Estimation of Smog Effects in the Hydrocarbon-Nitric Oxide System

Hydrocarbon components (propylene, simulated auto exhaust, or authentic auto exhaust) were irradiated in the presence of nitric oxide in large chambers instrumented for measurements of numerous variables. Eye irritation was measured using a selected panel of human subjects. The various dependent variables are presented as functions of the reactant concentrations by means of contour diagrams derived by computer treatment. The effect of “hydrocarbon” and nitric oxide levels on smog effects are discussed; the observed relationships between end effects and reaction rates are considered. The study simulated the effects of varying degrees of vehicular emissions control over one or both reactants and has a bearing on the establishment of vehicle emission standards in California.     

High throughput and miniaturised systems for biodegradability assessments

The society demands safer products with a better ecological profile. Regulatory criteria have been developed to prevent risks for human health and the environment, for example, within the framework of the European regulation REACH (Regulation (EC) No 1907, 2006). This has driven industry to consider the development of high throughput screening methodologies for assessing chemical biodegradability. These new screening methodologies must be scalable for miniaturisation, reproducible and as reliable as existing procedures for enhanced biodegradability assessment. Here, we evaluate two alternative systems that can be scaled for high throughput screening and conveniently miniaturised to limit costs in comparison with traditional testing. These systems are based on two dyes as follows: an invasive fluorescent dyes that serves as a cellular activity marker (a resazurin-like dye reagent) and a noninvasive fluorescent oxygen optosensor dye (an optical sensor). The advantages and limitations of these platforms for biodegradability assessment are presented. Our results confirm the feasibility of these systems for evaluating and screening chemicals for ready biodegradability. The optosensor is a miniaturised version of a component already used in traditional ready biodegradability testing, whereas the resazurin dye offers an interesting new screening mechanism for chemical concentrations greater than 10 mg/l that are not amenable to traditional closed bottle tests. The use of these approaches allows generalisation of high throughput screening methodologies to meet the need of developing new compounds with a favourable ecological profile and also assessment for regulatory purpose.     

Larval settlement and metamorphosis of the mussel <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> in response to biofilms

Biofilms were allowed to develop on glass slips immersed 1.0–1.5 m below the sea surface in Tachibana Bay, Nagasaki, Japan, for different periods of time from November 2003 to January 2005. The effects of age, immersion month, dry weight, bacterial and diatom densities of these biofilms on the settlement and metamorphosis of pediveliger larvae of the mussel Mytilus galloprovincialis were investigated in the laboratory. Furthermore, biofilms were subjected to various treatments to investigate the nature of the settlement and metamorphosis cue in the biofilm. Pediveliger larvae of the mussel settled and metamorphosed in response to biofilms. Settlement and metamorphosis to the post-larval stage significantly increased with the biofilm age. In addition, the biofilm activity varied depending on the immersion month (season), e.g., for biofilms with the same age, those immersed between June and August had higher activities than those immersed between November and March. The activity of the biofilm also positively correlated with the dry weight, bacterial and diatom densities. These three quantitative parameters of the biofilm were significantly affected by the film age but were not affected by the immersion month, suggesting that other parameters (e.g., community structures, extracellular products) also affected the inductive activity of the biofilm. The fixative agents (formalin and glutaraldehyde), heat, ethanol, ultraviolet irradiation and antibiotics treatments of the biofilm resulted in significant reduction or loss of its inductive activity. The survival of bacterial cells in the treated films where activities were either reduced or lost also decreased significantly. No settlement and metamorphosis were obtained when larvae were exposed to the conditioned water of the biofilm. Thus, larvae of M. galloprovincialis settled and metamorphosed in response to a cue produced by living bacteria in the biofilm. The cue may be a bacterial extracellular product which was susceptible to the above treatments.     

The return of the giants: ecological effects of an increasing elephant population

Northern Botswana and adjacent areas, have the world's largest population of African elephant (Loxodonta africana). However, a 100 years ago elephants were rare following excessive hunting. Simultaneously, ungulate populations were severely reduced by decease. The ecological effects of the reduction in large herbivores must have been substantial, but are little known. Today, however, ecosystem changes following the increase in elephant numbers cause considerable concern in Botswana. This was the background for the "BONIC" project, investigating the interactions between the increasing elephant population and other ecosystem components and processes. Results confirm that the ecosystem is changing following the increase in elephant and ungulate populations, and, presumably, developing towards a situation resembling that before the reduction of large herbivores. We see no ecological reasons to artificially change elephant numbers. There are, however, economic and social reasons to control elephants, and their range in northern Botswana may have to be artificially restricted.     

Portal absorption of 14C after ingestion of spiked milk with 14C-phenanthrene, 14C-benzo[a]pyrene or 14C-TCDD in growing pigs

Polycyclic aromatic hydrocarbons (PAHs) and dioxins are lipophilic organic pollutants occurring widely in the terrestrial environment. In order to study the PAHs and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) transfer in the food chain, pigs have been fed with milk mixed either with 14C-phenanthrene, with 14C-benzo[a]pyrene or with 14C-TCDD. The analysis of portal and arterial blood radioactivity showed that both PAHs and TCDD were absorbed with a maximum concentration at 4-6 h after milk ingestion. Then, the blood radioactivity decreased to reach background levels 24 h after milk ingestion. Furthermore, the portal and arterial blood radioactivities were higher for phenanthrene (even if the injected load was the lowest) than these of benzo[a]pyrene or these of TCDD, in agreement with their lipophilicity and water solubility difference. Main 14C absorption occurred during the 1-3 h time period after ingestion for 14C-phenanthrene and during the 3-6 h time period for 14C-benzo[a]pyrene and for 14C-TCDD. 14C portal absorption rate was high for 14C-phenanthrene (95%), it was close to 33% for 14C-benzo[a]pyrene and very low for 14C-TCDD (9%). These results indicate that the three studied molecules have a quite different behaviour during digestion and absorption. Phenanthrene is greatly absorbed and its absorption occurs via the blood system, whereas benzo[a]pyrene and TCDD are partly and weakly absorbed respectively. However these two molecules are mainly absorbed via the portal vein.     

