In aquafarming, 17α-methyltestosterone (MT) is widely used as an anabolic steroid to induce the sex of Nile tilapia fry to male in order to increase production yield. Nile tilapia fry is fed at a rate of 0.06 mg of MT/kg of feed during the first 21 days after hatching. MT not consumed by the fish fry may be sorbed onto the sediment in the fish ponds which may contaminate the environment when released from the ponds. Using soils and sediment from a Nile tilapia masculinization pond as sorbents in batch sorption experiments, the linear sorption coefficients (K d) of MT were found to range from 1.2 to 168.8 L/kg with an average K ₒc value of 9,450 L/kg. The linear sorption coefficients of MT were found to correlate with the organic carbon contents of the sorbents. Sorption of MT onto sand, garden soil, and sediment was not impacted by pH, but the sorption of MT onto sediment was found to be impacted by the salinity of the water. The salting out coefficient of MT in saline water was found to be approximately 0.87 L/mol.

The present work describes a detailed study about the adsorption of malachite green (MG) by a polyether-type polyurethane foam (PUF) using sodium dodecylsulfate (SDS) as a carrier. The adsorption process was based on the formation of a hydrophobic ionic-pair between the MG cationic dye and the dodecylsulfate anion, which presented high affinity for the PUF. The manifold employed in the study was built up by adjusting a cylinder of PUF with 200 mg in the arm of an overhead stirrer, which was soaked (and stirred) in the solution containing the dye and SDS. The adsorption process was characterized in relation to equilibrium and kinetic aspects. Langmuir (r 2 = 0.842) and Freundlich (r 2 = 0.996) isotherms were also employed for modeling the system as well as the Nernst partition law (r 2 = 0.999). A study about the recovery of MG and the PUF regeneration was conducted, and the acetonitrile was the most efficient solvent for the desorption of the adsorbed ionic pair. The obtained results showed that the concentration of SDS added to the medium plays an important role on the adsorption process, which can be better described by employing a second-order kinetic model.

Coagulation and flocculation are basic chemical engineering operations employed to remove suspended solids from water. The growing concern for environmental and ecological issues warrants the use of the biodegradable flocculants in wastewater and industrial effluent treatment. In this work, unconventional coagulant, namely lactic acid, calcium lactate, sodium lactate, and citric acid were studied in comparison with AlCl3, a usual coagulant widely employed to remove water turbidity. It was observed that lactic acid and calcium lactate were able to reduce the water turbidity similarly to AlCl3. This fact can be very interesting because lactic acid salts can be produced by biotechnological process, and contrarily to aluminium salts, they are biodegradable, reducing the risk for human and animal’s health.

A new sampling system has been developed for the measurement of time-averaged concentrations (TWA) and diffusion coefficients of organic micropollutants in aquatic environments. The system is based on the diffusion of targeted organic compounds through a rate-limiting membrane and the subsequent accumulation of these species in a bound, hydrophobic solid-phase material. Two separate prototype systems are described. One is suitable for the sampling of carbamates such as carbaryl, carbofuran, 3-hydroxycarbofuran, baygon, propham, clorpropham, and the other one for s-triazines such as atrazine, prometryn, propazine, simazine, terbuthylazine, terbutryn, metribuzin, cyanazine, and metamitron pesticides. The systems use solid-phase material (47-mm C₁₈ Empore disk) as the receiving phase but are fitted with rate-limiting membranes of either polysulfone or polycarbonate. For the two designs investigated, the cumulative uptake of all target analytes was considered over exposure periods of 7 days. The determined sampling rates ranged from 0.1323 to 0.0465 L day⁻¹ with both membranes. The best system was the one with the polysulfone membrane allowing a better cumulative uptake.

