Modeling steady-state methanogenic degradation of phenols in groundwater

Field and microcosm observations of methanogenic phenolic compound degradation indicate that Monod kinetics governs the substrate disappearance but overestimates the observed biomass. In this paper we present modeling results from an ongoing multidisciplinary study of methanogenic biodegradation of phenolic compounds in a sand and gravel aquifer contaminated by chemicals and wastes used in wood treatment. Field disappearance rates of four phenols match those determined in batch microcosm studies previously performed by E.M. Godsy and coworkers. The degradation process appears to be at steady-state because even after a sustained influx over several decades, the contaminants still are disappearing in transport downgradient. The existence of a steady-state degradation profile of each substrate together with a low biomass density in the aquifer indicate that the bacteria population is exhibiting no net growth. This may be due to the oligotrophic nature of the biomass population in which utilization and growth are approximately independent of concentration for most of the concentration range. Thus a constant growth rate should exist over much of the contaminated area which may in turn be balanced by an unusually high decay or maintenance rate due to hostile conditions or predation.     

The influence of obstetricians on the utilization of amniocentesis

A study of 173 Western New York State obstetricians was undertaken to study referral patterns for second-trimester amniocentesis in 1974–1978. Referral patterns were analysed in relation to obstetrician age, religion, board certification, hospital affiliation and practice location. Forty-seven per cent of the obstetricians had never referred a patient for amniocentesis. Those referring were overall younger than those not referring and were significantly more often board certified. Obstetrician religion was significantly related to referral with fewer Catholic obstetricians referring. Hospital affiliation (teaching versus non-teaching) and obstetrician practice location (urban versus rural) were not important factors after controlling for religion and board certification. Obstetrician factors account for a small but important part of the variability in referral, and other factors, such as cost and access to laboratory and obstetric care need further investigation.     

The mental health of expatriate and Kosovar Albanian humanitarian aid workers

The mental health consequences of exposure to traumatic events and the risk factors for psychological morbidity among expatriate and Kosovar Albanian humanitarian aid workers have not been well studied. In June 2000, we used standardised screening tools to survey 285 (69.5%) of 410 expatriate aid workers and 325 (75.8%) of 429 Kosovar Albanian aid workers from 22 humanitarian organizations that were implementing health programmes in Kosovo. The mean number of trauma events experienced by expatriates was 2.8 (standard deviation: 2.7) and by Kosovar staff 3.2 (standard deviation: 2.8). Although only 1.1% of expatriate and 6.2% of Kosovar aid workers reported symptoms consistent with the diagnosis for post-traumatic stress disorder, 17.2% and 16.9%, respectively, reported symptoms satisfying the definition of depression. Regression analysis demonstrated that the number of trauma events experienced was significantly associated with depression for the two sets of workers. Organisational support services may be an important mediating factor and should be targeted at both groups.     

Books for Review

BookReview

Books for Review     

Heavy metal content of moss from Kampinos National Park in Poland

The results are presented of studies on the content of Zn, Pb, Cu, Ni and Cd inPleurozium schreberi moss within the spatial system of Kampinos National Park (KPN) adjacent to the Warsaw urban agglomeration. Over a large area (64.3–78.3%) of the Park, mosses contain the following amounts of metals in mg kg^–1 dw: 80–120 of Zn, 60–80 of Pb, 10–15 of Cu, 4–8 of Ni and 0.6–0.9 of Cd. All trace metals were found to accumulate in elevated amounts in moss in the south-eastern portion of the Park bordering the urban area, and it is this part of the Park that should be considered as most polluted by heavy metals.     

Adding infection to injury: synergistic effects of predation and parasitism on amphibian malformations

We explored the importance of interactions between parasite infection and predation in driving an emerging phenomenon of conservation importance: amphibian limb malformations. We suggest that injury resulting from intraspecific predation in combination with trematode infection contributes to the frequency and severity of malformations in salamanders. By integrating field surveys and experiments, we evaluated the individual and combined effects of conspecific attack and parasite (Ribeiroia ondatrae) infection on limb development of long-toed salamanders (Ambystoma macrodactylum). In the absence of Ribeiroia, abnormalities involved missing digits, feet, or limbs and were similar to those produced by cannibalistic attack in experimental trials. At field sites that supported Ribeiroia, malformations were dominated by extra limbs and digits. Correspondingly, laboratory exposure of larval salamanders to Ribeiroia cercariae over a 30-day period induced high frequencies of malformations, including extra digits, extra limbs, cutaneous fusion, and micromelia. However, salamander limbs exposed to both injury and infection exhibited 3-5 times more abnormalities than those exposed to either factor alone. Infection also caused significant delays in limb regeneration and time-to-metamorphosis. Taken together, these results help to explain malformation patterns observed in natural salamander populations while emphasizing the importance of interactions between parasitism and predation in driving disease.