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Yolk is the most important temporary biological compartment of the early life stages of fish embryos. The sorption strength of a chemical to yolk components may significantly influence the distribution of that chemical in the fish embryo. We determined yolk-water partition coefficients (Kyolk/water , in liters of water per kilogram of yolk, normalized to dry wt) for 70 neutral organic chemicals. The log Kyolk/water values range from 0.76 to 6.56. On the basis of these values, we developed polyparameter linear free energy relationship models to predict yolk-water partitioning for a broad range of neutral organic chemicals with a root mean squared error of 0.37 and r2 of 0.919. These models can be applied for the prediction of internal concentrations at equilibrium (neglecting biotransformation and active transport) in the zebrafish embryo test system. Environ Toxicol Chem 2020;39:1506-1516. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Yolk is the most important temporary biological compartment of the early life stages of fish embryos. The sorption strength of a chemical to yolk components may significantly influence the distribution of that chemical in the fish embryo. We determined yolk–water partition coefficients (Kyolk/water, in liters of water per kilogram of yolk, normalized to dry wt) for 70 neutral organic chemicals. The log Kyolk/water values range from 0.76 to 6.56. On the basis of these values, we developed polyparameter linear free energy relationship models to predict yolk–water partitioning for a broad range of neutral organic chemicals with a root mean squared error of 0.37 and r2 of 0.919. These models can be applied for the prediction of internal concentrations at equilibrium (neglecting biotransformation and active transport) in the zebrafish embryo test system. Environ Toxicol Chem 2020;39:1506–1516. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

There are periods in the Earth’s history when environmental conditions and the climate sharply changed. Some of such changes were accompanied by mass extinction of living organisms and a decrease in the species diversity. At present, there exist numerous hypotheses and conflicting scenarios of terrestrial and extraterrestrial events which led to such consequences. In particular, the most striking such episode belonging to the Late Permian is related to eruption of volcanoes in Siberia, the impact of a large asteroid, and climatic fluctuations caused by a decrease in the ozone concentration in the atmosphere (see for instance, [1]). By the ratio of isotopes in sedimentary rocks, there was revealed a degradation of vegetation in that period, which was accompanied by an appreciable decrease in productivity of photosynthesis [2]. The photosynthesis reduction resulted in a decrease in O 2 and an increase in CO 2 concentrations in the atmosphere and oceans. Volcanic emission of CO 2 in Siberia in the Late Permian also contributed to a general increase in the CO 2 concentration on the Earth. The change in the radiation budget, the warmed-up climate of the Earth, and aridization of some regions on the planet could cause mass extinction of living organisms [1]. The mass extinction of living organisms on the Earth at the boundary between the Permian and Triassic is known to have lasted over a million years (within the interval of 252.3 ± 0.3‐251.4 ± 0.3 Ma ago), i.e., in a very short period of time in terms of geology. Died out during this period were 90% of sea species, 60% of reptile and amphibian families, 30% of insect varieties, and most terrestrial plants [3]. The gradual and continuous changes in the species diversity of living organisms indicate that the mass extinction was caused by a gradual effect rather than a geologically instantaneous event spanning over several years or centuries. This suggests that such global changes began due to terrestrial causes, and later other, probably, extraterrestrial factors came into play. This work discusses a new possible cause of changes in the state of the Earth’s system and mass extinction of living organisms at the boundary between the Permian and Triassic, which was related to an increased emission of volatile phytotoxicological halogenated hydrocarbons (HHCs) from hypersalt lakes and seas. The possibility for HHC to form actively in water and bottom sediments of such water bodies was revealed in recent years in the course of studying aridization processes during climatic warming [4, 5].

