Dynamics of trace metals in organisms and ecosystems: prediction of metal bioconcentration in different organisms and estimation of exposure risks

Metal ions interact with biological materials and their decomposition products by ligation (coordination complex-formation with certain moieties containing O, N, S, etc.). The extent of this interaction depends on the identities of both ligand and metal ion and can be described by some equation derived from perturbation theory. Uptake of metal ions - including highly toxic ones - from soils is controlled by a competition between root exudate components and soil organic matter (SOM) for the ions. SOM consists of a variety of potential ligands which evolve during humification towards more efficient binding (retention) of metals such as Cu, Ni, Cr but also of toxicants like U, Cd. The actual way of interaction can be inferred from stoichiometry of the involved compounds and the C/N ratio in the soil, providing predictions as to which metals will be most efficiently shuttled into green plants or fungi, respectively. The latter, selective process is crucial for closing nutrient cycles and sensitively depends on C/N ratio and the extent of "forcing" by onfalling leaf or needle litter. Therefore, analytical data on the soil can be used to predict possible risks of exposition to toxic metals also for human consumption of plant parts.     

Crown condition dynamics of oak in southern Sweden 1988’999

Crown defoliation of oak (Quercus robur and Q. petraea) was analysed in 808 trees during three forest condition surveys (1988, 1993, and 1999) in the southern Sweden. From 1988 to 1999 crown defoliation increased by more than 20%. Changes in crown defoliation were related to the pH in the upper 20–30 cm of the mineral soils, which was closely connected to other measures of soil fertility (cation exchange capacity, CEC and C/N ratio). Trees growing on soils with a high pH (≥4.00, in BaCl₂ filtrate), high CEC and low C/N ratio had significantly lower crown defoliation than trees growing on more acid soils (pH <4.00), indicating that less favourable soil conditions may further enhance oak decline. Age did not differentiate trees with respect to crown defoliation, indicating that decline in crown condition was not due to an age-related increase in crown transparency. Considering only trees younger than 100 years, a significant interaction was observed between changes in crown defoliation and soil pH. Trees younger than 100 years old growing on more acidic soils had a greater increase in crown transparency than trees on more basic soils between 1988 and 1999. Trees ≥100 years old had significantly higher defoliation on more acidic than on more basic soils, however defoliation dynamics of these trees over 1988–99 was not related to soil acidity. Two biotic agents (insect and fungal leaf infections) evaluated in this study did not prove to be important drivers of defoliation dynamics.     

Green house gas emissions from composting and mechanical biological treatment.

In order to carry out life-cycle assessments as a basis for far-reaching decisions about environmentally sustainable waste treatment, it is important that the input data be reliable and sound. A comparison of the potential greenhouse gas (GHG) emissions associated with each solid waste treatment option is essential. This paper addresses GHG emissions from controlled composting processes. Some important methodological prerequisites for proper measurement and data interpretation are described, and a common scale and dimension of emission data are proposed so that data from different studies can be compared. A range of emission factors associated with home composting, open windrow composting, encapsulated composting systems with waste air treatment and mechanical biological waste treatment (MBT) are presented from our own investigations as well as from the literature. The composition of source materials along with process management issues such as aeration, mechanical agitation, moisture control and temperature regime are the most important factors controlling methane (CH4), nitrous oxide (N2O) and ammoniac (NH3) emissions. If ammoniac is not stripped during the initial rotting phase or eliminated by acid scrubber systems, biofiltration of waste air provides only limited GHG mitigation, since additional N2O may be synthesized during the oxidation of NH3, and only a small amount of CH4 degradation occurs in the biofilter. It is estimated that composting contributes very little to national GHG inventories generating only 0.01-0.06% of global emissions. This analysis does not include emissions from preceding or post-treatment activities (such as collection, transport, energy consumption during processing and land spreading), so that for a full emissions account, emissions from these activities would need to be added to an analysis.     