Larval settlement and metamorphosis of the mussel <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> on different macroalgae

Settlement of mussels is commonly associated with macroalgae. The effects of 19 macroalgal species on the settlement and metamorphosis of pediveliger larvae of the mussel Mytilus galloprovincialis were investigated in the laboratory. Settlement and metamorphosis inducing activities of macroalgae Chlorodesmis fastigiata and Ceramium tenerrimum collected each month during the period between January 2005 and April 2006 were also investigated. Furthermore, C. fastigiata and C. tenerrimum were subjected to various treatments to investigate the roles of bacteria and diatoms on the algal surface in the induction of larval settlement and metamorphosis of M. galloprovincialis and the characteristics of the cues in these two macroalgae. Pediveliger larvae of M. galloprovincialis settled and metamorphosed in high percentages on Cladophora sp., Chlorodesmis fastigiata, Centroceras clavulatum, and Ceramium tenerrimum, all of which were filamentous in morphology. Macroalgae that were cylindrical, phylloid, flabellate, palmate and pinnate all showed low (<8%) percentages of post-larvae but four other filamentous macroalgae also had low mussel larval settlement, suggesting that chemical factors may also be involved. Seasonal variation had no effect on inductive activities of C. fastigiata and C. tenerrimum. Treatment of C. fastigiata and C. tenerrimum with formalin, ethanol and heat resulted in the significant decrease or loss of their inductive activities. Survival of algal cells within treated macroalgae also decreased significantly. Treatment of the two macroalgae with antibiotics and GeO₂ reduced the numbers of bacteria and diatoms on their surface but did not affect their inductive activities, indicating that the cue was produced by macroalgae and not by coexisting bacteria and diatoms. However, conditioned water and crude extracts of these two macroalgae did not induce larval settlement and metamorphosis. Thus, larvae of M. galloprovincialis settled and metamorphosed on specific filamentous macroalgae. The chemical cues produced by C. fastigiata and C. tenerrimum were susceptible to ethanol and heat treatments and were not recovered in the conditioned water nor in the extracts. The finding that inactive C. tenerrimum can be produced from culturing its apical segments provides a new tool to elucidate the chemical cue(s) from macroalgae through manipulation of their culture conditions.     

Correction to: Impact of biogas digestates on soil microbiota in agriculture: a review

Environmental Chemistry Letters -     

Distribution and abundance of zooplankton in relation to petroleum hydrocarbon content along the coast of Kollam (Quilon), south west coast of India

In the present study we examine status, impact and trends in prevailing situation of coastal ecosystem of Chavara, Neendakara, Tangasseri and Paravur zones of Kollam coast in terms of zooplankton density and petroleum hydrocarbon content (PHC). Zooplankton samples and water samples were collected during the period May 2003 to June 2004. The numerical count of zooplankton made and PHC content estimated. Paravur offshore recorded the maximum zooplankton count (1390 no./m3) and Tangasseri nearshore the lowest (700.5 no/m3). The petroleum hydrocarbon content was highest at Tangasseri nearshore (21.95 microg/l) and lowest at Paravur offshore (9.40 microg/l). We also observe statistically significant negative correlation between zooplankton density and PHC for a few organisms. The overall impact appears minor, yet, coastal ocean monitoring imperative for sustainable development.     

Pesticide pressure and fish farming in barrage pond in Northeastern France Part I: site characterization and water quality

Purpose

Fish farming in barrage pond is a rearing system commonly used worldwide. Obtaining good water quality is essential to improve sustainability of these ecosystems, both for health of fish consumers and environmental considerations. However, ponds are often located in agricultural landscape, but few study reports impact of pesticide pressure on these ecosystems. This study characterizes five sites in Northeastern France. This work establishes an initial framework for pesticide monitoring with the aim to improve understanding of the fate of pesticides in ponds.

Methods

This framework is based on surveys indicating managements and Geographical Information System (GIS) for five ponds and their watersheds (sites: C-0, C-25, C-45, C-75 and C-85) and completes with some analysis of a large spectrum of pesticide residues in surface waters.

Results

Watersheds show a gradient of crop proportion ranging from 0% to 82% of the watershed area, mainly rapeseed, wheat, barley and maize. Ponds were representative of local Northeastern France management. Many pesticides, and also nutrients, were measured in water with concentrations varying between sites and seasons. The sum of quantified molecules ranged from 0.17 ??g/l for site C-0 (March) to 8.81 ??g/l for site C-25 (October). Concentrations of metaldehyde, quinmerac, isoproturon and bentazon were sometimes above 1 ??g/l.

Conclusions

There is a strong connection between pond and watershed, due to water supply throughout the fish production cycle. Sites with small pond/big watershed are the most exposed to acute contamination a few days after spraying because water discharges are not diluted.