Movement of leachate from beneath turkey litter sited over chalk in southern England

Farm waste stores are widespread in the UK, with many overlying the principal aquifer, the Chalk. The stores pose a threat to groundwater quality through the infiltration of high concentrations of nitrogen species and organic carbon together with pathogenic microbes. Two cored boreholes have been drilled into the unsaturated chalk to depths of 15 and 20 metres, respectively, through a site which has been used to store turkey litter for in excess of 20 years. Porewaters were extracted from the cores and analysed for a range of chemical elements. In addition, chalk core material was also taken for microbial examination. Both boreholes showed very high concentrations of nitrate-N (3000 mg/L), ammonia (5000 mg/L), organic carbon (3000 mg/L), and potassium (10,000 mg/L) in the top 5 metres of the profile. Below this depth concentrations declined dramatically. Highest concentrations were found in the borehole constructed in the middle of the site. The borehole constructed at the edge of the store showed much lower concentrations but did show a peak of nitrate around 10 metres below ground level. The apparent lack of movement beneath the centre of the store suggests the turkey litter is relatively impermeable and most leaching occurs where the covering of litter is thin or when the litter is annually cleared. If the leachate continues to migrate at this apparent rate, it will take more than 100 years to reach the water table.     

Impact on blood Pb levels of maternal and early infant feeding practices of First Nation Cree in the Mushkegowuk Territory of northern Ontario,Canada

Exposure to Pb in-utero and in infancy has been associated with cognitive risk, even at low blood Pb levels of 0.48-0.96 micromol L(-1). Based on the hypothesis that wild game consumed by First Nation women of Mushkegowuk Territory contains Pb that might be transferred through blood or breast-milk to the fetus or infant, the study's objectives were to describe: (1) Pb in maternal and cord blood at birth and infant blood at 4 months, and (2) dietary influence on Pb status. Cord and maternal Pb were 0.10 +/- 0.08 and 0.11 +/- 0.06 micromol L(-1) (x +/- SD), respectively, and were significantly correlated (r = 0.77, p < 0.0001, n = 70), as was infant blood Pb (0.08 +/- 0.05 micromol L(-1)) with matched cord blood (r = 0.65, p < 0.0001, n = 30). Two cord blood samples (3%) were above 0.48 micromol L(-1). Pb in breast-milk at 0.010 +/- 0.008 micromol L(-1) (n = 25), was significantly lower than Pb in commercial formula or evaporated milk-based feedings (range 0.02-0.05 micromol L(-1), p < 0.05), and correlated with matched maternal blood Pb (r = 0.55, p < 0.005). However, in a sub-sample of infants (n = 31), blood Pb was similar for breastfed and formula-fed groups, though above the evaporated milk-fed group (p < 0.05). Maternal consumption of wild fowl, mammals and fish, estimated from the previous year, provided, respectively, 128 +/- 124, 46 +/- 68 and 8 +/- 13 MJ annum(-1). Traditional animal food intake, especially wild fowl, correlated significantly with cord blood Pb (Spearman rank correlation, p = 0.017). Although blood and milk Pb levels were largely within acceptable ranges, the presence of some elevated levels and association between blood Pb and traditional game consumption may reflect the legacy of using lead-containing ammunition.     

The scientific foundations of clinical enzymology

Clinical enzymology is the study of the activity and properties of enzymes in specimens (usually of blood) taken from patients, as an aid to the diagnosis and understanding of disease. Research in many areas of enzymology is undertaken to strengthen the foundations on which the clinical interpretation of such enzyme measurements rests. Some aspects of this research are briefly described.     

Regional Blue and Green Water Balances and Use by Selected Crops in the U.S.

The availability of freshwater is a prerequisite for municipal development and agricultural production, especially in the arid and semiarid portions of the western United States (U.S.). Agriculture is the leading user of water in the U.S. Agricultural water use can be partitioned into green (derived from rainfall) and blue water (irrigation). Blue water can be further subdivided by source. In this research, we develop a hydrologic balance by 8‐Digit Hydrologic Unit Code using a combination of Soil and Water Assessment Tool simulations and available human water use estimates. These data are used to partition agricultural groundwater usage by sustainability and surface water usage by local source or importation. These predictions coupled with reported agricultural yield data are used to predict the virtual water contained in each ton of corn, wheat, sorghum, and soybeans produced and its source. We estimate that these four crops consume 480 km³ of green water annually and 23 km³ of blue water, 12 km³ of which is from groundwater withdrawal. Regional trends in blue water use from groundwater depletion highlight heavy usage in the High Plains, and small pockets throughout the western U.S. This information is presented to inform water resources debate by estimating the cost of agricultural production in terms of water regionally. This research illustrates the variable water content of the crops we consume and export, and the source of that water.     

