Catalytic degradation of chlorothalonil in water using bimetallic iron-based systems

Modified zero valent iron (MZVI) was used to study the transformation of a chlorothalonil (CLT) solution and the variation of the observed degradation rate of the reduction reactions. This was carried out when transition metals e.g. Pd, Cu and Co plated on the surface of micrometric iron particles (< 150 microm) were used as reducing catalytic agents for pesticide removal. Reactions were undertaken under both oxic and anoxic conditions in the presence and the absence of a phosphate buffer solution (PBS). Results of batch studies in nitrogen sparged solutions revealed that incomplete slow dechlorination merely occurred with zero valent iron (ZVI), however, complete rapid dechlorination reactions took place with MZVI especially Fe/Pd. Dechlorination was depicted by studying UV absorbance and MS spectra of CLT and all corresponding by-products. Typical blue shifts (deltalambda = 4-6 nm/chlorine atom) were observed at the same time as chlorine cluster isotopes disappeared. After the plating process, metal loading was controlled by analyzing the remaining metal in the solution by atomic absorption spectroscopy. Experiments showed that CLT degradation mechanism is faster in nitrogen sparged solutions in the absence of PBS. Time needed for complete removal of 2.08 +/- 0.19 microM CLT solution was about 2 h when experiments were conducted with ZVI (t1/2 = 15.0 min) and about 10 min when the reaction was carried out under the same conditions with Fe/Pd 1% (t1/2 = 1.0 min). Degradation rates for all bimetallic systems were determined showing that Pd is the more exciting catalytic transition metal followed by Cu and Co. Furthermore, MZVI method showed obvious advantage to traditional CLT treatment methods.     

Effects of temperature and fertilization on total vs. active bacterial communities exposed to crude and diesel oil pollution in NW Mediterranean Sea

The dynamics of total and active microbial communities were studied in seawater microcosms amended with crude or diesel oil at different temperatures (25, 10 and 4 °C) in the presence/absence of organic fertilization (Inipol EAP 22). Total and hydrocarbon-degrading microbes were enumerated by fluorescence microscopy and Most Probable Number (MPN) method, respectively. Total (16S rDNA-based) vs. active (16S rRNA) bacterial community structure was monitored by Capillary-Electrophoresis Single Strand Conformation Polymorphism (CE-SSCP) fingerprinting. Hydrocarbons were analyzed after 12 weeks of incubation by gas chromatography-mass spectrometry. Total and hydrocarbon-degrading microbial counts were highly influenced by fertilization while no important differences were observed between temperatures. Higher biodegradation levels were observed in fertilized microcosms. Temperature and fertilization induced changes in structure of total bacterial communities. However, fertilization showed a more important effect on active bacterial structure. The calculation of Simpson's diversity index showed similar trends among temperatures whereas fertilization reduced diversity index of both total and active bacterial communities.     

Bioaccessibility of trace elements as affected by soil parameters in smelter-contaminated agricultural soils: a statistical modeling approach

An investigation was undertaken to identify the most significant soil parameters that can be used to predict Cd, Pb, and Zn bioaccessibility in smelter-contaminated agricultural soils. A robust model was established from an extended database of soils by using: (i) a training set of 280 samples to select the main soil parameters, to define the best population to be taken into account for the model elaboration, and to construct multivariate regression models, and (ii) a test set of 110 samples to validate the ability of the regression models. Total carbonate, organic matter, sand, P(2)O(5), free Fe-Mn oxide, and pseudototal Al and trace element (TE) contents appeared as the main variables governing TE bioaccessibility. The statistical modeling approach was reasonably successful, indicating that the main soil factors influencing the bioaccessibility of TEs were taken into account and the predictions could be applicable for further risk evaluation in the studied area.     

Compostability of Poly(lactide): Degradation in an Inert Solid Medium

Commercial poly(lactide) degradation was studied in an inert solid medium simulating compost conditions, with the aim to achieve a complete carbon balance of the polymer degradation. The mineralisation rate at the end of the test was compared to those obtained for poly(lactide) degradation in compost. It was shown that the mineralisation rate after 45 days of degradation was quite lower in inert solid medium than in compost but the standard deviation of data was enhanced. A protocol for both extraction and quantification of the carbon included in the different degradation by-products was proposed and the carbon balance of the polymer degradation was followed during the test with a satisfactory accuracy. The non-degraded PLA material was recovered during the test, hence the evolution of the glass transition temperature and the molecular weight was followed. A two-step degradation mechanism was highlighted in inert solid medium, showing the fundamental role of abiotic reactions for PLA degradation in compost.     