Through employing [14C]-PER exposure experiments it was shown for the first time that PER taken up by drought-stressed spruce needles via the air/needle pathway is preferably degraded to trichloroacetic acid (TCA) in the chloroplasts. TCA formed by oxidative biotransformation is mineralised to CO2 and HCl via various degradation routes. HCl contributes to increased proton concentration in the chloroplast, inducing a pH shift leading to a pathophysiological effect on H+ transport from the thylakoid interior into the stroma. As a result of their high degree of dissociation and related protonation, the PER metabolites, TCA and HCl, cause a change in protein structures. In addition to this, the TCA anions created in the process may lead to destabilisation of the thylakoid membrane potential. The damage to the chloroplasts inflicted by protons and trichloroacetate ions subsequently leads to an impairment of photosynthesis, most particularly to uncoupling of photosynthetic electron transport. Since progressive aridity as consequence of the climate change observed throughout the world is predicted, a regionally variable marked enhancement of the phytotoxic risk caused by PER emission is anticipated.

Trichloroacetic acid (TCA) is a phytotoxic substance that, until the 1980s was used in the form of sodium trichloroacetate (TCA-Na) as a herbicide in agriculture and forestry. Since then it has been banned almost everywhere in Europe and in many other countries in the world. Although much has been learned about the natural and anthropogenic sources of TCA over the past few years, at present little is known about the harmful effects of TCA and its atmospheric precursors (such as tetrachloroethylene, PER) on wild and forest plant species. Therefore experiments lasting a number of years were carried out on pine trees (Pinus sylvestris L.) and birch trees (Betula pendula Roth) with respect to the chronic uptake of airborne PER via the air/leaf pathway, the aim being to study the fate of PER and its metabolisation into TCA. This work was augmented by outdoor model experiments on pines about 10 years old regarding the uptake of TCA-Na via the soil/root pathway. Chlorophyll a fluorescence measurements on needles and leaf material affected by TCA-Na and PER indicated that the extent to which TCA influences photochemical and biochemical mesophyll processes varies depending on the entry pathway, the particular part of the plant directly affected by TCA, and weather-related factors. It was proven that TCA-Na applied via the soil/root pathway moderately raises the vitality of pine trees depending on the concentration involved, despite high levels of TCA in the needles (up to 1 800μg TCA kg –1 dry weight needles). By contrast, fumigating pine trees and birch trees with PER led to the accumulation of up to 70μg TCA kg –1 dw in the assimilation organs and exacerbated the trees’ sensitivity to stressors. Although physiological activity was initially stimulated, the effect of additional stress in the form of an artificially induced drought caused PER-affected birch trees, in particular, to sometimes undergo sharp losses of vitality of as much as 58% compared to the controls. One may thus expect that, future climate changes accompanied by long periods of drought are likely to exacerbate the ecotoxicological risk in regions with high PER pollution, possibly resulting in the vegetation in the terrestrial ecosystems of the areas concerned being destabilised.

One of the issues provided for by the 1993 existing substances regulation (793/93/EEC) is the assessment of the environmental risk emanating from waste materials. One such material is the highly volatile substance perchloroethene (PER; TECE). PER is produced in large quantities all over the world by the chemical industry. There are many industrial processes in which PER escapes into the environment, especially the atmosphere. It has since been proven that after entering plants via the air/leaf pathway, airborne PER can be metabolised into the phytotoxic substance trichloroacetic acid. However our own studies detected relatively high levels of TCA in environmental compartments in regions far away from industry which cannot be explained by the anthropogenic input of airborne substances into the relevant ecosystems. This indicates that natural PER emittents also exist and must be identified, in order to find out more about the global spread of PER. This paper reports on the findings of related fieldwork in the Kalmykian Steppe. This area of steppe in southern Russia spans an area extending west-to-east from the Black Sea and the Caspian Sea and north-to-south between the Greater Caucasus and Volgograd. The main aim of the experiments in the Kalmykian Steppe was to study water from lakes, rivers and springs with differing levels of salinity. The concentrations of the chlorinated hydrocarbons (VCHCs) chloroform (CHCl 3 ), tetrachloromethane (CCl 4 ), 1,1,1-trichloroethane (1,1,1-C 2 H 3 Cl 3 ), trichloroethene (TRI; C 2 HCl 3 ), tetrachloroethene (PER; C 2 Cl 4 ) and TCA in these waters were measured, along with the levels of cations and anions and the pH-value of the waters. The measurements indicate that in particular water from salt lakes located in semiarid/arid areas of the study region must be considered as new types of natural emittents of PER and other chlorinated hydrocarbons as well as trichloroacetic acid. Furthermore, attention is drawn to ecological impacts resulting from the occurrence of these substances in connection with the desertification observed in this area since the mid-20th century. Possible global associations between TCA phytotoxicity, the consumption of water by contaminated plants and the resulting impact on the regional water cycle are discussed.

