Uptake and enantioselective elimination of chlordane compounds by common carp (Cyprinus carpio, L.)

An analytical method involving supercritical fluid extraction (SFE) followed by a two-dimensional gas chromatography (2D-GC) analysis was developed to determine the concentration (first GC) and enantiomeric ratio (second GC) of cis- and trans-chlordanes at the ppb (ng/g) level in fish tissue. The SFE method allowed concentration of the compounds of interest, and reduced the number of extraction and sample clean-up manipulations as compared to classical solvent extraction techniques. Four hundred common carp fingerling (Cyprinus carpio, L.) were exposed for three days to water containing 5 ppb (5 ng/g) technical grade chlordane containing about 1 ppb of chlordane isomers. The fish concentrated the pesticides more than 200 times (162 and 312 ng/g of cis- and trans-chlordane, respectively). However, the uptake is not enantioselective. The concentration of the principle constituents and their enantiomeric ratio was followed during a fifty days growth period in chlordane free water. The first order decay of concentration was observed with a half time of about 18 days for both the cis- and trans-chlordane isomers. However it was found that the enantiomeric ratio of the trans-chlordane was significantly altered during this short period of time, decreasing from ER=1 to ER=0.7, while no enantiomeric changes were observed for the cis-chlordane. It seems that the (-)-trans-chlordane is metabolized significantly faster (t(1/2-)=15 days) in the river carp fish than the (+)-trans-enantiomer (t(1/2+)=20 days).     

Toxicity of the insecticide methoxychlor to the Dungeness crab Cancer magister

The toxicity of methoxychlor, determined in acute and chronic studies using larval, juvenile, and adult stages of the Dungeness crab, Cancer magister Dana, was inversely related to the age of the crabs after hatching and increased with the length of exposure. The 96-h LC₅₀'s for zoeae, juveniles, and adults were 0.42, 5.10, and 130 g/l, respectively. Levels causing decreased survival of these same stages during exposures of more than 60 days were 0.05, 0.40, and 4.0 g/l, respectively. Hatching of eggs was not adversely affected by methoxychlor concentrations up to 10 g/l, and molting from prezoeae to zoeae was reduced only 30% from controls at the latter exposure concentration. Methoxychlor concentrations of 0.05 and 4.0 g/l delayed motting of larval and juvenile crabs, respectively, and this delay was as much as 10 days for the juveniles. Sensitivity of adult and juvenile crabs to methoxychlor increased during ecdysis. In uptake experiments, juvenile crabs concentrated methoxychlor more rapidly than did adults. Juveniles exposed to 2.0 g/l of methoxychlor and adults exposed to 1.8 and 7.5 g/l had whole body methoxychlor concentrations after 12 days of 0.88, 0.10, and 0.51 mg/kg, respectively. Loss of the pesticide from adult crabs was rapid, and was 95% complete after 15 days of depuration. Concentrations of methoxychlor in individual tissues were found to be highest in the exoskeleton, gill, and hepatopancreas, in declining order, with less than a two-fold difference among these tissues. About 81% of the methoxychlor measured in whole body samples was associated with the exoskeleton, but it is not known whether or not the pesticide was transported through the culticle to internal tissues.Technical Paper No. 4133, Oregon Agricultural Experiment Station.     

The Potential Impact of Geophagia on the Bioavailability of Iron, Zinc and Calcium in Human Nutrition

Geophagia, the deliberate ingestion of soil, is a complex eating behaviour with obscure aetiology and numerous health/medical problems. It is conventionally assumed that geophagia may help supplement mineral nutrients in individuals with limited intake of trace elements such as Fe and Zn. This view, however, has largely been based on the bulk nutrient composition of geophagic materials and the assumption that these nutrients are potentially available for absorption in the body. We have tested this assumption by equilibrating five geophagic materials collected from Uganda, Tanzania, Turkey and India with mineral nutrient concentrations and conditions similar to the gastrointestinal tract. The results showed that all five geophagic materials, regardless of their composition, sorbed large amounts of Fe and Zn across a range of dietary intake scenarios, even under acidic conditions (pH 2) similar to the stomach. However, significant amounts of Ca desorption were observed from calcareous soil samples. The findings show that while calcareous geophagic materials may supplement Ca, geophagia can potentially cause Fe- and Zn-deficiency. This is consistent with mineral nutrient deficiency problems observed in clinical nutrition studies conducted amongst geophagic populations.     

