Wolfgang Grosse

Efficiency of constructed wetlands in decontamination of water polluted by heavy metals

A twin-shaped constructed wetland (CW) comprising a vertical flow (inflow) chamber with Cyperus alternifolius followed by a reverse-vertical flow (outflow) chamber with Villarsia exaltata was assessed for decontamination of artificial wastewater polluted by heavy metals. After application of Cd, Cu, Pb, Zn over 150 days, together with Al and Mn during the final 114 days, no heavy metals with the exception of Mn could be detected in either the drainage zone at the bottom, shared by both chambers, or in the effluent. The inflow chamber was, therefore, seen to be predominantly responsible for the decontamination process of more toxic metal species with final concentrations far below WHO drinking-water standards. About one-third of the applied Cu and Mn was absorbed, predominantly by lateral roots of C. alternifolius. Lower accumulation levels were observed for Zn (5%), Cd (6%), Al (13%). and Pb (14%). Contents of Cd, Cu, Mn, and Zn in soil were highest in top layer, while Al and Pb were evenly distributed through the whole soil column. Metal species accumulating mainly in the top layer can be removed mechanically. A vertical flow CW with C. alternifolius is an effective tool in phytoremediation for treatment of water polluted with heavy metals

Pressurized ventilation in wetland plants

Species of wetland plants that aerate their submerged organs by thermo-osmotic transport of gas have been identified in six genera of the angiosperm families Butomacea, Nymphaeacea and Menyanthaceae. Flow rates of 14 ml gas h−1 in the monocotyledon Hydrocleys nymphoides (Humb. & Bonpl. ex Willd.) Buchenau to 5000 ml in the dicotyledon Victoria amazonica (Poepp.) Sowerby are comparable to those rates found in Nelumbo nucifera Gaertn. from the Nelumbonacean family, but an order higher than those in Alnus glutinosa (L.) Gaertn. from the Betulacean family as reported in the literature. The aeration is driven by a pressurizaion of the gas in th e aerenchyma of young floating leaves as a consequence of the physical effect of thermo-osmosis of gases. Differences in hygrometric state of the leaves and the ambient air effect the flow rates. Increased transpirational cooling of the upper leaf surface seems to give rise to a steeper temperature gradient within the leaf, intensifying the aeration. As these five plant families are not closely related, the ability to generate a pressurized ventilation by thermo-osmosis of gas can be seen as a special adaptation of the wetland plants to the anoxic environment.

A history of pressurised gas-flow studies in plants

Abstract The history of discoveries in the field of pressurised ventilation in plants, and the physical phenomena causing them, is traced from the middle of the nineteenth century to the present day, and identifies two major periods of activity. Descriptions are given of observations, experiments and controversy during the early years (1840–1920) which revealed that pressurisation and flows were widespread among flating-leaved plants, and which broadly identified the major causal mechanisms as thermal transpiration and humidity-induced diffusion. The more recent period is one in which the flows (identified also in emergent macrophytes) have become better understood, and recognised to be of major importance in wetland plant survival and competition, and in the emissions of greenhouse gases from wetlands.

Sulphonated aromatic pollutants. Limits of microbial degradability and potential of phytoremediation.

Many synthetic sulphonated aromatic compounds are used as starting material to produce dyes and pigments, or are released as by-products in the effluents of the textile and dye industry. A large number of these chemicals are poorly biodegradable and cannot be eliminated by classical wastewater treatment plants. To limit the impact of these pollutants on the environment, new processes, based on the use of higher plants (constructed wetlands or hydroponic systems), are under development. Detergents and surfactants are essential for both industrial and domestic applications, the most important family being the alkylbenzene sulphonates. Originally, the alkyl side chains were branched and thus recalcitrant to biodegradation. Therefore, they have been replaced by linear alkylbenzene sulphonates. Although more acceptable, present formulations still have adverse environmental and toxic effects. In this context, phytoremediation appears to be a promising approach to remove these compounds from contaminated soils and waters.

Xenobiotics removal from polluted water by a multifunctional constructed wetland

Removal efficiencies on xenobiotics from polluted water in a twin-shaped constructed wetland consisting of a vertical flow chamber with the crop plant Colocasia esculenta L. Schott and a reverse vertical flow one with Ischaemum aristatum var. glaucum Honda, were assessed by chemical analysis and bioassays. After a four-month period of application, removal efficiencies of the applied pesticides parathion and omethoate were 100% with no detectable parathion and omethoate in the effluent. For the applied herbicides, the decontamination was less efficient with removal efficiencies of 36% and 0% for 4-chloro-2-methyl-phenoxyacetic acid and dicamba, respectively. As shown by toxicity assay with duckweed Lemna minor L., growth retardation may occur if the water treated for herbicide removal is used in irrigation of sensitive cultivars in agriculture or horticulture. In contrast to I. aristatum var. glaucum Honda, the crop C. esculenta L. Schott has a high yield in biomass production as a valuable source of renewable energy.

Latest on Enzymology of Serotonin Biosynthesis in Walnut Seeds

Serotonin (5-HT) accumulation in walnut cotyledons is seen as a detoxification mechanism protecting the sensitive plant tissues of seeds from highly toxic ammonia concentrations following seed desiccation. Different metabolic pathways and cell compartments are involved in biosynthesis and storage of 5-HT. Ammonia fixation and incorporation into the indole moiety of tryptophan is followed by 5-HT biosynthesis via tryptamine in a two-step pathway with the adaptive tryptophan decarboxylase and the constitutive tryptamine 5-hydroxylase. Evidence is provided that tryptamine 5-hydroxylase is a member of the cytochrome P450 family which is involved in lipid hydroxylation processes in the very early period of seed development.

