Suivi de la lixiviation du nitrate en plein champ par la technique lysimétrique : retour de huit années d'expérience

Monitoring of nitrate leaching in open fields by lysimeters: results from an eight year study. Since 2003, nitrate leaching has been monitored in six plots located in a loamy area (Hesbaye, Belgium), mainly dedicated to wheat, sugarbeet and vegetable crops. Open-field lysimeters have been used in order not to impede agricultural operations. Lysimeters are used as follow-up tools to quantify the amounts of nitrate leaching below the root zone. This study aims to evaluate the suitability of PLN (Potentially Leachable Nitrogen – APL in French) defined in the Sustainable Nitrogen Management Program (PGDA in French) as an environmental indicator by relating nitrogen management practices (including fertilization recommendations) to PLN values and groundwater quality. This study demonstrates that lysimeters are efficient in collecting representative amounts of leaching water. Lysimeters show that PLN is identified as being related to the nitrate content in leaching water, which will not be taken up by the next crop. The amount of nitrate leaching below the root zone demonstrates the necessity and the relevance of the organic nitrogen spreading limits defined in the Sustainable Nitrogen Management Program. The lysimeter tool also shows that respect for leaching water quality standards under agricultural plots needs to be considered from an integrated and generalized approach, taking into account complete crop sequences and rotations, including rational fertilization rates and the introduction of catch crops in rotation. Some suitable or unsuitable crop sequences with regard to good groundwater quality are listed

Ablation lesions in Koch's triangle assessed by three-dimensional myocardial contrast echocardiography

BACKGROUND: Myocardial contrast echocardiography (MCE) allows visualization of radiofrequency (RF) ablation lesions in the left ventricle in an animal model. Aim: To test whether MCE allows visualization of RF and cryo ablation lesions in the human right atrium using three-dimensional echocardiography. METHODS: 18 patients underwent catheter ablation of a supraventricular tachycardia and were included in this prospective single-blind study. Twelve patients were ablated inside Koch's triangle and 6, who served as controls, outside this area. Three-dimensional echocardiography of Koch's triangle was performed before and after the ablation procedure in all patients, using respiration and ECG gated pullback of a 9 MHz ICE transducer, with and without continuous intravenous echocontrast infusion (SonoVue, Bracco). Two independent observers analyzed the data off-line. RESULTS: MCE identified ablation lesions as a low contrast area within the normal atrial myocardial tissue. Craters on the endocardial surface were seen in 10 (83%) patients after ablation. Lesions were identified in 11 out of 12 patients (92%). None of the control patients were recognized as having been ablated. The confidence score of the independent echo reviewer tended to be higher when the number of applications increased. CONCLUSIONS: 1. MCE allows direct visualization of ablation lesions in the human atrial myocardium. 2. Both RF and cryo energy lesions can be identified using MCE

Childhood loneliness as a predictor of adolescent depressive symptoms: an 8-year longitudinal study

Childhood loneliness is characterised by children’s perceived dissatisfaction with aspects of their social relationships. This 8-year prospective study investigates whether loneliness in childhood predicts depressive symptoms in adolescence, controlling for early childhood indicators of emotional problems and a sociometric measure of peer social preference. 296 children were tested in the infant years of primary school (T1 5 years of age), in the upper primary school (T2 9 years of age) and in secondary school (T3 13 years of age). At T1, children completed the loneliness assessment and sociometric interview. Their teachers completed externalisation and internalisation rating scales for each child. At T2, children completed a loneliness assessment, a measure of depressive symptoms, and the sociometric interview. At T3, children completed the depressive symptom assessment. An SEM analysis showed that depressive symptoms in early adolescence (age 13) were predicted by reports of depressive symptoms at age 8, which were themselves predicted by internalisation in the infant school (5 years). The interactive effect of loneliness at 5 and 9, indicative of prolonged loneliness in childhood, also predicted depressive symptoms at age 13. Parent and peer-related loneliness at age 5 and 9, peer acceptance variables, and duration of parent loneliness did not predict depression. Our results suggest that enduring peer-related loneliness during childhood constitutes an interpersonal stressor that predisposes children to adolescent depressive symptoms. Possible mediators are discussed

Transposition de la Directive Nitrate (CE) en Région wallonne : azote potentiellement lessivable de référence pour les sols cultivés en Région wallonne