QUALITY OF WATER AND BOTTOM SEDIMENTS IN THE TRINITY RIVER1

ABSTRACT: Data were developed to determine the quality of water and bottom sediments in the Trinity River, and the mobility of various contaminants when bottom sediments were mixed with the river water under simulated dredging conditions. Thirteen sampling sites were selected. A number of chemical tests including heavy metals and pesticides were conducted on river water, elutriates, and bottom sediments. Statis bioassays using Daphnia magna were conducted on river water and elutriates. Results indicated that the river in the upper reach is grossly polluted due to discharge of waste water effluents from several large treatment plants. High concentrations of nitrogen, phosphorus, organic carbon, COD, heavy metals, and pesticides were found in water and bottom sediments. The concentrations of most of these pollutants exceeded the EPA recommended limits. Elutriation gave no consistent results, perhaps because of release or uptake of contaminants from the sediments. High mortality of D. magna were also recorded in the upper reach of the river. The quality of water and bottom sediments gradually improved in lower reaches.     

Toxicity of the fungicide captan to the Dungeness crab Cancer magister

Captan did not affect the survival of Dungeness crab (Cancer magister Dana) zoea exposed to 30 g l^-1 during a chronic toxicity test lasting 69 days, but larvae were quickly killed (mean survival time = 9 days) in the same test by exposure to 450 g l^-1 of the fungicide. Delay of molting occurred, however, for later stages at 30 g l^-1. Survival of juvenile crabs was not reduced by exposure to captan for 36 days at 510 g l^-1 or, in a second test, for 80 days at 290 g l^-1. No deaths of adults exposed for 75 days to 340 g l^-1 of captan were observed. Captan appeared to accelerate hatching of eggs at all concentrations tested from 100 to 10,000 g l^-1. The development from prezoeae during a 24-h period was not inhibited by the fungicide, but at 3,300 and 10,00 g l^-1, the two highest concentrations tested, developing zoeae exhibited a morphological deformity and were largely inactive. Under the prevailing conditions in the toxicity tests, the half-life of captan was estimated to be from 23 to 54 h. Because of the relatively low toxicity of captan to crab stages and its high rate of degradation in sewater, it is suggested that the agricultural application of captan near marine waters is not likely to affect natural crab populations or crabs in laboratory culture. Further-more, the prophylactic use of captan as a fungicidal treatment for Lagenidium sp. in larval crab cultures is considered safe when used at recommended dosages.Technical Paper No. 4131, Oregon Agricultural Experiment Station.     

Prevalence and characteristics of road traffic injuries among young drivers in Oman, 2009–2011

Objectives: Studies from different parts of the world have indicated that the impact of road traffic incidents disproportionally affects young adults. Few known studies have been forthcoming from Arabian Gulf countries. Within Oman, a high proportion of the population is under the age of 20. Coupled with the drastic increase in motorization in recent years, there is a need to understand the state of road safety among young people in Oman. The current research aimed to explore the prevalence and characteristics of road traffic injuries among young drivers aged 17–25 years.

Methods: Crash data from 2009 to 2011 were extracted from the Directorate General of Traffic, Royal Oman Police (ROP) database in Oman. The data were analyzed to explore the impact of road crashes on young people (17–25 years), the characteristics of young driver crashes, and how these differ from older drivers and to identify key predictors of fatalities in young driver crashes.

Results: Overall, young people were overrepresented in injuries and fatalities within the sample time period. Though it is true that many young people in crashes were driving at the time, it was also evident that young people were often victims in a crash caused by someone else. Thus, to reduce the impact of road crashes on young people, there is a need to generally address road safety within Oman. When young drivers were involved in crashes they were predominantly male. The types of crashes these drivers have can be broadly attributed to risk taking and inexperience. Speeding and nighttime driving were the key risk factors for fatalities.

