• Energy Research

AbstractThe flood event in July 2021 in the uplands of the Eifel-Ardennes mountains in Germany, Belgium and The Netherlands and their foreland was caused by heavy rainfall and resulted in one of the largest flood disasters in Western Europe for decades. Due to climate change, it can be assumed that such events will become more frequent in future. Even though such extreme flood can happen at any time, the consequences and impacts can be significantly reduced by appropriate technical and non-technical measures. However, such measures always require a comprehensive understanding and knowledge of previous events and comparable processes. Therefore, this special issue aims at collecting the scientific evaluation and its implications of the 2021 extreme summer flood. This editorial serves as an introduction for an article collection published in the journal Environmental Sciences Europe, providing an overview of the current state of integrative assessment of the 2021 summer flood in Central Europe.

AbstractThe flood event in July 2021 in the uplands of the Eifel-Ardennes mountains in Germany, Belgium and The Netherlands and their foreland was caused by heavy rainfall and resulted in one of the largest flood disasters in Western Europe for decades. Due to climate change, it can be assumed that such events will become more frequent in future. Even though such extreme flood can happen at any time, the consequences and impacts can be significantly reduced by appropriate technical and non-technical measures. However, such measures always require a comprehensive understanding and knowledge of previous events and comparable processes. Therefore, this special issue aims at collecting the scientific evaluation and its implications of the 2021 extreme summer flood. This editorial serves as an introduction for an article collection published in the journal Environmental Sciences Europe, providing an overview of the current state of integrative assessment of the 2021 summer flood in Central Europe.

The aim of this study is to identify potential toxic or environmentally relevant organic compounds in the aquifers of the Amynteo hydrogeological basin and to investigate a possible link of the identified organic contaminants with the Pliocene Amynteo lignites. For these purposes, 10 groundwater samples were collected from this area. A sequential liquid–liquid extraction procedure was applied and all extracts were analyzed by gas chromatography and gas chromatography–mass spectrometry (GC–MS) by means of a non-target screening approach. The results of the GC–MS analyses of the extracts are presented and discussed in this work. The identified organic compounds with a potential environmental relevance are: 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, triacetine, isopropyl palminate, isopropyl myristate, tributyl-, triethyl- and trioctylphosphates, N,N-dibutyl formamide, methyl dihydrojasmonate, nonylphenols and bumetrizole. However, all these organic micropollutants can derive either by anthropogenic emissions (plasticizers, industrial pollutants, pesticides, etc.) or by contaminations from the pump and the borehole structure itself. Noteworthy, coal-derived organic molecules (such as anthracene, fluorene, pyrene, phenanthrene, etc.) have not been detected. Hence, an influence of coal deposits to the groundwater quality is considered negligible. Peer Reviewed

The aim of this study is to identify potential toxic or environmentally relevant organic compounds in the aquifers of the Amynteo hydrogeological basin and to investigate a possible link of the identified organic contaminants with the Pliocene Amynteo lignites. For these purposes, 10 groundwater samples were collected from this area. A sequential liquid–liquid extraction procedure was applied and all extracts were analyzed by gas chromatography and gas chromatography–mass spectrometry (GC–MS) by means of a non-target screening approach. The results of the GC–MS analyses of the extracts are presented and discussed in this work. The identified organic compounds with a potential environmental relevance are: 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, triacetine, isopropyl palminate, isopropyl myristate, tributyl-, triethyl- and trioctylphosphates, N,N-dibutyl formamide, methyl dihydrojasmonate, nonylphenols and bumetrizole. However, all these organic micropollutants can derive either by anthropogenic emissions (plasticizers, industrial pollutants, pesticides, etc.) or by contaminations from the pump and the borehole structure itself. Noteworthy, coal-derived organic molecules (such as anthracene, fluorene, pyrene, phenanthrene, etc.) have not been detected. Hence, an influence of coal deposits to the groundwater quality is considered negligible. Peer Reviewed

Coals contain native polycyclic aromatic compounds (PACs), which include polycyclic aromatic hydrocarbons (PAHs), and heterocyclic aromatic compounds (NSO-PACs) in considerably varying amounts up to 2500 mg/kg. Whereas PAC bioavailability and toxicity from coals are generally considered to be low, few studies have considered potential variations arising from the composition of different coal types including native PAC content. In the present study, fine particles of different coal types exhibiting variable properties were systematically investigated regarding their PAC bioavailability. PAH content reached up to 79 mg/kg EPA-PAH and 865 mg/kg total PAH. Determination of the toxic potential of extracted PACs in bioassays showed inhibition of Caenorhabditis elegans reproduction (up to 94%) and increased mortality of Danio rerio embryos (up to 100%) after exposure to extracts from lignite, sub-bituminous, and bituminous coals. Anthracite extracts showed no effects. Contact assays using whole coal samples revealed no toxicity to D. rerio embryos in any of the coal samples, suggesting low bioavailability of PACs. In contrast, C. elegans reproduction was inhibited by direct coal contact; however, the observed toxicity probably resulted from other coal effects. The results suggest that despite the high toxic potential of PACs present, their bioavailability from different coal types is very limited and independent of coal properties and native PAH content.

