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.     

Predictive statistical modelling of cadmium content in durum wheat grain based on soil parameters

Regulatory limits on cadmium (Cd) content in food products are tending to become stricter, especially in cereals, which are a major contributor to dietary intake of Cd by humans. This is of particular importance for durum wheat, which accumulates more Cd than bread wheat. The contamination of durum wheat grain by Cd depends not only on the genotype but also to a large extent on soil Cd availability. Assessing the phytoavailability of Cd for durum wheat is thus crucial, and appropriate methods are required. For this purpose, we propose a statistical model to predict Cd accumulation in durum wheat grain based on soil geochemical properties related to Cd availability in French agricultural soils with low Cd contents and neutral to alkaline pH (soils commonly used to grow durum wheat). The best model is based on the concentration of total Cd in the soil solution, the pH of a soil CaCl₂ extract, the cation exchange capacity (CEC), and the content of manganese oxides (Tamm’s extraction) in the soil. The model variables suggest a major influence of cadmium buffering power of the soil and of Cd speciation in solution. The model successfully explains 88% of Cd variability in grains with, generally, below 0.02 mg Cd kg^?1 prediction error in wheat grain. Monte Carlo cross-validation indicated that model accuracy will suffice for the European Community project to reduce the regulatory limit from 0.2 to 0.15 mg Cd kg^?1 grain, but not for the intermediate step at 0.175 mg Cd kg^?1. The model will help farmers assess the risk that the Cd content of their durum wheat grain will exceed regulatory limits, and help food safety authorities test different regulatory thresholds to find a trade-off between food safety and the negative impact a too strict regulation could have on farmers.

     

What can we learn from monitoring PCBs in the European eel? A Belgian experience

Between 2000 and 2007 pooled muscle tissue samples of the European eel (Anguilla anguilla) from 48 sites in Flanders (Belgium) were analysed for 30 polychlorinated biphenyl (PCB) congeners. There was a large variation between individual sites (range 11-7752 ng/g wet weight (ww) for the sum of the ICES 7 PCBs), eels from the River Meuse basin (mean 1545 ng/g ww) being considerably more polluted than those from the River Scheldt (615) and IJzer (61) basins. Overall, PCB 153, PCB 138 and PCB 180 were the most prominent congeners, however PCB patterns varied between the monitored locations. Analysis of the weight percentage of congeners demonstrates obvious differences in PCB composition between sites, indicating differential sources of pollution. Due to the variation in patterns, atmospheric fallout does not seem to be the main source of the PCB spread, but instead both local and upstream sources linked to industrial activities seem to be the main cause for PCB presence in Flanders. Considering the levels of the Sum 7 PCBs, eels are not compliant with the Belgian legal limits for consumption (75 ng/g ww) in 71% of the sites. Regular consumption of eels from polluted sites leads to a considerable excess of the WHO Acceptable Daily Intake value. Consumption of wild eels should by all means be prevented, as it presents risks for human health, especially for local anglers consuming their catch.     

Managing tricky decentralised competencies: case study of a participatory modelling experiment on land use in the Lake Guiers area in Northern Senegal

We describe an action-research project whose objective was to help stakeholders at different organisational levels achieve sustainable land management by developing mediation models and tools. We chose to test a specific approach called companion modelling in the framework of a multidisciplinary research partnership and a formal local partnership (a ‘users committee’) involving an array of stakeholders at different organisational levels. The study area covers 10,000 km² of agro-pastoral land around Lake Guiers in northern Senegal. We conducted studies to update the knowledge base of the area and organised six field workshops that clearly revealed three important tool functions to support decision-making on land use at different scales, i.e. understanding maps, monitoring and evaluating land tenure, and foreseeing changes in land use. We found that a toolbox approach was the best way to implement the three functions and overcome the constraints faced by the research team and those linked to the timing of the project. Therefore, we produced five simple complementary tools aimed at various users: a farm-level optimisation model (for researchers and technical services), a database for land allocations and a discussion tool to assess the impact of land allocation decisions (for the rural council), a paper atlas (for local players) and a regional land use change simulation model (for regional and national planners). Participants were able to work with paper maps, to interpret computer-generated simulations of land use change and understand the strengths and limitations of each. Self-assessment of the research process emphasised the importance of the context and the critical role played by social capital at both the research and the field level, which, in turn, emphasised the need for major improvements in the design and implementation of a quality process for participatory modelling. It turns out that action-research may be an effective way to undertake sustainability science.     

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.     

Pilot scale application of a method for the analysis of perfluorinated compounds in surface soils

A growing number of studies now indicate that perfluorinated compounds (PFCs) are globally distributed in the environment. Their widespread distribution and presence in remote locations has led to questions about the importance of atmospheric and oceanic transport. Describing their distribution in surface soils is also an essential but neglected element in developing a comprehensive understanding of their occurrence in the environment. Soils are the critical link between global atmospheric and hydrologic processes where both local and distant contaminants can accumulate and be released into aquatic and terrestrial communities. Because PFC concentrations in soils will influence ground and surface water, wildlife, and crops, methods to accurately measure PFCs in soil are clearly needed. To help answer this need, we developed a method for the analysis of nine perfluorinated carboxylic acids and four perfluorinated sulfonic acids in soil. Samples from six nations (n = 10 per nation) were analyzed by LC-MS/MS to demonstrate the method performance parameters and to make preliminary observations about the occurrence of the PFCs in soils in different parts of the world. The resulting method shows acceptable performance characteristics for the target compounds in most soils while documenting the widespread occurrence of PFCs in surface soils.     

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.