215
9% of investigated wells didn’t meet the expectations for unpolluted groundwater.
Only Sweden stated that there is no concern about pesticide groundwater pollution
on its territory (EEA 2004). The presence of pesticides was detected in 24.4% of the
total 279 investigated wells during the national survey of pesticides in groundwater
in New Zealand performed in 2018 (Close and Humphries 2019). Most commonly
found were also herbicides from the group of triazines. The most frequently detected
was terbuthylazine followed by dieldrin, hydroxyatrazine, atrazine, and terbacil.
Bentazone, hexazinone, bromacil, terbacil, desethyl terbuthylazine, 2-hydroxyatrazine, alachlor, picloram, glyphosate, and the total atrazine and its metabolites were
found in concentration that exceeds the EU threshold value of 0.1 μg/l.
Triazines are of particular importance when it comes to groundwater pollution
due to their high persistence (long half-life), high water solubility, and poor absorption by soil particles. Atrazine and simazine are the most commonly found at concentrations above 0.1 μg/l. Therefore, atrazine and simazine together with alachlor,
anthracene, chlorfenvinphos, chlorpyrifos, 1,2-dichloroethane, dichloromethane,
diuron, endosulfan, hexachlorobenzene, hexachlorocyclohexane, isoproturon, pentachlorobenzene, pentachlorophenol, trifluralin, trichlorobenzenes, and tributyltin
compounds are classified in the priority group of pesticides by the Annex II of the
Directive 2008/105/EC set by the European Parliament and the Council of the
European Union (European Parliament 2008).
Some pesticides other than thе most commonly found may also be present in
groundwater but due to their low leaching capability and hydrogeoecological conditions of the region are present in undetectable concentrations. The goal of this study
was to investigate the presence of nine thermally labile nonvolatile (benalaxyl,
buprofezin, chlorpyrifos, malathion, methomyl, metribuzin, pirimiphos methyl,
pyrimethanil, and triadimenol) and two thermally stable, nonvolatile pesticides
(penconazole and pirimicarb) in groundwater situated under the agriculture land
where dripping irrigation is common practice, using GC/MS and liquid-liquid
extraction (LLE). To improve the method detection limits and to increase the
response of the thermally labile pesticides, an increased pulsed pressure during the
injection time was used. The obtained result was statistically processed to find the
best injection conditions for their identification and quantification.
7.1.1 Factors Contributing to Pesticide Leaching
Leaching of pesticides occupies the attention of scientists since the first pesticide
discovered in groundwater. Several factors are involved in this process. Physical and
chemical characteristics of the pesticide, geological, ecological, field conditions, as
well as agriculture practices are the most important factors contributing to pesticide
leaching. All of these factors act simultaneously and interdependently.
Water solubility is one of the most important features when it comes to pesticide
leaching. Highly water-soluble pesticides have greater potential to reach groundwater. Water solubility is related to the soil and water pH which influence pesticide
7 Improving Quantitative Analysis of GC-MS for Tracking Potential Contaminants…
9% of investigated wells didn’t meet the expectations for unpolluted groundwater.
Only Sweden stated that there is no concern about pesticide groundwater pollution
on its territory (EEA 2004). The presence of pesticides was detected in 24.4% of the
total 279 investigated wells during the national survey of pesticides in groundwater
in New Zealand performed in 2018 (Close and Humphries 2019). Most commonly
found were also herbicides from the group of triazines. The most frequently detected
was terbuthylazine followed by dieldrin, hydroxyatrazine, atrazine, and terbacil.
Bentazone, hexazinone, bromacil, terbacil, desethyl terbuthylazine, 2-hydroxyatrazine, alachlor, picloram, glyphosate, and the total atrazine and its metabolites were
found in concentration that exceeds the EU threshold value of 0.1 μg/l.
Triazines are of particular importance when it comes to groundwater pollution
due to their high persistence (long half-life), high water solubility, and poor absorption by soil particles. Atrazine and simazine are the most commonly found at concentrations above 0.1 μg/l. Therefore, atrazine and simazine together with alachlor,
anthracene, chlorfenvinphos, chlorpyrifos, 1,2-dichloroethane, dichloromethane,
diuron, endosulfan, hexachlorobenzene, hexachlorocyclohexane, isoproturon, pentachlorobenzene, pentachlorophenol, trifluralin, trichlorobenzenes, and tributyltin
compounds are classified in the priority group of pesticides by the Annex II of the
Directive 2008/105/EC set by the European Parliament and the Council of the
European Union (European Parliament 2008).
Some pesticides other than thе most commonly found may also be present in
groundwater but due to their low leaching capability and hydrogeoecological conditions of the region are present in undetectable concentrations. The goal of this study
was to investigate the presence of nine thermally labile nonvolatile (benalaxyl,
buprofezin, chlorpyrifos, malathion, methomyl, metribuzin, pirimiphos methyl,
pyrimethanil, and triadimenol) and two thermally stable, nonvolatile pesticides
(penconazole and pirimicarb) in groundwater situated under the agriculture land
where dripping irrigation is common practice, using GC/MS and liquid-liquid
extraction (LLE). To improve the method detection limits and to increase the
response of the thermally labile pesticides, an increased pulsed pressure during the
injection time was used. The obtained result was statistically processed to find the
best injection conditions for their identification and quantification.
7.1.1 Factors Contributing to Pesticide Leaching
Leaching of pesticides occupies the attention of scientists since the first pesticide
discovered in groundwater. Several factors are involved in this process. Physical and
chemical characteristics of the pesticide, geological, ecological, field conditions, as
well as agriculture practices are the most important factors contributing to pesticide
leaching. All of these factors act simultaneously and interdependently.
Water solubility is one of the most important features when it comes to pesticide
leaching. Highly water-soluble pesticides have greater potential to reach groundwater. Water solubility is related to the soil and water pH which influence pesticide
7 Improving Quantitative Analysis of GC-MS for Tracking Potential Contaminants…