Leaching behavior and transformation of total mercury and methylmercury from raw and lime-conditioned sewage sludge under simulated rain.

Mercury (Hg) that leaches from municipal sewage sludge (MSS) landfill under natural rain is of increasing concern. The column leaching experiments were conducted to investigate the leaching characteristics of total mercury (THg) and methylmercury (MeHg) as well as pH, total organic carbon (TOC), and total suspended solids (TSS) in the raw sludge (RS) and lime-conditioned sludge (LCS) under simulated rain with different acidities (pH 6.5 and 2.9). Results showed the release of MeHg in the leachates presented different patterns from THg. And the final amounts of MeHg in the MSS columns were 1.49 (RS at pH = 6.5), 1.88 (RS at 2.9), 1.97 (LCS at pH = 6.5), and 2.06 times (LCS at pH = 2.9) higher than the initial amounts, suggesting methylation of inorganic Hg (IHg) occurred in the leaching process. The leaching efficiencies of THg and MeHg in RS was lower than that in LCS, indicating lime was more favorable for the release of THg and MeHg. And lower values of pH of the simulated rain promoted the release of THg and MeHg from RS while the opposite was true for LCS. This study provides a better understanding of the release and biogeochemical transformations of Hg in MSS.

Avaliação do desempenho de canal gramado na remoção de material suspenso em escoamento superficial pluvial / Performance of natural channel on removing suspended matter from runoff

RESUMO Neste trabalho, buscou-se avaliar o desempenho de canal gramado na remoção de material suspenso presente em escoamento superficial em unidade construída em escala real. Para tal, foram investigadas diferentes concentrações iniciais de material particulado, o qual foi descarregado por meio de chuvas simuladas em canal de 100 m de extensão e declividade de 2%. As medidas de material particulado foram feitas mediante a análise de sólidos suspensos totais (SST) em diferentes posições ao longo do canal. Os hidrogramas de descarregamento e as lâminas de água no canal foram monitorados durante a passagem da onda de cheia. Avaliaram-se as frações removidas para cada evento isolado e também em conjunto, por intermédio da interpolação por krigagem. Remoções da ordem de 50% foram obtidas para a posição de 50 m do canal gramado e de 70% para a posição de 80 m. Os resultados mostraram que a remoção de material particulado é fortemente dependente da extensão do canal e que os aspectos dinâmicos decorrentes da passagem da onda de cheia influenciam no processo.

ABSTRACT In this study, the performance of a natural channel in removing particulate matter from runoff was evaluate. For this purpose, different initial concentrations of particles, which were discharged by means of simulated 100 m in length and slope of 2% channel rains, were investigated. The measurements of particulate matter were made by means of total suspended solids (TSS) at different positions along the channel. Hydrograph and water levels in the canal during the passage of the flood wave were monitored. The removed fractions for each one of the isolated essays and also in a combined way were evaluated, by applying kriging interpolation. Removals around 50% were obtained for the channel position of 50 m and 70% for channel position of 80 m. The results indicated that the removal of particulate material is strongly dependent on the extension of the channel and the dynamic aspects arising from the passage of the flood wave influence in the process.

Potencial de lixiviação de herbicidas utilizados na cana-de-açúcar em solos contrastantes / Potential of leaching of herbicide used in sugar cane in soils contrasting

O aumento no uso de herbicidas, aliado ao emprego inadequado dessas moléculas, aumentou também as preocupações com os riscos de contaminação ambiental, bem como com seus efeitos sobre os seres humanos e animais. Objetivou-se com este trabalho avaliar o potencial de lixiviação de herbicidas utilizados na cultura da cana-deaçúcar, em solos contrastantes. Utilizaram-se amostras de Neossolo Quartzarênico (NR ­ textura arenosa) e Latossolo Vermelho (LR ­ textura argilosa). Após a aplicação dos herbicidas ametryne (NR 1,60 kg ha-1 e LR 2,40 kg ha-1), clomazone (NR 0,90 kg ha-1 e LR 1,10 kg ha-1) e diuron (NR 1,60 kg ha-1 e LR 3,20 kg ha-1) foram irrigadas lâminas de 0, 20, 40, 60, 80 e 100 mm de água nas colunas de solos. Resultados indicam que o ametryne, em amostras NR apresentou movimentação até a camada de 5-10 cm quando aplicado lâminas de 20 e 40 mm de água. Evidenciou-se que o clomazone, independente do solo, não ultrapassou a camada de 0-5 cm nas lâminas de 0 e 20 mm de água e 5-10 cm de profundidade nas lâminas acima de 40 mm de água. Com lâminas de até 80 mm, o diuron lixiviou somente nas camadas de 0-5 cm de profundidade no LR. Conclui-se que o potencial de lixiviação do ametryne e diuron foi influenciado pela textura do solo juntamente com o teor de matéria orgânica, o mesmo não ocorreu para o clomazone.

