Aquatic humus from an unpolluted Brazilian dark-brown stream: general characterization and size fractionation of bound heavy metals

The main pool of dissolved organic carbon in tropical aquatic environments, notably in dark-coloured streams, is concentrated in humic substances (HS). Aquatic HS are large organic molecules formed by micro-biotic degradation of biopolymers and polymerization of smaller organic molecules. From an environmental point of view, the study of metal humic interactions is often aimed at predicting the effect of aquatic HS on the bioavailability of heavy metal ions in the environment. In the present work the aquatic humic substances (HS) isolated from a dark-brown stream (located in an environmental protection area near Cubat?o city in S?o Paulo-State, Brazil) by means of the collector XAD-8 were investigated. FTIR studies showed that the carboxylic carbons are probably the most important binding sites for Hg(II) ions within humic molecules. 13C-NMR and 1H-NMR studies of aquatic HS showed the presence of constituents with a high degree of aromaticity (40% of carbons) and small substitution. A special five-stage tangential-flow ultrafiltration device (UF) was used for size fractionation of the aquatic HS under study and for their metal species in the molecular size range 1-100 kDa (six fractions). The fractionation patterns showed that metal traces remaining in aquatic HS after their XAD-8 isolation have different distributions. Generally, the major percentage of traces of Mn, Cd and Ni (determined by ICP-AES) was preferably complexed by molecules with relatively high molecular size. Cu was bound by fractions with low molecular size and Co showed no preferential binding site in the various humic fractions. Moreover, the species formed between aquatic HS and Hg(II), prepared by spiking (determined by CVAAS), appeared to be concentrated in the relatively high molecular size fraction F1 (> 100 kDa).     

Comparison of the substrate effect on voc emissions from water based varnish and latex paint

BACKGROUND, AIMS AND SCOPE: The building materials are recognised to be major contributors to indoor air contamination by volatile organic compounds (VOCs). The improvement of the quality of the environment within buildings is a topic of increasing research and public interest. Legislation in preparation by the European Commission may induce, in the near future, European Union Member States to solicit the industries of paints, varnishes and flooring materials for taking measures, in order to reduce the VOC emissions resulting from the use of their products. Therefore, product characterisation and information about the influence of environmental parameters on the VOC emissions are fundamental for providing the basic scientific information required to allow architects, engineers, builders, and building owners to provide a healthy environment for building occupants. On the other hand, the producers of coating building materials require this information to introduce technological alterations, when necessary, in order to improve the ecological quality of their products, and to make them more competitive. Studies of VOC emissions from wet materials, like paints and varnishes, have usually been conducted after applying the material on inert substrates, due to its non-adsorption and non-porosity properties. However, in real indoor environments, these materials are applied on substrates of a different nature. One aim of this work was to study, for the first time, the VOC emissions from a latex paint applied on concrete. The influence of the substrate (uncoated cork parquet, eucalyptus parquet without finishing and pine parquet with finishing) on the emissions of VOC from a water-based varnish was also studied. For comparison purposes, polyester film (an inert substrate) was used for both wet materials. METHODS: The specific emission rates of the major VOCs were monitored for the first 72 h of material exposure in the atmosphere of a standardized test chamber. The air samples were collected on Tenax TA and analysed using thermal desorption online with gas chromatography provided with both mass selective detection and flame ionisation detection. A double exponential model was applied to the VOC concentrations as a function of time to facilitate the interpretation of the results. RESULTS AND DISCUSSION: The varnish, which was introduced in the test chamber 23 h after the application of the last layer of material, emitted mainly glycolethers. Only primary VOCs were emitted, but their concentrations varied markedly with the nature of the substrate. The higher VOC concentrations were observed for the parquets of cork and eucalyptus, which indicated that they have a much higher porosity and, therefore, a higher power of VOC adsorption than the finished pine parquet (and polyester film). The paint was introduced in the chamber just after its application. Only primary VOCs were emitted (esters, phthalates, glycolethers and white spirit) but some compounds, like 2-(2-butoxyethoxy)ethanol and diethylphthalate, were only observed for paint/polyester, which suggested that they were irreversibly adsorbed by the paint/concrete. Compared with the inert substrate, the rate of VOC emissions was lower for concrete in the wet-stage (first hours after the paint application) but slightly higher later (dry-stage) as a consequence of desorption. CONCLUSIONS: As to varnish, the substrates without finishing, like cork and eucalyptus parquets, displayed a higher power of adsorption of VOCs than the pine parquet with finishing, probably because they have a higher porosity. As concerns paint, the total masses of VOCs emitted were lower for concrete than for polyester, indicating that concrete reduces the global VOC emissions from the latex paint. Concrete is seen to have a strong power of adsorption of VOCs. Some compounds, namely 2-(2-butoxyethoxy)ethanol, diethylphthalate and TEXANOL (this partially), were either irreversibly adsorbed by the concrete or desorbed very slowly (at undetected levels). A similar behaviour had not been reported for gypsum board, a paint substrate studied before. RECOMMENDATIONS AND OUTLOOK: The present data suggest that concrete may be a recommendable substrate for paint in an indoor environment. As the nature of the substrate conditions the rate and nature of VOC emissions from wet materials, it must be explicit when emissions from composite materials are reported, in order to allow comparisons and labelling of the product in terms of indoor air quality.     