Einfluß von Ammonium and Nitrat auf Stickstoff-Metabolismus, Malatanhaufung and Malatenzym-Aktivität in Suspensionskulturen von Nicotiana tabacum var. «Samsun»

Summary Suspension cultures of Nicotiana tabacum var. Samsun were grown in defined media with either ammonium plus nitrate or with nitrate alone as nitrogen sources. Utilization of nitrate was not suppressed by ammonium. Growth and composition of the cells of both cultures revealed pronounced differences: During exponential growth cells in ammonium-nitrate-medium double their dry matter as well as their protein content within 48 hrs., those in media with nitrate as the sole nitrogen source reveal similar doubling times for dry matter but have much longer doubling times (70 hrs.) for protein. Correspondingly the latter contain considerably more carbohydrates than the former. Cells supplied with ammonium plus nitrate contain 50 to 100 times more glutamine and alanine, show 3 to 4 times lower activities of malic enzyme, and accumulate 10 to 15 times less malate than those fed with nitrate only. Addition of ammonium to nitrate-grown cells results in fast increases in glutamine and alanine, in a sharp drop in malate, and in a slow decline in malic enzyme activity. Transfer of cells from ammonium-nitrate- into nitrate-medium produces the reverse effect: a steep drop in glutamine and alanine accompanied by an increase in malate and in the activity of malic enzyme. There was no quantitative relationship between the amount of nitrate assimilated and malate accumulated in the nitrate grown cells. These results suggest that in the cultured tobacco cells malate synthesis does not take place as a result of nitrate reduction only, but rather point to a more complex regulation in carbohydrate metabolism influenced by the extent of the prevailing synthesis of nitrogenous substances.

Effects of cadmium on chlorophyll content, photochemical efficiency, and photosynthetic intensity of Canna indica Linn.

ABSTRACT The effects of cadmium (Cd2+) on growth status, chlorophyll (Chl) content, photochemical efficiency, and photosynthetic intensity were studied on Canna indica Linn. Plant specimens that were produced from a constructed wetland and precultivated hydroponically in 20 L of 1/10 Hoagland solution under greenhouse conditions for 1 week were exposed to cadmium in concentrations of 0, 0.4, 0.8, 1.6 and 3.2 mg L―1 Cd2+, respectively. The results show that leaves were injured in the Cd2+ solution by the third day of exposure and the injury became more serious with an increase in the applied heavy metal. Under 3.2 mg L―1 Cd2+ treatment, growth retardation, the decrease of chlorophyll content from 0.70 to 0.43 mg g―1 FW, and a decrease in Chl a/b ratio from 2.0 to 1.2 were observed. Chl a was more sensitive than Chl b to Cd2+ stress. The decrease was the same with photochemical efficiency. Photosynthetic intensity decreased by 13.3% from 1.5×104 μmol m―2s―1 CO2 in control to 1.3×104 μmol m―2s―1 CO2 in the treatment of 3.2 mg L―1. Because Canna species are used in heavy metal phytoremediation, these results show that C. indica can tolerate 0.4 to 0.8 mg L―1 Cd2+. Therefore, it is a potential species for phytoremediation of cadmium with some limitations only at higher concentrations.

Pressurized gas transport in two Japanese alder species in relation to their natural habitats

Oxygen uptake measurements have shown that pressurized gas transport, resulting from the physical effect of thermo-osmosis of gases, improves oxygen supply to the roots of the seedlings in two alder species Alnus japonica (Thunb.) Steud. and Alnus hirsuta (Spach) Rupr., which are both native in Japan. When gas transport conditions were established by irradiation of the tree stems the internal aeration was increased to a level nearly equal to the oxygen demand of the root system in leafless seedlings of A. hirsuta, but was higher in A. japonica so that excess oxygen was excreted into the environment. An increase of superoxide dismutase (SOD) activity, which protects plants from toxic oxygen radicals and post-anoxic injury, has been observed in root tissues of A. japonica when the seedlings were flooded for 3 days. The increase of SOD activity, in concert with high gas transport rates, may enable this tree species to grow in wet sites characterized by low oxygen partial pressure in the soil and by varying water tables. A less effective gas transport, flood-induced reduction of SOD activity in root tissues, and reduced height growth in waterlogged soil may be responsible for the fact that A. hirsuta is unable to inhabit wettland sites.

Effect of Sulfur Deficiency on Protein Synthesis and Amino Acid Accumulation in Cell Suspension Cultures of Nicotiana tabacum

Summary Sulfur starvation in photoheterotrophic and heterotrophic cell suspension cultures of Nicotiana tabacum var. Samsun affects growth, protein synthesis and the accumulation of soluble nitrogen compounds. After depletion of the sulfate supply in the medium no further net-protein synthesis was observed and large amounts of soluble nitrogen accumulated. In photohete-rotrophically grown cells this accumulation was mainly due to an intense increase in arginine and glutamine which accounted for 70–85 % of the free amino acid nitrogen. In heterotrophically grown cells only a small amount of arginine was formed and glutamine was the predominant soluble nitrogen compound accumulated. In contrast to the changes in the free amino acid fraction, the protein content of the cultures remained constant during the early period of sulfur deficiency and the amino acid composition of the bulk protein did not change appreciably. Therefore it appears that the amino acids accumulating during sulfur deficiency have been produced by de novo synthesis. Under sulfur starvation conditions photoheterotrophically grown cells contained citrulline and ornithine which were not present in detectable amounts in suspensions grown on sulfur-rich media. The observed twofold increase in arginine production under sulfur starvation also indicates a stimulation of arginine synthesis by these conditions.