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Biodegradation of polycyclic aromatic hydrocarbons in oil-contaminated beach sediments treated with nutrient amendments.

Microbial biodegradation of polycyclic aromatic hydrocarbons (PAHs) during the process of bioremediation can be constrained by lack of nutrients, low bioavailability of the contaminants, or scarcity of PAH-biodegrading microorganisms. This study focused on addressing the limitation of nutrient availability for PAH biodegradation in oil-contaminated beach sediments. In our previous study, three nutrient sources including inorganic soluble nutrients, the slow-release fertilizer Osmocote (Os; Scotts, Marysville, OH) and Inipol EAP-22 (Ip; ATOFINA Chemicals, Philadelphia, PA), as well as their combinations, were applied to beach sediments contaminated with an Arabian light crude oil. Osmocote was the most effective nutrient source for aliphatic biodegradation. This study presents data on PAH biodegradation in the oil-spiked beach sediments amended with the three nutrients. Biodegradation of total target PAHs (two- to six-ring) in all treatments followed a first-order biodegradation model. The biodegradation rates of total target PAHs in the sediments treated with Os were significantly higher than those without. On Day 45, approximately 9.3% of total target PAHs remained in the sediments amended with Os alone, significantly lower than the 54.2 to 58.0% remaining in sediment treatments without Os. Amendment with Inipol or soluble nutrients alone, or in combination, did not stimulate biodegradation rates of PAHs with a ring number higher than 2. The slow-release fertilizer (Os) is therefore recommended as an effective nutrient amendment for intrinsic biodegradation of PAHs in oil-contaminated beach sediments.

Biodegradation, Environmental↗
PubMed2003

Seasonal variation in phosphorus removal processes within reed beds--mass balance investigations.

The phosphorus (P) removal processes in two pairs of High and Low Loaded reed beds were investigated during five periods within a 27-month study. The uptake/release of P was measured in seven mass balance compartments. With the exception of the first year of operation, the reed beds consistently removed over 96% of the influent P load, with total phosphorus (TP) concentrations being reduced from 0.5 mg/L to generally less than 0.005 mg/L across the range of loading rates and seasons studied. During the first year, uptake by Phragmites australis accounted for greater than 75% of P removed, and was equally distributed between above and below-ground biomass. During the second and third years, three seasonal stages were identified in the uptake and cycling of P by P. australis. A period of rapid above-ground growth and uptake occurred during spring fuelled partly by P reserves accumulated in rhizomes during the previous year. During summer, uptake by above-ground biomass was governed by the influent P loading rate, while the amount of P held in below-ground biomass remained relatively stable. During autumn and winter, P appeared to be translocated from senescent shoots to reserves in the rhizomes. Approximately 85% of the below-ground biomass P occurred in the top 20 cm of the substrate. Gravel fixation increased in importance from 12% in the first year to approximately 30% of P removed in the second year, with a highly significant correlation between the influent P loading rate and P fixed by the gravel. The weakly-bound P fraction from a sequential extraction was the dominant form of P fixed by the gravel. HCI extracts were inappropriate for the examination of sorption processes as they dissolved large amounts of mineral P from within the basaltic gravel. The bottom 30 cm of the substrate became the most important site for gravel fixation during the second year. Incorporation of P into the detritus/microbiota/other compartment increased after the first year to become one of the most important P removal processes, probably consisting mainly of leaf litter and slowly accreted organic sediments.

Ecosystem↗
PubMed2006

Molecular phylogenetic and chemical analyses of the microbial mats in deep-sea cold seep sediments at the northeastern Japan Sea.

Microbial communities inhabiting deep-sea cold seep sediments at the northeastern Japan Sea were characterized by molecular phylogenetic and chemical analyses. White patchy microbial mats were observed along the fault offshore the Hokkaido Island and sediment samples were collected from two stations at the southern foot of the Shiribeshi seamount (M1 site at a depth of 2,961 m on the active fault) and off the Motta Cape site (M2 site at a depth of 3,064 m off the active fault). The phylogenetic and terminal-restriction fragment polymorphism analyses of PCR-amplified 16S rRNA genes revealed that microbial community structures were different between two sampling stations. The members of ANME-2 archaea and diverse bacterial components including sulfate reducers within Deltaproteobacteria were detected from M1 site, indicating the occurrence of biologically mediated anaerobic oxidation of methane, while microbial community at M2 site was predominantly composed of members of Marine Crenarchaeota group I, sulfate reducers of Deltaproteobacteria, and sulfur oxidizers of Epsilonproteobacteria. Chemical analyses of seawater above microbial mats suggested that concentrations of sulfate and methane at M1 site were largely decreased relative to those at M2 site and carbon isotopic composition of methane at M1 site shifted heavier ((13)C-enriched), the results of which are consistent with molecular analyses. These results suggest that the mat microbial communities in deep-sea cold seep sediments at the northeastern Japan Sea are significantly responsible for sulfur and carbon circulations and the geological activity associated with plate movements serves unique microbial habitats in deep-sea environments.

