Cadmium behavior in a karst environment hydrological cycle

Environmental Science and Pollution Research - Karst regions are important water providers, supplying approximately 25% of the world population. These areas present higher vulnerability to...     

Biodegradation of anthracene and different PAHs by a yellow laccase from Leucoagaricus gongylophorus

Environmental Science and Pollution Research - Laccases produced by Leucoagaricus gongylophorus act in lignocellulose degradation and detoxification processes. Therefore, the use of L....     

Ultraviolet-based female preferences in a viviparous fish

Studies on fish have demonstrated female-mating preferences based on dimorphic colours and colour patterns, but commonly focused on the 400-700 nm (visible) band. In experiment 1 we exposed females of the amarillo (Girardinichthys multiradiatus), a viviparous fish with visually based female mate choice, to two views of males either containing (UV+) or lacking (UV-) information in the 300-400 nm region. Experiments were conducted outdoors, and we found that females spent more time next to the male seen through the UV+ filter than the same seen through the UV- filter. Since the two images only differed in the content of UV radiation, we conclude that females of the amarillo can detect UV light. Experiments 2 and 3 were designed to test whether such an effect can be attributed to female preferences based on the males' UV-reflecting colour patterns. We first assessed which area(s) of the fish have UV-reflecting properties. Then, using an opaque gelatine powder to block skin reflectance, we found that, in the presence of environmental UV light, females spend more time close to the males with powder sprinkled outside the UV-reflecting area (control) than to the males with powder sprinkled over the UV-reflecting area (experiment 2). This could have been due to the concealment of signals in the visible spectrum, rather than in the UV spectrum; thus we repeated the same experiment indoors, in the absence of UV light (experiment 2b); here females failed to discriminate between males. Since we also found that females have UV-reflecting areas in their flanks, we conducted a third experiment to test whether the preferential association of females found in the first experiment was due to the tendency to school/associate with conspecifics, rather than to mate choice (experiment 3). We found no evidence of discrimination in this experiment. We conclude that the UV markings and vision in G. multiradiatus have a function in female mate choice. This is the first time that evidence has been found for the influence of UV for mate choice in fish.     

Replacement of H2O2 by O2 in Fenton and photo-Fenton reactions

The consumption of oxygen during the degradation of aniline by Fenton and photo-Fenton reactions is studied. The effect that parameters like aniline, Fe(II) and H2O2 initial concentration, pH, temperature and O2 flow rate have on the ratio O2 consumed/H2O2 consumed is examined. The determination of those combinations of experimental conditions for which an effective partial replacement of H2O2 by O2 as electron acceptor takes place is investigated. The results show that this replacement takes place in a variable extent, but the presence of H2O2 is necessary along the reaction, and the maximum consumption of O2 only takes place when the ratio amount of aniline mineralized vs. initial aniline concentration is minimal.     

Assessment of tin and butyltin species in estuarine superficial sediments from Gipuzkoa,Spain

Ten superficial sediments from river estuaries of Gipuzkoa (North Spain) were collected and analyzed for nine metals (including tin, Sn) and butyltin compounds (monobutyltin, MBT; dibutyltin, DBT; tributyltin, TBT). Total metal concentration in the fine fraction (<63 micrometer) of the sediment was determined in aqua regia--hydrofluoric acid extracts by atomic absorption spectrometry. The butyltin species (BTs) were firstly extracted from the sediments with hydrochloric acid-methanol mixture. After derivatization with sodium tetraethyl borate, the organotin compounds were extracted by solid phase microextraction (SPME) in headspace mode. A fiber coated with 100 micrometer poly(dimethylsiloxane) was used for SPME. The organotin species were analyzed by gas chromatography-flame ionization detection. Analysis of the certified reference sediment (PACS-2) shown the suitability of the procedures for determination of metal contents and DBT-TBT species in contaminated sediments. Factorial analysis was used to examine the main sources of metals. Three factors represented more than 89% of the total variance of the metal system, and the Sn was related with Cu-Zn-Pb suggesting the same pollution source. The BTs concentrations in the area were high (TBT ranged from 0.05 to 5.48 mg Sn kg(-1)). The percentage of total butyltin species ( summation operator BTs) respect to the total Sn amount was higher than 4% in all the sediments, showing in the Bidasoa river estuary a remarkable value higher than 20%. Hence, the studied estuarine sediments reflect a pollution that is related with historical industrial and fishing activities of the area.     

