The generalized MIC-Kepler system

This paper deals with dynamical system that generalizes the MIC-Kepler system. It is shown that the Schr\"{o}dinger equation for this generalized MIC-Kepler system can be separated in spherical and parabolic coordinates. The spectral problem in spherical and parabolic coordinates is solved.Comment: 8 page

CONTAMINANT FATE AND TRANSPORT IN THE VENICE LAGOON: RESULTS FROM A MULTI-SEGMENT MULTIMEDIA MODEL.

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Metals in Sediment Cores from Nine Coastal Lagoons in Central Vietnam

After being dramatically hit by war events, Vietnam is presently experiencing a huge economical and social development. However, very few data, relative to pollution levels and trends, are available for the correct management of critical areas such as coastal lagoons, where many economical activities are linked to high value environmental features. Approach: A set of sediment cores from nine coastal lagoons of central Vietnam (Lang Co, Truong Giang, An Khe, Nuoc Man, Nuoc Ngot, Thi Nai, O Loan, Thuy Trieu and Dam Nai) were sampled in 2008 and analyzed to assess metal and (Al, Cd, Cr, Cu, Fe, Hg, Li, Mn, Ni, Pb, V, U and Zn) and As levels and historical trends. Results: Concentrations are generally low, with the exception of As, which often exceeds ERL guidelines and Ni that does the same at O Loan. In some cases, concentrations-depth profiles account for recent increasing trends but surficial values are still low when compared to both international guidelines and polluted sediments all around the world. Sediment grain size seems to affect the depth distribution of a number of metals and when normalized to the content of silt and clay, values are particularly high at Dam Nai and Thi Nai, due to the very coarse composition of surficial sediments. Conclusion: Metal concentrations in lagoon sediments derive from the composition of rocks and soils in the watersheds. However, recent increasing trends need for further monitoring

Soils and sediments of the Thua Thien-Hue Province (central Vietnam): recognizing trace element sources and the likely influence of natural events.

Trace element concentrations have been measured in soil and sediment samples taken from the Thua Thien Hue (TT-H) Province and the Tam Giang–Cau Hai (TG–CH) Lagoon in 2002 and 2004. Results show that the lagoon is only slightly contaminated by elements such as Ag, Cd, Cr, Cu, Ni, Pb and Zn, whereas As, probably naturally enriched in this Asian region, reaches values above the lowest internationally accepted sediment quality guidelines. Concentrations in soils are ascribable to natural sources and distributions in the TG–CH Lagoon are mainly influenced by river inputs, with Ag and Cd undergoing estuarine desorption processes. However, concentration–depth profiles of most trace elements in sediments show a recent increasing trend that might be linked to the economic development of the area. The comparison of porosity and 210Pb depth profiles (confirmed also by Cd and As) from repeated samplings of the same core locations in the TG–CH Lagoon seems to account for a loss of 5–10 cm of surficial sediment that took place during the time interval between the two samplings. It is hypothesized that extreme meteorological events (e.g. a major typhoon that hit the area in November 2003) could be responsible for such sediment displacement

210Pb-derived history of PAHs and PCBs accumulationin sediments of a tropical inner Lagoon (Las Matas,Gulf of Mexico) near a major oil refinery

Concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in a sediment core from the tropical freshwater inner lagoon of Las Matas, near the petroleum industrial area of Minatitla´n-Coatzacoalcos, in the Gulf of Mexico. A 210Pb-derived chronology was used to reconstruct the historical PAH and PCB accumulation in the site during one century (1906–2005). Both geochemical and sedimentological data indicated that a major change occurred in 1947 ± 4, including a shift to coarser sediments and a significant decrease of Al, Li, Fe, organic C and total N contents. This was likely due to the changes in hydrology caused by the confinement of Las Matas Lagoon due to the construction of the Trans-Isthmus road in 1946. PAHs in these samples show relatively low concentrations (259–1176 ng g1), and the congener relative abundances indicate the influence of pyrogenic (petroleum combustion) sources. Total PCB concentrations in the sediments ranged from 24 to 77 ng g1, and are composed by low chlorinated PCBs, with 3- and 4-CB as the prevalent species (51–65% and 29–40%, respectively). PAHs and PCBs were detected at depths corresponding to the early 1900s, when Minatitla´n refinery started operations, although their time evolution appears to be influenced by different accumulation processes. The PCB background is most likely produced by the combustion of natural organic matter, and an industrial contribution can be recognized when normalizing with OC contents. We concluded that atmospheric deposition is the most significant source of PAHs and PCBs for this water body. This study also provided evidence of the alteration of the wetlands surrounding this industrial area due to urbanization; the fragmentation and alteration of Las Matas Lagoon hydrology contributes to the gradual loss of the wetlands in the zone

