Pesticide multiresidues in waters of the Lower Fraser Valley, British Columbia, Canada. Part I. Surface water.

In the period 2003 to 2005, a study was conducted to determine the occurrence, and spatial and temporal distribution of 78 pesticides in surface waters of the Lower Fraser Valley (LFV) region of British Columbia, Canada. A high resolution gas chromatography/electron impact high resolution mass spectrometry (HRGC/[EI]HRMS) method capable of detecting analytes at the subnanograms per liter level was developed for this study. Samples were collected and analyzed from three reference, five agricultural and two urban sites. Endosulfan sulfate was detected in all samples collected during the study period including the samples from the reference sites. The maximum concentration of a pesticide detected at the reference sites was 0.261 ng L(-1) for beta-endosulfan. Over the study period, the numbers of pesticides detected at the agricultural sites ranged from 22 to 33 of which 20.8 to 40.9% had a 100% detection frequency. At the agricultural sites, the greatest concentration was detected for diazinon (12,500 ng L(-1)), followed by linuron (1050 ng L(-1)) and simazine (896 ng L(-1)). The greatest pesticide concentration observed for the urban sites was 90.4 ng L(-1) for simazine followed by diazinon (5.39 ng L(-1)). With few exceptions, greater concentrations of herbicides were observed for samples collected during spring than for samples collected during fall. Pesticide data presented in this study provide reference levels for future pesticide monitoring programs in the region.

Pesticide multiresidues in waters of the Lower Fraser Valley, British Columbia, Canada. Part II. Groundwater.

In Part I of this work we presented pesticide levels in the surface waters of the Lower Fraser Valley (LFV) region of British Columbia, Canada. In Part II pesticide levels in the groundwater of the LFV are presented. During the period 2003 to 2005 a study was conducted to determine the occurrence and spatial distribution of 78 pesticides in the groundwater of the LFV. Samples were collected and analyzed from one reference, nine agricultural, one urban, and three urban-agriculture mixed sites. Overall 24 different pesticides were detected in the sites monitored. The maximum single pesticide concentration observed was for simazine (90 ng L(-1)) at one of the agricultural sites. All concentrations of pesticides detected in groundwater samples were below Canadian surface water quality criteria and below available drinking water quality criteria set by World Health Organization (WHO), Health Canada, USEPA, and the European Union (EU). Pesticide levels in surface and groundwater were compared in the Abbotsford area. Generally, a pesticide with a high groundwater concentration tended to also have a high surface water concentration (Simazine 29 ng L(-1) in groundwater and 58 ng L(-1) in surface water, atrazine 5.5 ng L(-1) in groundwater and 14 ng L(-1) in surface water). For pesticides that were detected above 1 ng L(-1) concentration the only exception to this was desethylatrazine that showed greater concentration in groundwater (2.2 ng L(-1)) than surface water (1.5 ng L(-1)). Herbicides were the predominant pesticides detected in the agricultural sites and insecticides were predominant in the urban sites. Pesticide data presented in this study provide reference levels for future pesticide monitoring programs in the region.

Effects of concentration, head group, and structure of surfactants on the degradation of phenanthrene.

The effects of concentration, polar/ionic head group, and structure of surfactants on the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in the aqueous phase, as well as their effects on the bacterial activity were investigated. The toxicity ranking of studied surfactants is: non-ionic surfactants (Tween 80, Brij30, 10LE and Brij35)

Effect of linear alkyl benzene sulfonates (LAS) on the fate of phenanthrene in a model ecosystem (water-lava-plant-air).

Advanced closed chamber system was used to study the fate of phenanthrene (3-rings PAHs) in the presence of linear alkylbenzene sulphonates (LAS). The results showed mineralization and metabolism of phenanthrene are fast in the "culture solution-lava-plant-air" model ecological system. The distribution proportions of applied 14C-activity in this simulative ecological system were 41%-45%, 14% to 10% and 1% in plant, lava and culture solution respectively, and 18% to 29%, 11% to 8% recovered in the forms of VOCs and CO2. Main parts of the applied 14C-activity exist in two forms, one is polar metabolites (25%) which mainly distribute in the root (23%), the other is unextractable part (23%) which have been constructed into plant root (8.98%), shoot (0.53%) or bonded to lava (13.2%). The main metabolites of phenanthrene were polar compounds (25% of applied 14C-activity), and small portion of 14C-activity was identified as non-polar metabolites (6% of applied 14C-activity) and apparent phenanthrene (1.91% of applied 14C-activity). Phenanthrene and its metabolites can be taken up through plant roots and translocated to plant shoots. The presence of LAS significantly increased the the concentration of 14C-activity in the plant and production of VOCs, at the same time it decreased the phenanthrene level in the plant and the production of CO2 at the concentration of 200 mg/L.

[Effects of surfactants on degradation of phenanthrene by Mycobacterium ssp].

With isotopic techniques, the effects of the concentration, ionic type, and straight chain length of surfactants on the degradation of phenanthrene by Mycobacterium ssp. KR2 were studied. The results showed that in the presence of surfactants, the degradation of phenanthrene was not increased. It was delayed in high concentrations of surfactants (> or = 20 mg.L-1). Tween 80 in its low concentration (< or = 10 mg.L-1) was used as a preferential substrate utilized by Mycobacterium ssp. KR2. The degradation was affected by the ionic types of surfactants, and the inhibition to the phenanthrene degradation was cationic surfactant TDTMA > anionic surfactant LAS > nonionic surfactant Tween 80. Different lengths of surfactant straight chains had different influence on the degradation of phenanthrene.

[Solubilization and behavior of surfactants in soil].

Solubility increment of hydrophobic organic compounds(HOCs) is mainly caused by the presence of surfactant micelle. Soil is exposed to a considerable quantity of surfactants, even at low concentrations, and surfactants seem to significantly alter soil physicsal, chemical and biological characteristics, with sorption process playing a dominant role. In addition, plant, soil microoganism, and bio-degradation and removal of surfactant are affected by the type, structure and concentration of surfactant, their existence circumstance, and species of microorganisms. The translocation and transformation of pollutants in soil are altered by all the above reasons, which should be paid more attention.

[Behaviors of polycylic aromatic hydrocarbons (PAHs) in the soil].

Adsorption equilibrium of PAHs in the soil can be reached by two mainly processes, "quick" and "slow". Although PAHs with low molecular may be absorbed by the plant root, and transferred and transformed into other upper part of plant, the main accumulation pathway for PAHs in plant is from the air to the leaf surface. Microbial degradation of PAHs by its enzymatic capacity is the main process of the degradation of PAHs in nature. In addition, factors effecting the biodegradation of PAHs are analyzed in details in this review.

[Advances in studies on the effect of surfactant on bioavailability of polycylcic aromatic hydrocarbons (PAHs) in soil].

The solubility and adsorption/desorption equilibrium of PAHs in soil and their interaction with soil bacterium can be altered by surfactants, which lead to the alternation of PAHs bioavailability. The bioavailability of PAHs can be enhanced by the decrease of interface tension between soil and water, the increasement of PAHs' solubility, and the transportation facilitation of PAHs in the presence of surfactants. It also can be inhibited by the surfactant toxicity to the bacteria or by the competitive ultilization between non-toxicitic surfactants and PAHs by the bacteria. In addition, the effects of surfactants on the PAHs of different existence-forms in soils are different. The bioavailability of PAHs can be affected by the type and concentrion of surfactants, PAHs and soil microorganisms, and also by soil physi-chemical characteristics.