Bacteria↗
PubMed2002

Polycyclic aromatic hydrocarbon contamination and LUMIStox solvent extract toxicity of marine sediments in the North Aegean Sea, Greece.

Organic extracts of surface marine sediment collected from six sites within the bay of Kavala (north Aegean Sea, Greece) were used for determining priority pollutant polycyclic aromatic hydrocarbons (PAHs) and doing toxicity testing. PAH analyses and LUMIStox acute toxicity measurements were conducted in two sediment grain-size fractions: silt/clay (< 63 microm) and sand (63-2000 microm). Sixteen PAH concentrations were found at low- to moderate levels, ranging from 44 to 166 ng/g dry weight in the fine fraction and from 45 to 148 ng/g dry weight in the coarse fraction. Molecular indices revealed that PAHs in the bay sediment originate mainly from pyrolytic sources, but some petroleum influence was also evident. A comparison of sedimentary PAH levels with sediment quality guidelines (SQGs) indicated an absence of acutely toxic concentrations. However, all sediment extracts were found to be toxic with the LUMIStox acute toxicity test, with 15-min EC(50)s in the ranges of 1.0-4.0 and 1.1-4.5 mg of dry sediment/mL for the fine and the coarse fractions, respectively. No significant correlations between EC(50)s and concentrations of individual or total PAHs was found, suggesting that chemical analysis of PAHs alone cannot be considered a reliable indicator of sediment toxicity.

Animals↗
PubMed2005

Traceability of environmental chemical analyses: can theory match practice?

According to the ISO definition, the traceability concept basically implies that measurement data are linked to stated references through an unbroken chain of comparisons, all with stated uncertainties. This concept may be quite clear in theory, but we may wonder how it may be applicable to complex chemical measurements such as environmental chemical analyses in practice. This paper discusses this issue, giving some examples of drawbacks that are being faced in different environmental sectors (water, sediment, soil, biota and particulate atmospheric samples).

Environmental Monitoring↗
PubMed2002

Evaluating sediment stability at sites with historic contamination.

The stability of cohesive sediment deposits during a rare storm is a critical component in the evaluation of remedial options at a contaminated sediment site. Estimating scour depths during a rare storm, and the resulting contaminant concentrations in the surficial layer of the bed, is necessary for comparing the efficacy of various remedial alternatives. Evaluation of sediment stability is accomplished using sediment transport analyses that employ quantitative procedures. Qualitative analyses or conceptual models can be useful for developing and validating quantitative analysis tools; however, qualitative techniques alone generally are insufficient for conducting defensible remedial alternative evaluations. The level of analysis used for a specific site depends on data availability, required level of accuracy, and time and budget constraints. A tier 1 analysis involves the use of approximate equations to produce order-of-magnitude estimates of scour depths during a rare storm. The second tier of this analysis scheme employs the development and application of a sediment transport model to evaluate bed stability. State-of-the-science sediment transport models have been effectively used as management tools for evaluating remedial options at several contaminated sediment sites. It should not be presumed that rare storm events cause catastrophic impacts at the site under review. Two case studies demonstrate that a rare storm is not necessarily catastrophic; significant increases in surficial bed concentrations caused by reexposure of elevated concentrations buried at depth in the bed will not necessarily occur during a rare storm. However, it is important to note that sediment stability is site-specific.

Environmental Monitoring↗
PubMed2004

Effect of human activities on overall trend of sedimentation in the lower Yellow River, China.

The Yellow River has been intensively affected by human activities, particularly in the past 50 years, including soil-water conservation in the upper and middle drainage basin, flood protection in the lower reaches, and flow regulation and water diversion in the whole drainage basin. All these changes may impact sedimentation process of the lower Yellow River in different ways. Assessing these impacts comprehensively is important for more effective environmental management of the drainage basin. Based on the data of annual river flow, sediment load, and channel sedimentation in the lower Yellow River between 1950 and 1997, the purpose of this paper is to analyze the overall trend of channel sedimentation rate at a time scale of 50 years, and its formative cause. It was found in this study that erosion control measures and water diversion have counteractive impacts on sedimentation rate in the lower Yellow River. Although both annual river flow and sediment decreased, there was no change in channel sedimentation rate. A regression analysis indicated that the sedimentation in the lower Yellow River decreased with the sediment input to the lower Yellow River but increased with the river flow input. In the past 30-40 years, the basin-wide practice of erosion and sediment control measures resulted in a decline in sediment supply to the Yellow River; at the same time, the human development of water resources that required river flow regulation and water diversion caused great reduction in river flow. The former may reduce the sedimentation in the lower Yellow River, but the reduction of river flow increased the sedimentation. When their effects counterbalanced each other, the overall trend of channel sedimentation in the lower Yellow River remained unchanged. This fact may help us to better understand the positive and negative effects of human activities in the Yellow River basin and to pay more attention to the negative effect of the development of water resources. The results of this study demonstrate that, if the overuse of river water cannot be controlled, the reduction of channel sedimentation in the lower Yellow River cannot be realized through the practice of erosion and sediment control measures.