Using thermal units for estimating critical period of weed competition in off-season maize crop

Brazilian off-season maize production is characterized by low yield due to several factors, such as climate variability and inadequate management practices, specifically weed management. Thus, the goal of this study was to determinate the critical period of weed competition in off-season maize (Zea mays L.) crop using thermal units or growing degree days (GDD) approach to characterize crop growth and development. The study was carried out in experimental area of the University of S?o Paulo, Brazil, with weed control (C), as well as seven coexistence periods, 2, 4, 6, 8, and 12 leaves, flowering, and all crop cycle; fourteen treatments were done. Climate data were obtained from a weather station located close to the experimental area. To determine the critical period for weed control (CPWC) logistic models were fitted to yield data obtained in both W and C, as a function of GDD. For an arbitrary maximum yield loss fixed in 2.5%, the CPWC was found between 301 and 484 GDD (7-8 leaves). Also, when the arbitrary loss yield was fixed in 5 and 10%, the period before interference (PBI) was higher than the critical weed-free period (CWFP), suggesting that the weeds control can be done with only one application, between 144 and 410 GDD and 131 and 444 GDD (3-8 leaves), respectively. The GDD approach to characterize crop growth and development was successfully used to determine the critical period of weeds control in maize sown off-season. Further works will be necessary to better characterize the interaction and complexity of maize sown off-season with weeds. However, these results are encouraging because the possibility of the results to be extrapolated and because the potential of the method on providing important results to researchers, specifically crop modelers.     

Atmospheric versus biological sources of polycyclic aromatic hydrocarbons (PAHs) in a tropical rain forest environment

To distinguish between pyrogenic and biological sources of PAHs in a tropical rain forest near Manaus, Brazil, we determined the concentrations of 21 PAHs in leaves, bark, twigs, and stem wood of forest trees, dead wood, mineral topsoil, litter layer, air, and Nasutitermes termite nest compartments. Naphthalene (NAPH) was the most abundant PAH with concentrations of 35 ng m(-3) in air (>85% of the sum of 21PAHs concentration), up to 1000 microg kg(-1) in plants (>90%), 477 microg kg(-1) in litter (>90%), 32 microg kg(-1) in topsoil (>90%), and 160 microg kg(-1) (>55%) in termite nests. In plants, the concentrations of PAHs in general decreased in the order leaves > bark > twigs > stem wood. The concentrations of most low-molecular weight PAHs in leaves and bark were near equilibrium with air, but those of NAPH were up to 50 times higher. Thus, the atmosphere seemed to be the major source of all PAHs in plants except for NAPH. Additionally, phenanthrene (PHEN) had elevated concentrations in bark and twigs of Vismia cayennensis trees (12-60 microg kg(-1)), which might have produced PHEN. In the mineral soil, perylene (PERY) was more abundant than in the litter layer, probably because of in situ biological production. Nasutitermes nests had the highest concentrations of most PAHs in exterior compartments (on average 8 and 15 microg kg(-1) compared to <3 microg kg(-1) in interior parts) and high PERY concentrations in all compartments (12-86 microg kg(-1)), indicating an in situ production of PERY in the nests. Our results demonstrate that the deposition of pyrolytic PAHs from the atmosphere controls the concentrations of most PAHs. However, the occurrence of NAPH, PHEN, and PERY in plants, termite nests, and soils at elevated concentrations supports the assumption of their biological origin.     

