Contamination of Urban Soils in an Area of Northern France Polluted by Dust Emissions of Two Smelters

The contamination of 27 urban topsoils has been assessed around two lead and zinc smelters (Metaleurop Nord and Umicore) in the North of France. Eighteen trace elements have been analysed (Ag, As, Bi, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Sb, Se, Sn, Tl, Th, U and Zn). The investigation included the study of the vertical distribution of Cd, Pb and Zn as indicators of pollution. It was shown that Cd, In, Pb, Sb and Zn were major pollutants followed in lesser quantities by Ag, Bi, Cu and Hg. In addition, As, Ni, Se, Sn and Tl were present at levels slightly higher than regional agricultural values. The other elements (Co, Cr, Th and U) were at endogenous levels. The observations have highlighted the strong heterogeneity of the physico-chemical parameters of urban soils and the existence of heavy contamination of the under layers by Cd, Pb and Zn. A potential transfer of metals from the topsoil to the deeper layers and especially Cd and Zn, is not excluded. Indeed the soil rework is not the only factor explaining contamination level of the deeper layers of the studied soils. The comparison of the studied element concentrations in urban soils with nearby local agricultural values shows that the dust emission originating from the Metaleurop and Umicore smelters were not the only source of contamination. Thus a large contamination of the studied urban soils by Sb and In could be explained by domestic combustion of coal for heating.     

Modifying the microclimate around young oaks through vegetation manipulation: Effects on seedling growth and branching

The objective of this research was to evaluate the influence of vegetation control on the microclimate (light, air temperature, vapor-pressure deficit (VPD)) and on the growth of young planted, sessile oak seedlings. Three types of vegetation control, creating a range of above-ground interaction intensity, were compared. In the open treatment, vegetation was chemically controlled and was maintained at a low height; in the closed treatment, vegetation was manually controlled and a few dominant individuals that overtopped the oak seedlings were cut; and in the sheath treatment, the vegetation in a 0.5-m diameter circle around each seedling was manually cut to a height equal to three quarters of the total seedling height. In all treatments, a strong reduction of incoming radiation was observed, as well as an increase in air temperature and VPD during the day, and a decrease in daily PET, compared to the reference located 4 m above the vegetation. However, the neighboring vegetation did not modify the microclimate around the seedling to a level that could have induced a significant reduction in seedling photosynthesis and, thus, in seedling growth. Seven years after planting, seedlings were shortest in the open treatment and tallest in the closed treatment (334, 372, 378 cm in the open, sheath and closed treatments, respectively). Seedlings in the open treatment allocated proportionally more biomass to diameter increment than to height growth, compared to seedlings in the sheath and closed treatments. The seedlings averaged 1.77, 1.10 and 1.00 forks in the open, sheath and closed treatments, respectively, and the average height of the lowest fork was 171, 206 and 226 cm in the same treatments. The reduction of the number of forks per seedling was not related to a reduction of the appearance of new forks, but rather to a reduction in the persistence of the existing forks. These changes in stem allometry and in fork development seemed to be related to the lateral shade afforded by the vegetation.     

ULTRASOUND-GUIDED TISSUE-CORE BIOPSY OF LIVER, SPLEEN AND KIDNEY IN NORMAL DOGS

Six normal dogs were subjected to ultrasound-guided biopsy of the liver, spleen and kidney to examine the accuracy of the technique (i.e. the presence of targeted tissue) and the histologic quality of the biopsies. Five consecutive tissue-core biopsies of each organ were taken on one or more occasions. The accuracy of the technique was 77% for hepatic, 90% for splenic, 53.5% for left kidney and 40% for right kidney biopsies. The histologic quality of the liver and kidney samples was sufficient, although for some samples the diagnostic value was limited by their size and in renal samples either cortical or medullary tissue was sometimes lacking. In contrast, the quality of the splenic sections was not good. The effect of reused and resterilized needles on the quality of the specimens was evaluated by histologic inspection of the samples and by the amount of biopsies lacking tissue. All tissue samples, including those taken with reused or resterilized needles had sharp-cut edges. Twenty-two of the total number of 120 biopsies (18%) contained no tissue. Absence of tissue in the samples was observed in biopsies taken with all needle types. The animals were observed for possible complications of the repeated needle biopsy. Apart from one case of hematuria, no complications were encountered.     

