(2017-02-13) Marei, A.; Salah, N.; Al-Rimawi, F.; Khayat, S.; Damiri, B.; A. Naser, A.
One of the most important pollutants that may reach the groundwater through agricultural return flow combined with abuse and ignorance is pesticides. This study focuses on the examination of the concentration of three pesticides: Abamectin, Imidacloprid, and ß-Cyfluthrin, all of which have been used in large quantities in the Lower Jordan Valley (LJV) for the last three decades. Twenty five groundwater samples were collected from water boreholes where water is abstracted from two phreatic aquifer systems which are the Plio-Plistocene aquifer system in Jericho and Lower Al Jeftlik areas and the Eocene carbonate aquifer system in the Middle of Al Jeftlik. The depth of the boreholes in both aquifer system ranges between 80 and 120 m. Water samples were analyzed for Abamectin, Imidacloprid, and ß-Cyfluthrin using the HPLC-UV method. These samples represent two main agricultural locations (Jericho, and the Al Jeftlik). Of the 25 wells sampled, Abamectin was detected in 11 wells in concentrations ranging between 1.24 ppb and 81.71ppb. Imidacloprid was detected in 24 wells in concentrations ranging between 1.60ppb and 325.0ppb. Finally, ß-Cyfluthrin was detected in 7 wells in concentrations ranging between 1.10 and 24.46ppb. Aquifer lithology, groundwater flow directions, type of agricultural activity are major factors in controlling pesticide concentrations in groundwater. The highest values were measured where the aquifer consists of gravel and sand sediments, combined with intensive agricultural activities, followed by sand-silt aquifer. The lowest concentrations were found in boreholes where carbonate aquifer is the main source of water which indicates that other source of water flow into the system. The results of this study demonstrate that these pesticides are used heavily and in an improper way in the lower Jordan Valley, increasing the risk of adverse environmental and public health effects. Much attention should be given to addressing the potential problem of environmental and groundwater contamination by these pesticides.
HPLC method is developed and validated for determination of three pesticides (abamectin, imidacloprid,
and -cyfluthrin) in water. These pesticides are used widely in agriculture for crops protection, and may be
leached to the groundwater. Reversed-phase method with C18 column (5 μm, 250mm × 4.6 mm inner
diameter) using a mobile phase consisting of acetonitrile/water (v:v = 4:1) at a flow rate of 1.5 mL/min and
UV detection at 220 nm was used. This method is validated according to new methods which include
accuracy, precision, linearity and range, limit of detection and limit of quantitation. The current method
exhibits good linearity over the range of 1-1000 ppb for abamectin, 0.5-1000 ppb for imidacloprid, and
0.4-1000 ppb for ß-cyfluthrin with r2 greater than 0.990. The percentage recovery of the method at three
concentration levels (5, 100, and 1000 ppb) is within 97.6 to 101.5% for the three pesticides. Relative
standard deviation of the area of six replicate injections of each pesticide at three concentration levels (5.0,
100.0, and 1000.0 ppb) was found to be less than 1% which reflect the precision of the method. Limit of
quantitation of the three pesticides using this method is low (1.0, 0.5, and 0.4 ppb) for abamectin,
imidacloprid, and -cyfluthrin, respectively which enables the determination of these three pesticides in
water at low concentration levels.