More than 30 epiphytic lichens, collected in Agadir (Morroco) and along a 150-km transect from the Atlantic Ocean eastward, were analyzed for their metal content and lead isotopic composition. This dataset was used to evaluate atmospheric metal contamination and the impact of the city on the surrounding area. The concentrations of Cu, Pb, and Zn (average ±â€‰1 SD) were 20.9 ±â€‰15.2 μg g−1, 13.8 ±â€‰9.0 μg g−1, and 56.6 ±â€‰26.6 μg g−1, respectively, with the highest values observed in lichens collected within the urban area. The 206Pb/207Pb and 208Pb/207Pb ratios in the lichens varied from 1.146 to 1.186 and from 2.423 to 2.460, respectively. Alkyllead-gasoline sold in Morocco by the major petrol companies gave isotopic ratios of 206Pb/207Pb = 1.076–1.081 and 208Pb/207Pb = 2.348–2.360. These new, homogeneous values for gasoline-derived lead improve and update the scarce isotopic database of potential lead sources in Morocco, and may be of great value to future environmental surveys on the presence of lead in natural reservoirs, where it persists over time (e.g., soils and sediments). The interest of normalizing metal concentrations in lichens to concentrations of a lithogenic element is demonstrated by the consistency of the results thus obtained with lead isotopic ratios. Leaded gasoline contributed less than 50% of the total amount of lead accumulated in lichens, even in areas subject to high vehicular traffic. This strongly suggests that the recent banishment of leaded gasoline in Morocco will not trigger a drastic improvement in air quality, at least in Agadir.

Grazing livestock excrete large volumes of faecal material on pasture. Understanding the magnitude of this faecal burden is important for attributing sources of agricultural pollutants to different spatial and temporal scales. This field-based study evaluated the utility and transferability of a rapid approach often used in plant ecology (the line intercept method (LIM)) for estimating faecal burden from grazing cattle on pasture. Results from the LIM were of equivalent magnitude, with no significant difference observed, to those derived from more time-consuming sampling of faecal material from pasture using a quadrat-style methodology (herein termed burden sampling). However, the variability in estimates using the LIM was much larger (839–7,079 kg fresh weight faeces over the 50,000 m² field) compared with estimates provided by the burden sampling of pasture at 0.2 % area sampled (1,616–3,979 kg/50,000 m²), 0.4 % area sampled (1,753–2,723 kg/50,000 m²) and 0.8 % area sampled (1,212–2,344 kg/50,000 m²). The LIM offers a rapid and cost-effective alternative to time-consuming sampling campaigns of faecal burden on pasture and provides estimations that are preferable to back-of-the-envelope calculations based on the over-simplification of livestock excretion rates.

Recently, specific air quality problems have been detected in the northern region of Portugal. The nitrogen oxide (NO₂) annual limit value has been surpassed at several air quality monitoring stations in the northern region, and according to European legislation, air quality plans must be designed and implemented to reduce those levels. The analysis of the air quality data from the stations concerning NO₂ exceedances indicates that traffic is responsible for an increase of more than 40 % compared with the urban background value. Specific measures to reduce NOx emissions have been selected and are related not only mainly to the traffic sector but also to the industrial and residential combustion sectors. The main objective of this study is to investigate the impact of the selected measures on the ambient levels of NO₂ in northern Portugal using a numerical modelling tool—The Air Pollution Model (TAPM). TAPM was applied over the study region using a 120 × 120-km² simulation domain and a spatial resolution of 4.8 × 4.8 km². The entire year of 2010 was simulated and was set as the base year to analyse the impact of the selected measures. Two scenarios have been defined and simulated: the base situation, which considers current NOx emissions, and the reduction scenario for which NOx emissions were re-estimated considering the implementation of the measures. The modelling results demonstrate a decrease of 4–5 μg m⁻³ in the annual NO₂ levels in the study region. Moreover, the implementation of the selected measures will allow compliance with the NO₂ annual limit values in three of the five air quality stations that measured levels surpassing those established by legislation. This situation demands additional measures that should be implemented at the local level and that particularly focus on the traffic sector.