China↗
PubMed2006

Seasonal variability of heavy metals in surface sediment of Lake Sapanca, Turkey.

Lake Sapanca is exposed to heavy urbanization and industrialization because of its natural beauty and its proximity to the metropolitan Istanbul, Turkey. In this study, it was aimed to investigate seasonal changes of some heavy metals (Pb, Cr, Cu, Mn, Ni, Zn and Cd) concentration of surface sediment. Nine different stations were chosen as sampling points. Samples were taken every three months and the seasonal and annual average concentration of the elements were determined. Seasonal highest values of heavy metals were observed as follows; Cr, Cu, Mn, Ni and Zn in Summer, Cd in Autumn. There was no seasonal difference for Pb, Cr and Cd. It seems that Lake Sapanca has not been polluted yet. However, it was found that Cu and Ni concentrations in surface sediment exceed lowest effect level.

Geologic Sediments↗
PubMed2006

Pyrethroids, pyrethrins, and piperonyl butoxide in sediments by high-resolution gas chromatography/high-resolution mass spectrometry.

A new method for determination of pyrethroids, pyrethrins, and piperonyl butoxide (PBO) by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) was developed for aquatic sediments. The method detection limits for pyrethroids (15 compounds), pyrethrins, and PBO ranged from 0.16 to 1.50 ng/g sediment, which was suitable for detecting these chemicals at environmentally relevant concentrations (low ng/L range) that are toxicologically significant to benthic organisms. Recovery of the analytes from a low level spiked sediment ranged from 89.7% to 135%. Resmethrin showed the lowest recovery at 23.5% and pyrethrins showed the highest recovery at 154%. To confirm the utility of this new method for environmental applications, sediment samples collected from five tributaries of the San Francisco Bay, California were analyzed. Individual pyrethroids were detected in concentrations of up to 17.6 ng/g, while PBO was detected in all sediment samples in concentrations of 0.010-0.215 ng/g. Pyrethrins were not found in the sediment samples.

California↗
PubMed2006

Improvements in the analysis of decabromodiphenyl ether using on-column injection and electron-capture detection.

During the development of a method to determine polybrominated diphenyl ethers (PBDEs) using GC/MS-MS equipped with a programmed temperature vaporizer (PTV) injector, a dramatic decrease in sensitivity to decabromodiphenyl ether (BDE-209) occurred and lack of sensitivity and repeatability was observed. An alternative method using GC/ECD equipped with an on-column injector was evaluated for this congener optimizing pre-column and column length. A coated retention gap (50 cm of length, 0.53 mm I.D., 0.15 microm d(f)) connected to a short capillary column (7 m of length, 0.32 mm I.D., 0.25 microm d(f)) showed the better sensitivity and repeatability. Finally, a double system based on the programmed temperature vaporizer injector/MS detector (for tri- to hepta-BDEs) and on-column injector/electron-capture detector (for BDE-209) was evaluated using two candidate certified materials (fish muscle tissue and river sediment).

Animals↗
PubMed2001

Clostridium perfringens as a potential indicator for the presence of sewage solids in marine sediments.

Marine sediment cores collected from several depths of water and distances from a California sewage outfall were tested to see if sediments influenced by sewage solids were a reservoir of enteric pathogens, and if concentrations of indicator bacteria were related to the presence of sewage solids. Vertical distributions of microorganisms in marine sediments were determined; there was a decrease of indicator bacteria with increasing sediment depth. Aeromonas was randomly isolated, but none of the enteric bacterial pathogens or viruses were detected. While classic indicator bacteria were of little value in predicting the presence of pathogens, or relative amounts of sewage solids, Clostridium perfringens may be a suitable indicator. Clostridium perfringens concentrations were not related to the presence of pathogens in sediments.

Biomarkers↗
PubMed2003

Degradation rates of low molecular weight PAH correlate with sediment TOC in marine subtidal sediments.

The degradation rate of low molecular weight (LMW) polycyclic aromatic hydrocarbons (PAH) in subtidal marine sediments was found to correlate with sediment total organic carbon (TOC) in stations sampled two or more times after the North Cape No. 2 fuel oil spill. With 2.5-5 months between samplings, stations with lower sediment TOC had lower fractions of LMW PAH remaining at the time of the second sampling. Apparent first-order degradation rate constants calculated for each station varied by nearly an order of magnitude between stations with a range of TOC from 0.4% to 7.3%. The correlation of degradation rate with sediment TOC can be used to provide improved and site-specific predictions of the initial time-course of LMW PAH concentrations in sediments after oil spills.

Biodegradation, Environmental↗