Heavy metals in Morocco Lagoon and river sediments

Analyses of Mn, Cd, Cr, Cu, Pb, and Zn were carried out in a short core from a salt marsh of the Nador Lagoon (north-eastem Morocco) and in surficial sediment samples collected in the Martil river, which borders the industrial town of Tétouan. Three soit samples and a reservoir sediment were also collected around the town to check the effects of atmospheric delivery of contaminants. $^{137}$Cs and $^{210}$Pb activity-depth profiles were used to establish a chronology for the core, obtaining an apparent accumulation rate of 0.41 cm y$^{-1}$. The concentrations of anthropogenic metals in this marsh sediment are low and probably represent natural backgrounds. A recent decrease can be an effect of changing grain size. The Martil River sediments are slightly contaminated by Cu and Pb, whereas the soil samples present anomalous values of Cd and Zn

STUDY OF CHEMICAL POLLUTION IN SEDIMENT CORES FROM THE NADOR LAGOON (MOROCCO). ORGANIC AND INORGANIC CONTAMINANTS

The north of Africa is currently experiencing a great deal of economic development, which often, as confirmed by many examples, brings about the risk of pollution by toxic chemicals. The Nador Lagoon, the subject of several environmental studies, is located on the northern coast of Morocco. This lagoon is a great point of interest for the natural environment and for the increasing anthropogenic pressure due to adjacent businesses. This work aims to obtain further information about the status of contamination of this lagoon through analysis of sediment cores taken in June 2009. Chemical analyses were carried out of persistent organic compounds (POPs), in particular Polychlorinated biphenyls (PCBs) and Polybrominated diphenyl ethers (PBDEs), as well as the elements of interest for the determination of inorganic contamination. This study addressed four sediment cores taken in some of the most interesting places of the lagoon. For measuring the lagoon sediment chronology the radionuclides 210Pb and 137Cs have been used. These also show the possible perturbation of sediments during the years. The sediment dating allowed us to choose the best cores for organic and inorganic chemical analysis. The organic contamination was detected mostly in one sediment core, taking into account the most important samples along the core; for the other three cores only the upper sediment samples have been analyzed. The inorganic contamination was detected in two complete cores. The experimental part concerning the organic compounds involved automatic systems for extraction and purification; the determination was carried out by HRGC-LRMS. The elemental analysis was carried out using analytical protocols already developed in the laboratory: digestion with acids by means of a microwave digester, sample dilution, and then ICP-MS has been used for the analysis. In addition, we used multivariate statistical approaches to develop the results of the analyses and obtain more information about the samples correlation and the origin of the pollution. The Nador lagoon seems to be a not really polluted environment. This analytical research shows the low contamination of the investigated area, moreover shows also the increasing pollution in recent years linked to growing human activity in the surrounding region

Heavy metals in coastal sediments of the Ligurian sea off Vado Ligure

This paper combines data from a survey on heavy metal contamination of surficial sediments and the analysis of a short sediment core (30 cm) carried out in 1999 and 2001, respectively. Heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) and Al were analysed by AAS after complete dissolution of the samples. Surficial sediments are particularly rich in Cr, Cu, Hg and Pb, which reach concentrations of 322, 47.0, 5.85 and 145 mg kg$^{-1}$, respectively. While most metals show high concentrations close to the built-up area, the maximum values of Cr characterise offshore samples, thus suggesting a different origin. Sediment accumulation rates and chronologies were calculated on the basis of both $^{137}$Cs and $^{210}$Pb activity-depth profiles. The depth distribution of Al is peculiar, showing several peaks (from ca. 17 to ca. 106 mg g$^{-1}$) that are not justified by changes in sediment grain size and mineralogical composition. Very recent inputs of Cr and Ni are accounted for by surficial peak values, whereas Hg and Cu reach high concentrations at depth in core (before the early 1960s) and then decrease. Cu shows also a recent peak. Sediment grain size as well as organic carbon content do not seem to be correlated and significantly influence the metal distributions. Hg concentrations exceed the ERM guidelines all over the study area, whereas Cr is higher than the ERM at the top of the core. Only Cd is always lower than the ERL guidelines