Four anoxic sediment cores were collected from Chini Lake, Malaysia in order to investigate the variability of polycyclic aromatic hydrocarbon (PAH) and perylene concentrations. The study also determined significant differences of perylene concentrations in different sediment layers. Total PAH concentrations ranged from 248 to 8098 ng g−1 in the samples. Diagnostic PAH ratios such as methylphenanthrenes/phenanthrene (MP/P), phenanthrene/anthracene (P/A) and fluoranthene/(fluoranthene + pyrene) (Fl/(Fl + Py) revealed a dominance of pyrogenic influences and partial petrogenic inputs to the top sediment layers. Perylene concentrations were high in the top layers (<12 cm) and increased with increasing depth. There is a significant positive correlation (r = 0.705, p = 0.01) between perylene concentrations and TOC. Analysis of variance (ANOVA) and LSD revealed significant differences (p < 0.05) in TOC-normalized perylene concentrations between the upper (<12 cm) and bottom layers (>12 cm). The average perylene concentrations accounted for 26–50% (0–12 cm) and 50–77% (12–36 cm) of pentacyclic-aromatic hydrocarbon isomers (PAI) present whereas it made up 10–34% (0–12 cm) and 46–66% (12–36 cm) of the total PAH. The average pyrene concentrations decreased with increasing depth and accounted for 62% (0–3 cm), 20–23% (3–12 cm) and 3–1.4% (12–36 cm) of perylene present. The results of hierarchical cluster analysis based on these ratios suggested different input sources for the top and bottom layers. It is concluded that the activity of termites on woody plants produced perylene which is supplied to the lake by run-off from the heavy and frequent rains in this Asian tropical climate. In addition, there was also in situ formation of perylene in the bottom layers due to diagenetic processes. 相似文献
The Mendejin pluton is located in the Mianeh area, NW Iran, 550 km from Tehran. This pluton is probably of Oligo-Miocene age and is the result of extensive magmatism which occurred during and after the Alpine Orogeny. Similar plutons are common in the Alborz–Azarbaijan structural zone of Iran, and it is likely that there are concealed plutons related to this extensive Cenozoic magmatism, but due to their youth and low rates of erosion they have not yet been exposed. The Mendejin pluton is a composite body made up of four types of plutonic rocks: pink tonalite, grey tonalite, diorite and aplite. The pink tonalite is porphyritic and contains phenocrysts of plagioclase, K-feldspar and hornblende in a groundmass consisting of quartz, plagioclase, K-feldspar, hornblende, zircon, monazite, leucoxene, apatite and hematite. The grey porphyritic tonalite has more biotite, pyroxene and pyrite and less accessory phases compared with the pink tonalite. The diorite has a microporphyritic texture with phenocrysts of plagioclase, hornblende and augite. This rock also occurs as xenoliths in the Mendejin pluton. The aplitic dykes are the youngest magmatic products at Mendejin. The Mendejin tonalite contains more Cl, As, S, Cu, Ni and Zn than the global granite. These rocks are of I-type, peraluminous and calc-alkaline, with medium to high potassium, and were formed as part of a volcanic arc. The Mendejin pluton contains up to 8 ppb gold and could potentially have been the source of an economic gold deposit by leaching of Au from wall rocks and deposition in extensive hydrothermally altered marginal zones. 相似文献
Theoretical and Applied Climatology - This study examined the effect of different attributes on regionalization of potential evapotranspiration (ETp) in Urmia Lake Basin (ULB), Iran, using the... 相似文献
In this paper, the effect of different curvatures on the spatial variation of coherent flow structure inside two physical
models with both strongly curved and mild multi-bend meanders is investigated. Three dimensional flow velocities at three
sequential meanders were measured using an Acoustic Doppler Velocity meter (Micro-ADV). Three dimensions of flow velocity
are classified into two major classes and eight different bursting events. The contribution probability and transition probability
of each zone is calculated from experimental data. The results indicated that the effect of curvature in sequential bends
was important particularly for strongly curved bends. The contribution probability of the events for strongly curved meanders
with relative curvature (Rc/B) of 2.6 were found to be higher than for mild curved meanders with relative curvature (Rc/B) of 4.43. The minimum contribution probability was found in external inward interaction event. In addition, analysis of
bursting events showed that the highest values of transition probabilities occurred in the stable organizations for both models.
