Effect of sediment on the fate of metolachlor and atrazine in surface water

Rice, Pamela J.; Anderson, Todd A.; Coats, Joel R.

doi:10.1897/03-110

Cited by 34 publications

(21 citation statements)

References 39 publications

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“…44) Triazine herbicides were mostly resistant to biodegradation in river waters, 49,90,113,118) but some of them were degraded at moderate rates after a long lag period. 119) By using 14 C-labeled atrazine (52), Rice et al 120) have reported about 10% contribution of biotic processes in its degradation via N-dealkylation and hydrolytic dechlorination.…”

Section: Organophosphorus Pesticides (Ops)mentioning

confidence: 99%

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Aerobic microbial transformation of pesticides in surface water

Katagi

2013

J. Pestic. Sci.

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Aerobic transformation by microbial organisms is a dissipation process of pesticides in surface water, but the corresponding information is much less available as compared with their microbial degradation in soil. Bacteria freely floating in water or associated with suspended particles are the key microorganisms degrading pesticides; their species and populations, however, depend on sites and seasons. The various factors related to pesticide properties, experimental conditions and characteristics of surface water are involved in the complex control of microbial processes. Bottom sediment and macrophytes with associated biofilms not only act as sink for pesticides but also provide the habitat for both bacteria and fungi that degrade pesticides. More understanding of each factor is necessary to utilize laboratory biodegradation data for the refined assessment of pesticide behavior in surface water.

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Section: Organophosphorus Pesticides (Ops)mentioning

confidence: 99%

“…46,107,120,145,156) The catalytic hydrolysis by clay minerals and metal cations from sediments is assumed, but it is considered limited to some types of pesticides. 17) An insignificant sediment effect for an ionic pesticide that is slowly biodegraded was also observed.…”

Section: Sedimentmentioning

confidence: 99%

Aerobic microbial transformation of pesticides in surface water

Katagi

2013

J. Pestic. Sci.

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“…loss of atrazine and metolachlor in the presence of natural sediments, attributing this to more rapid biodegradation as well as sequestration by the sediments (Rice et al, 2004). Up to 10% of the herbicides were physically associated with sediments in that study, highlighting differences in the potential of sediments (affected by type) on removal of herbicides from the water column and their potential bioavailability.…”

Section: Discussionmentioning

confidence: 75%

“…Up to 10% of the herbicides were physically associated with sediments in that study, highlighting differences in the potential of sediments (affected by type) on removal of herbicides from the water column and their potential bioavailability. The inclusion of sterile sediment treatments allowed Rice et al, (Rice et al, 2004) to postulate that the presence of sediments may also influence non-biotic degradation rates. For example, humic acids often associated with sediments have been shown to increase photodegradation and hydrolysis of a range of contaminants (Cessna, 2008;Lin et al, 2008;Steen et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, the differences in degradation rates under the four experimental conditions highlights the strong effects of light and the presence of sediments on herbicide persistence in seawater. Different sediment types (and levels) will contain different concentrations of minerals and humic acids which may further aid non-biotic degradation processes and differentially sequester herbicides from the water column (Rice et al, 2004). It is highly likely that full sunlight conditions would enhance photodegradation processes, although the highest concentrations of herbicides are found in river plumes where light penetration is strongly attenuated.…”

Section: Discussionmentioning

confidence: 99%

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Herbicide persistence and toxicity in the tropical marine environment

