Changes in soil organic matter chemical properties after organic amendments

Organic inputs are used to improve soil physical and chemical properties, but the corresponding changes in soil organic matter (SOM) chemical properties are not well known. In this study, we compared some characteristics of the SOM of a soil receiving either no organic inputs, or two different amendments during 15 years (straw or conifer compost). Quantities of organic carbon and C/N values were determined on particle size fractions after physical soil fractionation to localize changes due to amendments. Contents in reactive functional groups, acid-base properties and copper binding affinities were determined by titration experiments for the soluble fraction of SOM: the fulvic acid fraction (FA). Data of FA extracted from the bulk soil were compared to data of FA extracted from the <20 microm size fraction with the help of either a discrete or a continuous model (fit of data with FITEQL or NICA, respectively). Copper binding characteristics of FA extracted from the <20 microm size fraction did not change significantly after organic inputs, while those of FA extracted from the bulk organic-amended soils were found different from the ones with no amendment. Minor effects observed in the finer soil fractions were ascribed to their low turn-over of organic carbon and/or to a greater homogeneity in the nature of the organic carbon entering these fractions. Our results show major chemical changes in coarser soil organic fractions after organic amendments.     

Incorporating multidimensional behavior into a risk management tool for a critically endangered and migratory species

Conservation of migratory species exhibiting wide-ranging and multidimensional behaviors is challenged by management efforts that only utilize horizontal movements or produce static spatial–temporal products. For the deep-diving, critically endangered eastern Pacific leatherback turtle, tools that predict where turtles have high risks of fisheries interactions are urgently needed to prevent further population decline. We incorporated horizontal–vertical movement model results with spatial–temporal kernel density estimates and threat data (gear-specific fishing) to develop monthly maps of spatial risk. Specifically, we applied multistate hidden Markov models to a biotelemetry data set (n = 28 leatherback tracks, 2004–2007). Tracks with dive information were used to characterize turtle behavior as belonging to 1 of 3 states (transiting, residential with mixed diving, and residential with deep diving). Recent fishing effort data from Global Fishing Watch were integrated with predicted behaviors and monthly space-use estimates to create maps of relative risk of turtle–fisheries interactions. Drifting (pelagic) longline fishing gear had the highest average monthly fishing effort in the study region, and risk indices showed this gear to also have the greatest potential for high-risk interactions with turtles in a residential, deep-diving behavioral state. Monthly relative risk surfaces for all gears and behaviors were added to South Pacific TurtleWatch (SPTW) ( https://www.upwell.org/sptw ), a dynamic management tool for this leatherback population. These modifications will refine SPTW's capability to provide important predictions of potential high-risk bycatch areas for turtles undertaking specific behaviors. Our results demonstrate how multidimensional movement data, spatial–temporal density estimates, and threat data can be used to create a unique conservation tool. These methods serve as a framework for incorporating behavior into similar tools for other aquatic, aerial, and terrestrial taxa with multidimensional movement behaviors.     

Introducing a common taxonomy to support learning from failure in conservation

Although some sectors have made significant progress in learning from failure, there is currently limited consensus on how a similar transition could best be achieved in conservation and what is required to facilitate this. One of the key enabling conditions for other sectors is a widely accepted and standardized classification system for identifying and analyzing root causes of failure. We devised a comprehensive taxonomy of root causes of failure affecting conservation projects. To develop this, we solicited examples of real-life conservation efforts that were deemed to have failed in some way, identified their underlying root causes of failure, and used these to develop a generic, 3-tier taxonomy of the ways in which projects fail, at the top of which are 6 overarching cause categories that are further divided into midlevel cause categories and specific root causes. We tested the taxonomy by asking conservation practitioners to use it to classify the causes of failure for conservation efforts they had been involved in. No significant gaps or redundancies were identified during this testing phase. We then analyzed the frequency that particular root causes were encountered by projects within this test sample, which suggested that some root causes were more likely to be encountered than others and that a small number of root causes were more likely to be encountered by projects implementing particular types of conservation action. Our taxonomy could be used to improve identification, analysis, and subsequent learning from failed conservation efforts, address some of the barriers that currently limit the ability of conservation practitioners to learn from failure, and contribute to establishing an effective culture of learning from failure within conservation.     

