Session 3 - Soil and groundwater contamination and remediation

[CEST2019_00572] Geochemical modelling as a tool to investigate chromium contamination in groundwater
by Apollaro C., Fuoco I.

Geochemical modelling is an essential tool to understand the water-rock interaction processes. In this work has been used the reaction path modelling to investigate the release and fate of geogenic Cr in ophiolitic Italian areas. During the water-rock interaction the geogenic trivalent Cr hosted in Cr-bearing minerals (serpentine minerals, spinels, pyroxene, etc.) of serpentinites rocks is oxidized in Cr (VI) highly toxic, resulting largely dangerous for environment and human health. This geochemical modelling was performed varying Fe2O3/(FeO+Fe2O3) weight ratios considering the trivalent Fe the main oxidant present in suitable amounts in serpentinite rock. The reaction paths reproduces the analytical concentrations of relevant solutes, including Cr(VI), in the Mg-HCO3 groundwaters hosted in the ophiolitic aquifers of Italy.

Session: 3, Room: C, at Thu, 09/05/2019 - 10:15 to 10:30
Oral presentation in Soil and groundwater contamination and remediation
[CEST2019_00530] Technology Critical Elements in industrial wastes as the source of soil contamination
by Rachwał M., Jabłońska-Czapla M.,Grygoyć K., Fornalczyk A.,Willner J.

The intensive development of industry, especially the mining and metallurgy, automotive and electrical industries, affects the increasing amount of Potentially Toxic Elements (PTE), including Technology Critical Elements (TCE) in the environment. This preliminary study focuses on the following TCE: Ga, Ge and Tl. The main thing they have in common is that they have not been much studied and the level of knowledge concerning the environmental impact of their use is quite slight. Additionally, content of more common PTE (As, Cd, Cu, Pb, Sb, Zn) was determined in order to discover some relationships between these both group.
Soil samples were collected from topsoil (0-5 cm) and subsoil (25-30 cm) in industrial area influenced by metallurgical slag dump and road traffic. Concentrations of elements were determined with High-Resolution Inductive Coupled Plasma-Mass Spectrometry (HR-ICP-MS) after HNO3 microwave digestion. Results revealed that almost all studied elements were in higher amount in the topsoil suggesting the anthropogenic pollution as a source of their content in soil.

Session: 3, Room: C, at Thu, 09/05/2019 - 10:30 to 10:33
Flash presentation in Soil and groundwater contamination and remediation
[CEST2019_00500] Groundwater quality and hydrogeochemical characterization of Khetri copper mining region, India
by Punia A., Siddaiah N.S., Bharti R.

The impact of copper mine on groundwater quality in the semi-arid region is evaluated, and also characterized for hydrogeochemical processes. Groundwater samples (post monsoon and pre monsoon) from Khetri copper mine region of Rajasthan, India were studied. In majority of groundwater samples, the values of analyzed parameters such as EC, Ca2+, Mg2+, Na+, HCO3- and Cl- exceed the WHO (2011) and Bureau of Indian Standards (2012) permissible limits. Higher concentrations of ions were observed near the mining activities (mines, tailings, overburden rocks and abandoned mine) and in the downstream of groundwater flow from mines suggesting significant influence of mines on water quality. High concentration of major ions is attributed to oxidation of sulfides or acid mine drainage (AMD). The Gibbs plot for cations and anions as a function of TDS indicates the evolution of groundwater from rock-water interaction in both seasons. Thus, increased major ions concentration is due to dissolution of minerals by AMD.

Session: 3, Room: C, at Thu, 09/05/2019 - 10:36 to 10:39
Flash presentation in Soil and groundwater contamination and remediation
[CEST2019_00481] Origin of the salinity in the groundwater of the El Attaf alluvial aquifer
by Richa A., Touil S., Djezzar M., Douaoui A.

The choice of this research theme was guided by the desire to better understand environmental issues, namely salinity and its origin, through the use of geophysical data from various surveys carried out between 1969 (CGG) and 2002 (IFES), to highlight the impact of the geological and structural upheavals that occurred during the earthquake of October 10, 1980, on the hydrodynamic processes. The interpretation of the resistivity data revealed that water salinity is highly variable and generally high near Jebel Temoulga. Chemical analyzes of all wells in the region confirm this. The hydrochemical study has shown the influence of local geology on the chemistry of the waters of the neighboring aquifer, and raises the question of the importance of gypso-saliferous facies in the region of El Attaf. The multifunctional statistical analysis revealed two chemical profiles within the same aquifer, but it should be noted that the highest concentrations were recorded on the Hay Bel Abbes - Bir Saf Saf axis.

