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The importance of considering the bioavailability of metals in understanding and assessing their toxicity in freshwaters has been recognised for many years. Currently, Biotic Ligand Models (BLM) are being applied for the derivation and implementation of Environmental Quality Standards for metals under the Water Framework Directive in Europe. bio-me...
National Environmental Quality Standards (EQS) for zinc used for the assessment of ecological status in freshwaters have been shown to vary by over two orders of magnitude across 25 European countries. Such variability is unlikely to reflect consistent ecological protection or environmental relevance. Recent European technical guidance on EQS deriv...
Zinc is an essential element, indispensable for all life, including aquatic life in the Netherlands. In the development of an environmental policy in the Netherlands the consequences of the fact of zinc being an essential element have hardly been taken into account. This addendum deals with a critical analysis of the literature and the Integrated C...
Metal ores and concentrates are complex substances, for which the environmental and human health hazard identification and classification present particular challenges. These relate to the great variability of their compositions and the various mitigating effects of their mineralogical and physical structures and forms.
Based on the UN GHS guidelin...
The assessment of environmental exposure and risks associated with the production or use of a substance on an industrial site includes the estimation of the releases to the environment. In absence of measured release data on the specific substance, a risk assessor would rely on default release factors to the environmental compartments as developed...
A risk assessment report (RAR) on zinc and zinc compounds has recently been prepared in the framework of the European Union (EU) Council Regulation 793/93/EEC on Existing Chemicals. The EU Scientific Committee on Human and Environmental Risks (SCHER) has, however, expressed some fundamental, science-based concerns about the approach followed and th...
Environmental quality standards are an important tool for assessing the chemical quality of water bodies under the Water Framework Directive. However, there must be confidence in assessments of any failure to avoid disproportionate investment in unnecessary risk reduction. Metals present a number of unique challenges for environmental regulators in...
Dwarf beans ( Phaseolus vulgaris L. cv. Limburgse Vroege) were grown on a nutrient medium containing a toxic non‐lethal ZnSO 4 concentration. The electron transport and photophosphorylation activities of chloroplasts, isolated from these beans, and from control plants, grown under standard nutrient conditions, were compared. Electron transport was...
A method is proposed for determining the hazard identification, based on acute aquatic toxicity, and subsequent classification if necessary, of metals and sparingly soluble inorganic metal compounds. The method is based on establishing a relationship between the measured reaction kinetics of the substance with an aqueous medium and the measured sur...
The study aimed at assessing the evolution of cadmium (Cd)-induced renal tubular dysfunction in Cd workers according to the severity of the microproteinuria observed at the time the exposure was substantially decreased. Male workers employed in the Cd production industry for whom formerly high exposure had markedly decreased by 1984 and for whom st...
To reduce the environmental impact of a 135-ha bare industrial area with a highly phytotoxic soil contaminated by non-ferrous metals, a rehabilitation strategy was developed, aimed at the restoration of a vegetation cover. Two different techniques to overcome the high phytotoxicity of the soil were first evaluated on a laboratory scale: reduction o...
The possibility of restoring a vegetation on a bare, industrial dumping ground, strongly contaminated by several non-ferrous metals, was studied. The potential beneficial effect of this restoration on metal leaching was estimated. On a laboratory scale, the high phytotoxic potential of the dump's surface substratum could be reduced significantly by...
Net photosynthesis of bean (Phaseolus vulgaris L.) seedlings decreased after assimilation of toxic amounts of zinc by the roots. This effect was related to the substitution of essential bivalent cations by zinc in at least two important metalloproteins of the chloroplast: 1) replacement of Mn2+ by Zn2+ in the water splitting enzyme of the thylakoid...
. Uptake of phytotoxic amounts of metal by higher plants or algae can result in inhibition of several enzymes, and in increase in activity (= induction) of others. Two mechanisms of enzyme inhibition predominate: (1) binding of the metal to sulphydryl groups, involved in the catalytic actionor structural integrity of enzymes, and (2) deficiency of...
The potential soil phytotoxicity in the surroundings of an old zinc smelter closed in 1966, was evaluated by a biological test system. This system is based on the analysis of shoot growth and (iso-) enzymes in leaves and roots of 2-week-old seedlings of Phaseolus vulgaris grown on soil samples under controlled environmental conditions. The biologic...
Toxic doses of zinc and cadmium inhibit shoot growth but increase the capacity of several leaf enzymes in dwarf beans (Phaseolus vulgaris L.). Both effects were studied as a function of the metal concentration applied to the plant. There was a linear relationship between the metal content of the primary leaf and the nutrient solution. When leaf met...
Results are presented indicating that (iso)-enzyme measurements in two weeks old test plants (dwarf beans; Phaseolus vulgaris cv. Limburgse Vroege) can be used as a biological criterion to evaluate the phytotoxic effect of soils, contaminated with several heavy metals. Total soil phytotoxicity is reflected by the increase in capacity of the enzymes...
Dwarf beans (Phaseolus vulgaris L.cv Limburgse Vroege) were cultivated on a medium containing a toxic non-lethal Zn2+ concentration.The ribulose-1,5-bisphosphate carboxylase/oxygenase capacity of these Zn2+ treated plants was compared with the capacity of control plants, grown under standard nutrient conditions.The carboxylase capacity, measured on...
Inhibition of photosynthesis by heavy metals is well documented. In this review the results are compared between in vitro experiments on isolated systems (chloroplasts, enzymes -.), experiments on excised leaves and intact plants and algae in vivo. In vitro experiments suggest potential sites of heavy metal interaction with photosynthesis at severa...
As a result of toxic zinc nutrition applied to Phaseolus vulgaris seedlings, the zinc content of the primary leaves rises to about 400 pg per gram dry matter during the third week after sowing.Net photosynthesis and growth of these plants are significantly inhibited, compared to control plants, which received optimal zinc nutrition, and contained...
Photosynthetic activity of many species of green algae and higher plants is inhibited by accumulation of toxic amounts of heavy metals.
Evidence is presented that zinc toxicity impairs photosynthetic electron transport, mainly at the oxidizing side of PS 2, inducing a decrease of photophosphorylation capacity and NADPH production. In addition Ribu...
Ribulose-1,5-bisphosphate carboxylase activity (RuBPC), chlorophyll (chl) and protein (prot) concentrations and chlorophyll/protein
(chl/prot) ratios were determined in five differentPopulus clones together with their maximal net CO2 uptake rates (Pmax). A classic reference clone (Populus ×euramericana “Robusta” (Dode) Guinier) was compared with fo...
Supra-optimal levels of zinc in primary leaves of Phaseolus vulgaris increased the CO2 compensation point and inhibited net photosynthesis. Leaf morphology was modified: mesophyll intercellular area, stomatal slit length and interstomatal distance were reduced, but stomatal density increased. Internal and stomatal conductances to CO2 diffusion decr...
