The influence of heavy metals upon the growth of sitka-spruce in South Wales forests

Abstract

Summary Experiments on sitka-spruce seedlings grown in acidic peaty gley soils under greenhouse conditions, where the soils where doped with increasing amounts of Cd, Cu and Pb up to maximum levels of metal added of 16 ppm, 32 ppm and 400 ppm resPectively, showed that the levels of Cd and Pb in shoots and roots increased with increasing levels in the soil, whereas levels of copper appeared to be independent. The addition of these three metals to the soils did not influence the uptake of other heavy metals, or of the nutrients potassium or calcium. Increases in the shoot cadmium levels significantly reduced the yields of the plant shoots. However, the plant yields were only affected by the highest level of lead that was added to the soil (400 ppm Pb) and unaffected by all the copper treatments (0-32 ppm Cu in the soil).The lengths of the sitka-spruce roots were reduced when cadmium and lead levels in the soil exceeded certain threshold concentrations (2.5 ppm total Cd, where 0.3 ppm was extractable with 0.5 M acetic acid; and 48 ppm total Pb, where 1.7 ppm was extractable). However, root lengths were not reduced by copper. This was probably related to the fact that copper appears to be relatively unavailable in the type of soil used, as only 1.1 ppm Cu was extractable from a total of 32 ppm Cu added. Root branching was apparently reduced by increases in the soil levels of cadmium, copper and lead. The roots of some control plants had symbiotic mycorrhizal associations (4 out of 19 plants), whereas the roots of all the plants gr0wn in the soils with added heavy metals did not develop these.

Ecophysiological characteristics and cadmium accumulation in Downy Oak (Quercus pubescens Willd.)

“…substrato, rispettivamente. Le proporzioni riscontrate in questo studio sono state simili a quelle riportate in altri lavori su semenzali di specie forestali (17-20%) da Burton et al (1984) in Picea sitchensis (Bong.) Carrière e Kim et al (2003) in Pinus sylvestris L. Ciò indicherebbe che potrebbe instaurarsi un equilibrio fra Cd solubile ed il substrato nel suo complesso in un periodo di 15 settimane (durata dell'esperimento, rispetto a 14 e 11 settimane dei lavori citati, anche nel caso di pH relativamente più alto).…”

“…Particolarmente grave è l'aumento della concentrazione di Cd in suoli trattati con fanghi di depurazione di origine industriale, dove si stima che dopo circa venti anni di apporti si può verificare un incremento da 1 a 12 mg Cd kg -1 suolo, in funzione della quantità di fanghi applicati. Applicazioni di concimi organici con basso tenore di metalli pesanti hanno determinato in suoli con simili caratteristiche un modesto incremento valutabile di circa 0.4 mg Cd kg -1 suolo (Brooks 1995). I meccanismi d'accumulo del Cd nel suolo ed il trasferimento di questo inquinante in altri ecosistemi non sono ancora del tutto chiari.…”

Remedial investigation/feasibility study of the Clinch River/Poplar Creek Operable Unit. Volume 3. Risk assessment information. Appendixes E, F

“…The lowest concentration tested (5 ppm Cd) was responsible for a 30% reduction in leafweight. Burton et al (1984) grew Sitka-spruce seedlings fiom 4 weeks of age in a mixture of acidic peaty gley soil and sand with Cd added (0.1,0.4,1,2,4,8, and 16 ppm as CdCIJ. Two ppm Cd lead to a reduction of about 45% in root and shoot weight of the 18-week old seedlings.…”

Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Terrestrial Plants

“…The lowest concentration tested (50 ppm Cd) was 2 responsible for a 30% reduction in leaf weight. Burton et al (1984) grew Sitka-spruce seedlings from 4 weeks of age in a mixture of acidic peaty gley soil and sand with Pb added as PbCl . Lead added at 100 ppm resulted in a reduction of about 25% 2 in root and shoot weight of the 18-week old seedlings.…”