Implications of soil mixing for NAPL source zone remediation: Column studies and modeling of field-scale systems

Soil remediation is often inhibited by subsurface heterogeneity, which constrains contaminant/reagent contact. Use of soil mixing techniques for reagent delivery provides a means to overcome contaminant/reagent contact limitations. Furthermore, soil mixing reduces the permeability of treated soils, thus extending the time for reactions to proceed. This paper describes research conducted to evaluate implications of soil mixing on remediation of non-aqueous phase liquid (NAPL) source zones. The research consisted of column studies and subsequent modeling of field-scale systems. For column studies, clean influent water was flushed through columns containing homogenized soils, granular zero valent iron (ZVI), and trichloroethene (TCE) NAPL. Within the columns, NAPL depletion occurred due to dissolution, followed by either column-effluent discharge or ZVI-mediated degradation. Complete removal of TCE NAPL from the columns occurred in 6-8 pore volumes of flow. However, most of the TCE (>96%) was discharged in the column effluent; less than 4% of TCE was degraded. The low fraction of TCE degraded is attributed to the short hydraulic residence time (<4 days) in the columns. Subsequently, modeling was conducted to scale up column results. By scaling up to field-relevant system sizes (>10 m) and reducing permeability by one-or-more orders of magnitude, the residence time could be greatly extended, potentially for periods of years to decades. Model output indicates that the fraction of TCE degraded can be increased to >99.9%, given typical post-mixing soil permeability values. These results suggest that remediation performance can be greatly enhanced by combining contaminant degradation with an extended residence time.

Long-term potential of in situ chemical reduction for treatment of polychlorinated biphenyls in soils

Polychlorinated biphenyls (PCBs) are well-known for being hydrophobic and persistent in the environment. Although many treatment approaches have been demonstrated to result in degradation of PCBs in water or water/cosolvent systems, few examples exist where such approaches have been applied successfully for PCB degradation in soil-water systems. A possible explanation for the limited treatment of PCBs in soil-water systems is that reactants that are capable of degrading PCBs in the aqueous phase are unlikely to persist long enough to achieve meaningful treatment of slowly-desorbing PCBs associated with the soil phase. To investigate this explanation, laboratory studies were conducted to evaluate chemical reductants, including zero valent metals, palladium (Pd) catalyst, and emulsified zero valent iron (EZVI), for dechlorination of PCBs in the presence and absence of soil. In the absence of soil, Pd-catalyzed treatments (Pd with electrolytic ZVI or iron/aluminum alloy) achieved rapid destruction of a model PCB congener, 2-chlorobiphenyl, with half-lives ranging from 43 to 110 min. For treatment of soils containing Aroclor 1248 at an initial concentration of approximately 1,500 mg kg(-1), Pd-catalyzed treatments achieved no measurable enhancement over the background PCB depletion rate (i.e., that measured in the untreated control) of 5.3 mg kg(-1)week(-1). In the presence of soils, EZVI was the only approach evaluated that resulted in a clear enhancement in PCB dechlorination rates. EZVI achieved PCB concentration reductions of greater than 50% at an average rate of 19 mg kg(-1)week(-1). The results suggest that slow PCB desorption limits treatment effectiveness in soils.

Lesion kinetics in a non-human primate model of endometriosis

BACKGROUND

Endometriosis is a common cause of pelvic pain and infertility in women of reproductive age. It is characterized by the presence of endometrial tissue outside the normal location, predominantly in the pelvic peritoneum causing severe abdominal pain. However, the severity of the symptoms of endometriosis does not always correlate with the anatomic severity of the disease. This lack of correlation may be due to morphological lesion variation during disease progression. This study examined lesion kinetics in a non-human primate model of endometriosis to better understand lesion dynamics.

METHODS

Endometriosis was experimentally induced in nine normal cycling female adult olive baboons (Papio anubis) by i.p. inoculation of autologous menstrual endometrium on Day 2 of menses for two consecutive menstrual cycles. Diagnostic laparoscopies were performed between Day 8-12 post-ovulation at 1, 3, 6, 9 and 12 months, followed by a necropsy at 15 months, after the second inoculation. In two animals, lesions were excised/ablated at 6 months and they were monitored for lesion recurrence and morphological changes by serial laparoscopy. Furthermore, five control animals underwent surgeries conducted at the same time points but without inoculation.

