Environmental fate and distribution of sodium [14C] pentachlorophenate in a section of urban wasteland ecosystem.

An urban terrestrial microecosystem has been used under outdoor conditions to study the transfer of chemical residues within the system components. The microecosystem consisted of soil monoliths obtained from a site with an established vegetation cover dominated by goldenrod, Solidago gigantea. The microecosystem contained integrated food chain elements composed of primary producers, herbivores and carnivores.

[Assimilation of nitrate in the dark by Lemna minor L].

1. Lemna minor is able to reduce nitrate in the dark when the nutrient medium contains yeast extract and glucose in addition to minerals salts. 2.

[A seasonal rhythm of growth in Lemna minor L].

Lemna minor cultured in continuous light at constant temperature exhibits a seasonal rhythm in the rate of dry matter production with a maximum in summer and a minimum in winter. This confirms the observations of PIRSON and GöLLNER in 1953. Both the protein content and the protein/carbohydrate ratio are correlated with the rate of dry matter production and reach a maximum in summer.