Neophobia and social tolerance are related to breeding group size in a semi-colonial bird

In semi-colonial species, some individuals choose to breed in isolation while others aggregate in breeding colonies. The origin and the maintenance of this pattern have been questioned, and inherited phenotype dependency of group breeding benefits has been invoked as one of the possible mechanisms for the evolution of semi-coloniality. Using field observations and behavioural tests in the semi-colonial barn swallow (Hirundo rustica), we tested the hypothesis that breeding group size is related to personality. We measured neophobia (the fear and avoidance of new things) and social tolerance of adults and showed that these two independent traits of personality are strongly related to breeding group size. The biggest colonies hosted birds with higher neophobia, and larger groups also hosted females with higher social tolerance. This parallel between group size and group composition in terms of individual personality offers a better understanding of the observed diversity in breeding group size in this species. Further studies are, however, needed to better understand the origin of the link between individual personality and group breeding strategies.     

Helium isotopic constraints on simulated ocean circulations: implications for abyssal theories

There is ongoing controversy as to the dynamical significance of geothermal heat flow in shaping the abyssal circulation. In this paper, we gauge the impact of geothermal heating and vertical mixing parameterizations in the general circulation model OPA. The experiments are evaluated by comparing simulated mantle ³He with observations collected during the GEOSECS and WOCE programs. This tracer is particularly adapted to the validation of our numerical simulations because its injection into the ocean interior is tightly linked to geothermal processes. In agreement with previous studies, the model circulation is found very sensitive to the parameterization of the vertical mixing. The meridional overturning circulation (MOC) is globally intensified when moving from a constant mixing to a version with enhanced mixing near the ocean bottom, with the most drastic variation observed for AABW (+ 50%). Adding the geothermal heat flux mainly affects AABW circulation in the model, enhancing it all the more as the meridional circulation is slow (low vertical mixing), but proportionally less so when it is more vigorous (enhanced vertical mixing). This can be understood from the requirement of the abyssal ocean to maintain heat balance. The evaluation with mantle ³He simulations reveals that the version with low vertical mixing, with its sluggish circulation, produces unrealistically high a ³He isotopic composition. However, with a vertical mixing that is enhanced at depth, the ³He distribution falls within an acceptable range of values in the deep ocean. Finally, adding the geothermal heating to this enhanced mixing case provides a substantial improvement of the simulation of AABW in all basins but the Indian Ocean. ³He isotopic composition is then in good agreement with the observations. Taken jointly with observational estimates of the MOC intensity, these independent isotopic constraints suggest that both geothermal heating and enhanced diapycnal mixing at depth are key ingredients in the realistic simulation of abyssal circulation.     

Tributyltin and triphenyltin uptake by lettuce

This paper provides quantitative information on the transfer of TBT (tributyltin) and TPhT (triphenyltin) from sludged soil to cultivated lettuce. The effect of their initial concentrations in the soil (varying from 20 to 50 microg(Sn)kg(-1) for each triorganotin), sludge amount (between 1% and 9%), and cultivation duration (32-54 days) was evaluated by means of experimental designs. The impact of the cultivation temperature at 13 degrees C and 19 degrees C on organotin fate in the soil/plant system was also considered. The final concentration of a given organotin in the plant roots was found to depend directly on its initial concentration in the soil. A total of (85+/-15)% of initial TBT in the soil was still present at the end of the experiments, regardless of the cultivation duration. Consequently, TBT appeared to be taken up by lettuce continually. A total of (75+/-5)% of TPhT was found to be degraded in the soil at 54 days. So, this compound could have been taken up by the plant at the beginning of the cultivation. Sludge amount seemed to have a negative effect on TPhT concentration in a plant at 32 days. This could be due to the quantitative TPhT sorption onto the sludge, observed just after spiking. Organotin plant uptake appeared to be more important at 19 degrees C than at 13 degrees C. TBT and TPhT were mainly accumulated in the roots, and up to 2% and 10% of TPhT and TBT, respectively, were translocated to the shoots. Despite TPhT degradation, products in large amounts were present in the soil and were not significantly taken up by the plant. They possibly remained immobilized on solid phases of the sludged soil.     