Defense against parasites by hitchhikers in leaf-cutting ants: a quantitative assessment

Summary A curious behavior in leaf-cutting ants in the genus Atta is the hitchhiking of small minim workers on leaf fragments carried by larger workers. Two functions of these hitchhikers have been proposed: (1) defense of leaf carriers against parasitic flies in the family Phoridae (ant protection hypothesis; Eibl-Eibesfeldt and Eibl-Eibesfeldt 1967) and (2) reduction of transport costs of small minims that collect plant fluids (energy conservation hypothesis; Stradling 1978).We studied hitchhiking behavior in colonies of Atta colombica on Barro Colorado Island, Panama, and found strong evidence in favor of the ant protection hypothesis. Females of Apocephalus attophilus (Diptera: Phoridae) attack leaf carriers of A. colombica and deposit eggs in the head capsules of these ants. Our observations indicate that parasites require leaf fragments to stand on during oviposition, and, as a result, only leaf carriers are susceptible to parasitic attack. The presence of hitchhikers reduces significantly both the time parasites spend on leaf fragments and the probability that they will land in the first place. Results of experimental introductions of parasites and a year of biweekly censuses at ten colonies indicate that leaf-cutting ants adjust the level of hitchhiking to accommodate both daily and seasonal changes in the abundance of parasites.We found little evidence in support of the energy conservation hypothesis. If it is assumed that all minim workers hitchhike back to the nest, our calculations indicate that total transport costs along a foraging trail are reduced by 10% or less. However, our observations indicate that only 50% of returning minim workers hitchhike, and therefore energy savings are actually considerably less than 10%. Leaf-cutting ants in the genera Atta and Acromyrmex are attacked by over 20 species of parasitic phorids. In the discussion we review what is known about these associations and suggest that these parasites have influenced the ecology and evolution of polyethism in leaf-cutting ants. Offprint requests to: D.H. Feener (at his present address)     

单取代苯衍生物的QSAR研究——分子表面积和活性基团表面积的应用

本文对３０种单取代苯衍生物的结构和毒性关系进行了研究，由于取代基的多样性和性质的各不相同，用量子化学计算所得电子性质参数，拓扑指数和某些经验参数作描述参数，均不能得到好的与毒性的相关性，为此，引入了与取代基相关的取代基活性基团表面积，再加上反映分子总体性质和形状分子表面积及三阶形状指数，所得回归方程较好反映了结构和毒性关系，这也说明了对于单取代苯衍生物，取代基在致毒作用中可能起重要作用。     

Effects of Antecedent Streamflow and Sample Timing on Trend Assessments of Fish,Invertebrate, and Diatom Communities

Detecting trends in biological attributes is central to many stream monitoring programs; however, understanding how natural variability in environmental factors affects trend results is not well understood. We evaluated the influence of antecedent streamflow and sample timing (covariates) on trend estimates for fish, invertebrate, and diatom taxa richness and biological condition from 2002 to 2012 at 51 sites distributed across the conterminous United States. A combination of linear regression and Kendall‐tau test for trends were used to evaluate covariate influence on trend estimates. Adjusting for covariates changed the magnitude of trend estimates in two‐thirds of cases on average by 21%, most often reducing the estimated magnitude of the trend. Additionally, covariates influenced the interpretation of over one‐third of trend estimates by either strengthening or weakening trends after adjustment. Our findings clearly indicate that antecedent streamflow and sample timing influences trend estimates and subsequent interpretation. Accounting for covariates during trend analysis will enhance stream monitoring programs by providing a better understanding and interpretation of estimated changes in biological endpoints at monitored sites. Failure to account for antecedent streamflow and sample timing may lead to mischaracterization of a trend and/or misunderstanding of potential causes.     

The effects of performance attributions and outcome dependence on leader feedback behavior following poor subordinate performance

While feedback is considered to be among the most effective motivational tools available in organizations, there is substantial evidence that leaders are often poor sources of feedback. Following poor subordinate performance, leaders have been shown to avoid providing feedback, delay providing feedback, and distort feedback to make it less negative. While these findings are strong, there is evidence that this ‘mum’ effect may be limited by certain boundary conditions. A 2×2 experimental study was designed to determine the extent to which leader performance attributions (effort and ability) and outcome dependence (high and low) affected the frequency, latency, and type of feedback provided to poor performers. The results suggest that the feedback offered to poor performers by leaders is significantly affected by both performance attributions and outcome dependence. © 1998 John Wiley & Sons, Ltd.