A Mathematical Framework for Resilience: Dynamics,Uncertainties, Strategies,and Recovery Regimes

Resilience is a rehashed concept in natural hazard management—resilience of cities to earthquakes, to floods, to fire, etc. In a word, a system is said to be resilient if there exists a strategy that can drive the system state back to “normal” after any perturbation. What formal flesh can we put on such a malleable notion? We propose to frame the concept of resilience in the mathematical garbs of control theory under uncertainty. Our setting covers dynamical systems both in discrete or continuous time, deterministic or subject to uncertainties. We will say that a system state is resilient if there exists an adaptive strategy such that the generated state and control paths, contingent on uncertainties, lay within an acceptable domain of random processes, called recovery regimes. We point out how such recovery regimes can be delineated thanks to so-called risk measures, making the connection with resilience indicators. Our definition of resilience extends others, be they “à la Holling” or rooted in viability theory. Indeed, our definition of resilience is a form of controllability for whole random processes (regimes), whereas others require that the state values must belong to an acceptable subset of the state set.     

Competitive Markets for Pollution Permits: Impact on Factor Income and International Equilibrium

We are interested in the impact of pollution permits on wages and profits. We analyze important consequences of introducing a market of pollution permits. A fundamental issue concerns the initial allocation of such permits: should they be allocated freely by grandfathering or be auctioned. The international symmetric case allows us to capture the essence of the problem on income factor. We show that allocating permits to factors in proportion of their contribution to production leads to an efficient (neoclassical) distribution. Considering the international asymmetric case, we show that a permit market does not modify the competitive world equilibrium without permits when the total allocation is large enough. When it is not, if allocation of permits is not proportional to the emissions in the world without permits, there is a reduction factor of emissions that results from the equilibrium allocation of capital.     

Phytoremediation of contaminated soils and groundwater: lessons from the field

Background, aim, and scope

The use of plants and associated microorganisms to remove, contain, inactivate, or degrade harmful environmental contaminants (generally termed phytoremediation) and to revitalize contaminated sites is gaining more and more attention. In this review, prerequisites for a successful remediation will be discussed. The performance of phytoremediation as an environmental remediation technology indeed depends on several factors including the extent of soil contamination, the availability and accessibility of contaminants for rhizosphere microorganisms and uptake into roots (bioavailability), and the ability of the plant and its associated microorganisms to intercept, absorb, accumulate, and/or degrade the contaminants. The main aim is to provide an overview of existing field experience in Europe concerning the use of plants and their associated microorganisms whether or not combined with amendments for the revitalization or remediation of contaminated soils and undeep groundwater. Contaminations with trace elements (except radionuclides) and organics will be considered. Because remediation with transgenic organisms is largely untested in the field, this topic is not covered in this review. Brief attention will be paid to the economical aspects, use, and processing of the biomass.

Conclusions and perspectives

It is clear that in spite of a growing public and commercial interest and the success of several pilot studies and field scale applications more fundamental research still is needed to better exploit the metabolic diversity of the plants themselves, but also to better understand the complex interactions between contaminants, soil, plant roots, and microorganisms (bacteria and mycorrhiza) in the rhizosphere. Further, more data are still needed to quantify the underlying economics, as a support for public acceptance and last but not least to convince policy makers and stakeholders (who are not very familiar with such techniques).     

Sampling atmospheric pesticides with SPME: Laboratory developments and field study

To estimate the atmospheric exposure of the greenhouse workers to pesticides, solid phase microextraction (SPME) was used under non-equilibrium conditions. Using Fick's law of diffusion, the concentrations of pesticides in the greenhouse can be calculated using pre-determined sampling rates (SRs). Thus the sampling rates (SRs) of two modes of SPME in the lab and in the field were determined and compared. The SRs for six pesticides in the lab were 20.4-48.3 mL min⁻¹ for the exposed fiber and 0.166-0.929 mL min⁻¹ for the retracted fiber. In field sampling, two pesticides, dichlorvos and cyprodinil were detected with exposed SPME. SR with exposed SPME for dichlorvos in the field (32.4 mL min^-1) was consistent with that in the lab (34.5 mL min^-1). SR for dichlorvos in the field (32.4 mL min⁻¹) was consistent with that in the lab (34.5 mL min⁻¹). The trends of temporal concentration and the inhalation exposure were also obtained.     

