Elevated Soil Arsenic Levels at a Former Crude Oil Storage Facility-Assessment,Remediation, and Possible Sources

Surface and near-surface soil arsenic levels were measured at a former crude oil storage facility within the greater Los Angeles area of Southern California. Arsenic was present in soil within some portions of the site at concentrations defined as being hazardous by both the State of California and the United States Environmental Protection Agency. The elevated soil total arsenic concentrations ranged from about 30 to 2300?mg/kg and generally occurred in, and adjacent to, the former washing and storage tank locations and along piping runs. In contrast, background concentrations of arsenic in soil at the site ranged from less than the analytical method detection limits (0.5?mg/kg) to approximately 8.0?mg/kg. The elevated soil arsenic concentrations are believed to be the result of the use of arsenical corrosion inhibitors within production wells and possibly the use of arsenical biocides in washing and skimmer tanks. Flow lines from production wells within the oil field to the crude oil storage facility contained crude oil and produced (formation) water. Arsenical corrosion inhibitors placed into the oil wells may have flowed with the crude oil/produced-water streams into the washing and skimmer tanks. Over the course of approximately 55 years of operation, tankage and piping leaks at the facility may have contributed to the elevated soil arsenic concentrations encountered at the site. A site-specific cleanup goal of 22?mg/kg total arsenic was established by the regulatory agency with oversight for the site. Remediation of the arsenic-impacted soil was accomplished by excavation and on site treatment using a chemical fixation process. Confirmatory samples collected after the fixation process was completed verified that the treatment reduced the concentrations of arsenic that could by leached from the soil to nonhazardous levels. The treated soil was subsequently transported offsite to an asphalt recycling facility for incorporation into asphalt paving products.     

The effect of extraction,storage, and analysis techniques on the measurement of airborne endotoxin from a large dairy

The objective of this study was to fill in additional knowledge gaps with respect to the extraction, storage, and analysis of airborne endotoxin, with a specific focus on samples from a dairy production facility. We utilized polycarbonate filters to collect total airborne endotoxins, sonication as the extraction technique, and 0.05% Tween 20 in pyrogen-free water (PFW) as the extraction solution. Endotoxin concentrations were determined via the Limulus amebocyte lysate (LAL) assay. The endotoxin concentrations in extracts after 15 and 30 min of filter sonication were similar, while the concentration in 60 min extracts was about twofold lower. Rapidly vortexing samples for up to 15 min after sonication did not increase the endotoxin concentration. However, concentrations were 13 and 26% lower in extracts that were centrifuged at 1,000 and 10,000g for up to 15 min, respectively. Field samples and endotoxin standard were also sonicated in glass or polypropylene tubes for up to 120 min. Regardless of the extraction vessel, a decrease in endotoxin concentration occurred when sonicated for >30 min. Samples and endotoxin standard subjected to 12 freeze–thaw cycles at −20°C only showed a slight but not significant decrease in endotoxin concentration. Our results also demonstrate the importance of simultaneously adding LAL reagent to 96-well plates before initiating the LAL assay.     

SKIN SWABBING FOR GENETIC ANALYSIS: APPLICATION TO DUSKY DOLPHINS (LAGENORHYNCHUS OBSCURUS)

Exfoliated skin was collected from bowriding dolphins with the use of a sterilized nylon scrub pad affixed to a wooden dowel. Initial tests of the effectiveness of the technique and dolphin behavioral responses were conducted on dusky dolphins off Kaikoura, New Zealand. During 14 sampling days, 128 contacts using this procedure were made with bowriding dolphins, of which 114 showed behavioral response. Responses during sampling were mild, with 11% of contacted individuals showing no visible response, and 66% of individuals which could be monitored for 30 sec after contact returning to bowride within 30 sec. Mean return time was 10 sec postcontact and did not vary significantly for groups of different sizes. Behavioral controls suggest that a proportion of responses could be explained by typical dolphin behavior in the presence of boats. Seventy-eight percent of contacts resulted in successful collection of tissue samples. Sample time was three minutes on average. Size of group and behavioral state did not appear to influence sample time. Preliminary genetic analyses revealed that tissue collected by this technique was suitable for amplification and sequencing of mitochondrial DNA (mtDNA) via PCR. Comparisons of mtDNA control region sequences with those from known L. obscurus and other delphinid samples verified that this technique was robust against contamination from elements in sea water.     

Polarized light therapy: Shining a light on the mechanism underlying its immunomodulatory effects

This study investigates the immunomodulatory effects of polychromatic polarized light therapy (PLT) on human monocyte cells. While there is some evidence demonstrating a clinical effect in the treatment of certain conditions, there is little research into its mechanism of action. Herein, U937 monocyte cells were cultured and exposed to PLT. The cells were then analyzed for change in expression of genes and cell surface markers relating to inflammation. It was noted that 6 hours of PLT reduced the expression of the CD14, MHC I and CD11b receptors, and increased the expression of CD86. It was also shown that PLT caused downregulation of the genes IL1B, CCL2, NLRP3 and NOD1, and upregulation of NFKBIA and TLR9. These findings imply that PLT has the capacity for immunomodulation in human immune cells, possibly exerting an anti‐inflammatory effect.     

Arrested succession in logging gaps: is tree seedling growth and survival limiting?

Thirty years after selective timber harvest in the Kibale National Park, Uganda, many abandoned logging gaps are dominated by Acanthus pubescens, and show little forest recovery. To examine if this arrested successional state was caused by limited tree seedling growth and survival, we planted seedlings of four forest tree species (Albizia grandibracteata, Mimusops bagshawei, Prunus africana and Uvariopsis congensis) in A. pubescens‐dominated logging gaps and in control areas of adjacent forest. To assess if clearing A. pubescens facilitates forest regeneration, we planted seedlings of two species (A. grandibracteata and U. congensis) in small clearings cut within the logging gaps. We examined mortality, growth, herbivory and site characteristics among the treatments. Finally, we described the physical attributes of the A. pubescens‐dominated gaps. Seedlings of all the four species survived and grew equally well in A. pubescens and forest treatments, and most site characteristics were also similar. Seedlings planted in clearings grew more than in either forest or A. pubescens sites. Very few established trees were found in A. pubescens sites, and most of these were near the forest edges. We also discussed the role of elephants (Loxodonta africana) and collapsing A. pubescens canopies in the maintenance of an arrested successional state in these logging gaps.