Conclusion: The results highlight the need to address young driver safety in Oman. From these findings, the introduction of a graduated driver licensing system with nighttime driving restrictions could significantly improve young driver safety.     

Production of Nephrops norvegicus larvae in the Irish Sea

Plankton survey data from 1982, 1985 and 1995 were used to estimate the annual production of Nephrops norvegicus (L.) larvae in the Irish Sea. The larval abundance data from each set of surveys were analysed using the same temperature-to-stage-duration relationships. The production of larvae was similar in all 3?yr at approx. 360?×?10⁹ Stage I larvae per year. The estimated production in the eastern Irish Sea was 5% of the value for the western Irish Sea. This corresponded well to the sizes of the fisheries and the relative areas of the mud patches. Larvae in both areas were found to hatch over 5½?wk, centred on the first week in May. The time lag between onset of production of each stage reflected the estimated stage durations, but the lag between maximum production of each stage was much shorter than expected.     

Recovery of sulfate saturated soils in the Plynlimon catchments, mid-Wales following reductions in atmospheric S inputs from the 1980s to 2011

Sulfate adsorption capacity of B-horizons of base-poor, predominantly stagnopodzol, soils from the Plynlimon catchments, mid-Wales was determined by combination of laboratory adsorption and desorption isotherms. Results show that sulfate adsorption capacity of a range of stagnopodzol (Histic-stagno-podzol (Leptic), WRB), brown podzolic soil (Histic-umbrisol (Leptic), WRB) and stagnohumic gley (Histic-stagno-gleysol, WRB) B-horizons was positively related to the amounts of extractable (pyrophosphate and oxalate) Fe + Al, with the stagnopodzol and brown podzolic soil Bs horizon having the largest adsorption capacity and stagnohumic gley Bg horizon the smallest adsorption capacity. Results show that dissolved organic carbon (DOC) has a negative but limited effect on sulfate adsorption in these soils. Results obtained from a set of historical soil samples revealed that the grassland brown podzolic soil Bs horizon and afforested stagnopodzol Bs horizon were highly saturated with sulfate in the 1980s, at 63% and 89% respectively, whereas data from some recently sampled soil from two sites revisited in 2010-11 indicates that percentage sulfate adsorption saturation has since fallen substantially, to 41% and 50% respectively. Between 1984 and 2009 the annual rainfall-weighted mean excess SO(4)-S concentration in bulk precipitation declined linearly from 0.37 mg S l(-1) to 0.17 mg S l(-1). Over the same period, flow weighted annual mean stream water SO(4)-S concentrations decreased approximately linearly from 1.47 mg S l(-1) to 0.97 mg S l(-1) in the plantation afforested Hafren catchment compared to a drop from 1.25 to 0.69 mg S l(-1) in the adjacent moorland catchment of the Afon Gwy. In flux terms, the mean decrease in annual stream water SO(4)-S flux has been approximately 0.4 kg S ha(-1) yr(-1), whilst the recovery in stream water quality in the Afon Cyff grassland catchment has been partly offset by loss of SO(4)-S by desorption from the soil sulfur pool of approximately 0.2 kg S ha(-1) yr(-1).     

Drain-blocking techniques on blanket peat: A framework for best practice

In recent years there has been a dramatic increase in artificial drain-blocking in world peatlands. The UK blanket peatlands have been severely drained over the past few decades but now drains are being blocked in an attempt to improve peatland environments. The drain-blocking has been a disparate process with limited knowledge transfer between organisations and within organisations operating in different geographic areas. Consequently, there has been no compilation of techniques used and their effectiveness. During this study thirty-two drain-blocked sites were surveyed and all the key stakeholders interviewed. Drain-blocking using peat turf was preferred by practitioners and was also the most cost-effective method. Peat turves were successful except on steep slopes, in areas of severe erosion, in very wet or very dry locations, or if the mineral substrate was exposed. A drain-blocking best practice guide is offered by this paper, providing information on the most suitable methods for blocking peatland drains under different circumstances. Additional considerations are provided for practitioners to ensure peatland drain-blocking is as successful as possible.