The influences of different curvatures on distributions of the Reynolds shear stress, the turbulent kinetic energy, the streamwise
velocity and the vertical velocity were also shown to be in good agreement with eroded bed. The above results can be useful
for finding meandering patterns inside rivers and also in river training works. 相似文献
The Nasirabad manganese occurrence is located to the south of the Neyriz in the Fars province. Structurally and lithologically, this occurrence lies in the southwest part of the Zagros Thrust Belt and was deposited as Mn-nodules and interconnected ore-bearing interlayer's with radiolarite cherts in the vicinity of the Neyriz ophiolites. The present work deals with the geology and geochemistry of the Nasirabad manganese occurrence with a discussion of its genesis. High Mn/Fe (average 18.85) and high Ba (average 28,830 ppm) with low Pb (2.0 ppm) and LREE > HREE, Lan/Ndn (average 4.5), Dyn/Ybn (average 1.2) and negative Eu anomaly suggest distal hydrothermal source. The Co/Zn (average 2.2), Ce/La ratio (average 0.67) and trace element discrimination diagrams indicate hydrothermal–hydrogenous processes. Y/Ho ratio (average 24.85) and strong positive correlation coefficient between major oxides and some high field strength elements (HFSE) like; TiO2 vs Fe2O3 (r = 0.98), Al2O3 vs Zr (r = 0.97), Al2O3 vs Fe2O3 (r = 0.98), Zr vs K2O (r = 0.98), Nb vs TiO2 (r = 0.92), Th vs Fe2O3 (r = 0.76), Th vs MgO (r = 0.86) reveal the presence of volcaniclastics and (or) terrigenous detritals of mafic composition being deposited into the depositional basin. It seems that intermittent interlayering of mafic detrital material derived from volcanic eruption of the Neyriz island arc directly affected the physicochemical conditions of hydrothermal ore precipitation in this basin and consequently the Nasirabad manganese ores represent hydrothermal–hydrogenous geochemical characteristics. The Nasirabad is an example of non-sulphidic, oxic Mn-mineralization. Similar trend between the enrichment and depletion of some bioessential elements (e.g., Mn, As, Ba, Sr, Co, Ce) might have been resulted from selective sequestering of metal ions by microbial processes and hence hydrogenous characteristics may also be the result of biogenetic processes. Moreover the high dilution of distal hydrothermal exhalations by sea water cannot be ruled out. 相似文献
Phosphorus (P) desorption characteristics may be altered due to the biosolids decomposition during the incubation period. In our previous work we studied the phosphorus release kinetics in biosolids-amended calcareous soils with no prior incubation. The objectives of this work were (1) to assess the phosphorus desorption behavior in soils as influenced by biosolids after 5 months of incubation and (2) to evaluate the influences of six levels of the biosolids on phosphorus availability and salinity of soil. The results showed that the biosolids addition significantly increased the soil available P and salinity. The P availability and salinity of the soils increased as level of the biosolids application increased. However, there was no significant difference between some application rates for some soils. The results indicated that the incubation can affect the factors controlling the P release rate. Also, the results showed that the soil organic matter negatively affected the P desorption rate in the biosolids-treated soils. 相似文献
Geotechnical and Geological Engineering - Soil-geosynthetic interface behavior under cyclic loading will differ from that under static loading. To this end, a series of static and multistep tests... 相似文献
Characterization of karst systems and forecast of their state variables are essential for groundwater management and engineering in karst regions. These objectives can be met by the use of process-based discrete-continuum models (DCMs). However, results of DCMs may suffer from inversion nonuniqueness. It has been demonstrated that the joint inversion of observations regulated by different natural processes can tackle the nonuniqueness issue in groundwater modeling. However, this has not been tested for DCMs thus far. This research proposes a methodology for the joint inversion of hydro-thermo-chemo-graphs, applying to two small-scale sink-to-spring experiments at Freiheit Spring, Minnesota, USA. In order to address conceptual uncertainty, a multimodel approach was implemented, featuring seven mutually exclusive variants. Spring hydro-thermo-chemo-graphs, for all the variants simulated by MODFLOW-CFPv2, were jointly inverted using a weighted least squares algorithm. Subsequently, models were compared in terms of inversion and forecast performances, as well as parameter uncertainties. Results reveal the suitability of the DCM approach for simultaneous inversion and forecast of hydro-physico-chemical behavior of karst systems, even at a scale of meters and seconds. The estimated volume of the tracer conduit passage ranges from approximately 46–51 m3, which is comparable to the estimate from the flood-pulse method. Moreover, it was demonstrated that the thermograph and hydrograph contain more information about aquifer characteristics than the chemograph. However, this finding can be site-specific and should depend on the analysis scale, the considered conceptual models, and the hydrological state, which are potentially affected by minor unaccountable processes and features.