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Many decades of research have shown that humic compounds as part of the soil organic matter (SOM) are essential for the stability and ecosystem services of soils. James P. Martin and Konrad Haider based on several pioneers in humus research improved the basis for the current knowledge of key processes in the soil environment, in particular structure and formation of humus triggered mainly by soil fungi. Other major contributions are briefly described but not in the focus of this article, such as their innovative tracer experiments with isotope-labelled xenobiotic chemicals and natural litter to study their fate. Both scientists inspired generations of younger researchers to advance their approaches and laid the cornerstone of the current understanding of soil organic matter formation. This article values the key experiments of Martin and Haider in this field and the related follow-up research finally resulting in the current view on formation mechanisms of SOM and non-extractable residues (NER) of xenobiotics. The improved understanding of these processes considering necromass with tissue residues of plants, microbes and animals challenges the traditional views of humic matter as macromolecular organic matrix, which according to the research of the last years represents only a variable part of the total organic matter besides associates of low molecular weight molecules. We discuss views on soil organic matter and humic substances that are nowadays considered not to differ in molecular diversity. We will start by demonstrating the understanding of humus characteristics and humus formation three decades ago closely related to the findings of Martin and Haider. Methodological approaches to characterize relevant structural and mechanistic pictures of SOM such as the priming effect, clay mineral catalysed reactions and the various mechanisms by which natural and xenobiotic chemicals are protected in soil are briefly illustrated by examples. Fungal activities in producing secondary metabolites like polyketides and their probably minor contributions to SOM formation are presented. Open research questions stimulated by these two soil scientists are sketched which are nowadays possible to address by new sophisticated high-resolution techniques.

Modern societies depend on environmental sustainability and on new generations of individuals well-trained by environmental research and teaching institutions. In the past, significant contributions to the identification, assessment, and management of chemical stressors with legal consequences have been made.Within this article, we intend to elucidate the merits and the emerging challenges of chemicals-related environmental sciences. The manuscript is supported by more than 70 professors and university academics of leading institutions in Germany, Switzerland, Austria, and other countries in Europe, but addresses topics of global concern.Many environmental problems of pollutants remain to be addresses, since new chemical compounds or classes of new compounds are continuously developed and brought to the market and sooner or later "emerge" in the environment. Further issues are the inclusion of transformation products and chemical mixtures in environmental risk assessment, the long-term presence of xenobiotics bound to soils and sediments, as well as an understanding of the ecological relevance of ecotoxicological end points.We point out the need for a strong academic research and education system in chemicals-related environmental sciences to ministries, politicians, and research funding institutions and we propose to create specific units in the national funding bodies that address basic and interdisciplinary research in this field.

Natural low molecular weight organic acids (NLMWOA) have been shown to be useful in enhancing phytoextraction without a high leaching probability. Nevertheless, their efficiency has in many cases been unsatisfactory. The objective of this study was to investigate the reason for the inefficiency of three NLMWOAs (citric acid, oxalic acid and tartaric acid) in enhancing phytoextraction. In several experiments attention was directed not only to the biodegradation of the NLMWOAs, but also to the microorganisms involved, and their influence on the bioavailability of Cu. During a time period of 96 h the biodegradation of the NLMWOAs increased the natural pH-value of the soil by approximately 1 unit and decreased the bioavailability of Cu from 175 mg kg−1 to approximately 140 mg kg−1. As microorganisms were detected with polymerase chain reaction sequencing and with the aid of high performance liquid chromatography measurements, it can be deduced that the fungi, Cordyceps sp., Paecilomyces sp. and the bacteria Burkholderia sp. can degrade all three used NLMOWA. A successive application of the three NLMWOAs to increase the efficiency is therefore not feasible, because with each NLMWOA application the number of microorganisms which can degrade the NLMWOAs increases and thus the degradation is accelerated. These results combined with result from previous studies show that the NLMWOAs are unsuitable in enhancing phytoextraction of heavy metals from the soil.

Clay minerals in soils control the sorption and mobility of nitroaromatics in munitions contaminated soils. Therefore, effect of exchangeable cations (NH4+ , K+, Ca2+, and Al3+) on sorption-desorption of trinitrotoluene (TNT) was studied in two reference soils viz sandy loam and silty clay. Compared to control soils, K+ ion saturation significantly increased TNT sorption in both the soils, while other cations decreased TNT sorption. Effect of K+ saturation on sorption of TNT was more pronounced in organic matter poor sandy loam soil (seven times) then silty clay (two times). Desorption followed the reverse trend and greater amounts of sorbed TNT were retained in the K+ saturated soils.

Heavy metal phytoextraction is a soil remediation technique, which makes use of plants in removing contamination from soil. The plants must thus be tolerant to heavy metals, adaptable to soil and climate characteristics, and able to take up large amounts of heavy metals. Most of the high biomass productive plants such as, maize, oat and sunflower are plants, which do not grow in cold climates or need intensive care. In this study three “weed” plants, Borago officinalis; Sinapis alba L. and Phacelia boratus were investigated for their ability to tolerate and accumulate high amounts of Cd and Pb. Pot experiments were performed with soil containing Cd and Pb at concentrations of up to 180 mg kg−1 and 2,400 mg kg−1 respectively. All three plants showed high levels of tolerance. Borago officinalis; and Sinapis alba L. accumulated 109 mg kg−1 and 123 mg kg−1 Cd, respectively at the highest Cd spiked soil concentration. Phacelia boratus reached a Cd concentration of 42 mg kg−1 at a Cd soil concentration of 100 mg kg−1. In the case of Pb, B. officinalis and S. alba L. displayed Pb concentrations of 25 mg kg−1 and 29 mg kg−1, respectively at the highest Pb spiked soil concentration. Although the Pb uptake in P. boratus reached up to 57 mg kg−1 at a Pb spiked soil concentration of 1,200 mg kg−1, it is not suitable for phytoextraction because of its too low biomass.

Increased use of nanomaterials in everyday products leads to their environmental release and therefore, the information need on their fate and behaviour. Nanomaterials have to be suspended with high repeatability and comparability for studies on environmental effects. They also have to be well characterised with a focus on the state of agglomeration and particle size distribution. Dynamic light-scattering (DLS) is a common technique used for these measurements. If suspensions are prepared in different laboratories, then concern has risen about the comparability of the measured results, especially when different DLS instruments are used. Therefore, for quality assurance, a round-robin test was conducted to assess the comparability of different DLS instruments and a dispersion protocol in ten independent laboratories. Polystyrene and TiO2 were chosen as test (nano)materials. For the comparability of the DLS instruments, the average sizes of the PSL and a stabilised TiO2 suspension were measured. The measured average hydrodynamic diameter shows an overall good inter-laboratory comparability. For the PSL suspension, an average hydrodynamic diameter of 201 ± 13 nm and for the TiO2 suspension an average diameter of 224 ± 24 nm were detected. For the TiO2 suspension that was prepared at each laboratory following an established suspension preparation protocol, an average hydrodynamic diameter of 211 ± 11 nm was detected. The measured average particle size (mode) increased up to 284 nm with a high standard deviation of 119 nm if the preparation protocol could not established and different procedures or different equipment were employed. This study shows that no significant differences between the employed DLS instrument types were determined. It was also shown that comparable measurements and suspension preparation could be achieved if well-defined suspension preparation protocols and comparable equipment can be used.