An experimental and theoretical analysis of the effect of added weight on the energetics and hydrostatic function of the swimbladder of European sea bass (Dicentrarchus labrax)

We conducted experiments to determine the effect of the increasing ultrasonic/radio transmitter weight on the routine metabolic rate of sea bass. We measured the oxygen consumption (MO₂) of fish tagged externally with a dummy transmitter made of a hollow pipe, the weight of which was adjusted with lead to represent in water 0, 1 and 4% (R_tf) of the animal weight. We then developed a theoretical model to estimate, for a given fish size, the range of added weight that fish can compensate for through swimbladder regulation. When R_tfБ%, MO₂ of untagged and tagged fish did not differ significantly. However, when R_tf reached 4%, fish that carried a tag incurred a significant elevation of oxygen consumption, which represented 28% of their total useable power (or metabolic scope). This result strongly supports the view that a high R_tf ratio contributes to a decrease in available metabolic energy by diverting energy from, e.g., growth or swimming performance. A comparison between the tagged fish and the theoretical model reinforced the hypothesis that, when R_tf attained 4%, the increase in metabolic rate reflected a supplementary and costly swimming effort necessary to maintain vertical position. In this condition, the swimbladder cannot regulate the buoyancy of tagged fish.     

Production of zeolitic materials in pilot scale based on coal ash for phosphate and potassium adsorption in order to obtain fertilizer

Environmental Science and Pollution Research - The use of different types of zeolites (X, Na-P1, and 4A) synthesized by different methods and scales were tested in this work to adsorb nutrients...     

Monitoring of pyrrolizidine alkaloids in beehive products and derivatives on the Belgian market

Pyrrolizidine alkaloids (PAs) and related N-oxides (PANOs) are secondary plant metabolites thought to be found in approximately 3% of the flowering plants worldwide and exhibiting hepatotoxic properties to humans. As a consequence, beehive products are prone to be contaminated with those compounds by bees foraging PA-producing plants. Downstream contamination can also occur through food items containing honey. Analytical methods based on UHPLC separation and MS/MS detection were developed with a focus on very low LOQs and validated for the analysis of 16 PAs and 14 PANOs in honey, honey-based candies and snacks, as well as beehive product–based food supplements. A maximum level of 182 ng/g of PAs was detected in a Mediterranean honey, and high levels of heliotrine-type compounds were reported for the first time. An extensive sampling of honeys harvested in Belgium was performed (N = 374), the concentration levels were more limited with a maximum of 60 ng/g, and the contamination pattern was dominated by senecionine-type PAs. The PA levels in honey-based candies and snacks were very low, with respective maxima of 7.61 ng/g and 0.36 ng/g. Seventy-five percent among the pre-dosed food supplements based on beehive products were contaminated, with a maximum of 43 ng/g. The highest level was detected in a bee-collected pollen sample (1672 ng/g). The analytical results were consistent with the previously reported data for beehive products and confirmed that PA/PANO contamination in these food commodities is recurrent.     

Brazil’s Amazonian protected areas as a bulwark against regional climate change

Regional Environmental Change - Brazil’s Amazonian protected areas play an important role in maintaining the environmental services of the region, including Amazonia’s role in regional...     

Assessment and optimisation of VOC mass transfer enhancement by advanced oxidation process in a compact wet scrubber

Dimethyl disulphide (DMDS) removal was investigated in a compact scrubber (hydraulic residence time ≈20 ms), composed of a wire mesh packing structure where liquid and gas flow at co-current and high gas superficial velocity (>12 m s⁻¹). In order to regenerate the scrubbing liquid and to maintain a driving force in the scrubber, ozone and hydrogen peroxide were added to water since they allow the generation of nonselective and highly reactive species, hydroxyl radicals HO. Three ways of reagent distribution were tested. The influence of several parameters (liquid flow rate(s), ozone flow rate, pH and reagent concentrations) was investigated. The best configuration was obtained when ozone is transferred in the scrubbing liquid before introduction at the top of the scrubber simultaneously with the hydrogen peroxide solution, allowing to generate hydroxyl radical in the scrubber. With this configuration, DMDS removal could be increased from 16% with water to 34% at the same gas and liquid flow rates in the scrubber showing the potentiality of advanced oxidation process.     

A tale of two cities: restoring water services in Kabul and Monrovia

Kabul and Monrovia, the respective capitals of Afghanistan and Liberia, have recently emerged from long-lasting armed conflicts. In both cities, a large number of organisations took part in emergency water supply provision and later in the rehabilitation of water systems. Based on field research, this paper establishes a parallel between the operations carried out in the two settings, highlighting similarities and analysing the two most common strategies. The first strategy involves international financial institutions, which fund large-scale projects focusing on infrastructural rehabilitation and on the institutional development of the water utility, sometimes envisaging private-sector participation. The second strategy involves humanitarian agencies, which run community-based projects, in most cases independently of the water utilities, and targeting low-income areas. Neither of these approaches manages to combine sustainability and universal service. The paper assesses their respective strengths and weaknesses and suggests ways of improving the quality of assistance provided.