Plant responses to a phytomanaged urban technosol contaminated by trace elements and polycyclic aromatic hydrocarbons

Medicago sativa was cultivated at a former harbor facility near Bordeaux (France) to phytomanage a soil contaminated by trace elements (TE) and polycyclic aromatic hydrocarbons (PAH). In parallel, a biotest with Phaseolus vulgaris was carried out on potted soils from 18 sub-sites to assess their phytotoxicity. Total soil TE and PAH concentrations, TE concentrations in the soil pore water, the foliar ionome of M. sativa (at the end of the first growth season) and of Populus nigra growing in situ, the root and shoot biomass and the foliar ionome of P. vulgaris were determined. Despite high total soil TE, soluble TE concentrations were generally low, mainly due to alkaline soil pH (7.8–8.6). Shoot dry weight (DW) yield and foliar ionome of P. vulgaris did not reflect the soil contamination, but its root DW yield decreased at highest soil TE and/or PAH concentrations. Foliar ionomes of M. sativa and P. nigra growing in situ were generally similar to the ones at uncontaminated sites. M. sativa contributed to bioavailable TE stripping by shoot removal (in g ha^?1 harvest^?1): As 0.9, Cd 0.3, Cr 0.4, Cu 16.1, Ni 2.6, Pb 4, and Zn 134. After 1 year, 72 plant species were identified in the plant community across three subsets: (I) plant community developed on bare soil sowed with M. sativa; (II) plant community developed in unharvested plots dominated by grasses; and (III) plant community developed on unsowed bare soil. The shoot DW yield (in mg ha^?1 harvest^?1) varied from 1.1 (subset I) to 6.9 (subset II). For subset III, the specific richness was the lowest in plots with the highest phytotoxicity for P. vulgaris.     

The impact of an industrial effluent on the water quality,submersed macrophytes and benthic macroinvertebrates in a dammed river of Central Spain

This research was conducted in the middle Duratón River (Central Spain), in the vicinity of Burgomillodo Reservoir. An industrial effluent enters the river 300 m downstream from the dam. Fluoride and turbidity levels significantly increased downstream from the effluent, these levels being to some extent affected by differential water releases from the dam. The community of submersed macrophytes exhibited slighter responses and, accordingly, lower discriminatory power than the community of benthic macroinvertebrates, this indicating that metrics and indices based on macroinvertebrates may be more suitable for the biological monitoring of water pollution and habitat degradation in dammed rivers receiving industrial effluents. However, in relation to fluoride bioaccumulation at the organism level, macrophytes (Fontinalis antipyretica and Potamogeton pectinatus) were as suitable bioindicators of fluoride pollution as macroinvertebrates (Ancylus fluviatilis and Pacifastacus leniusculus). Fluoride bioaccumulation in both hard and soft tissues of these aquatic organisms could be used as suitable bioindicator of fluoride pollution (even lower than 1 mg F⁻ L⁻¹) in freshwater ecosystems. Echinogammarus calvus exhibited a great sensitivity to the toxicity of fluoride ions, with a 96 h LC₅₀ of 7.5 mg F⁻ L⁻¹ and an estimated safe concentration of 0.56 mg F⁻ L⁻¹. The great capacity of E. calvus to take up and retain fluoride during exposures to fluoride ions would be a major cause of its great sensitivity to fluoride toxicity. It is concluded that the observed fluoride pollution might be partly responsible for the absence of this native amphipod downstream from the industrial effluent.     

Photolysis of estrone generates estrogenic photoproducts with higher activity than the parent compound

In the present study, we aimed to evaluate the effect of UV-visible irradiation on the estrogenicity of an estrone aqueous solution by using chemical analysis associated with an in vitro bioassay and in silico analysis. An estrone aqueous solution was irradiated with an UV-visible high-pressure mercury lamp. By using the MELN in vitro cellular bioassay, based on the induction of a luciferase reporter gene upon the activation of the estrogen receptor by chemicals, we showed that the estrogenic potency of the solution increased after irradiation. High-performance liquid chromatography fractionation of the photolyzed solution followed by in vitro testing of fractions allowed the quantitation of the estrogenic potency of each fraction. Nine photoproducts were detected and characterized by liquid chromatography-mass spectrometry coupling. The observed estrogenic activity is mediated by mono- and multi-hydroxylated photoproducts; it is influenced by the position of hydroxyl groups on the steroidal skeleton. In addition, a structure-activity analysis of the hydroxylated photoproducts confirmed their ability to act as estrogen receptor ligands.