Dendroanalysis: a tool for biomonitoring environmental pollution?

Trees of temperate regions usually form visible annual growth rings, which can be dated accurately. It is therefore possible to collect wood samples of different age and analyse their heavy metals content in order to get a chronological record of trace elements pollution in the tree's environment. This method of retrospective biomonitoring was called dendroanalysis. A basic assumption of dendroanalysis is the stability of the mineral distribution patterns, i.e. once the elements are stored, no significant mobility should occur. Additionally, neighbouring trees growing in the same environment should show similar radial element patterns. While some studies presented good correlations between radial distributions of heavy metals in tree rings and temporal records of pollution from industry or traffic, others failed in using dendroanalysis as a chronological record of pollution. Probably some elements can move at a certain rate in radial direction through the ray parenchyma cells. In this way the radial element distributions are subsequently changed. Growth rates of tree rings can also influence the concentrations of elements in wood. During periods of slow growth higher concentrations of elements can be found in the wood. Therefore, radial distribution patterns of heavy metals in tree rings should be used with caution as a tool for retrospective biomonitoring of environmental pollution.

[Left ventricular papillary fibroelastomas without relation to a heart valve--a report of 2 cases]. / Linksventrikuläre papilläre Fibroelastome ohne Beziehung zu einer Herzklappe--Ein Bericht über zwei Fälle.

Papillary fibroelastomas are rare benign tumors of the heart. We report about two cases in which these tumors do not--as characteristically--arise from a heart valve but originate from the free wall of the left ventricle. In the case of a 74-year-old woman with signs of a cerebral ischemia in the vascular system of the A. cerebri posterior, the tumor was resected transaortically. At a 67-year-old patient with symptoms of instable angina pectoris and increasing dyspnoea echocardiography or coronary angiography showed an aortic stenosis III degrees, a coronary artery disease as well as a tumor within the region of the apex of the left ventricle. Beside a fourfold aortocoronary venous bypass and an aortic valve replacement tumor excision via left ventriculotomy was carried out. In the diagnostics of intracardiac tumors transthoracic and transesophageal echocardiography provide the methods of choice to visualize quickly and noninvasively the extent, mobility, and origin of the tumor. Considering the systemic thromboembolic potential with the high risk of cerebrovascular respectively neurological symptoms total surgical tumor excision is clearly indicated.

Radial distributions of Pb in stems of young Norway spruce trees grown in Pb-contaminated soil.

Concentrations of Pb in individual stem xylem rings of 5-year-old Norway spruce trees (Picea abies (L.) Karst.) were determined after one growing season in soil containing a low, medium or high concentration of Pb. In trees in the control and low-Pb soil treatments, Pb concentrations increased from the outer annual rings toward the stem center, whereas in trees grown in the soil treatment containing a medium Pb concentration, all of the four tree rings analyzed contained similar concentrations of Pb. Although trees grown in the high-Pb soil treatment had higher concentrations of Pb in the outer annual rings than both control trees and trees in the low-Pb soil treatment, the highest concentrations of Pb were never observed in the outermost rings, which were formed during the period of exposure to increased soil Pb. We conclude that radial distribution patterns of Pb in Norway spruce stems do not directly reflect changes in soil Pb concentration but depend on several internal, physiological factors and, therefore, do not provide reliable information about past variations in Pb contamination of soil.