Triazine herbicide resistance in Chenopodium album L.: Occurrence and characteristics of an intermediate biotype

Intermediate (I) biotypes for triazine herbicide resistance in Chenopodium album (as defined by a peculiar fluorescence curve), had the same ID₅₀ values as resistant(R) plants for chloroplast response to atrazine, but proved to be more susceptible at lower doses. Furthermore, the lethal dose in seedling treatments was lower than that of the R plants, but six times higher than for susceptible (S) plants. These I characteristics of I biotypes were maternally inherited in crosses. I biotypes were isolated from various progenies of susceptible precursor (Sp) plants in two garden populations. This could be the first step in the occurrence of triazine herbicide resistance. However, Sp plants have not been observed in field populations. The significance of the presence of a single isozyme pattern for all Sp plants is discussed. The results suggest an evolutionary pathway from S to R plants via I biotypes.     

Differences in temperature requirements between Polymyxa sp. of Indian origin and Polymyxa graminis and Polymyxa betae from temperate areas

The temperature requirements of three single cystosorus strains of Polymyxa sp. from India were studied at 15–18, 19–22, 23–26 and 27–30 °C (night-day temperature), and compared with the temperature requirements of three strains of P. graminis from Belgium, Canada and France and two strains of P. betae from Belgium and Turkey. Sorghum was used as the host-plant for the Indian strains; the strains of P. graminis and P. betae from temperate areas were cultivated on barley and sugar beet, respectively. The cystosori germination and the development of plasmodia, zoosporangia and cystosori of Polymyxa sp. from India were optimal at 27–30 °C. Infection progression was slower at 23–26 °C than at 27–30 °C. At 19–22 °C, infection was insignificant. No infection occurred below 19 °C. In contrast, the infection of barley with P. graminis strains from temperate areas was optimal at 15–18 °C, but at 19–22 °C the progression appeared inconsistent and infection stayed low. Above 22 °C, infection was insignificant. P. betae strains showed consistent infection in the range of 15–18 °C to 27–30 °C. Plasmodia formation and cystosori detection of the Belgian strain were slightly advanced at 23–26 °C compared to 19–22 °C but clearly restrained at 27–30 °C. Fungus development of the P. betae strain from Turkey was almost as high at 27–30 °C as at the lower temperatures. These results strengthen the case for distinguishing between Polymyxa sp. from India and P. graminis or P. betae from temperate areas.     

Role of Bordetella bronchiseptica adenylate cyclase in nasal colonization and in development of local and systemic immune responses in piglets

Two Bordetella bronchiseptica mutants, lacking the adenylate cyclase (Cya) or both Cya and pertactin (Prn), were compared with their parental strain NL1013 in their abilities to colonize the nose of neonate piglets and to induce local and systemic antibody responses against filamentous hemagglutinin (FHA) after intranasal (i.n.) inoculation. The number of bacteria recovered and the duration of infection in the nasal secretions were greater for the wild-type parent strain than for the Cya-deficient mutant, indicating that Cya plays an important role during B. bronchiseptica colonization of the nasal cavity. The double mutant did not colonize the nasal cavity and was less able to adhere to epithelial cells in vitro than the other two strains, supporting the hypothesis that Prn plays a major role in cell adhesion. In piglets inoculated with the wild type strain, anti-FHA IgM was found in the nasal secretions one week after inoculation, followed two weeks later by anti-FHA IgA; their presence was concomitant with decreases in bacterial counts. Anti-FHA IgG appeared at six weeks after infection in the serum. In contrast, i.n. inoculation with either mutant failed to induce a nasal secretory antibody response but did induce an earlier and higher IgM response in the serum than inoculation with the wild type strain. However, only the Cya-deficient mutant was able to prime the piglets for the development of a secondary nasal IgM and serum IgG response to FHA after intranasal inoculation with the wild type B. bronchiseptica.     

