Characterization of humic-rich hydrocolloids and their metal species by means of competing ligand and metal exchange--an on-site approach

An improved on-site characterization of humic-rich hydrocolloids and their metal species in aquatic environments was the goal of the present approach. Both ligand exchange with extreme chelators (diethylenetetraaminepentaacetic acid (DTPA), ethylendiaminetetraacetic acid (EDTA)) and metal exchange with strongly competitive cations (Cu(II) were used on-site to characterize the conditional stability and availability of colloidal metal species in a humic-rich German bogwater lake (Venner Moor, Münsterland). A mobile time-controlled tangential-flow ultrafiltration technique (cut-off: 1 kDa) was applied to differentiate operationally between colloidal metal species and free metal ions, respectively. DOC (dissolved organic carbon) and metal determinations were carried out off-site using a home-built carbon analyzer and conventional ICP-OES (inductively-coupled plasma-optical emission spectrometry), respectively. From the metal exchange equilibria obtained on-site the kinetic and thermodynamic stability of the original metal species (Fe, Mn, Zn) could be characterized. Conditional exchange constants Kex obtained from aquatic metal species and competitive Cu(II) ions follow the order Mn > Zn > > Fe. Obviously, Mn and Zn bound to humic-rich hydrocolloids are very strongly competed by Cu(II) ions, in contrast to Fe which is scarcely exchangeable. The exchange of aquatic metal species (e.g. Fe) by DTPA/EDTA exhibited relatively slow kinetics but rather high metal availabilities, in contrast to their Cu(II) exchange.     

Higher soybean production using honeybee and wild pollinators, a sustainable alternative to pesticides and autopollination

This is the first report showing that using honeybee (Apis mellifera) and wild pollinators complementary pollination can enhance soybean productivity (Glycine max). Current industrial production of soybean involves autopollination and high loads of pesticides. Therefore, growers have neglected possible biotic pollination despite suggestions that soybean benefit from insect pollinators. Reports advocating possible biotic pollination are based on experiments where bees are caged with flowering plants and the absence of pesticides, thus not in field conditions. Therefore, here we compared in field conditions soybean yield produced (1) independently of biotic pollinators, (2) with wild pollinators and (3) with honeybee colonies. Results showed an increase of +6.34 % of soybean yield in areas where wild pollinators had free access to flowers. The introduction of honeybee colonies further raised the yield of +18.09 %. Our findings therefore show that, though soybean is autogamous, allowing pollination by wild pollinators leads to higher yields. Moreover, adding honeybee mitigates pollination deficits and improves yield compared to current practices.     

Weed seedbank evaluating method to generate spatial distribution maps

The objective of this work was to develop a fast and practical method of weed seedbank evaluation to generate spatially distributed maps for use in site-specific weed management. Soil cores were collected at 0.20 m depth, air-dried, and then submitted to seedling growth in greenhouse. The sampling grid of 20 by 20 m was georeferenced by Global Positioning System, obtaining 73 soil cores with three replicates. During the greenhouse trial, there were two peaks of weed seedling growth: one in 119 days after water irrigation and another after KNO3 application. Weeds seedbank maps were obtained at different stages of seedling growth. The Pearson correlation was 0.99 for Brachiaria plantaginea seedbank map, 0.95 for Commelina benghalensis, and 0.85 for Cyperus rotudus generated at 119 days compared with 392 days after seedling growth in the greenhouse. The Brachiaria plantaginea seedbank map evaluated at 35 days presented correlation of 0.97 with 392 days. It was concluded that, for site-specific weed seedbank management, the evaluation of seedling growth in greenhouse until the first emergence peak is enough to generate weed seedbank maps.     

Some aspects of heavy metals contamination remediation and role of biosurfactants

Contamination by heavy metals is the result of different industrial activities. The presence of heavy metals in soil and water causes serious problems, as these materials are not biodegradable and do contaminate both biological systems and the subsoil. Biological surface-active compounds otherwise known as biosurfactants in general and rhamnolipids biosurfactants in particular have been successfully employed in the remediation of environments contaminated with heavy metal ions. The aim of the present review is to highlight potential applications of these tensioactive compounds for use in environmental heavy metals removal and bioremediation and processes involved.     

