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Title:	Multi residue pesticides analysis in organic and conventional paddy cultivation
Authors:	Khitam Jaber Nabhan (P67324)
Supervisor:	Md Pauzi Abdullah, Prof. Dr.
Keywords:	Paddy Pesticides Extraction Universiti Kebangsaan Malaysia -- Dissertations
Issue Date:	Aug-2017
Description:	The aim of this study was to compare the status and the environmental fate of 14 Organochlorine (OCP) and 3 organophosphorus (OPP) pesticides, respectively, between conventional and organic paddy field environments. The study involves optimization of extraction methods and determination of the pesticide residues occurrence from various agricultural matrices namely water, soil, plant, paddy and rice. The pesticide concentrations in water were extracted by solid phase extraction (SPE/C18), the optimum conditions for extractions were obtained using sample volume of 1000 mL, 10 mL of 1:1 (methanol: organic free water) for conditioning and 10 mL 1:1 (acetone: n-hexane) for elution. For soil, the soil samples were Soxhlet extracted using 150 mL acetone: n-hexane (1:1) for 3 hours, then cleaned up using SPE/Florisil and elution with 10 mL n-hexane: ethyl acetate (1:1). Grains (paddy and rice) were extracted using 240 mL acetone: n-hexane (1:1) for 4 hours, the samples were cleaned up using SPE/Florisil and then elution with 8 mL 1:1 n-hexane: ethyl acetate (1:1). Plant samples were extracted after they were homogenized using acetonitrile, then cleaned up with tandem SPE PSA/GCB and finally eluted with acetone: toluene (1:1). All samples were analyzed using gas chromatography-electron capture detector (GC-ECD). Calibration curves were constructed for all compounds and the resulting correlation coefficients (r2) for the calibration curves were >0.992. The recoveries of pesticides from the spiked samples based on triplicate analysis were in the range of 74.25± 4.07% to 111.15± 2.47%. In this study, samples were collected from paddy fields in Ledang, Johor (organic and conventional paddy fields), Sungai Petani, Kedah (organic paddy field) and Kuala Perlis, Perlis (conventional paddy field). A total of 155 samples were collected during October 2015 until May 2016. The concentrations found for OCPs and OPPs in Ledang were in the range of ND to 0.680 μg/L in water, from ND to 0.690 μg/kg in soil, ND to 0.670 μg/kg in plant, from ND to 0.550 μg/kg in paddy and from ND to 0.185 μg/kg in rice. These levels were considered low and for the organic field, the presence of pesticide residues was probably from historical leftover residues or contamination from the conventional field since they were very close. Bioconcentration factors (BCFs) results indicated that plants accumulate pesticides more from the soil. In Perlis the mean concentration of OCPs and OPPs from the conventional field in all matrices (water, soil and plant) were from ND to 0.47 μg/L, ND to 0.51 μg/kg and ND to 0.41μg/kg for OCPs and OPPs respectively. These values were lower than those detected in Ledang. No pesticide was detected in Kedah organic paddy field, since pesticides have not been previously applied in this area and also it is located far away from any paddy field. In the case of soil samples from Ledang, the study indicated that pesticides were present in the top soil up to 30 cm depth. The relationship between OCPs and OPPs in all samples from conventional and organic plots illustrated that the soil was the predominant source of pesticides. The DDD+DDE/DDT ratio was >1 indicating no new use of DDT. Cluster analysis (CA) and principal component analysis (PCA) with factor analysis (FA) indicated that contamination of water and soils were not from the same source. HCH isomers, DDE, heptachlor epoxide and endosulfan compounds were recognized as the main contributors of pollutants in this area. The calculated values of hazard quotient (HQ), for the consumption of rice from Ledang, for adults and children were in the range of 1.78 x 10-3 - 1.90x10-2 and 1.75x 10-4 - 1.87 x 10-3, respectively indicating no risk to humans.,Certification of Master's/Doctoral Thesis" is not available
Pages:	214
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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