Seasonal distribution of multiclass pesticide residues in the surface waters of northwest Croatia

Figure 1

Figure 2

Mass concentrations of pesticide pollutants in river/stream water samples collected in the northwest part of Croatia across application season

Pesticide compound	March 2015 (N=8)			June 2015 (N=8)			August 2015 (N=7)
	γ (ng/L)			γ (ng/L)			γ (ng/L)
	n	Rangea	Medianb	n	Rangea	Medianb	n	Rangea	Medianb
Mesotrione	0			3	36–107	0	0
Tembotrione	0			7	51–216	77	0
AMBA	0			6	54–444	74	1	61	<LOD
Terbuthylazine	3	9–13	<LOD	8	20–419	42	5	10–26	13
DET	1	9	<LOD	4	38–200	19	2	14–45	<LOD
Atrazine	5	10–16	11	5	12–34	13	5	9–24	14
DIA	5	5–32	6	6	17–123	28	2	19–24	<LOD
DEA	4	8–11	4	7	7–24	11	5	6–32	10
Isoproturon	1	146	<LOD	0			0
Diuron	0			2	22–30	<LOD	0
Acetochlor	0			1	28	<LOD	0
Metolachlor	7	9–11	9	8	11–3015	147	6	10–63	11
Chlorpyrifos-methyl	0			1	26	<LOD	0
Chlorpyrifos-methyl-oxon	1	21	<LOD	8	23–145	64	3	34–198	<LOD
Imidacloprid	1	73	<LOD	8	12 – 34	26	0

Methods for determination of pesticides and their degradation products in natural waters by SPE and HPLC-UV(DAD) or GC-MS(ITD) analysis

Method of analysis	HPLC-UV(DAD)			GC-MS(ITD)
	Method 1 – λ (nm)	Method 2 – λ (nm)	Method 3a – λ (nm)	Method 4a – m/z	Method 5 – m/z
Pesticide	Mesotrione – 220	Terbuthylazine – 222	Atrazine – 222	Trifluralin – 264	Terbuthylazine – 214
	AMBA – 220	DET – 214	DEA – 214	Atrazine – 200	Chlorpyrifosmethyl – 286
	Tembotrione – 205	Malathion – 205	DIA – 214	Terbuthylazine – 214	Chlorpyrifosethyl – 314
		Chlorfenvinphos – 205	Terbuthylazine – 222	Acetochlor – 223	Malathion – 173
		Chlorpyrifos-methyloxon – 205	DET – 214	Alachlor – 188	Chlorfenvinphos – 267
		Imidacloprid – 270	Diuron – 210, 245	Metolachlor – 162	α-Cypermethrin – 163
			Linuron – 210, 245
			Chlortoluron – 210, 245
			Isoproturon – 202, 245
SPE	OASIS HLB	C18	SDB-1	C18	C18 Polar plus/ SDB-1
Activation	MeOH+H2O	ACN+H2O	MeOH+H2O	MeOH+H2O	MeOH+H2O
Solvent volume (mL)	2+2	5+5	2+5	2+5	2+5
Sample volume (mL)	500	500	500	1000	500
Eluent	MeOH	ACN+Et.ac	Ac	Et.ac	Et.ac
Eluent volume (mL)	10	10+5	2	2	10

Number (N) of individual pesticide compounds, their mass concentration range, and the sum of pesticides mass concentrations (Σ) by river/stream across application season

River/Stream	March 2015				June 2015				August 2015
	N	γ (ng/L)			N	γ (ng/L)			N	γ (ng/L)
		Min	Max	Σ		Min	Max	Σ		Min	Max	Σ
Sutla	3	8	22	41	9	9	2564	3455	3	10	63	99
Krapina	7	9	146	219	10	22	3015	3992	5	6	198	248
Sava 1	2	9	73	81	11	10	242	947	4	9	45	77
Sava 2	4	6	11	35	11	7	149	498	– not analysed –
Drava	2	5	10	15	6	22	86	323	2	11	14	25
Plitvica	2	10	16	25	7	16	115	331	4	10	32	76
Bistrica	3	9	32	52	10	11	216	582	5	13	61	147
Bednja	5	7	16	56	10	12	444	867	6	11	66	161

Pesticides and pesticide degradation products analysed in this study

Class/Pesticide	Chemical name	Sa (mg/L)	log Kowa	pKaa
Dinitroaniline herbicide
Trifluralin	2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)aniline	0.221	5.27	ND
s-Triazines and metabolites
Atrazine	6-chloro-N2-ethyl-N4-(1-isopropyl)-1,3,5-triazine-2,4-diamine	35	2.7	1.7
Deethylatrazine (DEA)	6-chloro-N4-isopropyl-1,3,5-triazine-2,4-diamine	2700	1.51	1.3b
Deisopropylatrazine (DIA)	6-chloro-N2-ethyl-1,3,5-triazine-2,4-diamine	980	1.15	1.2b
Terbuthylazine	6-chloro-N2-tert-buthyl-N4-ethyl-1,3,5-triazine-2,4-diamine	6.6	3.4	1.9
Deethylterbuthylazine (DET)	6-chloro-N2- tert-buthyl -1,3,5-triazine-2,4-diamine	327.1	2.3	1.35c
Phenylurea herbicides
Diuron	3-(3,4-dichlorophenyl)-1,1-dimethylurea	35.6	2.87	ND
Linuron	3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea	63.8	3.0	ND
Chlortoluron	3-(3-chloro-4-methylphenyl)-1,1-dimethylurea	76	2.5	ND
Isoproturon	3-(4-isopropylphenyl)-1,1-dimethylurea	70.2	2.5	ND
Chloroacetanilide herbicides
Acetochlor	2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl) acetamide	282	4.14	ND
Alachlor	2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide	240	3.09	0.62
Metolachlor	(RS)-2-chloro-N-(2-ethyl-6-methyl-phenyl)-N-(1-methoxypropan-2-yl)acetamide	530	3.4	ND
Triketone herbicides and metabolite AMBA
Mesotrione	2-[4-(methylsulfonyl)-2-nitrobenzoyl]cyclohexane-1,3-dione	1500	0.11	3.12
2-Amino-4-(methylsulfonyl) benzoic acid (AMBA)	2-amino-4-(methylsulfonyl)benzoic acid	NA	0.38d	4.24d
Tembotrione	2-[2-chloro-4-methylsulfonyl-3-(2,2,2-trifluoroethoxymethyl) benzoyl]cyclohexane-1,3-dione	71000	-1.09	3.18
Organophosphorous insecticides and oxo- metabolite
Chlorpyrifos-methyl	O,O-dimethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate	2.74	4.00	ND
Chlorpyrifos-ethyl	O,O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate	1.05	4.7	ND
Chlorpyrifos-methyl-oxon	Dimethyl (3,5,6-trichloropyridin-2-yl) phosphate	NA	1.91e	NA
Malathion	Diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate	148	2.75	ND
Chlorfenvinphos	[(EZ)-2-chloro-1-(2,4-dichlorophenyl)ethenyl] diethyl phosphate	145	3.8	ND
Pyrethroid insecticide
α-Cypermethrin	Racemate comprising (R) and (S) α-cyano-3-phenoxybenzyl- (1R,3R)-3-(2,2-dichlorovinyl)- 2,2-dimethylcyclopropane- carboxylate	0.004	5.8	ND
Neonicotinoid insecticide
Imidacloprid	N-{1-[(6-chloro-3-pyridyl)methyl]-4,5-dihydroimidazol-2-yl}nitramide	610	0.57	ND