Computed tomographic features of the normal canine thyroid gland.

The computed tomographic (CT) features of the normal thyroid gland were compiled from images acquired in 25 client-owned dogs without thyroid gland disease. The mean pre- and postcontrast attenuation values were 107.5 and 169.0 Hounsfield Units, respectively. After injection of intravenous contrast medium (600 mg iodine/kg), the apparent thyroid gland volume (both lobes combined) increased from a mean value of 1148.0 nm3 to a mean value of 1188.9 mm3. All thyroid lobes were homogeneous on pre- and postcontrast images. In a craniocaudal direction, the gland spanned a region from the 1st to the 8th tracheal ring and the right lobe was often more cranial than the left. On transverse images the lobe shape was ovoid in 72%, and its location was dorsolateral to the trachea in 90% of dogs. Parathyroid glands could not be identified and an isthmus connecting both thyroid lobes was only seen in one dog. Considering the excellent visibility of the normal canine thyroid gland, CT can be beneficial in the differentiation of thyroidal versus nonthyroidal neck masses. CT also yields potential in the staging of thyroid carcinomas.     

Growth Effects of Governmental Policies: A Comparative Analysis in a Multi‐Country Context

The potential interactions among governmental policies, investments andeconomic growth are complex and manifold. This paper will perform a systematic comparative analysis of the various economic insights that are currently available on these complex relationships, both theoretically (by a selective literature review) and empirically (by reviewing the empirically obtained insights). Despite the wide variety of potential theoretical relationshipsbetween government expenditures, taxation and growth, most empirical analyses are restricted to simple linear regressions of growth on some measure of government expenditures. We will indicate directions for future empirical research that may enrich our knowledge about the complex relationship between fiscal policies and economic growth, not only nationally but also regionally.     

Fallow residue management effects on upland rice in three agroecological zones of West Africa

Improving fallow quality in upland rice-fallow rotations in West Africa through the site-specific use of leguminous cover crops has been shown to sustain the productivity of such systems. We studied the effects of a range of residue management practices (removal, burning, mulching and incorporation) on fallow biomass and N accumulation, on weed biomass and yield response of upland rice and on changes in soil physical and chemical characteristics in 2-year field trials conducted in three agroecological zones of Côte d'Ivoire. Across fallow management treatments and agroecological zones, rice yields were on average 20–30% higher in legume than in natural fallow plots. Weed biomass was highest in the savanna zone and lowest in the bimodal forest and tended to be less following a legume fallow. Regardless of the type of fallow vegetation and agroecological zone, biomass removal resulted in the lowest rice yields that varied from 0.5?t ha^–1 in the derived savanna zone to 1.5?t ha^–1 in the Guinea savanna zone. Burning of the fallow vegetation significantly increased yield over residue removal in the derived savanna (0.27?t ha^–1, P<0.05) and bimodal forest zones (0.27?t ha^–1, P<0.01), but not in the Guinea savanna. In both savanna environments, residue incorporation was superior to the farmers' practice of residue removal and rice yield increases were related to amounts of fallow N returned to the soil (r²=0.803, P<0.01). In the forest zone, the farmers' practice of residue burning produced the highest yield (1.43?t ha-1 in the case of legumes) and resulted in the lowest weed biomass (0.02?t ha^–1). Regardless of the site, improving the quality of the fallow or of its management had no significant effects on either soil physical or soil chemical characteristics after two fallow cycles. We conclude that incorporation of legume residues is a desirable practice for rice-based fallow rotation systems in savanna environments. No promising residue management alternatives to slash-and-burn were apparent for the forest zone. Determining the possible effects on soil productivity will require longer-term experiments.