Mercurio¹

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Agricultural herbicides are ubiquitous in the nearshore water bodies of the World Heritage listed Great Barrier Reef (GBR). The main transport mechanism for herbicides is via offsite migration during intense monsoonal rainfall events of the wet season. However, some herbicides can be detected year round, indicating potentially long persistence. Despite the high mobility and potential toxicity of herbicides, there is very little information on the degradation of herbicides in the marine environment. This study was comprised of 4 major components: Finally, to assess the potential contribution of toxicity by transformation products of four priority PSII herbicides, I directly compared the acute toxicity of partially degraded herbicides iii (including transformation products) with their parent herbicide to: (i) coral symbionts (Symbiodinium sp.) and (ii) the green algae Dunaliella sp. (iii) prawn (Penaeus monodon) larvae.Concentration dependent effects on photosynthetic efficiency (∆F/Fm') by all parent herbicides was observed in both phototrophic test species. The toxicity in all degraded solutions could be accounted for by the measured concentrations of the parent compound apart from diuron. The increased potency of the degraded diuron solution may be due to transformation products; however, it was unlikely to be caused by the most well-known breakdown product 3,4-DCA, which did not inhibit ∆F/Fm' in Symbiodinium sp. at concentrations detected in the degraded mixture. Parent herbicides affected prawn larval metamorphosis only at unrealistically high concentrations (≥ 1000 µg l -1 ). In contrast, larval prawn metamorphosis was sensitive to the transformation products of atrazine, with both DIA and DEA, significantly inhibiting metamorphosis at 3.5 and 3.8 µg l -1 , respectively. These transformation products may have contributed to inhibition observed in the degraded atrazine mixtures. 3,4-DCA caused significant inhibition in metamorphosis at 188 µg l -1and was likewise more toxic to prawn larvae than its parent herbicide diuron.Reliable data on the persistence of chemicals is important for the development of fate models applied to the spatial and seasonal distribution of these chemicals and associated the much needed risk assessments for priority herbicides found in the GBR. The experiments found that: (i)PSII herbicides were more persistent in seawater than common non-PSII herbicides in the presence of natural microbial communities; (ii) environmental conditions including temperature, light and sediments has strong influences on degradation rates, probably due to differences in microbial communities and (iii) some but not all degradation mixtures can be more toxic to phototrophic and non-phototrophic species than expected from the contributions of the parent herbicides. These experiments generated some of the most relevant and reliable data available on the persistence of high priority herbicides but more information is needed to improve our understanding of the potential persistence of emerging pesticide...

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Occurrence and endocrine effects of agrichemicals in a small Nebraska, USA, watershed

Jeffries

Abbott

Cowman

et al. 2011

Enviro Toxic and Chemistry

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The Bow Creek watershed (Nebraska, USA) is dominated by the production of beef cattle and row crops; therefore, surface waters are likely to receive runoff containing steroid hormones and pesticides. The goal of the present study was to determine the occurrence and endocrine effects of agrichemicals in this watershed. To accomplish this, four sites within the watershed-Pearl, Bow, and East Bow Creeks and a site at the confluence with the Missouri River-were selected. In June of 2008, polar organic chemical integrative samplers (POCIS) were deployed at each site, whereas in June of 2009, water and sediment samples were collected. Caged fathead minnows (Pimephales promelas) were deployed at all of the selected sites in both years. Analysis of these samples revealed that steroid hormones were not present; however, pesticides were present in POCIS extracts and water samples. In general, the amount of pesticides was higher in POCIS retrieved from Pearl and Bow Creeks than in POCIS from East Bow Creek and the confluence. This variation between sites appeared to be related to row crop density, as row crop land cover surrounding the Pearl and Bow Creek sites was higher than that surrounding the East Bow and confluence sites. To determine the endocrine effects of agrichemicals within this watershed, the hepatic mRNA expression of vitellogenin and estrogen receptor α (ERα), as well as the gonadal expression of P450 aromatase A, was determined for the caged minnows. Females deployed at East Bow Creek and the confluence experienced decreases in the expression of ERα, suggesting that these females had been defeminized; however, this defeminization could not be attributed to any of the pesticides detected at these sites.

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Effect of sediment on the fate of metolachlor and atrazine in surface water

Cited by 34 publications

References 39 publications

Aerobic microbial transformation of pesticides in surface water

Aerobic microbial transformation of pesticides in surface water

Herbicide persistence and toxicity in the tropical marine environment

Occurrence and endocrine effects of agrichemicals in a small Nebraska, USA, watershed

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