Singlet molecular oxygen—mediated photooxidation of monochloro and mononitrophenols. A kinetic study

A kinetic and mechanistic study on the aerobic dye sensitized photooxidation of the mono—nitro and chlorophenols was carried out. A singlet molecular oxygen mechanism operates in the photooxidation. Solvent and substituent effects, suggest the intermediacy of a complex with partial charge transfer character, as has been postulated for other phenols.

Chemical (reactive) and physical interactions of the substrates with singlet molecular oxygen were discriminated. Quantum yields for photooxidation (higher for the chlorophenols) range from 3 × 10^‐2 to 2 × 10^‐3, as measured by substrate or oxygen consumption. These values indicate the viability of a singlet molecular oxygen photooxidation as a way for the degradation of nitro and chlorophenol environmental contaminants.     

Roe and red deer as bioindicators of heavy metals contamination in north-western Poland

The present paper examines the degree of environmental contamination in areas covered by the Natura 2000 programme, located in north-western Poland, with selected heavy metals based on their concentration in target organs of roe and red deer. Lead, cadmium, copper, iron, and zinc concentrations were determined by inductively coupled plasma–atomic emission spectrometry. Residues of lead and cadmium were found in most of the analysed samples of roe and red deer organs The concentration of cadmium in the organs of the animals studied was much higher than that of lead. The median for Pb in liver and kidneys was 0.055 and 0.092 μg/g dry weight (d.w.) in roe deer, and 0.067 and 0.081 μg/g d.w. in red deer, respectively. The median for liver and kidney cadmium was 0.770 and 6.139 μg/g d.w. in roe deer, and 0.422 and 6.365 μg/g d.w. in red deer, respectively. Our study has demonstrated that this area is laden with lead and cadmium. This is evidenced by the fact that maximum permissible levels of these elements in the organs of red and roe deer, which were used as bioindicators of environmental contamination, were exceeded.     

Heavy Metals in Macroalgae of Havana's Northern Littoral,Cuba

Copper, iron, lead, manganese, and zinc contents were determined in various phyla of macroalgae typical of the rocky mesolittoral zone of Cuba and widely distributed in the Caribbean Region. the samples were collected in different zones along the shores of Havana City which are more or less influenced by anthropogenic activities. Differences in metal contents were observed due to seasonal variations and differences between sampling sites. of the analyzed species, only one brown alga, Padina vickersiae is considered as a suitable candidate for the monitoring of metal contamination.     

Changes in transport accessibility as a result of flooding: a case study of the Mazovia Province (Eastern Poland)

This paper presents the results of research investigating the impact of flooding on the temporal aspect of transport accessibility at national, regional and local levels in the Mazovia Province – an administrative region in Poland. For the purposes of this study the authors measured the theoretical journey times by private transport between settlement units for two variants: journeys made under normal circumstances, that is, without a flood; and journeys made during a flood event, which would necessitate diversions to avoid flooded road sections. This allowed the theoretical journey time differences to be calculated. It was assumed that vehicles move at the highest permissible speed along routes allowing the shortest travel times. The methods of accessibility assessment employed in this paper are based on distance measurements and use isochrones and a cumulative approach. Analysis carried out by the authors has shown that for interregional, intraregional and local journeys, the flooding of a part of the Mazovia region results in changes in travel times, but their absolute and relative magnitudes vary widely. It was found that in the case of national scale journeys the majority of relative journey time increases were no greater than three times the normal duration, while on a local scale they do not exceed 75%. For areas with a high risk of flooding there should be obligatory analyses of changes in transport accessibility; this would facilitate effective flood risk management. Appropriate traffic management in crisis situations would facilitate emergency and rescue services and help inhabitants and any other persons in flooded areas.     

Estimating the influence of overhead transmission power lines and landscape context on the density of little bustard Tetrax tetrax breeding populations

Collision with conductors and earth cables is a known impact generated by transmission power lines, however there is virtually no information on how these infrastructures might affect bird distribution in a landscape context. With this work we specifically hypothesise that transmission power lines may affect the occurrence of a threatened bird, the little bustard (Tetrax tetrax). To test this hypothesis we used a Stochastic Dynamic Methodology (StDM), analysing the effects of power lines in a landscape perspective and simulating population trends as a response to power line installation and habitat changes induced by agricultural shifts in southern Portugal. The data used in the dynamic model construction included relevant gradients of environmental conditions and was sampled during the breeding seasons of 2003-2006. Transmission power lines were significantly avoided by the little bustard and the developed StDM model showed that the distance to these utility structures is the most important factor determining breeding densities in sites with suitable habitat for the species, which possibly leads to displacement of populations and habitat fragmentation. The model simulations also provided the base to analyse the cumulative effects caused by the habitat degradation that can ultimately lead to the extinction of local populations. Within priority conservation sites, the dismantling of existing transmission lines should be considered whenever possible, in order to ensure adequate breeding habitat. The model is considered useful as an auxiliary tool to be used in environmental impact assessments, management and conservation studies.     