RESULTS

A total of 542 endometriotic lesions were observed. The location, macroscopic (different colours) and microscopic appearance confirmed distinct endometriosis pathology in line with human disease. The majority of the lesions found 1 month after tissue inoculation were red lesions, which frequently changed colour during the disease progression. In contrast, blue lesions remained consistently blue while white lesions were evident at the later stages of the disease process and often regressed. There were significantly lower numbers of powder burn, blister and multicoloured lesions observed per animal in comparison to black and blue lesions (P-value≤0.05). New lesions were continually arising and persisted up to 15 months post-inoculation. Lesions reoccurred as early as 3 months after removal and 69% of lesions excised/ablated had reoccurred 9 months later. Interestingly, endometriotic lesions were also found in the non-inoculated animals, starting at the 6-month time point following multiple surgeries.

CONCLUSIONS

Documentation of lesion turnover in baboons indicated that lesions changed their colour from red to white over time. Different lesion types underwent metamorphosis at different rates. A classification of lesions based on morphological appearance may help disease prognosis and examination of the effect of the lesion on disease symptoms, and provide new opportunities for targeted therapies in order to prevent or treat endometriosis. Surgical removal of endometriotic lesions resulted in a high incidence of recurrence. Spontaneous endometriosis developed in control baboons in the absence of inoculation suggesting that repetitive surgical procedures alone can induce the spontaneous evolution of the chronic disease. Although lesion excision/ablation may have short-term benefits (e.g. prior to an IVF cycle in subfertile women), for long-term relief of symptoms perhaps medical therapy is more effective than surgical therapy.

CEO expectation: the Star Wars materiel manager of the 1990s, or C-3PO as role model

Materiel-intensive expenditures account for a significant portion of all hospital costs, second only to salaries and wages, yet materiel managers may often be overlooked as key members of the management team. This is alarming since the potential exists for materiel managers to impact annual savings of hundreds of thousands of dollars by operating efficient departments. Materiel managers have a tremendous opportunity to enhance their image and improve hospital productivity in the coming decade. The challenges of the 1990s will stretch materiel managers' skills toward enhancing their professionalism and achieving the expectations of themselves and top management. If materiel managers will effectively utilize (C3)PO they will increase their educational levels, continue to learn new skills, maintain a customer-oriented management style, exercise creativity, develop and adhere to standards, and be proactive in their responsibilities. The benefits of their success will be felt by patients, hospitals, the industry, and materiel managers everywhere.

A study of the exploratory behavior of legally blind and sighted preschoolers

This study investigated the exploratory behavior 0f 15 legally blind preschoolers as they compared to 15 sighted preschoolers (matched for age, sex, and socioeconomic status). Each child was videotaped interacting with a novel toy and a commercial toy for the purpose of looking for initiative-aggressiveness, interest, mode of examination, sensory utilization, assistance needed to solve each toy, and verbalizations during exploration and about the “solution” of each toy.

The uses of hypnotherapy with learning disabled children

Explored the impact of group hypnotic and self-hypnotic training on the academic performance and self-esteem of learning disabled (LD) children. Three hypnotic training sessions and instructions for 6 weeks of daily self-hypnotic practice that contained suggestions for imagery related to improvement in these areas were given to 15 children (12 males and 3 females, ages from 7 to 13), their reading teacher, and both their parents, and their responses were compared to a similar but untreated control group of 18. No overall differences were observed between groups. A multiple regression analysis revealed important predictors of self-esteem improvement for the experimental group. The child's hypnotic susceptibility score and self-hypnotic practice by children and parents were the most relevant. These LD children were at least as hypnotically susceptible as a normative sample. Hypnotherapy is seen as feasible in group administration by persons only moderately trained in hypnosis and of potential benefit to self-esteem improvement in LD children, depending on individual difference factors.