Ocorrência de agrotóxicos em águas subterrâneas de áreas adjacentes a lavouras de arroz irrigado

-Accelerated herbicide degradation consists in its faster degradation in areas where it has been previously applied, due to the adaptation of microbial population to that particular compound. Accelerated degradation can reduce herbicide persistence and reduce its efficacy in soil. The objective of this study was to investigate if imidazolinone herbicides have enhanced microbial degradation in rice paddy soils. A laboratory experiment was conducted, evaluating the CO 2 evolution rate from soils with and without history of herbicide application (imazapyr + imazapic and imazethapyr + imazapic), incubated with imidazolinone herbicides: imazethapyr, imazapyr, imazapic, imazamethabenz, imazamox and an untreated check. The amount of CO 2 released from the soil was measured. As a result, the prior application of imidazolinones does not stimulate microbial degradation of herbicides from the same chemical group.Keywords: residual effect, herbicide, microbial activity, Oryza sativa. RESUMO -A degradação acelerada consiste na rápida dissipação de um herbicida, sendo decorrente da adaptação da população microbiana do solo ao composto, o qual pode ser utilizado como fonte de carbono, energia e/ou nutrientes. Diversos herbicidas têm sua degradação estimulada quando aplicados em áreas com histórico de aplicação de produtos idênticos e/ou semelhantes. O objetivo deste trabalho foi verificar a degradação de imidazolinonas em solos com e sem histórico de aplicação das misturas formuladas imazethapyr + imazapic e imazapyr + imazapic. Para isso

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“…These herbicides are very mobile in the soil profile and may contaminate water sources (Silva et al, 2011).…”

Section: Resultsmentioning

confidence: 99%

Imidazolinone Degradation in Soil in Response to Application History

et al. 2015

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“…However, these herbicides may cross the soil impermeable layer and reach groundwater sources (Silva et al, 2011). This question is very important, since water sources, besides serving as rivers recharge, are also a source of drinking water for human consumption.…”

Section: Podem Persistir No Ambiente E Causar Danos àS Culturas Não Tmentioning

confidence: 99%

Carryover of Imazethapyr + Imazapic on Ryegrass and Non-tolerant Rice as Affected by Thickness of Soil Profile

et al. 2015

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-Herbicides used in Clearfield ® rice system may persist in the environment, damaging non-tolerant crops sown in succession and/or rotation. These damages vary according to soil characteristics, climate and soil management. The thickness of the soil profile may affect carryover effect; deeper soils may allow these molecules to leach, reaching areas below the roots absorption zone. The aim of this study was to evaluate the effect of the thickness of soil profile in the carryover of imazethapyr + imazapic on ryegrass and nontolerant rice, sown in succession and rotation to rice, respectively. Lysimeters of different thicknesses (15, 20, 30, 40, 50 and 65 cm) were constructed, where 1 L ha -1 of the imazethapyr + imazapic formulated mixture was applied in tolerant rice. Firstly, imidazolinone-tolerant rice was planted, followed by ryegrass and non-tolerant rice in succession and rotation, respectively. Herbicide injury, height reduction and dry weight of non-tolerant species were assessed. There was no visual symptoms of herbicide injury on ryegrass sown 128 days after the herbicide application; however it causes dry weight mass reduction of plants. The herbicides persist in the soil and cause injury in non-tolerant rice, sown 280 days after application, and the deeper the soil profile, the lower the herbicides injury on irrigated rice.Keywords: degradation, imidazolinone, Lolium multiflorum, leaching, Oryza sativa. (15, 20, 30, 40, 50 RESUMO -Os herbicidas usados na cultura do arroz

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“…However, considering the size of the country and the total amounts of pesticides applied, the number of studies describing pesticides in surface water [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and in ground water [16][17][18][19][20][21][22][23][24][25] is not large. Most of these studies have examined organochlorine pesticides, most of which have been banned in Brazil since the 1980s, except for endosulfan, which will be prohibited beginning in 2013.…”

Section: Introductionmentioning

confidence: 99%

Currently used pesticides in water matrices in Central-Western Brazil

Nogueira¹,

Dores²,

Pinto³

et al. 2012

J. Braz. Chem. Soc.

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Este estudo fornece dados sobre a presença dos pesticidas atrazina, clorpirifós, a-endossulfam, β-endossulfam, flutriafol, malatiom e metolacloro em água de áreas urbanas e rurais das cidades de Campo Verde e Lucas do Rio Verde, no estado do Mato Grosso, Brasil. Amostras de água superficial, de chuva e subterrânea foram coletadas nas estações de seca e chuva em 2007 e 2008 nessas importantes áreas produtoras de grãos. Os resultados revelaram maior diversidade de substâncias e frequência de detecção em amostras de água de chuva. Concentrações de atrazina, endossulfam e malatiom foram encontradas acima dos níveis permitidos pela legislação brasileira em algumas amostras de água superficial e subterrânea, e os metabólitos DIA (de-isopropil-atrazina) e endossulfam sulfato foram encontrados em níveis maiores do que os compostos parentais em algumas amostras. Nossos resultados demonstram a vulnerabilidade dos recursos hídricos nessas áreas e apontam para o risco de contaminação de áreas de nascentes de importantes córregos por pesticidas.This study provides data on the presence of the pesticides atrazine, chlorpyrifos, a-endosulfan, β-endosulfan, flutriafol, malathion and metolachlor in water matrices in urban and rural areas of Campo Verde and Lucas do Rio Verde Cities, Mato Grosso State, Brazil. Surface, rain, and groundwater samples were collected in the rainy and dry seasons during 2007 and 2008 in these important grain-producing areas. The findings revealed a higher diversity of compounds and frequency of detection in the rain water than in surface and groundwater samples. Concentrations of atrazine, endosulfan and malathion above those permitted by Brazilian regulations were found in some surface and groundwater samples, and the degradation products DIA (deisopropylatrazine) and endosulfan sulfate, rather than their parental compounds, were found at higher levels in some samples. Our findings show the vulnerability of water systems in these areas and point to the risk of pesticide contamination in important headwater streams.

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Ocorrência de agrotóxicos em águas subterrâneas de áreas adjacentes a lavouras de arroz irrigado

Cited by 26 publications

References 13 publications

Imidazolinone Degradation in Soil in Response to Application History

Imidazolinone Degradation in Soil in Response to Application History

Carryover of Imazethapyr + Imazapic on Ryegrass and Non-tolerant Rice as Affected by Thickness of Soil Profile

Currently used pesticides in water matrices in Central-Western Brazil

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