The increased use of herbicides, coupled with inadequate use of these molecules, also increased concerns about the risks of environmental contamination and its effects on humans and animals. The objective of this work evaluates the potential for leaching of herbicides in the crop of cane sugar, in contrasting soils. Used samples were used Psament (NR - sandy texture) and Oxisol Red (LR ­ clay texture). After application of herbicides ametryne (NR 1.60 kg ha-1 and LR 2.40 kg ha-1), clomazone (NR 0.90 kg ha-1 and LR 1.10 kg ha-1) and diuron (NR 1.60 kg ha-1 and LR 3.20 kg ha-1), were irrigated blades of 0, 20, 40, 60, 80 and 100 mm of water in soil columns. Results indicate that ametryne in NR samples submitted to the handling layer of 5-10 cm when applied blades of 20 and 40 mm of water. It was evident that the clomazone, regardless of the soil, did not exceed 0-5 cm water depths of 0 to 20 mm of water and 5-10 cm deep in the blades above 40 mm of water. With blades up to 80 mm, the diuron leaching only in layers 0-5 cm deep in LR. Conclude that the potential of leaching of diuron and ametryne was influenced by soil texture together with the organic matter content, the same was not true for clomazone.

Espectros de gotas e idade de trifólios e sua interação com a área abaixo da curva de progresso da ferrugem da soja / Drops spectra and leaflets age and its interaction with the area under disease progress curve of soybean rust

O objetivo do presente trabalho foi avaliar o efeito de espectros de gotas (grossas, médias e finas) na velocidade de absorção de fungicidas, para trifólios de diferentes idades, através de medida indireta expressa pelo residual de controle de ferrugem asiática da soja (Phakopsora pachyrhizi). O delineamento experimental utilizado foi inteiramente casualizado, com quatro repetições, em arranjo fatorial (3x3x5x4), cujos fatores foram compostos por: três espectros de gotas (grossas, médias e finas); três idades fisiológicas de trifólios na planta (1°, 3° e 5° trifólios); quatro períodos de tempo entre a aplicação de fungicidas e chuva simulada (0, 30, 60 e 120min.), mais uma testemunha sem chuva; três tratamentos com fungicida: azoxistrobina + ciproconazol (60+24g i.a. ha-1) + óleo mineral 0,6L ha-1, azoxistrobina (50g i.a. ha-1) + óleo mineral 0,6L ha-1 e ciproconazol (30g i.a. ha-1), mais uma testemunha sem aplicação. Avaliou-se densidade de gotas por centímetro quadrado, diâmetro mediano volumétrico, diâmetro mediano numérico, amplitude relativa, número de dias para o aparecimento da primeira pústula e a área abaixo da curva de progresso da doença. Verificou-se que gotas de menor DMV proporcionam maior velocidade de absorção de fungicidas. Trifólios mais novos absorvem os fungicidas mais rapidamente. A utilização da mistura de azoxistrobina + ciproconazol proporcionou menor evolução da doença com consequente menor área abaixo da curva de progresso da doença.

This research aimed to evaluate the effect of large, medium and fine droplets spectra and its interaction with the fungicide absorption rate and leaflets age through indirect measurement expressed by the residual of Asian soybean rust (Phakopsora pachyrhizi) control. The experimental design was composed by completely randomized design with four replications in a factorial (3x3x5x4), which factors were composed of: three drops spectra (large, medium and fine); three fisiological leaflets ages setting on the plant (1st, 3rd and 5th leaflets), four time periods between the fungicide application and simulated rain (0, 30, 60 and 120') and a control with no rain; three fungicide treatments with Azoxystrobin+Cyproconazole (60+24g a.i. ha-1) + 0.6L ha-1, Azoxystrobin (50g a.i. ha-1) + 0.6L ha-1 and Cyproconazole (30g a.i. ha-1), and control without spray. It were evaluated the density of droplets per square centimeter, volume median diameter, number median diameter, relative amplitude, number of days for the first pustule display and the area under disease progress curve. It was found that drops with smaller volume median diameter have higher fungicides absorption rates. Newer leaflets provide more quickly fungicides absorption. The use of Azoxystrobin + cyproconazole provided lower disease progress with consequent lower area under the disease progress curve.