Session: 3, Room: C, at Thu, 09/05/2019 - 10:33 to 10:36
Flash presentation in Soil and groundwater contamination and remediation
[CEST2019_00159] Thermal Decomposition of Chlorpyrifos - an Experimental Investigation
by Weber N., Stockenhuber S., Dixon L., Lucas J., Grimison C., Stockenhuber M., Mackie J., Benhelal E.,Kennedy E.

Organophosphate compounds are a group of chemicals that are commonly used in pest control. One widely used organophosphate is chlorpyrifos (CPF), which has been associated with acetylcholinesterase inhibition (AChE), an acute neurotoxin. Further, under thermal decomposition conditions, such as those that occur in bushfires, CPF has been shown to produce a dioxin-like compound 2,3,7,8-tetrachloro-[1,4]-dioxinodipyridine (TCDDpy). To assist in understanding the reaction of CPF, an experimental methodology was developed which enabled the study of its thermal decomposition. CPF was pyrolysed in a three-zone furnace, leading to the formation of its major degradation product, 3,5,6-trichloro-2-pyridinol (TCP). The study revealed that ethylene gas and a solid sulfur/phosphorous compound were also generated with the TCP product. TCP undergoes further thermal decomposition to form several chlorinated products. Experiments undertaken under oxidative conditions revealed that TCP (at temperatures above 900 K and at a residence time of 9 s) also produced HCl and cis and trans forms of TCDDpy. The results of this study compare favourably with our previous theoretical work.

Session: 3, Room: C, at Thu, 09/05/2019 - 10:00 to 10:15
Oral presentation in Soil and groundwater contamination and remediation
[CEST2019_00155] Thermal degradation of perfluorooctanoic acid (PFOA)
by Stockenhuber S., Weber N., Dixon L., Lucas J., Grimison C., Bennett M., Stockenhuber M., Mackie J., Kennedy E.,

Per - and polyfluoroalkyl substances (PFAS) are a group of environmental contaminants, that are dispersed throughout the world. A number of areas have been affected by their persistence and biomagnification. PFAS remediation of contaminated material requires extensive knowledge of the species involved. A method to simplify the study of the thermal degradation of PFAS is presented in this paper, providing a solution to experimental and analytical challenges. A three-zone furnace allowed manipulation of both reaction temperature and gas flowrate (and consequently residence time). The PFAS compound could be charged and vaporised in a separate zone. Adopting this experimental methodology, a kinetic model describing the decomposition of the PFAS can be devised. When reacting under an inert nitrogen atmosphere, perfluorooctanoic acid (PFOA) degraded at temperatures above 450 °C. The products observed were found to be hydrofluoric acid (HF) and carbon dioxide (CO2), along with a perfluoro-1-heptene species. Additional products of 1H-perfluorohexane or 1H-perfluoroheptane were also observed when residence times were increased. The effect of water vapour was also investigated, with similar behaviour to pyrolysis being observed, where a significantly higher concentration of HF was detected under otherwise similar reaction conditions. These preliminary results suggest water vapour accelerates the rate of PFAS decomposition.

Session: 3, Room: C, at Thu, 09/05/2019 - 09:45 to 10:00
Oral presentation in Soil and groundwater contamination and remediation
[CEST2019_00113] Screening of polar pesticides in groundwater in Hebei Province, China
by Huang Y.,Guo X., Rao Z., Yang Z., Liu C., Shi Z.

As a big agricultural country,China has a relatively high pesticide usage in unit area , which is three times higher than developed countries. About 80% of pesticides directly enter the soil and the water through leaching or surface runoff during the usage of pesticides. In particular, some of the polar compounds are easier to migrate than other compounds, causing pollution of surface water and groundwater. The groundwater samples in Hebei Province, a major agriculture province in China, were screened by multi-residue liquid chromatography-tandem mass spectrometry for two consecutive years in 2014 and 2015. The results showed that among 44 polar compounds, 27 pesticides were detected in 2014 and 19 in 2015. Atrazine-desethyl-desisopropyl, 2,4-D and fomesafen were 434.3 ng/L, 711.5 ng/L and 508.2 ng/L respectively, which were significantly higher than those in other provinces in China. Atrazine and its metabolites were detected in both years. Except for Atrazine-desethyl-desisopropyl, other components were detected in high concentration in 2014. The detected concentrations of bentazone, hexaconazole, triadimenol, and triazolone were similar in the two years. Pesticides such as methomyl, isopropyl, diniconazole and imazethapyr were detected in 2014, but not in 2015, which is presumably related to the actual use of pesticides.

Session: 3, Room: C, at Thu, 09/05/2019 - 09:30 to 09:45
Oral presentation in Soil and groundwater contamination and remediation