Hype or Hope: The Potential of Phytoremediation as an Emerging Green Technology

Phytoremediation is defined as the use of green plants and their associated microorganisms, soil amendments, and agronomic techniques to remove, contain, or render harmless environmental pollutants. At the present time, phytoremediation is an emerging technology and there is still a significant need to pursue both fundamental and applied research to fully exploit the metabolic and growth habits of higher plants. It is precisely the purpose of the European COST Action 837 to stimulate the development and evaluate the potential of plant biotechnology for the removal of organic pollutants and toxic metals from wastewater and contaminated sites. However, green plants grow under nonsterile conditions and thus strongly interact with many microorganisms, like bacteria and mycorrhizal fungi. In this context, an Inter‐COST Workshop on bioremediation was recently organized to address the significance of soil microorganisms for plants, and the importance of their interactions, with regard to their potential for phytoremediation. Based on the outcomes of this workshop, the potential use of phytoremediation is presented in this article. © 2001 John Wiley & Sons, Inc.     

Genetic structure at different spatial scales in the pearl oyster (Pinctada margaritifera cumingii) in French Polynesian lagoons: beware of sampling strategy and genetic patchiness

In order to study further the genetic structure of the pearl oyster Pinctada margaritifera in French Polynesia with a special consideration for the sampling scale, we analyzed or re-analyzed sets of data based on nuclear DNA markers obtained at different spatial scales. At a large scale (several 1,000 km), the remote Marquesas Islands were confirmed to be significantly differentiated from Tuamotu–Gambier and Society archipelagos, with a marked difference however for the two main islands that are different from each other. At a medium scale (several 10 to several 100 km), overall homogeneity was observed within and between these two archipelagos, with some exceptions. This could be attributed both to large-scale larval dispersal and to human-driven spat translocations due to pearl oyster cultivation. These results contrast with those observed (1) at a small scale (less than 10 km) in a lagoon heavily impacted by translocation and cultural practices, where significant genetic differentiation was detected among three laying beds, and (2) at a micro scale where we detected an important variability of the genetic composition of young spat recruited on artificial collectors. Such patterns could result from a high variance in the number of genitors at the origin of each cohort, or from pre- or post-settlement selection on linked loci. Altogether, our data support the hypothesis that under certain conditions populations of bivalves may exhibit patterns of chaotic genetic patchiness at local scale, in line with the increasing report of such patchiness in marine benthic organisms. This underlines the importance of sampling scale that should be rigorously defined depending on the questions to be answered. Nevertheless, a survey of about 80 articles dealing with population genetics of marine invertebrates showed that only 35% of those studies disclosed details about the sampling strategy (particularly the area explored). These results emphasize the need for cautious interpretation of patterns of genetic structure at medium scale when rigorous sampling strategies are not deployed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

New genetic markers to identify European resistant abalone to vibriosis revealed by high-resolution melting analysis,a sensitive and fast approach

Increasing temperature of seawater is often associated with increased exposure incidence of disease in field and in aquaculture populations. Numerous episodic mass mortalities of the abalone Haliotis tuberculata have been observed along the northern Brittany coast of France caused by a complex interaction between the host, pathogen and environmental factors. Here, we evaluated the potential of high-resolution melting (HRM) analysis for mutation genotyping and development of genetic markers for resistance to vibriosis in the gastropod species H. tuberculata. Small amplicon assays were developed and revealed genetic polymorphism between surviving and susceptible abalone obtained after two successive infections of aquaculture families in controlled conditions. Together with specific COI haplotypes, we identified particular genotypes in nascent polypeptide-associated complex subunit alpha and ferritin genes linked to the susceptibility or resistance of abalone to vibriosis. Selection of genitors based on these genes may increase the proportion in offspring of resistant individuals of more than 76 %. Finally, HRM assays constitute a very efficient genotyping tool to validate the genetic markers on a representative number of individuals of wild populations and thus identify future resistant genitors for aquaculture or conservation purposes.     

An ultraviolet signal generates a conflict between sexual selection and species recognition in a newt

Whether sexual selection and species recognition involve distinct preferences and signals is still debated. Earlier work showed that traits under sexual selection can reduce the efficiency of species recognition but remains uncertain on how frequently such a conflict occurs. We can, however, hypothesise that overlapping distributions of sexual signals may enhance the hybridization risk in many species. We tested this hypothesis in a newt, Lissotriton vulgaris, which hybridises with Lissotriton helveticus. The two species also share an ultraviolet (UV) colour trait, which influences male attractiveness in L. vulgaris, though this trait is probably not functional for sexual communication in L. helveticus. We predicted that the shared trait would affect species recognition when UV radiation is present in the environment. We staged binary choice preference tests under UV+ and UV? conditions. In the UV+ treatment, female preference depended on the values of the shared UV trait and total brightness, regardless of male species identity. Thus, species recognition was enhanced or reversed depending on the difference in the male trait. Females preferred no male type in the UV? treatment, likely explained by our design, which alternated different sensory environments, and the limited prior exposure of subjects to the other species’ morph. We conclude that the presence of this shared trait used in sexual communication contributes to the production of hybrids in syntopic ponds. To our knowledge, this is the first experimental evidence of the influence of an UV sexual signal modulating species recognition.     