There has been an accelerated expansion of deserts in the past five decades. Recent data reveal that the atmogenically formed organic compound, trichloroacetic acid (TCA) is a contributory factor in addition to anthropogenic and natural sources. The aim of this study was to use TCA as an indicator for the possible occurrence of C2-chloroacetic acids; to assess the burden on the vegetation by using pine needles as a bio-indicator system and to deliberate on the possible role of TCA in the dynamics of the vegetation in southern Africa. Field experiments conducted on pine trees and on C3 and C4 crop plants under controlled laboratory conditions, have revealed that plants could be influenced positively or negatively by TCA. To obtain an integrated assessment of the pollution emission over a time span of at least one year, two-year-old pine needles of different Pinus species were used as a bio-indicator for TCA pollution at different measuring sites. The data of our investigation clearly indicate that areas exist in South Africa where the vegetation is burdened by ecotoxicologically relevant TCA contents comparable to those in central Europe and southern Russia where TCA was shown to play a role in the destabilisation of the steppe vegetation.

Trichloroacetic acid (TCA, CCl(3)COOH) is a phytotoxic chemical. Although TCA salts and derivates were once used as herbicides to combat perennial grasses and weeds, they have since been banned because of their indiscriminate herbicidal effects on woody plant species. However, TCA can also be formed in the atmosphere. For instance, the high-volatile C(2)-chlorohydrocarbons tetrachloroethene (TECE, C(2)Cl(4)) and 1,1,1-trichloroethane (TCE, CCl(3)CH(3)) can react under oxidative conditions in the atmosphere to form TCA and other substances. The ongoing industrialisation of Southeast Asia, South Africa and South America means that use of TECE as solvents in the metal and textile industries of these regions in the southern hemisphere can be expected to rise. The increasing emissions of this substance--together with the rise in the atmospheric oxidation potential caused by urban activities, slash and burn agriculture and forest fires in the southern hemisphere--could lead to a greater input/formation of TCA in the vegetation located in the lee of these emission sources. By means of biomonitoring studies, the input/formation of TCA in vegetation was detected at various locations in South America, North America, Africa, and Europe.

Salting-out in aqueous NaCl solutions is relevant for the environmental behavior of organic contaminants. In this study, Setschenow (or salting-out) coefficients (K(s) [M(-1)]) for 43 diverse neutral compounds in NaCl solutions were measured using a shared headspace passive dosing method and a negligible depletion solid phase microextraction technique. The results were used to calibrate and evaluate estimation models for K(s). The molar volume of the solute correlated only moderately with K(s) (R(2) = 0.49, SD = 0.052). The polyparameter linear free energy relationship (pp-LFER) model that uses five compound descriptors resulted in a more accurate fit to our data (R(2) = 0.83, SD = 0.031). The pp-LFER analysis revealed that Na(+) and Cl(-) in aqueous solutions increase the cavity formation energy cost and the polar interaction energies toward neutral organic solutes. Accordingly, the salting-out effect increases with the size and decreases with the polarity of the solute molecule. COSMO-RS, a quantum mechanics-based fully predictive model, generally overpredicted the experimental K(s), but the predicted values were moderately correlated with the experimental values (R(2) = 0.66, SD = 0.042). Literature data (n = 93) were predicted by the calibrated pp-LFER and COSMO-RS models with root mean squared errors of 0.047 and 0.050, respectively. This study offers prediction models to estimate K(s), allowing implementation of the salting-out effect in contaminant fate models, linkage of various partition coefficients (such as air-water, sediment-water, and extraction phase-water partition coefficients) measured for fresh water and seawater, and estimation of enhancement of extraction efficiency in analytical procedures.

