222
and unregulated use (Popovska and Geshovska 2014). Twenty groundwater samples
were collected from the existing boreholes on the field occupied with the greenhouse production of early vegetables mostly from Solanaceae, Brassicaceae, and
Cucurbitaceae families. Groundwater is a primary source of irrigation water,
exploited mainly through domestic boreholes located on the field. Dripping irrigation systems are common practice in the region. Twenty groundwater samples were
collected in the period 2014–2015. Groundwater sampling was done according to
EPA guidelines (Johnston 2007). For that purpose water was left to flow around
10 minutes until stabilization of ECw. For pesticide analysis, an amount of 1 l was
collected in clean glass bottles and kept at 4 °C and analyzed within 48 hours. For
determination of major ions and heavy metals, amount of 2 l was collected in glass
bottles and preserved with H 2 SO 4 for determination of calcium bicarbonate (CaCO 3 ),
ammonium ions (NH 4
+
), nitrates (NO 3
−
), nitrites (NO 2
−
), and phosphates (PO 4
3−
)
and HNO 3 for determination of heavy metals (HM) and sulfates (SO 4
2−
).
7.2.2 Analysis of Physical and Chemical Characteristics
of Groundwater
A total number of 25 physical and chemical properties of collected groundwater
samples were determined including depth (d), temperature (T), hydrogen ion activity (pH), conductivity (ECw) and hardness (CaCO 3 ), major ions (Mg
+
, Na
+
, K
+
,
Ca
2+
, Cl
−
, NO 3
−
, NO 2
−
, NH 4
+
, HCO 3
−
, SO 4
2−
, and PO 4
3−
), heavy metals (Cd, Cu, Cr,
Mn, Zn, Fe, and Pb), and the trace mineral boron (B). Groundwater depth and temperature were determined in situ; pH was determined using the pH meter HANNA
HI 2211-01 according to the standard procedure prescribed by the manufacturer.
Conductivity was determined by the conductometer Jenway 4520. Major ions like
Cl
−
, NH 4
+
, NO 3
−
, NO 2
−
, SO 4
2−
, and PO 4
2−
and total hardness expressed as CaCO 3
were determined by a colorimetric method using UV-Vis spectrophotometer, type
Jenway 6715, according to the US EPA Methods 325.2 (1978), 350.2 (1974), 352.1
(1971), 354.1 (1971), 365.3 (1978), and 130.1 (1971). Heavy metals were analyzed
by inductively coupled plasma-mass spectrometry (ICP-MS, Agilent 7500 CX).
The equipment was linearly calibrated for the detector response in the range of 1 to
100 μg/l, using a certified standard solution (Sigma ICP multielement standard solution). Linearity was checked after every ten samples. Accuracy has been tested by
analyzing a certified reference material, NIST SRM 1643 c “trace elements in
water.” Bias ranged from 2% to 7%. Precision, expressed as intermediate precision,
was better than 10% for all analyzed elements.
B. Kovacevik et al.
and unregulated use (Popovska and Geshovska 2014). Twenty groundwater samples
were collected from the existing boreholes on the field occupied with the greenhouse production of early vegetables mostly from Solanaceae, Brassicaceae, and
Cucurbitaceae families. Groundwater is a primary source of irrigation water,
exploited mainly through domestic boreholes located on the field. Dripping irrigation systems are common practice in the region. Twenty groundwater samples were
collected in the period 2014–2015. Groundwater sampling was done according to
EPA guidelines (Johnston 2007). For that purpose water was left to flow around
10 minutes until stabilization of ECw. For pesticide analysis, an amount of 1 l was
collected in clean glass bottles and kept at 4 °C and analyzed within 48 hours. For
determination of major ions and heavy metals, amount of 2 l was collected in glass
bottles and preserved with H 2 SO 4 for determination of calcium bicarbonate (CaCO 3 ),
ammonium ions (NH 4
+
), nitrates (NO 3
−
), nitrites (NO 2
−
), and phosphates (PO 4
3−
)
and HNO 3 for determination of heavy metals (HM) and sulfates (SO 4
2−
).
7.2.2 Analysis of Physical and Chemical Characteristics
of Groundwater
A total number of 25 physical and chemical properties of collected groundwater
samples were determined including depth (d), temperature (T), hydrogen ion activity (pH), conductivity (ECw) and hardness (CaCO 3 ), major ions (Mg
+
, Na
+
, K
+
,
Ca
2+
, Cl
−
, NO 3
−
, NO 2
−
, NH 4
+
, HCO 3
−
, SO 4
2−
, and PO 4
3−
), heavy metals (Cd, Cu, Cr,
Mn, Zn, Fe, and Pb), and the trace mineral boron (B). Groundwater depth and temperature were determined in situ; pH was determined using the pH meter HANNA
HI 2211-01 according to the standard procedure prescribed by the manufacturer.
Conductivity was determined by the conductometer Jenway 4520. Major ions like
Cl
−
, NH 4
+
, NO 3
−
, NO 2
−
, SO 4
2−
, and PO 4
2−
and total hardness expressed as CaCO 3
were determined by a colorimetric method using UV-Vis spectrophotometer, type
Jenway 6715, according to the US EPA Methods 325.2 (1978), 350.2 (1974), 352.1
(1971), 354.1 (1971), 365.3 (1978), and 130.1 (1971). Heavy metals were analyzed
by inductively coupled plasma-mass spectrometry (ICP-MS, Agilent 7500 CX).
The equipment was linearly calibrated for the detector response in the range of 1 to
100 μg/l, using a certified standard solution (Sigma ICP multielement standard solution). Linearity was checked after every ten samples. Accuracy has been tested by
analyzing a certified reference material, NIST SRM 1643 c “trace elements in
water.” Bias ranged from 2% to 7%. Precision, expressed as intermediate precision,
was better than 10% for all analyzed elements.
B. Kovacevik et al.