Kraft lignin (KL) is the chief contaminant which is responsible for dark coloration, toxicity and high chemical oxygen demand (COD) of paper pulp mill effluent. The present study investigated the diverse potentials of Planococcus sp. TRC1 in the biodegradation of KL. Preliminary evaluation indicated that the strain was able to grow on broad spectrum of lignin-derived compounds, decolorize lignin-mimicking dyes and catabolize substrates of ligninolytic enzymes. Response surface methodology (RSM) was executed to perform the optimization of different process parameters. The results displayed that Planococcus sp. TRC1 could completely utilize 100 mg L?1 of KL and 78% of 200 mg L?1 of KL as sole source of carbon with concurrent reduction in COD and color. The biokinetic details of KL biodegradation showed that the values of \(\mu^{*}\), µmax, \(q^{*}\) and qmax were 0.018 h?1, 0.01 h?1, 0.023 g g?1 h?1 and 0.05 g g?1 h?1, respectively. UV–visible spectrophotometry, SEM and FTIR indicated the significant alterations in the surface morphology, functional groups and chromophores during the course of biodegradation. XRD revealed the emergence of peak signifying the formation of low molecular weight intermediates after bacterial treatment. Considering the environmental impact, bacterial-treated KL illustrated less phytotoxicity using Vigna radiata seed bioassay. These results suggested that Planococcus sp. TRC1 could be a promising strain for the degradation of KL in an ecofriendly way. 相似文献
Distribution of the trace elements Cr, Cu, Ni, Pb and Zn in surficial sediments of the river/sea environment in Danang –
Hoian area (Vietnam) was investigated to examine the degree of metal pollution caused by anthropogenic activities. Point sources
from domestic and industrial wastes are identified as dominant contributors of trace element accumulation. Surficial sediments
of Hoian River show extremely high total concentrations of Cu (Average Concentration 295 μg/g), Ni (AC 112 μg/g), Pb (AC 396 μg/g)
and Zn (AC 429 μg/g) that exceed assigned safety levels ER-M. Similarly, the sediments of Han River show high Pb (AC 188 μg/g)
and Zn (AC 282 μg/g) contents. In marine sediments of Thanhbinh beach Pb is also enriched (138 μg/g) above guideline levels.
In contrast the sediments of the Cude River are dominated by trace element concentrations close to background values.
Received: 17 December 1998 · Accepted: 6 May 1999 相似文献
The Carnian Raibl group of the Eastern Alps consists of three 50–100 m thick, alternating carbonate and clastic third-order cycles, each of which can be traced for hundreds of kilometers. Tectono-eustatic sea-level fluctuations of a few tens of metres, spanning a few millions of years, are the driving mechanism of this cyclicity. The carbonate intervals represent restricted marginal marine, tidal and evaporitic environments. The clastic intervals represent inner and outer shelf facies, and are related to the fluviatile “Schilfsandstein” of the Germanic facies belt. In the Raibl group, contrary to other carbonate/clastic depositional settings, relative sea-level lowstands are dominated by carbonate production, and highstands are dominated by clastic deposition.
Each of the three Raibl cycles corresponds to a type-2 sequence, containing shelf margin, transgressive and highstand systems tracts. During sea-level lowstands, deltaic point sources were near the shelf margin, allowing clastics to bypass the carbonate platform. This setting corresponds to a shelf margin systems tract. Transgressive and highstand systems tracts developed during the subsequent sea-level rise, as deltaic clastics were reworked and redistributed over the carbonate platform, and the deltas retrograded to the inner shelf. The highstand systems tracts are capped by a type 2 sequence boundary, which is conformable in the study area. The systems tracts can be further subdivided into shallowing upward subcycles, caused by fourth-order sea-level fluctuations, believed to represent Milankovitch rhythms.
The middle Raibl cycle is consistently thinner, and may represent a shorter termed, third-order sea-level fluctuation. Our data also corroborate a second-order transgressive trend for the Carnian. 相似文献
This paper reports differences in the occurrence statistics of global positioning system (GPS) L-band scintillations at observational sites located in the inner regions of the northern and southern crests of the equatorial ionization anomaly. Ground-based GPS data acquired at the closed magnetically aligned stations of Manaus (3.1°S; 59.9°W; dip lat. 6.2°N) and Cuiabá (15.5°S; 56.1°W; dip. lat. 6.2°S), Brazil, from December 2001 to February 2007 are used in the analysis. The drift dynamics of Fresnel-scale ionospheric irregularities at the southern station of Cuiabá are also investigated. Only geomagnetically quiet days with the sum of daily Kp < 24 were used in the analysis statistics and in the irregularity drift studies. The results reveal a clear dependence of the scintillation occurrence with the solar activity, but there exists an asymmetry in the percentage of scintillation occurrence between the two stations throughout the period analyzed. The nocturnal occurrence of the scintillations over Cuiabá is predominantly larger than over Manaus, but this scenario seems to change with the decline in the solar activity (mainly during local post-midnight hours). A broad minimum and maximum in the scintillation occurrence appears to occur over both the stations, respectively, during the June solstice (winter) and December solstice (summer) months. The dynamics of the Fresnel-scale irregularities, as investigated from the estimations of the mean zonal drift velocities, reveals that the amplitude of the eastward drifts tends to reduce with the decline in the solar activity. The magnitude of the zonal drift velocities during the December solstice months is larger than during the equinoxes, with the differences being more pronounced at solar maximum years. Other relevant aspects of the observations, with complementary data from a low-latitude ionospheric model, are highlighted and discussed. 相似文献
The REE distribution patterns and Nd whole-rock and mineral isotope ratios of the Kingash ultramafic-mafic massif enabled
us to propose a multistage history for its evolution at 1410 and 875 Ma. These stages reflect the magmatic evolution of the
Siberian paleocontinent margin during the Late Precambrian. The age of metamorphism of the massif during collision and accretion
in the Early Paleozoic (∼500 Ma) was obtained based on a Sm-Nd mineral isochron from rheomorphic veined albitite. The Nd and
Sr isotopic compositions of rocks from the Kingash massif suggest mantle sources for picritic and basic magmas, which are
thought to have originated by mixing of different proportions of depleted (PREMA or DM) and enriched (EM) melts. The initial
isotope ratios of the parental melts transformed during interaction with Sr-rich material from the host metasedimentary complexes. 相似文献