Artemisia lerchiana is a wormwood species of the Central Asian steppe regions, where it completely cover whole areas. For the first time it was possible to show through field experiments that C1/C2 halocarbons (VCHCs), such as chloroform (CHL), tetrachloroethene (PER) and hexachloroethane (HEX), can be taken up by test plants of the species A. lerchiana via the soil/root pathway and metabolised inter alia into trichloroacetic acid (TCA) under semi-aride conditions. At the same time, chlorophyll a fluorescence measurements carried out on the test plants revealed a phytotoxic influence on plant vitality (max. decline in vitality of 52% with application of CHL) and less efficient energy flows in the photosynthesis mechanism of the A. lerchiana test plants. The authors examine possible links between the simultaneous appearance of VCHCs and additional drought stress in the acceleration of desertification processes.

[1] It is shown for the first time that the volatile highly chlorinated C2 hydrocarbons (VCHCs) trichloroethene (TRI; C2HCl3), tetrachloroethene (PER; C2Cl4) and methyl chloroform (MC; C2H3Cl3), but also C1 hydrocarbons tetrachloromethane and chloroform can be naturally formed in the sediment of salt lakes (ssl). Archaic halobacteria appear to play a key role in the microbial formation involved. TRI, PER and MC can be transformed into trichloroacetic acid (TCA) in the atmosphere. TRI and PER can also be metabolised into TCA following uptake by plants. Already considerably phytotoxic by itself, TCA's phytotoxicity is exacerbated if the vegetation concerned is simultaneously exposed to drought-stress. TRI and PER, emitted by these newly identified natural sources, can accelerate desertification in semi-arid and arid climate zones in consequence of the destabilisation of vegetation by its phytotoxic metabolite TCA.

Trichloroacetic acid (TCA; CCl3COOH) is a phytotoxic chemical. Although TCA salts and derivatives were once deployed as herbicides against perennial grasses and weeds, their use has since been banned because of their indiscriminate herbicidal effects on woody plant species. However, TCA can also be formed in the atmosphere. For instance, high-volatile C2-chlorohydrocarbons tetrachloroethene (TECE, C2Cl4) and 1,1,1-trichloroethane (TCE, CCl3CH3) can react to TCA and other substances under oxidative conditions here. Owing to further industrialisation of Southeast Asia, South Africa and South America, a rise can be expected in the use of TECE as solvents in the metal and textile industries of these regions in the southern hemisphere (SH). The increasing emissions of this substance-together with the rise in the atmospheric oxidation potential caused by urban activities, slash and burn agriculture and forest fires in the SH-will result in the increased input/formation of TCA in the vegetation located on the lee side of these emission sources. By means of biomonitoring studies, inputs/formation of TCA related to the climatic conditions were detected at various locations in South America, Africa, and Europe. Fil: Weissflog, Ludwig. Helmholtz Zentrum Für Umweltforschung; Alemania Fil: Pfennigsdorff, Andrea. Helmholtz Zentrum Für Umweltforschung; Alemania Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Puliafito, Enrique. Universidad de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Figueroa, Dante. Universidad de Concepción; Chile Fil: Elansky, Nikolai. Russian Academy Of Sciences; Rusia Fil: Nikonov, Vyasheslav. The Russian Academy Of Sciences. Institute Of North Industrial Ecology Problems Kola Science Centre; Rusia Fil: Putz, Erich. Karl-franzens-universitat Graz; Austria Fil: Krüger, Gert. Potchefstroom University; Sudáfrica Fil: Kellner, Klaus. Potchefstroom University; Sudáfrica