Coals contain native polycyclic aromatic compounds (PACs), which include polycyclic aromatic hydrocarbons (PAHs), and heterocyclic aromatic compounds (NSO-PACs) in considerably varying amounts up to 2500 mg/kg. Whereas PAC bioavailability and toxicity from coals are generally considered to be low, few studies have considered potential variations arising from the composition of different coal types including native PAC content. In the present study, fine particles of different coal types exhibiting variable properties were systematically investigated regarding their PAC bioavailability. PAH content reached up to 79 mg/kg EPA-PAH and 865 mg/kg total PAH. Determination of the toxic potential of extracted PACs in bioassays showed inhibition of Caenorhabditis elegans reproduction (up to 94%) and increased mortality of Danio rerio embryos (up to 100%) after exposure to extracts from lignite, sub-bituminous, and bituminous coals. Anthracite extracts showed no effects. Contact assays using whole coal samples revealed no toxicity to D. rerio embryos in any of the coal samples, suggesting low bioavailability of PACs. In contrast, C. elegans reproduction was inhibited by direct coal contact; however, the observed toxicity probably resulted from other coal effects. The results suggest that despite the high toxic potential of PACs present, their bioavailability from different coal types is very limited and independent of coal properties and native PAH content.

Investigations of the bioavailability and toxicity of polycyclic aromatic compounds (PAC) have rarely considered the heterogeneity of coals and the impact of more polar PAC besides polycyclic aromatic hydrocarbons (PAH). Earlier, we investigated the toxicity of eight heterogeneous coals and their extracts. In the present study, the hazard potential with respect to mechanism-specific toxicity of polar fractions of dichloromethane extracts from coals was studied. Polar extract fractions of all coal types except for anthracite induced EROD activity (determined in RTL-W1 cells), independent of coal type (Bio-TEQs between 23 ± 16 and 52 ± 22 ng/g). The polar fractions of all bituminous coal extracts revealed mutagenic activity (determined using the Ames Fluctuation test). No significant mutation induction was detected for the polar extract fractions from the lignite, sub-bituminous coal and anthracite samples, which indicates a higher dependency on coal type for polar PAC here. Additionally, information on bioavailability was derived from a bioaccumulation test using the deposit-feeding oligochaete Lumbriculus variegatus which was exposed for 28 days to ground coal samples. Despite the high toxic potential of most coal extracts and a reduced biomass of Lumbriculus in bituminous coal samples, bioaccumulation of PAH and mortality after 28 days were found to be low. Limited bioaccumulation of PAH (up to 3.6 ± 3.8 mg/kg EPA-PAH) and polar PAC were observed for all coal samples. A significant reduction of Lumbriculus biomass was observed in the treatments containing bituminous coals (from 0.019 ± 0.004 g to 0.046 ± 0.011 g compared to 0.080 ± 0.025 g per replicate in control treatments). We conclude that bioavailability of native PAC from coals including polar PAC is low for all investigated coal types. In comparison to lignite, sub-bituminous coals and anthracite, the bioavailability of PAC from bituminous coals is slightly increased.

Investigations of the bioavailability and toxicity of polycyclic aromatic compounds (PAC) have rarely considered the heterogeneity of coals and the impact of more polar PAC besides polycyclic aromatic hydrocarbons (PAH). Earlier, we investigated the toxicity of eight heterogeneous coals and their extracts. In the present study, the hazard potential with respect to mechanism-specific toxicity of polar fractions of dichloromethane extracts from coals was studied. Polar extract fractions of all coal types except for anthracite induced EROD activity (determined in RTL-W1 cells), independent of coal type (Bio-TEQs between 23 ± 16 and 52 ± 22 ng/g). The polar fractions of all bituminous coal extracts revealed mutagenic activity (determined using the Ames Fluctuation test). No significant mutation induction was detected for the polar extract fractions from the lignite, sub-bituminous coal and anthracite samples, which indicates a higher dependency on coal type for polar PAC here. Additionally, information on bioavailability was derived from a bioaccumulation test using the deposit-feeding oligochaete Lumbriculus variegatus which was exposed for 28 days to ground coal samples. Despite the high toxic potential of most coal extracts and a reduced biomass of Lumbriculus in bituminous coal samples, bioaccumulation of PAH and mortality after 28 days were found to be low. Limited bioaccumulation of PAH (up to 3.6 ± 3.8 mg/kg EPA-PAH) and polar PAC were observed for all coal samples. A significant reduction of Lumbriculus biomass was observed in the treatments containing bituminous coals (from 0.019 ± 0.004 g to 0.046 ± 0.011 g compared to 0.080 ± 0.025 g per replicate in control treatments). We conclude that bioavailability of native PAC from coals including polar PAC is low for all investigated coal types. In comparison to lignite, sub-bituminous coals and anthracite, the bioavailability of PAC from bituminous coals is slightly increased.