastics

Polyhydroxyalkanoic acids (PHAs) are natural polyesters that can be used to produce bioplastics which are biodegradable. Numerous microorganisms accumulate PHAs as energy reserves. Combinations of different PHAs monomers lead to the production of bioplastics with very different properties. In the present work, we show the capability of strains belonging to various phylogenetic lineages within the genus Mesorhizobium, isolated from Lotus corniculatus nodules, to produce different PHA monomers. Among our strains, we found the production of 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxydodecanoate, and 3-hydroxyhexadecanoate. Most of the PHA-positive strains were phylogenetically related to the species M. jarvisii. However, our findings suggest that the ability to produce different monomers forming PHAs is strain-dependent.     

Leaching and persistence of ametryn and atrazine in red–yellow latosol

This study evaluated the mobility and persistence of atrazine and ametryn in red–yellow latosols using polyvinyl chloride columns with a diameter of 100 mm and a height of 15 cm. The assays simulated 60-mm rainfall events at 10-day intervals for 70 days. The persistence and leaching were evaluated for these two herbicides. The analytes obtained from the samples were quantified by gas chromatography using flame ionization detection. Compared with ametryn, atrazine showed a greater potential to reach depths below 15 cm over 30 days of simulated rain. Ametryn, however, showed greater persistence in soil at 70 days after application. The persistence of atrazine and ametryn in soil under sunlight was 10 and 144 days respectively. Atrazine was more susceptible to sunlight than ametryn because sunlight favored atrazine degradation in hydroxyatrazine. The results indicate that in red–yellow latosol, atrazine has a high leaching potential in short term, but that ametryn is more persistent and has a high leaching potential in long term.     

The Governance of the Mitigation of the Baltic Sea Eutrophication: Exploring the Challenges of the Formal Governing System

This article focuses on the governing system of the mitigation of eutrophication in the Baltic Sea. Policies and measures of the Baltic Sea coastal countries, the macro--regional (HELCOM) level, and the level of the European Union are described and governance challenges explicated. We found that the main challenges at different governance levels include: differences between coastal countries in terms of environmental conditions including environmental awareness, overlaps of policies between different levels, the lack of adequate spatial and temporal specification of policies, and the lack of policy integration. To help to meet these challenges, we suggest closer involvement of stakeholders and the public, the improvement of the interplay of institutions, and the introduction of a “primus motor” for the governance of the mitigation of eutrophication in the Baltic Sea.     

The size distribution of organic carbon in headwater streams in the Amazon basin

Despite the strong representativeness of streams in the Amazon basin, their role in the accumulation of coarse particulate organic carbon (CPOC), fine particulate organic carbon (FPOC), and dissolved organic carbon (DOC) in transport, an important energy source in these environments, is poorly known. It is known that the arboreal vegetation in the Amazon basin is influenced by soil fertility and rainfall gradients, but would these gradients promote local differences in organic matter in headwater streams? To answer this question, 14 low-order streams were selected within these gradients along the Amazon basin, with extensions that varied between 4 and 8 km. The efficiency of the transformation of particulate into dissolved carbon fractions was assessed for each stream. The mean monthly benthic organic matter storage ranged between 1.58 and 9.40 t ha^?1 month^?1. In all locations, CPOC was the most abundant fraction in biomass, followed by FPOC and DOC. Rainfall and soil fertility influenced the distribution of the C fraction (p?=?0.01), showing differentiated particulate organic carbon (POC) storage and DOC transportation along the basin. Furthermore, the results revealed that carbon quantification at the basin level could be underestimated, ultimately influencing the global carbon calculations for the region. This is especially due to the fact that the majority of studies consider only fine particulate organic matter and dissolved organic matter, which represent less than 50 % of the stored and transported carbon in streambeds.