Simulation of 1-year-old Populus tremuloides response to ozone stress at Ithaca, USA, and Suwon, Republic of Korea

The growth of 1-year-old aspen was simulated using TREGRO, a computer simulation model of individual tree growth, to assess potential effects of ozone (O3). TREGRO was parameterized using information from a field experiment conducted at Ithaca, NY, USA; the model was then applied using environmental information from Suwon, Korea, where O3 exposures of aspen had not been conducted. In the parameterization at Ithaca, the simulated and measured total biomass differed by about 3% and the differences between measured and simulated biomass gain of leaf, shoot, and root were 15.4, 8.3, and 4.4%, respectively. Simulating growth at Suwon required adjustment in growth rates to match measured growth due to the different weather conditions at the two cities. The assimilated carbon was evenly distributed to each tissue (foliage, branch, stem, coarse, fine roots) in Suwon, whereas it was mainly allocated to vigorous stem growth in Ithaca. The vigorous growth under Suwon conditions resulted in less total non-structural carbon and perhaps trees more vulnerable to O3 stress. Although the ambient O3 in Suwon (1.2 ppm.h of sum of the hourly concentrations greater than 0.06 ppm [SUM06]) was lower than that in Ithaca (2.1 ppm.h of SUM06), a reduction of 8% of total assimilated carbon was found compared to simulation without O3. Severe effects on root growth at elevated O3 (1.7 times ambient) were predicted; however, the effects on leaf growth would not be as severe.     

A 25-year record of polycyclic aromatic hydrocarbons in soils amended with sewage sludges

We studied polycyclic aromatic hydrocarbons (PAHs) in crop soils amended with 1000 tonnes dry weight of sewage sludges per 10,000 m² from 1974 to 1992, then after sludges addition from 1993 to 1999. The absence of variations of total PAHs levels of control soils, averaging at 123 μg/Kg, shows the absence of horizontal contamination. During sludges addition, the total PAHs levels in amended soils increased from 232 to 402 μg/Kg. Seven years after sludges addition, it decreased to 275 μg/Kg, which is still more than twice –the levels of control soils. This finding shows that sludges PAHs are preserved in crop soils for long periods of time, on a human scale.     

Solitary and eusocial nests in a population of Augochlorella striata (Provancher) (Hymenoptera; Halictidae) at the northern edge of its range

Summary Augochlorella striata was studied at the northern limit of its range. The study population contained a mixture of solitary and social nest foundresses. Eusocial foundresses produced 1 or 2 workers before switching to a male biased brood. Solitary foundresses produced males first. Cells vacated by eclosed offspring were reused late in summer. A female biased brood resulted from cell reuse in both solitary and eusocial nests. Workers were slightly smaller than their mothers and were sterile although most of them mated. In comparison to published data from a Kansas population of this species, the Nova Scotia population had i) a lower proportion of multiple foundress nests, ii) a smaller worker brood and iii) a briefer period of foraging activity but iv) comparable overall nest productivity.     

Prenatal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency by amniotic fluid steroid analysis

The concentration of 17OH-progesterone was measured in second trimester amniotic fluid samples from 12 mothers who previously had had an infant with congenital adrenal hyper-plasia due to 21-hydroxylase deficiency. In 4 affected pregnancies, the concentrations were more than 2 S.D. higher than those determined in 44 samples from normal pregnancies (mean ± S.D., 8·1 ± 2·4 nmol/1). The remaining 8 pregnancies were predicted to be unaffected based on the results of amniotic fluid concentrations within the normal range. In each instance, the infant was normal. The results indicate that measurement of amniotic fluid 17OH-progester-one concentrations during the second trimester is an accurate prenatal test for 21-hydroxylase deficiency. The results should be supplemented with determination of fetal sex by karyotype analysis on the amniotic fluid cells.     

Topsoil inversion as a restoration measure in sand dunes,early results from a UK field-trial

Over-stabilisation and eutrophication affect many dune systems in north-west Europe. This leads to lower diversity of typical dune species and an accumulation of soil nutrients. Existing management techniques to remove excess nutrients include mowing, with removal of cuttings, and turf stripping. A new restoration technique called topsoil inversion or deep ploughing may also be able to counter some of the negative effects of eutrophication. It simulates the burial of established soils with fresh mineral sand, by inverting the soil profile. A trial was carried out on two small blocks of eutrophic dune grassland in North Wales, UK. Nutrient-rich surface soils were buried beneath mineral sub-sand using a double-bladed plough, designed to plough to depths of up to 100 cm. Results show that the organic soil horizons were buried to a depth of 80 cm, and covered with 40–50 cm of mineral sand. The pH and organic matter of the surface layers became comparable to those of mobile dunes. Fifteen months after ploughing, bare sand cover was still 70–90%, but significant sand loss through wind erosion resulted in a thinning of the mineral sand over-burden, leaving the buried organic layer closer to the surface. Natural vegetation colonisation was slow, with the first surviving plants observed after 8 months. The majority of species present at 15 months were present before ploughing and had regenerated from rhizomes or root fragments. The effect of excluding disturbance caused by rabbits, people and dogs was assessed within fenced areas. After 11 months, vegetation cover was greater in the fenced areas than in plots exposed to disturbance, therefore disturbance replaced physical conditions as the dominant influence on plant growth and establishment. These early results suggest the trial has been partially successful, but that topsoil inversion could be combined with other methods such as turf stripping or by stabilisation of the ploughed surface by planting with pioneer species, depending on the ultimate restoration goal.     

Determination of S02 Emission from Oil Combustion Sources by Fuel Analyses and S02/C02 Relations

The current S0₂ emission test methods, based on wet chemistry, are time consuming and costly. Final results depend on at least 10 separate measurements of quantities which may introduce significant errors due to human factors especially under unfavorable field environment. Performance evaluation of several promising S0₂ instrumental methods indicated that results were reliable and reproducible, but instrumental problems still exist. The problems were found to be calibration, mechanical and electronic components, and sample conditioning system. An alternative method proposed requires only two separate analyses: ultimate fuel analysis and stack gas analysis for C0₂. This method can be further simplified with reasonable accuracy by a single measurement of sulfur in the fuel if results are corrected to 12% C0₂. The method can be a useful addition to the current methods, especially if cost and manpower preclude actual stack tests. A test program was conducted at four industrial and utility power plants. Results are presented with discussion to show the application and validity of the simplified method.     

Agricultural practices in grasslands detected by spatial remote sensing

The major decrease in grassland surfaces associated with changes in their management that has been observed in many regions of the earth during the last half century has major impacts on environmental and socio-economic systems. This study focuses on the identification of grassland management practices in an intensive agricultural watershed located in Brittany, France, by analyzing the intra-annual dynamics of the surface condition of vegetation using remotely sensed and field data. We studied the relationship between one vegetation index (NDVI) and two biophysical variables (LAI and fCOVER) derived from a series of three SPOT images on one hand and measurements collected during field campaigns achieved on 120 grasslands on the other. The results show that the LAI appears as the best predictor for monitoring grassland mowing and grazing. Indeed, because of its ability to characterize vegetation status, LAI estimated from remote sensing data is a relevant variable to identify these practices. LAI values derived from the SPOT images were then classified based on the K-Nearest Neighbor (KNN) supervised algorithm. The results points out that the distribution of grassland management practices such as grazing and mowing can be mapped very accurately (Kappa index?=?0.82) at a field scale over large agricultural areas using a series of satellite images.