Use of Oxidation Onset Temperature Measurements for Evaluating the Oxidative Degradation of Isotatic Polypropylene

The widespread use of polymeric materials in many applications requires polymers that are weather resistant. The aim of this study is to examine the usefulness of oxidation onset temperature measurements as a tool for evaluating oxidative degradation of isotatic polypropylene. Differential scanning calorimetry was used to measure the oxidation onset temperature in formulations of isotatic polypropylene containing different concentrations of light and thermal stabilizers after aging in a Weather-Ometer. Oxidation onset temperature gave better results than oxidation induction time for evaluating the degradation of isotatic polypropylene during aging in a Weather-Ometer. However, both tests showed a poor correlation with the appearance of cracks seen by optical microscopy.     

MULTIVARIATE ANALYSIS OF WATER QUALITY AND PHYSICAL CHARACTERISTICS OF SELECTED WATERSHEDS IN PUERTO RICO1

ABSTRACT: Multivariate analyses were used to develop equations that could predict certain water quality (WQ) conditions for unmonitored watersheds in Puerto Rico based on their physical characteristics. Long term WQ data were used to represent the WQ of 15 watersheds in Puerto Rico. A factor analysis (FA) was performed to reduce the number of chemical constituents. Cluster analysis (CA) was used to group watersheds with similar WQ characteristics. Finally, a discriminant analysis (DA) was performed to relate the WQ clusters to different physical parameters and generate predicting equations. The FA identified six factors (77 percent of variation explained): nutrients, dissolved ions, sodium and chloride, silicacious geology, red ox conditions, and discharge. From the FA, specific conductance, sodium, phosphorous, silica, and dissolved oxygen were selected to represent the WQ characteristics in the CA. The CA determined five groups of watersheds (forested, urban polluted, mixed urban/rural, forested plutonic, and limestone) with similar WQ properties. From the five WQ clusters, two categories can be observed: forested and urban watersheds. The DA found that changes in forest cover, percent of limestone, mean annual rainfall, and watershed shape factor were the most important physical features affecting the WQ of watersheds in Puerto Rico.     

The post-political nature of marine spatial planning and modalities for its re-politicisation

ABSTRACT

Marine spatial planning (MSP) has become the most adopted approach for sustainable marine governance. While MSP has transformative capacity, evaluations of its implementation illustrate large gaps between how it is conceptualised and how it is practiced. We argue that these gaps arise from MSP being implemented through post-political processes. Although MSP has been explored through post-political lenses, these evaluations are incomplete and do not provide sufficient detail about the complex nature of the post-political condition. Drawing on seminal literature, we conceptualise the post-political as consisting of highly interconnected modalities of depoliticisation, including: neoliberalism; choreographed participation; path dependency; technocratic-managerialism; and the illusion of progressive change. Using these modalities as an analytical framework, we evaluate English MSP and find that it focuses on entrenching neoliberal logic through: tokenistic participation; wholescale adoption of path-dependent solutions; obstructionist deployment of inactive technological solutions; and promising progressive change. We do not, however, view the post-political condition as unresolvable and we develop a suite of suggestions for the re-politicisation of MSP which, collectively, could form the basis for more radical forms of MSP.     

More than Biodiversity: The Socio-economic Impact of Implementing Biodiversity Action Plans in the UK

Biodiversity action plans (BAPs), which are designed to protect and enhance wildlife, can also provide additional benefits to the local economy in terms of job creation and income generation. This paper considers the socio-economic benefits of implementing the BAP for species-rich hedges in Devon. It identifies employment and income generation for hedge contractors, farm labour, trainers, suppliers, processors of hedge products and the tourist industry as a result of 1 million expenditure on hedge restoration work to meet BAP targets. Using data from a survey of hedgerow contractors and key informants in related industries a multiplier analysis identified that funding for hedge restoration can have significant employment and income generation impacts on the local economy. In particular, this multiplier effect is enhanced because both hedge contractors and materials are largely sourced locally.     

Comparing species abundance models

Five regression models (Poisson, negative binomial, quasi-Poisson, the hurdle model and the zero-inflated Poisson) were used to assess the relationship between the abundance of a vulnerable plant species, Leionema ralstonii, and the environment. The methods differed in their capacity to deal with common properties of ecological data. They were assessed theoretically, and their predictive performance was evaluated with correlation, calibration and error statistics calculated within a bootstrap evaluation procedure that simulated performance for independent data.