Phenylureas sediment

Pesticides arrive in the Ebro River at least from two main sources. Chlorinated pesticides (DDT, HCHs, etc.), currently limited or banned in Europe, are or have been produced by different factories in Monzon and Flix, along with its subproduct HCB. These compounds are present not only in the Flix residues, but also in sediments and fauna all along the low Ebro River. In addition, modem, more sophisticated pesticides, including triazines, phenylureas, anilines, and organopho-sphates, are currently used in the intensive agricultural practices currently common in the Ebro Delta [6, 7, 10]. 

Attaway, H.H., Paynter, M.J.B., and Camper, N.D. Degradation of selected phenylurea herbicides by anaerobic pond sediment, J. Environ. Sci. Elealth, B17 683-700, 1982a. 

Robertson, A.M. and J.N. Lester (1994). Supercritical fluid extraction of s-triazines and phenylurea herbicides from sediment. Environ. Sci. Technol., 28(2) 346-351. 

It was reported that the recoveries of 17 PAHs from six certified reference marine sediments and soils [77] increased from 70 to 75% when the temperature was increased from 50° C to 115°C, and remained at 75% from 115 to 145°C. In the extraction of OCPs from sediments, recovery was unchanged from 100 to 120°C [74]. In the extraction of phenylurea herbicides from soils, the recovery peaked in the range 60 to 80°C and decreased at lower or higher temperatures [75]. In the extraction of sulfonylurea herbicides from soils, recovery dropped from 70 to 80% to 1 to 30%. due to decomposition when temperature increased from 70°C to 115°C [79]. The recovery of oligomers from poly(ethyleneterephthalate) increased as temperature rose... 

Chefetz, B., Bilkis, Y.I., Polubesova, T. (2004) Sorption-desorption behavior of triazine and phenylurea herbicides in Kishon river sediments. Water Res. 38, 4383 -394. 

Metolachlor 2-Chloro-N-[2-ethyl-6-methylphenyl]-N-[2-methoxy-l-methylethyl] acetamide atrazine 2-chloro-4-ethylamino-6-isopropylamino-j-triazine. Prometon 2,4-bis(isopropylamino)-6-methoxy-5-triazine. Cyanazine 2-[[4-chloro-6-(ethylamino)-5-triazin-2-yl]amino]-2-methylpropionitrile. Fenuron 1,1-dimethyl-3-phenylurea. Monuron l,l-dimethyl-3-(4-chlorophenyl)urea. Isotherms in water suspensions at room temperature unless otherwise indicated. Standard error of the slope. Assuming organic matter is twice the organic carbon. U.S. Environmental Protection Agency reference sediments. 

Phenylurea herbicides are also degraded under anaerobic conditions. N-(3,4-Dichlorophenyil)-N -dimethylurea (Diuron) and Linuron have shown to be dechlorinated in anaerobic sediments with elimination of the chlorine atom in the pam position [220, 221]. 

Supercritical fluid extraction (SEE) allows the analysis not only of the water samples but more complicated systems as well, e.g., of pesticides in soil samples (41a) and triazines and phenylureas in sediment (41b). Heptachlor and its metabolites, dieldrin, endrin (41c) were extracted from animal tissues by this method using only CO2 or organic solvent containing COj. Twelve OP and OC insecticides were extracted from quite different soil samples, i.e., sand, clay, etc., by SEE either with CO2 or with 3% methanol containing CO2 gas (41d) (Table 1). 

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