Presence Of Different Sources Research Articles

Distribution and sources of surfzone bacteria at Huntington Beach before and after disinfection on an ocean outfall – A frequency-domain analysis

Fecal indicator bacteria (FIB) were measured approximately 5 days a week in ankle-depth water at 19 surfzone stations along Huntington Beach and Newport Beach, California, from 1998 to the end of 2003. These sampling periods span the time before and after treated sewage effluent, discharged into the coastal ocean from the local outfall, was disinfected. Bacterial samples were also taken in the vicinity of the outfall during the pre- and post-disinfection periods. Our analysis of the results from both data sets suggest that land-based sources, rather than the local outfall, were the source of the FIB responsible for the frequent closures and postings of local beaches in the summers of 2001 and 2002. Because the annual cycle is the dominant frequency in the fecal and total coliform data sets at most sampling stations, we infer that sources associated with local runoff were responsible for the majority of coliform contamination along wide stretches of the beach. The dominant fortnightly cycle in enterococci at many surfzone sampling stations suggests that the source for these relatively frequent bacteria contamination events in summer is related to the wetting and draining of the land due to the large tidal excursions found during spring tides. Along the most frequently closed section of the beach at stations 3N-15N, the fortnightly cycle is dominant in all FIBs. The strikingly different spatial and spectral patterns found in coliform and in enterococci suggest the presence of different sources, at least for large sections of beach. The presence of a relatively large enterococci fortnightly cycle along the beaches near Newport Harbor indicates that contamination sources similar to those found off Huntington Beach are present, though not at high enough levels to close the Newport beaches.

Nickel speciation in the presence of different sources and fractions of dissolved organic matter

This study evaluated nickel (Ni) speciation in the presence of different fractions (humic acid (HA), fulvic acid (FA)) and sources (natural sediment, Suwannee River, peat moss) of dissolved organic matter (DOM) at Ni concentrations toxicologically relevant to the freshwater amphipod, Hyalella azteca. The free Ni ion, Ni 2+, was measured in reconstituted water (with or without DOM) using a miniaturized ion-exchange technique (IET). Ni speciation from these experiments was compared to calculated results obtained from equilibrium modelling (WHAM, Model VI). While it is known that Ni will complex with DOM, it was found that under acutely toxic Ni exposure concentrations ([Ni Total]=5 mg/L, or 85.1 μM) representative surface-water DOC concentrations (∼10 mg/L) played little or no role in Ni speciation. Conversely, at sublethal Ni exposure concentrations ([Ni Total]=0.2 and 0.5 μg/L, or 3.4 and 8.51 μM, respectively) DOM significantly affected Ni speciation with [Ni 2+] decreasing with increasing concentration of DOM. It was found that for similar concentrations of DOC (same fraction, different sources), the measured Ni 2+ concentrations were reduced (relative to the control), but similar to one another. Conversely, at similar DOC concentrations, the HA fraction reduced Ni 2+ levels to a greater extent than the associated FA fraction. Overall, this study provides proof of principle that Suwannee River and peat humic substances are suitable analogues for natural sediment pore-water DOM when evaluating Ni bioavailability in freshwater.

PLUTONIUM CONTAMINATION IN SOILS AND SEDIMENTS AT MAYAK PA, RUSSIA

The Mayak Production Association (Mayak PA) was established in the late 1940's to produce plutonium for the Soviet Nuclear Weapons Programme. In total, seven reactors and two reprocessing plants have been in operation. Today, the area comprises both military and civilian reactors as well as reprocessing and metallurgical plants. Authorized and accidental releases of radioactive waste have caused severe contamination to the surrounding areas. In the present study, [alpha]-spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS) have been used to determine plutonium activities and isotope ratios in soil and sediment samples collected from reservoirs of the Techa River at the Mayak area and downstream Techa River. The objective of the study was to determine the total inventory of plutonium in the reservoirs and to identify the different sources contributing to the plutonium contamination. Results based on [alpha]-spectrometry and ICP-MS measurements show the presence of different sources and confirmed recent reports of civilian reprocessing at Mayak. Determination of activity levels and isotope ratios in soil and sediment samples from the Techa River support the hypothesis that most of the plutonium, like other radionuclides in the Techa River, originated from the very early waste discharges to the Techa River between 1949 and 1951. Analysis of reservoir sediment samples suggest that about 75% of the plutonium isotopes could have been released to Reservoir 10 during the early weapons production operation of the plant, and that the majority of plutonium in Reservoir 10 originates from discharges from power production or reprocessing. Enhanced 240Pu/239Pu atom ratios in river sediment upper layers (0-2 cm) between 50 and 250 km downstream from the plant indicate a contribution from other, non-fallout sources.