Organisational learning and continuous improvement of health and safety in certified manufacturers

Certified management systems have increasingly been applied by firms in recent decades and now cover the management of health and safety, principally through the OHSAS 18001 standard. In order to become certified, firms must not only observe the relevant legislation, but also improve performance and raise goals within health and safety on a continuous basis. The article examines how certified occupational and health management systems influence this process to evaluate how far they hinder or support learning. It presents a model with which it is possible to identify and analyse improvement processes. The model is applied to five cases from a qualitative study of Danish manufacturers with certified health and safety management systems. The cases illustrate the wide variation in health and safety management among certified firms.Certification is found to support lower levels of continuous improvement performance in handling health and safety issues. However, more advanced improvement practices are shown to be connected to the integration of health and safety in other managerial areas, as well as to the employment of similar advanced improvement processes within firms. The article argues that certified health and safety management does not obstruct learning, and can support advanced learning. Improvement practices with regard to health and safety are mainly dependent upon the firm’s overall organisational processes and do not automatically arise from the standard alone.     

Bio-based films/nanopapers from lignocellulosic wastes for production of added-value micro-/nanomaterials

Environmental Science and Pollution Research - The growing demand for products with lower environmental impact and the extensive applicability of cellulose nanofibrils (CNFs) have received...     

Modelling the temperature and the phytoplankton distributions at the Aveiro near coastal zone,Portugal

The main objective of this paper is to implement a coupled three-dimensional physical and ecological model for the Aveiro coast, and to apply it to study the temperature and the phytoplankton biomass spatial distributions along the coastal ecosystem. The Aveiro coast is located at Portugal within the upwelling system of the Atlantic Iberian coast, characterized by nutrients availability and phytoplankton biomass accumulation, from April to October. In order to implement the ecological model, its validation was assessed by comparing simulations to data relative to the horizontal and vertical distributions of the temperature, nutrients and phytoplankton biomass, obtained during the CICLOS I survey off the Portuguese coast [Moita, M.T., 2001. Estrutura, Variabilidade e Dinâmica do Fitoplâncton na Costa de Portugal Continental. PhD Thesis. Faculdade de Ciências da Universidade de Lisboa, 272 pp.]. A sensitivity analysis of the model has been performed in order to assess the influence of the main ecological model variables. The simulation results show that the model is capable of predicting realistic the temperature, the nutrients and the chlorophyll-a distributions for the study area. The scenarios evidence the setup of a thermal stratification pattern resulting from the upwelling of deep and rich in nutrients water to the surface layer and a chlorophyll-a maxima extending offshore, along the picnocline and the nutricline. The results confirm the crucial role played by the physical processes in the phytoplankton bloom along the Aveiro coast. They also evidence the close link between the surface phytoplankton distribution and the surface temperature distribution.     

Kinetics and thermodynamic studies of Methyl Orange removal by polyvinylidene fluoride-PEDOT mats

We report the preparation of poly(3,4-ethylene dioxythiophene) (PEDOT)-modified polyvinylidene fluoride electrospun fibers and their use as a novel adsorbent material for the removal of the anionic dye Methyl Orange (MO) from aqueous media. This novel adsorbent material can be used to selectively remove MO on a wide pH range (3.0–10.0), with a maximum capacity of 143.8 mg/g at pH 3.0. When used in a recirculating filtration system, the maximum absorption capacity was reached in a shorter time (20 min) than that observed for batch mode experiments (360 min). Based on the analyses of the kinetics and adsorption isotherm data, one can conclude that the predominant mechanism of interaction between the membrane and the dissolved dye molecules is electrostatic. Besides, considering the estimated values for the Gibbs energy, and entropy and enthalpy changes, it was established that the adsorption process is spontaneous and occurs in an endothermic manner. The good mechanical and environmental stability of these membranes allowed their use in at least 20 consecutive adsorption/desorption cycles, without significant loss of their characteristics. We suggest that the physical-chemical characteristics of PEDOT make these hybrid mats a promising adsorbent material for use in water remediation protocols and effluent treatment systems.