Climate change mediates marine chemical and physical environments and therefore influences marine organisms. While increasing atmospheric CO2 level and associated ocean acidification has been predicted to stimulate marine primary productivity and may affect community structure, the processes that impact food chain and biological CO2 pump are less documented. We hypothesized that copepods, as the secondary marine producer, may respond to future changes in seawater carbonate chemistry associated with ocean acidification due to increasing atmospheric CO2 concentration. Here, we show that the copepod, Centropages tenuiremis, was able to perceive the chemical changes in seawater induced under elevated CO2 concentration (>1700 µatm, pH < 7.60) with avoidance strategy. The copepod's respiration increased at the elevated CO2 (1000 µatm), associated acidity (pH 7.83) and its feeding rates also increased correspondingly, except for the initial acclimating period, when it fed less. Our results imply that marine secondary producers increase their respiration and feeding rate in response to ocean acidification to balance the energy cost against increased acidity and CO2 concentration.

PURPOSE: In order to better understand if the metabolic responses of echinoids could be related to their acid–base status in an ocean acidification context, we studied the response of an intertidal sea urchin species, Paracentrotus lividus, submitted to low pH at two different temperatures. METHODS: Individuals were submitted to control (8.0) and low pH (7.7 and 7.4) at 10°C and 16°C (19 days). The relation between the coelomic fluid acid–base status, the RNA/DNA ratio of gonads and the individual oxygen uptake were studied. RESULTS: The coelomic fluid pH decreased with the aquarium seawater, independently of temperature, but this explained only 13% of the pH variation. The coelomic fluid showed though a partial buffer capacity that was not related to skeleton dissolution ([Mg2+] and [Ca2+] did not differ between pH treatments). There was an interaction between temperature and pH on the oxygen uptake (V O2) which was increased at pH 7.7 and 7.4 at 10°C in comparison with controls, but not at 16°C, indicating an upregulation of the metabolism at low temperature and pH. However, gonad RNA/DNA ratios did not differ according to pH and temperature treatments, indicating that even if maintenance of physiological activities has an elevated metabolic cost when individuals are exposed to stress, they are not directly affected during short-term exposure. Long-term studies are needed in order to verify if gonad production/growth will be affected by low pH seawaters exposure.

BACKGROUND AIM AND SCOPE: Though the tidal Anacostia River, a highly polluted riverine system, has been well characterized with regard to contaminants, its overall resident bacterial populations have remained largely unknown. Improving the health of this system will rely upon enhanced understanding of the diversity and functions of these communities. Bacterial DNA was extracted from archived (AR, year 2000) and fresh sediments (RE, year 2006) collected from various locations within the Anacostia River. Using a combination of metabolic and molecular techniques, community snapshots of sediment bacterial diversity and activity were produced. RESULTS: Employing Biolog EcoPlates, metabolic analysis of RE sediments from July revealed similar utilization of amines, amino acids, carbohydrates, carboxylic acids, and polymers at all sites. Normalized optical density measurements demonstrated that for most compounds, utilizations were similar though when differences did occur, the downstream site was enhanced compared to one or both of the upstream sites. Using denaturing gradient gel electrophoresis, bacterial diversity fingerprints of operational taxonomic units (OTUs) were obtained. Dendograms of the banding patterns revealed qualitative relationships as well as differences between replicate samples from similar sites. Replicates from the AR sites shared several common OTUs, while RE sites were more varied. Species richness and Shannon diversity indices generally increased with increasingly downstream locations, and were significant for the AR sediments (analysis of variance, P < 0.0001). Carbon and nitrogen content and concentration of fine grain sediment (<63 μm) were positively correlated with OTU richness (r 2 = 0.37, P = 0.0008; r 2 = 0.45, P < 0.0001; r 2 = 0.48, P = 0.001, respectively). CONCLUSIONS: This study demonstrated that the bacterial communities from all regions sampled were not only metabolically active with the capacity to utilize several different compounds as energy sources but also were genetically diverse. This study is the first to focus on the overall bacterial community, providing insight into this vital component of stream ecosystems. Understanding the bacterial components of aquatic systems such as the Anacostia River will increase our knowledge of the overall structure and function of the ecological communities in polluted systems, subsequently enhancing our ability to improve the health of this important tidal river.