Broadband channel capacities

We study the communication capacities of bosonic broadband channels in the presence of different sources of noise. In particular we analyze lossy channels in presence of white noise and thermal bath. In this context, we provide a numerical solution for the entanglement assisted capacity and upper and lower bounds for the classical and quantum capacities.

Implementing Speech and Simulated Data Link Commands: The Role of Task Interference and Message Length

The present study investigated the ability of individuals to correctly execute different numbers of commands presented in speech and text format (simulating voice and data link communications). These commands were executed in the presence of different sources of task interference drawing upon visual, verbal, and central executive resources. The results showed that performance decreased as the number of commands in the message set increased from two to four, regardless of presentation format. Visual interference was less disruptive than both verbal and central executive interference. These findings have implications for the design of data link systems and suggest that during periods of high workload, communications should include fewer commands within a message set particularly when there is insufficient time to request clarification.

Increased apoptotic neutrophils and macrophages and impaired macrophage phagocytic clearance of apoptotic neutrophils in systemic lupus erythematosus.

To evaluate whether patients with systemic lupus erythematosus (SLE) have a higher rate of apoptosis in and secondary necrosis of polymorphonuclear neutrophils (PMNs) and macrophages compared with controls; to compare the rate of macrophage phagocytic clearance of apoptotic PMNs in patients with SLE and healthy controls; to evaluate whether in vitro PMN and macrophage apoptosis and secondary necrosis, and the ability of macrophages to phagocytose apoptotic bodies, are correlated with lupus disease activity; and to determine whether macrophage clearance of apoptotic bodies in patients with SLE and normal controls is related to certain serum factors. Thirty-six patients with SLE and 18 healthy, nonsmoking volunteers were studied. PMNs and monocytes were isolated from fresh blood and cultured in the presence of different sources of serum. Apoptotic PMNs and macrophages were examined by annexin V binding and morphology on May-Giemsa-stained cytopreparations, at different time points. The presence of secondary necrotic PMNs and macrophages was verified by staining with trypan blue. Macrophage phagocytosis of apoptotic PMNs was measured using a coded, observer-blinded, microscopically quantified phagocytosis assay. Cells were cultured in the presence of serum obtained from healthy subjects or from patients with SLE. At 5 and 24 hours, the percentage of apoptotic PMNs from patients with SLE was significantly higher than that of PMNs from healthy subjects. At 24 and 48 hours, the percentage of secondary necrotic PMNs from patients with SLE was also significantly higher than the percentage of necrotic PMNs from controls. Serum from patients with SLE accelerated the rate of apoptosis in and secondary necrosis of PMNs from healthy subjects. Macrophages from SLE patients were less capable of phagocytosing apoptotic PMNs compared with macrophages obtained from controls. Macrophages from patients with active SLE were less capable of phagocytosing apoptotic PMNs than were macrophages from patients with inactive SLE, but the difference was not statistically significant. The percentage of phagocytosis of apoptotic PMNs by macrophages from SLE patients correlated negatively with the SLE Disease Activity Index, serum levels of anti-double-stranded DNA, and the erythrocyte sedimentation rate, and correlated positively with serum levels of C3, C4, and albumin, the hemoglobin level, and the leukocyte count. Serum from SLE patients not only significantly increased macrophage apoptosis in cells from healthy subjects but also remarkably down-regulated the clearance of apoptotic PMNs by macrophages from healthy subjects. In contrast, serum from healthy subjects significantly increased phagocytosis of apoptotic PMNs by macrophages from SLE patients. The observed increase of apoptotic PMNs and macrophages and the poor ability of macrophages from patients with SLE to phagocytose apoptotic bodies may indicate an impaired clearance mechanism, which may be mediated by factors in a patient's serum.