Speciation and toxicological relevance of manganese in humans

Although manganese is an essential trace element, concerns are rising about the Mn exposure of humans being related to neurotoxic effects. This review summarizes several aspects of this topic to provide updated information on Mn related investigations, including chemical speciation of Mn-compounds. The paper starts with some chemical aspects of Mn and its compounds, enlightening oxidation states in general and in biological matrices. This is followed by considerations on natural sources of human exposure, on occupational sources and on anthropogenically caused environmental sources, for example from the use of methylcyclopentadienyl manganese tricarbonyl (MMT). Next, the paper deals with Mn levels in the human organism, showing normal Mn concentrations in various tissues or body fluids, and continues with the toxicology of Mn, i.e. absorption, distribution and excretion. Of specific concern is the transfer of Mn to the brain which is the relevant neurotoxic target. In this context, parallels and differences between primary and Mn-dependent Parkinsonism are discussed, concluding with a risk assessment and a consideration of susceptible groups. The main part of this review focuses on recent investigations on Mn speciation. Analytical problems and their solutions are also described for correct identification of relevant Mn-compounds in matrices of human origin. Finally, future needs are discussed, such as further investigations on those Mn-species which may overcome neural barrier control, on disease-modulated barrier control, on susceptibility to certain Mn-species, and on the interaction of Mn with Fe-homeostasis in the brain.     

The central role of centralisation in environmental policy initialisation

While economic research on environmental policy is mainly concerned with instruments, political science concentrates on actors. The issue of centralisation needs to be analysed using a multidisciplinary approach because it is connected with both actors and instruments. Linking the Advocacy Coalition Framework with an economic approach, the paper first develops an innovative model in order to understand the mechanisms of centralisation and decentralisation in the different phases of policy processes. Focusing on environmental policy, the idea is developed that environmental policy needs the push of centralisation in order to institutionalise the prevailing social norm, but then should be organised decentrally to account for regional differences. The examples of air pollution, climate change and urban sprawl are used to test the explanatory power of the theoretical approach.     

Factorial analysis of the trihalomethane formation in the reaction of colloidal,hydrophobic, and transphilic fractions of DOM with free chlorine

Background, aim, and scope  

This study focuses on the factors that affect trihalomethane (THMs) formation when dissolved organic matter (DOM) fractions (colloidal, hydrophobic, and transphilic fractions) in aqueous solutions were disinfected with chlorine.     

Whole effluent assessment of industrial wastewater for determination of BAT compliance. Part 2: metal surface treatment industry

Background, aim and scope  

Toxicity testing has become a suitable tool for wastewater evaluation included in several reference documents on best available techniques of the Integrated Pollution Prevention and Control (IPPC) Directive. The IPPC Directive requires that for direct dischargers as well as for indirect dischargers, the same best available techniques should be applied. Within the study, the whole effluent assessment approach of OSPAR has been applied for determining persistent toxicity of indirectly discharged wastewater from the metal surface treatment industry.     

Removal of 4-chlorobenzoic acid from spiked hydroponic solution by willow trees (<Emphasis Type="Italic">Salix viminalis</Emphasis>)

Background  

Chlorobenzoic acids (CBA) are intermediate products of the aerobic microbial degradation of PCB and several pesticides. This study explores the feasibility of using basket willows, Salix viminalis, to remove 4-CBA from polluted sites, which also might stimulate PCB degradation.     

Food web assessments in the Baltic Sea: Models bridging the gap between indicators and policy needs

Ecosystem-based management requires understanding of food webs. Consequently, assessment of food web status is mandatory according to the European Union’s Marine Strategy Framework Directive (MSFD) for EU Member States. However, how to best monitor and assess food webs in practise has proven a challenging question. Here, we review and assess the current status of food web indicators and food web models, and discuss whether the models can help addressing current shortcomings of indicator-based food web assessments, using the Baltic Sea as an example region. We show that although the MSFD food web assessment was designed to use food web indicators alone, they are currently poorly fit for the purpose, because they lack interconnectivity of trophic guilds. We then argue that the multiple food web models published for this region have a high potential to provide additional coherence to the definition of good environmental status, the evaluation of uncertainties, and estimates for unsampled indicator values, but we also identify current limitations that stand in the way of more formal implementation of this approach. We close with a discussion of which current models have the best capacity for this purpose in the Baltic Sea, and of the way forward towards the combination of measurable indicators and modelling approaches in food web assessments. Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01692-x.