一种新的海洋生物地球化学自主观测平台:Bio-Argo浮标

借助于强大的全球海洋观测网络——Argo计划,生物光学浮标Bio-Argo将成为一种全新的海洋生物地球化学自主观测平台,对未来的海洋观测与海洋研究将产生巨大的影响。本文以法国的PROVBIO为例,详细介绍了Bio-Argo浮标的结构设计、观测数据、工作模式、传输与通讯、以及数据质量控制等方面的问题,为我国的Argo计划和海洋观测方法提供有益的借鉴。     

Rapid removal of flutriafol in water by zero-valent iron powder

A study of the effect of zero-valent iron (ZVI) powder is carried out for the first time on the degradation of flutriafol ((RS)-2,4'-difluoro-alpha-(1H-1,2,4-triazol-1-ylmethyl)-benzhydryl alcohol, C(16)H(13)F(2)N(3)O), a bifluorinated soil and water persistent triazole pesticide using a laboratory scale device consisting of a 20 ml pyrex serum vials fixed to a Vortex agitator. Different amounts of ZVI powder (10-50 g l(-1)) at pH 6.6 and room temperature were investigated. Experiments showed an observed degradation rate k(obs) directly proportional to the surface of contact of flutriafol with ZVI. Flutriafol degradation reactions demonstrated first order kinetic with a half-live of about 10.8+/-0.5 min and 3.6+/-0.2 min when experiments were conducted at [ZVI]=10 g l(-1) into oxygenated and anoxic solutions, respectively. Three analytical techniques were employed to monitor flutriafol degradation and to understand solution and by-products behaviors: (1) A UV-Vis spectrophotometer; (2) a high performance liquid chromatography (HPLC) coupled with a photo diode array (PDA) and fluorescence detectors; (3) a similar HPLC coupled with a PDA and a mass spectrometer detectors equipped with an atmospheric pressure photoionization source. Results showed a complete disappearance of flutriafol after 20 min of contact with ZVI, the loss of fluorescence properties of the final by-products, the defluorination of the triazole pesticide via hydroxylation reaction and finally the hydrogenation of the triazole ring.     

In vitro and in vivo studies of lead immobilization by synthetic hydroxyapatite

Apatite appears a useful compound for removing lead from water, due to its ability to immobilize the metal by precipitation. In dilute solution, dissolved hydroxyapatite [HA, Ca1O(P04)6(OH)2] provided phosphates that were reactive with aqueous lead (molar ratio HA/Pb= 1/10) forming precipitates at around pH 6. These dissolved at a more acidic pH (3). Solid HA in contact with Pb2+ions, led to the formation of pyromorphite [Pblo(P04)6(OH)2], identified by X-ray diffraction and insoluble at pH tested (3-8). The amount of pyromorphite increased with the weight ratio of HA/Pb. When this one increased from 1 to 1000, lead precipitated as pyromorphite rose from 19 to 99%. In vivo experiments on rats confirmed the in vitro results. In fact, lead bioavailability assessed by intestinal perfusion was unchanged in the presence of dissolved HA, whereas it was significantly lower in the presence of solid HA, evaluated by gastric intubation, at a weight ratio equal to 10 (amount of lead absorbed decreased by 60%). Apatite could bean effective means of immobilizing lead in drinking or sewage, since accidental pyromorphite ingestion does not yield bioavailable lead.     

Hummingbird with modern feathering: an exceptionally well-preserved Oligocene fossil from southern France

Hummingbirds (Trochilidae) today have an exclusively New World distribution, but their pre-Pleistocene fossil record comes from Europe only. In this study, we describe an exceptionally preserved fossil hummingbird from the early Oligocene of southeastern France. The specimen is articulated, with a completely preserved beak and feathering. Osteological characters allow to identify it as Eurotrochilus sp. This genus is a stem group representative of Trochilidae and was recently described from the early Oligocene of southern Germany. The new fossil reveals that these European Trochilidae were remarkably modern in size, skeletal proportions and the shape of the wing, tail and beak and hyoid bones. These features confirm the early acquisition of the abilities of hovering and nectarivory in hummingbirds, probably before the Oligocene. In several morphological characteristics, they resemble members of the 'true hummingbirds' (subfamily Trochilinae) and differ from hermits (Phaethornithinae). These features, which include a short and square tail and a moderately long, almost straight beak, appear to be primitive within the family Trochilidae.