A practical methodology for information fusion in presence of uncertainty: application to the analysis of a nuclear benchmark

This work is devoted to some methodological developments on information fusion in presence of uncertainty and their application in the frame of the BEMUSE Programme. In nuclear safety studies, different uncertainty analyses using different codes and implying different experts are generally performed. It is then useful to define formal methods to combine all these information sources in order to improve the reliability of the expertise process and especially to detect possible conflicts (if any) between the sources. Starting from the IRSN methodology already introduced in Destercke and Chojnacki (Nucl Eng Des 238(9):2484–2493, 2008), this paper presents a more convenient reformulation of its construction to allow its use by engineers. It is then applied to analyse the results coming from the BEMUSE Programme.     

Greenhouse gas emissions along a peat swamp forest degradation gradient in the Peruvian Amazon: soil moisture and palm roots effects

Tropical peatlands in the Peruvian Amazon exhibit high densities of Mauritia flexuosa palms, which are often cut instead of being climbed for collecting their fruits. This is an important type of forest degradation in the region that could lead to changes in the structure and composition of the forest, quality and quantity of inputs to the peat, soil properties, and greenhouse gas (GHG) fluxes. We studied peat and litterfall characteristics along a forest degradation gradient that included an intact site, a moderately degraded site, and a heavily degraded site. To understand underlying factors driving GHG emissions, we examined the response of in vitro soil microbial GHG emissions to soil moisture variation, and we tested the potential of pneumatophores to conduct GHGs in situ. The soil phosphorus and carbon content and carbon-to-nitrogen ratio as well as the litterfall nitrogen content and carbon-to-nitrogen ratio were significantly affected by forest degradation. Soils from the degraded sites consistently produced more carbon dioxide (CO₂) than soils from the intact site during in vitro incubations. The response of CO₂ production to changes in water-filled pore space (WFPS) followed a cubic polynomial relationship with maxima at 60–70% at the three sites. Methane (CH₄) was produced in limited amounts and exclusively under water-saturated conditions. There was no significant response of nitrous oxide (N₂O) emissions to WFPS variation. Lastly, the density of pneumatophore decreased drastically as the result of forest degradation and was positively correlated to in situ CH₄ emissions. We conclude that recurrent M. flexuosa harvesting could result in a significant increase of in situ CO₂ fluxes and a simultaneous decrease in CH₄ emissions via pneumatophores. These changes might alter long-term carbon and GHG balances of the peat, and the role of these ecosystems for climate change mitigation, which stresses the need for their protection.

     

Analysis of PFAAs in American alligators part 1: Concentrations in alligators harvested for consumption during South Carolina public hunts

Environmental contamination resulting from the production or release of harmful chemicals can lead to negative consequences for wildlife and human health. Perfluorinated alkyl acids (PFAAs) were historically produced as protective coatings for many household items and currently persist in the environment, wildlife, and humans. PFAAs have been linked to immune suppression, endocrine disruption, and developmental toxicity in wildlife and laboratory studies. This study examines the American alligator, Alligator mississippiensis, as an important indicator of ecosystem contamination and a potential pathway for PFAA exposure in humans. Alligator meat harvested in the 2015 South Carolina (SC) public hunt season and prepared for human consumption was collected and analyzed for PFAAs to determine meat concentrations and relationships with animal body size (total length), sex, and location of harvest. Of the 15 PFAAs analyzed, perfluorooctane sulfonate (PFOS) was found in all alligator meat samples and at the highest concentrations (median 6.73 ng/g). No relationship was found between PFAA concentrations and total length or sex. Concentrations of one or all compounds varied significantly across sampling locations, with alligators harvested in the Middle Coastal hunt unit having the highest PFOS concentrations (median 16.0 ng/g; p = 0.0001). Alligators harvested specifically from Berkley County, SC (located in the Middle Coastal hunt unit) had the highest PFOS concentrations and the greatest number of PFAAs detected (p < 0.0001). The site-specific nature of PFAA concentrations in alligator meat observed in this study suggests a source of PFAA contamination in Berkley County, SC.     

Sediment measurement and transport modeling: impact of riparian and filter strip buffers

Well-calibrated models are cost-effective tools to quantify environmental benefits of conservation practices, but lack of data for parameterization and evaluation remains a weakness to modeling. Research was conducted in southwestern Oklahoma within the Cobb Creek subwatershed (CCSW) to develop cost-effective methods to collect stream channel parameterization and evaluation data for modeling in watersheds with sparse data. Specifically, (i) simple stream channel observations obtained by rapid geomorphic assessment (RGA) were used to parameterize the Soil and Water Assessment Tool (SWAT) model stream channel variables before calibrating SWAT for streamflow and sediment, and (ii) average annual reservoir sedimentation rate, measured at the Crowder Lake using the acoustic profiling system (APS), was used to cross-check Crowder Lake sediment accumulation rate simulated by SWAT. Additionally, the calibrated and cross-checked SWAT model was used to simulate impacts of riparian forest buffer (RF) and bermudagrass [ (L.) Pers.] filter strip buffer (BFS) on sediment yield and concentration in the CCSW. The measured average annual sedimentation rate was between 1.7 and 3.5 t ha yr compared with simulated sediment rate of 2.4 t ha yr Application of BFS across cropped fields resulted in a 72% reduction of sediment delivery to the stream, while the RF and the combined RF and BFS reduced the suspended sediment concentration at the CCSW outlet by 68 and 73%, respectively. Effective riparian practices have potential to increase reservoir life. These results indicate promise for using the RGA and APS methods to obtain data to improve water quality simulations in ungauged watersheds.