All clear? Meerkats attend to contextual information in close calls to coordinate vigilance

Socio-demographic factors, such as group size and their effect on predation vulnerability, have, in addition to intrinsic factors, dominated as explanations when attempting to understand animal vigilance behaviour. It is generally assumed that animals evaluate these external factors visually; however, many socially foraging species adopt a foraging technique that directly compromises the visual system. In these instances, such species may instead rely more on the acoustical medium to assess their relative risk and guide their subsequent anti-predator behaviour. We addressed this question in the socially foraging meerkat (Suricata suricatta). Meerkats forage with their head down, but at the same time frequently produce close calls (‘Foraging’ close calls). Close calls are also produced just after an individual has briefly scanned the surrounding environment for predators (‘Guarding’ close calls). Here, we firstly show that these Guarding and Foraging close call variants are in fact acoustically distinct and secondly subjects are less vigilant (in terms of frequency and time) when exposed to Guarding close call playbacks than when they hear Foraging close calls. We argue that this is the first evidence for socially foraging animals using the information encoded within calls, the main adaptive function of which is unrelated to immediate predator encounters, to coordinate their vigilance behaviour. In addition, these results provide new insights into the potential cognitive mechanisms underlying anti-predator behaviour and suggest meerkats may be capable of signalling to group members the ‘absence’ of predatory threat. If we are to fully understand the complexities underlying the coordination of animal anti-predator behaviour, we encourage future studies to take these additional auditory and cognitive dimensions into account.     

Distribution and availability of trace elements in municipal solid waste composts

Trace element contamination is one of the main problems linked to the quality of compost, especially when it is produced from urban wastes, which can lead to high levels of some potentially toxic elements such as Cu, Pb or Zn. In this work, the distribution and bioavailability of five elements (Cu, Zn, Pb, Cr and Ni) were studied in five Spanish composts obtained from different feedstocks (municipal solid waste, garden trimmings, sewage sludge and mixed manure). The five composts showed high total concentrations of these elements, which in some cases limited their commercialization due to legal imperatives. First, a physical fractionation of the composts was performed, and the five elements were determined in each size fraction. Their availability was assessed by several methods of extraction (water, CaCl(2)-DTPA, the PBET extract, the TCLP extract, and sodium pyrophosphate), and their chemical distribution was assessed using the BCR sequential extraction procedure. The results showed that the finer fractions were enriched with the elements studied, and that Cu, Pb and Zn were the most potentially problematic ones, due to both their high total concentrations and availability. The partition into the BCR fractions was different for each element, but the differences between composts were scarce. Pb was evenly distributed among the four fractions defined in the BCR (soluble, oxidizable, reducible and residual); Cu was mainly found in the oxidizable fraction, linked to organic matter, and Zn was mainly associated to the reducible fraction (iron oxides), while Ni and Cr were mainly present almost exclusively in the residual fraction. It was not possible to establish a univocal relation between trace elements availability and their BCR fractionation. Given the differences existing for the availability and distribution of these elements, which not always were related to their total concentrations, we think that legal limits should consider availability, in order to achieve a more realistic assessment of the risks linked to compost use.     

Hydrothermal carbonization of biomass and waste: A review

Environmental Chemistry Letters - The replacement of traditional and non-renewable resources by shifting towards renewable-based strategies is a strategy implemented by the European Union...     

Essential and non-essential trace element concentrations in muscle and liver of a pregnant Munk’s pygmy devil ray (Mobula munkiana) and its embryo

During gestation, essential and non-essential trace elements are transferred from the pregnant females to embryos. This study aimed to determine and compare the concentrations of seven essential trace elements (Fe, Zn, Se, Cu, Mn, Cr, Co) and six non-essential trace elements (As, Cd, V, U, Tl, Ag) in the muscle and the liver of a Munk’s pygmy devil ray pregnant female, Mobula munkiana, and its embryo. Transfer evidence of essential and non-essential trace elements was detected in M. munkiana tissues. Arsenic was found in elevated concentrations in the pregnant female and the embryo tissues. Elevated levels of Cd, V, U, and Ag were found in the pregnant female liver, but were minimal in the embryo tissue. This is the first study to investigate maternal transfer of essential and non-essential trace elements in these species and their reproductive strategy.