Evaluation des déversements de pluies d'orage et de leurs effets sur un petit ruisseau périurbain, le Peugue

Objective of the three-year monitoring study on the Peugue, which started in 1996, was to understand the effects of wet weather flows and runoff pollutants on the Peugue ecosystem from upstream to downstream, in order to design an optimal management program for flood protection while maintaining protection for the Peugue ecosystem, and then to develop a transposable general methodology for measuring the effects of stormwater on the aquatic ecosystem. During rainfall events, the Peugue river is used as a separate stormwater sewer system. The basin drains a 676-ha semi-urban area. In the upstream part of this catchment, the residential development is new and sparse with many wooded areas. Housing becomes more and more dense in the downstream part. The descriptive linear approach of the Peugue stream allowed the highlighting of various basic elements relative to the functioning of this system. On a hydrological level, the inertia of the flow related to the rain is weak. The flow variations (measured at Le Burck) are significant and sudden, able to pass in one hour from a few tens of l/s to more than one m3/s. From the whole of the analytical results obtained, the physicochemical quality of the Peugue water arises strongly degrading from upstream to downstream. The metal contents of the sediments are in the same order of magnitude as those measured on surface corings carried out in the laying-up of Bourgailh basin. Macrophyte index results are in good coherence with the results of physicochemical quality of water. This is particularly well illustrated between Peugue and its affluent. More generally, a good correlation between the various biological (macrophytes, diatoms) and physico-chemical parameters and the various discharges indexed is registered

Combination Service for Time-variable Gravity Fields: operational GRACE-FO combination and validation of Chinese GRACE time-series

The Combination Service for Time-variable Gravity Fields (COST-G) of the International Association of Geodesy (IAG) provides combined monthly gravity fields of its associated and partner Analysis Centers (ACs). In November 2020, the combination of monthly GRACE-FO gravity fields started its operational mode, providing consolidated L2 (spherical harmonics) and L3 (gridded and post-processed) products with a latency of currently 3 months. We present an overview and quality assessment of the available products. COST-G aims at the extension of its service to include further GRACE and GRACE-FO analysis centers. In January 2020 a collaboration with representatives of five Chinese ACs was initiated, who provided GRACE time-series according to the COST-G requirements. We present the results of a test combination with the Chinese AC models, including comparison and quality assessment of all contributing time-series and validation of the combined gravity fields

Combination Service for Time-variable Gravity Fields (COST-G): operations and new developments

Since its start of operations in July 2019, IAGâ?Ts Combination Service for Time-variable Gravity fields (COST-G) is providing a complete time-series of combined monthly GRACE gravity fields and a regularly updated time-series of monthly gravity fields derived from kinematic Swarm orbits. Starting from October 2020, the COST-G product line is complemented by a time-series of operationally combined and monthly updated GRACE-FO gravity fields. All these combinations are performed by variance component estimation on the solution level. We report on new developments, i.e., a planned extension of COST-G to include Chinese analysis centers of GRACE and GRACE-FO data, a re-consideration of the combination strategy to better focus on the range of spherical harmonic coefficients most relevant for the users, and the potential application of COST-G products for orbit determination of altimeter satellites

Curing of Plasmid pXO1 from Bacillus anthracis Using Plasmid Incompatibility

The large plasmid pXO1 encoding the anthrax toxin is important for the virulence of Bacillus anthracis. It is essential to cure pXO1 from B. anthracis to evaluate its role in the pathogenesis of anthrax infection. Because conventional methods for curing plasmids (e.g., curing agents or growth at elevated temperatures) can induce mutations in the host chromosomal DNA, we developed a specific and reliable method to eliminate pXO1 from B. anthracis using plasmid incompatibility. Three putative replication origins of pXO1 were inserted into a temperature-sensitive plasmid to generate three incompatible plasmids. One of the three plasmids successfully eliminated the large plasmid pXO1 from B. anthracis vaccine strain A16R and wild type strain A16. These findings provided additional information about the replication/partitioning of pXO1 and demonstrated that introducing a small incompatible plasmid can generate plasmid-cured strains of B. anthracis without inducing spontaneous mutations in the host chromosome