Towards a climate change adaptation strategy for coffee communities and ecosystems in the Sierra Madre de Chiapas, Mexico

The mountain chain of the Sierra Madre de Chiapas in southern Mexico is globally significant for its biodiversity and is one of the most important coffee production areas of Mexico. It provides water for several municipalities and its biosphere reserves are important tourist attractions. Much of the forest cover outside the core protected areas is in fact coffee grown under traditional forest shade. Unless this (agro)forest cover can be sustained, the biodiversity of the Sierra Madre and the environmental services it provides are at risk. We analyzed the threats to livelihoods and environment from climate change through crop suitability modeling based on downscaled climate scenarios for the period 2040 to 2069 (referred to as 2050s) and developed adaptation options through an expert workshop. Significant areas of forest and occasionally coffee are destroyed every year by wildfires, and this problem is bound to increase in a hotter and drier future climate. Widespread landslides and inundations, including on coffee farms, have recently been caused by hurricanes whose intensity is predicted to increase. A hotter climate with more irregular rainfall will be less favorable to the production of quality coffee and lower profitability may compel farmers to abandon shade coffee and expand other land uses of less biodiversity value, probably at the expense of forest. A comprehensive strategy to sustain the biodiversity, ecosystem services and livelihoods of the Sierra Madre in the face of climate change should include the promotion of biodiversity friendly coffee growing and processing practices including complex shade which can offer some hurricane protection and product diversification; payments for forest conservation and restoration from existing government programs complemented by private initiatives; diversification of income sources to mitigate risks associated with unstable environmental conditions and coffee markets; integrated fire management; development of markets that reward sustainable land use practices and forest conservation; crop insurance programs that are accessible to smallholders; and the strengthening of local capacity for adaptive resource management.     

Somatic Coliphage Profiles of Produce and Environmental Samples from Farms in Northern México

Somatic coliphages were quantified in 459 produce and environmental samples from 11 farms in Northern Mexico to compare amounts of somatic coliphages among different types of fresh produce and environmental samples across the production steps on farms. Rinsates from cantaloupe melons, jalapeño peppers, tomatoes, and the hands of workers, soil, and water were collected during 2011–2012 at four successive steps on each farm, from the field before harvest through the packing facility, and assayed by FastPhage MPN Quanti-tray method. Cantaloupe farm samples contained more coliphages than jalapeño or tomato (p range <0.01–0.03). Across production steps, jalapeños had higher coliphage percentages before harvest than during packing (p = 0.03), while tomatoes had higher coliphage concentrations at packing than all preceding production steps (p range <0.01–0.02). These findings support the use of targeted produce-specific interventions at multiple points in the process of growing and packing produce to reduce the risk of enteric virus contamination and improve food safety during fruit and vegetable production.     

A double‐edged sword: Realities of artisanal and small‐scale mining for rural people in the Alaotra region of Madagascar

A growing number of people are entering the artisanal and small‐scale mining (ASM) sector worldwide. In Madagascar, millions of individuals depend on this informal activity. Through a case study in the Alaotra‐Mangoro region of Madagascar, our research aimed to understand the “bottom‐up” dynamics and ripple effects of the sector, by looking at the realities for rural communities where inhabitants are both directly and indirectly affected by ASM. We were interested in community members' and miners' perceptions of the socio‐economic and environmental impacts of ASM, and in identifying the factors attracting people living in one of the country's agricultural hubs to this activity. Our results show a wide diversity of push and pull factors leading people to enter the sector. Although many positive impacts of ASM exist for miners and communities within the vicinity of mines, most miner participants considered themselves worse off since starting to mine, highlighting the high risk and low probability of return of ASM. ASM's potential for local and national development will remain squandered if its negative impacts continue to go unmanaged. Accounting for local contexts and the ripple effects of ASM will be crucial in achieving safety and security for miners, and to tap into the benefits it may offer communities while minimising environmental damage.