Espectro de gotas e idade de trifólios na taxa de absorção e efeito residual de fungicidas em soja / Drops spectra and leaflets age on the fungicides absorption rate and residual effect in soybean

O objetivo do presente trabalho foi avaliar o efeito de espectros de gotas (grossas, médias e finas) na velocidade de absorção de fungicidas, para trifólios de diferentes idades através de medida indireta expressa pelo residual de controle de ferrugem asiática da soja (Phakopsora pachyrhizi). O delineamento experimental utilizado foi inteiramente casualizado, com quatro repetições, em arranjo fatorial (3x3x5x4), cujos fatores foram compostos por: três categorias de gotas (grossas, médias e finas); três diferentes posições de avaliação na planta (1°, 3° e 5° trifólios); quatro períodos de tempo entre a aplicação de fungicidas e aplicação de chuva simulada (0, 30, 60 e 120min), mais uma testemunha sem chuva; testemunha sem aplicação, mais os fungicidas azoxistrobina + ciproconazol (60+24g i.a. ha-1) + óleo mineral 0,6L ha-1, azoxistrobina (50g i.a. ha-1) + óleo mineral 0,6L ha-1 e ciproconazol (30g i.a. ha-1). Avaliou-se a densidade de gotas por centímetro quadrado, diâmetro mediano volumétrico, diâmetro mediano numérico e amplitude relativa, além do número de dias para o aparecimento da primeira pústula. Verificou-se que gotas de menor DMV proporcionam maior velocidade de absorção de fungicidas. Trifólios mais novos absorvem os fungicidas mais rapidamente. A utilização de azoxistrobina + ciproconazol + óleo mineral proporcionou o maior número de dias até o aparecimento da primeira pústula.

This research aimed to evaluate the effect of large, medium and fine droplets spectra and its interaction with the fungicide absorption rate and leaflets age through indirect measurement expressed by the residual control of Asian soybean rust (Phakopsora pachyrhizi). The experimental design was completely randomized with four replications in a factorial scheme (3x3x5x4), which factors were composed of: three drops spectra (large, medium and fine); three different positions in the plant evaluated (1st, 3rd and 5th leaflets), four time periods between the fungicide application and simulated rain (0, 30, 60 and 120') and a control with no rain; control without fungicide application, Azoxystrobin+Cyproconazole (60+24g a.i. ha-1) + 0.6L ha-1, Azoxystrobin (50g a.i. ha-1) + 0.6L ha-1 and Cyproconazole (30g a.i. ha-1). It was evaluated the density of droplets per square centimeter, volume median diameter, number median diameter and relative amplitude, and the number of days for the first pustule display. It was found that drops with smaller volume median diameter have higher fungicides absorption rates. Newer leaflets provide more quickly fungicides absorption. The use of Azoxystrobin + Cyproconazole provided the greatest number of days until the appearance of the first pustule.

EROSION OF WAXES FROM LEAF SURFACES BY SIMULATED RAIN.

Effects of simulated rain on the epicuticular wax of glaucous leaves have been studied. Droplets (250 to 400 µm) travelling at low or medium velocity (0.25 to 5 m s-1 ) fractured the dendrites and tubes on leaves of Brassica spp., the tubes on Eucalyptus globulus Labillardere and the ribbons on the adaxial surfaces of Pisum sativum L. and Fragaria ananassa Duchesne. Rates of erosion for Brassica and E. globulus leaves were high during an initial application equivalent to 1 mm rainfall but declined markedly with extended exposure. In contrast, erosion from P. sativum and F. ananassa proceeded at a fairly uniform rate throughout the exposure period. The composition of the detached wax deposits was identical with that of the intact leaf wax for Brassica species but differed for the other species. The practical consequences of wax erosion of field crops are considered.