Comprehensive primary particulate organic characterization of vehicular exhaust emissions in France

A study to characterize primary particulate matter (PM_2.5 and PM₁₀) from the French vehicular fleet was conducted during winter 2008, in a tunnel in Marseille, France. The carbonaceous fraction represents 70% of the aerosol mass and elemental carbon fraction (EC) represent 60% of the carbonaceous fraction. The organic carbon OC was characterized in term of its water soluble fraction, functionalization rate and HULIS content. Seventy trace organic compounds including alkanes, polycyclic aromatic hydrocarbons (PAH), petroleum biomarkers and carboxylic acids were also quantified, in order to determine an organic emission profile for chemical mass balance modeling studies. Such source profiles were still missing in Europe and particularly in France. The profile obtained in this study is consistent with profiles determined in tunnel or dynamometer studies performed in other countries during the last ten years. These results suggest that organic compounds profiles from vehicular exhaust emissions are not significantly influenced by the geographic area and are thus suitable for use in aerosol source apportionment modeling applied across extensive regions. The chemical profile determined here is very similar to those obtained for diesel emissions with high concentrations of EC relative to OC (EC/OC = 1.8) and low concentrations of the higher molecular weight PAH. These results are consistent with the high proportion of diesel vehicles in the French fleet (49%).     

Pesticides in urban multiunit dwellings: hazard identification using classification and regression tree (CART) analysis

Many units in public housing or other low-income urban dwellings may have elevated pesticide residues, given recurring infestation, but it would be logistically and economically infeasible to sample a large number of units to identify highly exposed households to design interventions. Within this study, our aim was to devise a low-cost approach to identify homes in public housing with high levels of pesticide residues, using information that would allow the housing authority and residents to determine optimal strategies to reduce household exposures. As part of the Healthy Public Housing Initiative, we collected environmental samples from 42 public housing apartments in Boston, MA, in 2002 and 2003 and gathered housing characteristics; for example, household demographics and self-reported pesticide use information, considering information available with and without a home visit. Focusing on five organophosphate and pyrethroid pesticides, we used classification and regression tree analysis (CART) to disaggregate the pesticide concentration data into homogenous subsamples according to housing characteristics, which allowed us to identify households and associated networks impacted by the mismanagement of pesticides. The CART analysis demonstrated reasonable sensitivity and specificity given more extensive household information but generally poor performance using only information available without a home visit. Apartments with high concentrations of cyfluthrin, a pyrethroid of interest given that it is a restricted use pesticide, were more likely to be associated with Hispanic residents who resided in their current apartment for more than 5 yr, consistent with documented pesticide usage patterns. We conclude that using CART as an exploratory technique to better understand the home characteristics associated with elevated pesticide levels may be a viable approach for risk management in large multiunit housing developments.     

Impact of salt-marsh management on fish nursery function in the bay of Aiguillon (French Atlantic coast), with a focus on European sea bass diet

The Bay of Aiguillon is a national French Nature Reserve of great importance for birds. Recently, the managers of the Reserve (ONCFS-LPO) paid attention to the influence of saltmarshes management on the nursery function for fish feeding in creeks at high tide. A study carried out from March to July 2012 aimed to evaluate the use of saltmarshes by fish juvenile fraction according to the mowing intensity in salt marshes surrounding creeks: ceased, irregular or annual mowing. This community approach was completed by a focus on the European sea bass Dicentrarchus labrax individual diet, vacuity index and growth, and the biomass of a main potential prey (the amphipod Orchestia gammarella). Whatever the mowing intensity, the juvenile fraction was very high for the main species, which were the grey mullet Liza ramada, the European sea bass, undetermined clupeid and the European flounder Platichthys flesus. Adult and subadult for these species were anecdotic or totally absent. Despite very different biomasses of amphipods between mown and natural sites, vacuity index, prey composition and their relative abundance in the diet of European sea bass juveniles were little different, contrary to their hypothetical growth (i.e. when assuming site fidelity), which appeared higher in non-mown site. The low distance between sampling sites could allow fish exchange over time between optimal and suboptimal creeks to feed on, as a hypothesis to explain such results. Because mowing was subsidized by European Union (EU) to favour open habitats for geese and maintain an economic activity, indirect impacts on nursery for fish called into question the appropriateness of such agro-environmental measure on natural habitats, and related fish nursery function.     

Environmental evaluation of dredged sediment submitted to a solidification stabilization process using hydraulic binders

Environmental Science and Pollution Research - Purpose: Dredging of sediments, a requirement for harbor maintenance, removes millions of tons of mineral wastes, contaminated at varying degrees with...