Transposition of the Nitrate Directive (EC) in the Walloon Region (Belgium): establishment of the potentially leachable nitrogen references in the Walloon Region. October 10th, 2002, the Walloon Government transposed the Nitrate Directive (91/676 EC) in the Walloon right and initiated the Durable Management Programme of Nitrogen in agriculture (in french PGDA). PGDAspecifies agricultural practices ensuring the protection of water quality, develops a Quality Approach (in french DQ) and set up a framing structure ensuring the follow-up of the Directive and an assistance to the farmers. In the farms registered in DQ, five fields are sampled each year in order to establish the profile for nitric nitrogen concentration in the soil. These results are compared with Potentially Leachable Nitrogen values (in french APL) of reference (in terms of reasoned fertilization) established annually by GRENeRA and ÉCOP (UCL). These references are built on the basis of measurements carried out annually in a serie of selected points representative of the Walloon agriculture called Agricultural Surfaces Survey (in french SSA) set up by these two scientific partners of Nitrawal. Twenty five farms currently constitute this SSA in which two hundred plots are followed annually for nitric nitrogen concentration in the soil

Mise en oeuvre du Programme de Gestion Durable de l'Azote et évaluation d'impact à l'échelle d'un bassin versant agricole (Arquennes, Belgique)

Application of the Action Programme and impact evaluation at a catchment scale (Arquennes, Belgium). Two water catchments exploited by a water supply company (SWDE) in the rural village of Arquennes (Hainaut Province, Belgium) are contaminated by nitrate (concentrations higher than 50 mg NO3 -.l-1). Catched water is no longer used for distribution. The catchment basins (31 ha and 47 ha) are located exclusively in a cultivated area, mainly on loamy soils. Since October 2004, these basins are used as pilot areas for environmental evaluation of good agricultural practices in respect of use of nitrogen fertilizers. Farmers are supervised concerning nitrogen fertilisation with the aim to improve water quality, keeping optimum yield in the same time. This supervision fits into the general pattern of the Sustainable Nitrogen Management Program (PGDA in French), transposition of the European Nitrates Directive in Walloon legislation. Another objective of the working scheme is to study and to set up a decision-making tool concerning prevention of water contamination by agricultural nitrate around water catchments. Water and nitrate flux modelisation in both saturated and non-saturated zones is undertaken. Eight piezometers were drilled on the basins in order to describe soil, subsoil and aquifer and also to follow water table and water quality. Tracer tests in saturated and non-saturated zone were also achieved in order to determine transfer time of contaminants between soil surface and water catchments. The study shows that the impact of a modification of practices in surface can be detected in catched water quality within four or five years at the earliest. A gradual improvement in water quality is being seen in water catchments since the beginning of 2009

Suivi de la percolation du nitrate en terres cultivées par la technique lysimétrique

Monitoring of nitrate leaching in croplands by lysimeters. The European Nitrates Directive (91/676/CEE) aims at moderating or preventing water pollution with nitrates issued from agricultural practices. The Walloon region transposed it into its law and initiated a Sustainable Nitrogen Management Program on 2002, also called PGDA in French. Six lysimeters have been implemented in agricultural open fields, being under real condition of industrial harvest crops, especially vegetable ones. The lysimeters are used as follow up tools to monitor and quantify the amount of nitrates leaching beyond root zone towards underground water ressource. This study demonstrates that lysimeters are efficient and permit to collect representative quantity of seepage water. Their nitrates content, combined with data related to agricultural practices, fertilisation rates and advised, climate, the defined environmental indicator (APL) provide a global approach to link agricultural practices and underground water protection from nitrates pollution. The lysimeters validate the reliability of the environmental indicator (APL) with the nitrates content in leaching water, which will not be catched up by the next crop. Unfortunately, it is also demonstrated that even when the nitrogen management is respectful of the related legislation, the warranty to respect the targeted norms of water quality on nitrates is not ensured. The lysimeter tool clearly shows that the respect of seepage water quality standards issued from industrial agriculture does not have to be considered crop per crop but rather from an integrated and global approach of the complete crop sequences and rotations, in respect with best agricultural practices, reasonable fertilisation rates, inset crops, etc. for each individual crops. Some favourable and non favourable crop sequences to nitrates content of underground water are listed. Experiments are in progress on crop sequences evaluation and fertilisation levels and advises for Walloon industrial crops and their impacts on the leaching water quality and nitrates content collected by lysimeters

Développement d'un système harmonisé de surveillance de la qualité des terres agricoles en Région wallonne anticipant la future directive européenne sur les sols

Setting-up of a soil monitoring system in Walloon Region anticipating the future European directive on soil. The European Commission currently finalizes its Framework Directive for soil protection waited for the end 2004. The project ARVA of the Walloon Region aims setting up the monitoring of arable land. The project proceeds in four phases: (i) the development of a soil monitoring which complies with the requirements of both the European regulation and the Walloon agriculture practices; (ii) the inventory of existing knowledge on the quality of soil in the Walloon Region and their relevance at Regional scale; (iii) the best estimate of the accuracy needed to detect evolutions in soil. To do this, test sites will help to validate the methodology used; (iv) an analysis of the strategies for structuring a future monitoring network. This strategy depends on the threat taken into consideration, as the selected options shall not compromise future needs for monitoring