Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons.

Oaks (Quercus velutina Lam.) growing over a shallow aquifer contaminated by chlorinated hydrocarbons were studied to determine if it was possible to estimate the approximate year that contamination began. The annual rings of some trees downgradient from the contaminant release site contained elevated concentrations of chloride possibly derived from dechlorination of contaminants. Additionally, a radial-growth decline began in these trees at approximately the same time that chloride became elevated. Growth did not decline in trees that contained smaller concentrations of chloride. The source of elevated chloride and the corresponding reductions in tree growth could not be explained by factors other than contamination. On the basis of tree-ring evidence alone, the release occurred in the late 1960s or early 1970s. Contaminant release at a second location apparently occurred in the mid- to late 1970s, suggesting that the area was used for disposal for at least 5 years and possibly longer.

[The captopril test as a part of the examination in arterial hypertension. Value and immediate complications]. / Captopril-test som led i udredningen af hypertensio arterialis. Vaerdien heraf og umiddelbare komplikationer.

The results and immediate complications of oral administration of 6.25 mg captopril in 47 patients with arterial hypertension are described. The blood pressure was measured every 15 minutes for 90 minutes and the plasma renin concentration was measured before the test and at the conclusion of the test. Eleven of the patients had stenosis of the renal arteries. This investigation rendered it possible to differentiate this group from other patients with hypertension from other causes. Patients with renovascular hypertension had thus significant decrease in diastolic blood pressure and significant increase in plasma renin concentration in contrast to the remaining patients. Seven patients developed cerebral symptoms in connection with the decrease in blood pressure. Angiographic examination in two of these patients revealed stenosis of the vessels in the neck. Angiotensin converting enzyme inhibitors should be avoided in patients with recognized poor cerebral circulation or murmurs over the vessels in the neck.