Historical record of polycyclic aromatic hydrocarbons (PAH) and heavy metals in floodplain sediments from the Rhine River (Hessisches Ried, Germany)

The depth-related content of polycyclic aromatic hydrocarbons (PAH) and heavy metals was determined for two soil profiles (i.e. one Fluvisol and one Gleyic Cambisol) which developed in sediments from floodplains located at an old meander of the Rhine river. The meander had been cut off from the main river in 1829. The separation of the meander from the main river caused a change in sediment deposition (i.e. from sand to silt) which is clearly visible in the soil-profiles. Since that time, approximately 100 cm of sediments have accumulated due to temporary flooding of the area. Each soil profile was separated into 18 samples. The samples were analysed for their content of PAH after solvent extraction. Additionally, several trace elements (Co, Ni, Cd, Pb, Zn, Cr and Cu) were determined in the same sample set, and depth-related concentration profiles for both PAH and trace elements were developed. The distribution patterns of PAH with more than 3 condensed rings did not provide any evidence for PAH biodegradation or vertical transport after deposition of the sediments. Thus, in the case of PAH, the historical record can be derived not only from subhydric sediments but also from floodplain sediments. It was not possible to distinguish between atmospheric and fluvial input of PAH into the sediments from the observed distribution patterns due to the same origin of PAH from pyrolytic processes. A source determination of the PAH was not possible except for perylene, for which biogenic formation can be assumed. A comparison of the results shows that the depth-related PAH and trace element concentrations display similar trends over most of the total profiles. In the uppermost section of the profiles, the concentration of most trace elements declines whereas the PAH concentration remains high. This indicates the presence of different sources for PAH and trace elements in the last decades.

The influence of carbon sources and mononucleotides on the production of extracellular alkaline phosphatase by bacillus intermedium

The biosynthesis of extracellular alkaline phosphatase in the streptomycin-resistant strains Bacillus intermedius S3-19 and S7 in the presence in the medium of 5'-nucleoside monophosphates and different sources of carbon--glucose, sodium pyruvate, sodium lactate, or glycerol--was studied. It was established that, in the presence of mononucleotides, the content of extracellular alkaline phosphatase in both strains increased; the maximal effect was caused by 5'-AMP at a concentration of 20 micrograms/ml. In medium with a low orthophosphate content, where active biosynthesis of alkaline phosphatase occurred, 1% glucose and 0.5% pyruvate stimulated this process 2.5-4 times, and 2% sodium lactate and sodium pyruvate, on the contrary, inhibited it by 20-40%. Analysis of the dynamics of growth and accumulation of extracellular phosphatase in the presence of different sources of carbon in the medium gives evidence of an interrelationship between the biosynthesis of alkaline phosphatase and carbon metabolism in Bacillus intermedius.

Investigation on different contributions to the magnetic irreversibility in Bi2Sr2CaCu2O8 single crystals

Hysteresis cycles and relaxation measurements as a function of temperature and field are reported for a very thin Bi2Sr2CaCu2O8 single crystal (thickness=5 μm). A fishtail effect was observed between 15 and 26 K at a field of ≈400 Oe, at which the relaxation rate was found to rapidly increase. The observed behaviour gives evidence of a field-induced 3d-2d dimensional crossover in the vortex lattice in presence of different sources of irreversibility (point and extended planar defects, surface barriers), each of them dominating in different regions of the B-T phase diagram.

Analysis and occurrence of toxic planar PCBs, PCDDs and PCDFs in milk by use of carbosphere activated carbon

A method is described for the determination of the toxicologically related planar PCB-congeners 3,3′,4,4′-tetra, 3,3′,4,4′,5-penta and 3,3′,4,4′,5,5′-hexachloro-biphenyl, based on the former Carbosphere methodology for the isomer-specific analysis of the seventeen toxic 2,3,7,8- chlorine substituted PCDD and PCDF congeners. The method proved to be rapid, accurate and reproducible (SD 8 %) for the analysis of low ppt levels of planar PCBs in cow's milk. The method has been applied to the analysis of planar PCBs, PCDDs and PCDFs in cow's milk from the vicinity of several sources and in human milk. A level of planar PCBs in human milk in the Netherlands was found of 9.2 pg TEQ/g fat. In samples of cow's milk from the vicinity of municipal waste incinerators and a metal reclamation plant, planar PCB levels ranged between 1.1 and 6.1 pg TEQ/g fat, whereas PCDD/Fs levels ranged between 1.3 and 12.9 pg TEQ/g fat. The factors that may be involved in the occurrence of planar PCBs in cow's milk are discussed in view of the presence of different sources in combination with the influence of kinetics of the individual PCB congeners in the cow.