Occurrence of phthalate diesters in rivers of the Paris district (France)

The occurrence and fate of six phthalate esters were investigated in the River Seine and two tributaries in the Paris area, at six sites from upstream to downstream, throughout different seasons, with special attention given to a flood episode. At all sites, except the River Marne, whatever the period, diethylhexyl phthalate (DEHP) displayed the highest concentration (0·323–0·779 µg l^?1 as mean values), followed by di‐n‐butyl phthalate (DnBP; 0·211–0·526 µg l^?1 as mean values), which is consistent with the production pattern. High phthalate concentrations appeared to be related to population density and industrial distribution. The strongest values were located downstream from wastewater treatment plant effluent inputs. Seasonal variations were closely related to river flow and air and water temperature. The annual evolution of phthalates was linked to the hydrological conditions. During the flood episode at Paris, the DEHP concentration displayed a sharp increase (260 to 1123 ng l^?1) occurring 9 days before the flood peak. The simultaneous fluctuations of NH₄, typical of domestic origin, and of DEHP suggests a similar origin from combined sewer overflows for both compounds. Other elevated values corresponded to the highest precipitation amounts, and demonstrated the contribution of non‐point‐source runoff and wastewater overflow to DEHP inputs. The DEHP concentration relationship with river flow displayed a clockwise hysteresis loop, corresponding to a ‘first‐flush’ effect in which the finite supplies are swept along in the early stage of the flood. Annual fluxes for 2004 at Paris were 2257 kg of DEHP and 1613 kg of DnBP. The flood period seemed to have a minor impact on annual phthalate transport (29·5% and 41% of the total for DEHP and for DnBP, respectively), which is contrary to annual suspended solids transport (69%). Copyright © 2007 John Wiley & Sons, Ltd.     

Impact of gamma densitometry on the luminescence signal of quartz grains

Most of the marine sediment cores collected in the past 10 years by the ODP and IMAGES programs have been processed using a multi-sensor core logger (MSCL, Geotek). This system estimates the density of sediment using the γ-ray attenuation of a ¹³⁷Cs source. To date, optically stimulated luminescence (OSL) dating has not been applied to sediments from cores treated in this way, because of the possible impact of this exposure on the existing luminescence signal. We have investigated the effect of such γ-ray irradiation by test exposure, measurement and estimation, and conclude that the usual ¹³⁷Cs exposure from γ-ray attenuation densitometry has no impact on the luminescence signal of quartz grains in sediment cores. For longer exposure to the ¹³⁷Cs source, a formula is provided to calculate the received dose. This result will permit the OSL dating technique to be applied to the voluminous body of marine cores already collected and processed by MSCL.     

Unprecedented risk of spring frost damage in Switzerland and Germany in 2017

Spring frosts are feared by farmers, fruit growers, and wine growers as they can cause significant damage to crops when they occur during the development of the plants. In the second half of April 2017, following a very warm period that had caused premature vegetation growth, a cold air mass from the Arctic penetrated central and western Europe, causing severe damage to natural and cultivated vegetation over broad areas. Here, we analyze how exceptional this event was in Switzerland and Germany in relation to the accumulated growing degree days (GDD), used as a proxy for plant phenology advancement. Although this damaging frost was not the latest on record in terms of calendar days, our results show that it was, in some regions, unprecedented in relation to the accumulated warmth during the preceding period, at least since the beginning of instrumental temperature records (1864). Our results also highlight how global warming has considerably increased the number of days with mean temperature above 5 °C in late winter and early spring, especially since 1970 (+?16.8?±?4.7 °C days decade^?1). However, in spite of earlier spring phenology due to climate warming, our results suggest that the risk of damaging frost events to vegetation has remained unchanged over the last 150 years in lowlands of Switzerland and Germany, due to the concurring earlier occurrence of the last potentially damaging frosts (about ??20 days since 1864). Our analyses reveal therefore that the April 2017 damaging frost was a true outlier in terms of risk of frost damage to plants.     

Physical and chemical control of the phytoplankton of Ahe lagoon, French Polynesia

The environmental characteristics of Ahe deep lagoon (Tuamotu Archipelago, French Polynesia) were studied over 3 years with the aim of explaining the spatial and temporal variability of the natural food available for pearl oysters with a special focus on phytoplankton biomass and global photosynthesis/respiration ratio of the lagoon. Chlorophyll averaged 0.34±0.01 μg L(-1) and our findings did not confirm increased phytoplankton biomass in deep lagoonal waters. Phytoplankton production appears to be limited firstly by nitrogen and respiratory processes overpass photosynthetic processes at least in the north-eastern edge of the atoll. Grazing by pearl oysters in culture seems to decrease the POC concentration but not the phytoplankton biomass. Oysters graze mainly on non chlorophyllian particles.     

Raman spectroscopic properties and Raman identification of CaS‐MgS‐MnS‐FeS‐Cr2FeS4 sulfides in meteorites and reduced sulfur‐rich systems

Raman spectra were acquired on a series of natural and synthetic sulfide minerals, commonly found in enstatite meteorites: oldhamite (CaS), niningerite or keilite ((Mg,Fe)S), alabandite (MnS), troilite (FeS), and daubreelite (Cr₂FeS₄). Natural samples come from three enstatite chondrites, three aubrites, and one anomalous ungrouped enstatite meteorite. Synthetic samples range from pure endmembers (CaS, FeS, MgS) to complex solid solutions (Fe, Mg, Ca)S. The main Raman peaks are localized at 225, 285, 360, and 470 cm^?1 for the Mg‐rich sulfides; at 185, 205, and 285 cm^?1 for the Ca‐rich sulfides; at 250, 370, and 580 cm^?1 for the Mn‐rich sulfides; at 255, 290, and 365 cm^?1 for the Cr‐rich sulfides; and at 290 and 335 cm^?1 for troilite with, occasionally, an extra peak at 240 cm^?1. A peak at 160 cm^?1 is present in all Raman spectra and cannot be used to discriminate between the different sulfide compositions. According to group theory, none of the cubic monosulfides oldhamite, niningerite, or alabandite should present first‐order Raman spectra because of their ideal rocksalt structure. The occurrence of broad Raman peaks is tentatively explained by local breaking of symmetry rules. Measurements compare well with the infrared frequencies calculated from first‐principles calculations. Raman spectra arise from activation of certain vibrational modes due to clustering in the solid solutions or to coupling with electronic transitions in semiconductor sulfides.