Biochar obtained from eucalyptus, rice hull, and native bamboo as an alternative to decrease mobility of hexazinone, metribuzin, and quinclorac in a tropical soil

Mobile herbicides have a high potential for groundwater contamination. An alternative to decrease the mobility of herbicides is to apply materials with high sorbent capacity to the soil, such as biochars. The objective of this research was to evaluate the effect of eucalyptus, rice hull, and native bamboo biochar amendments on sorption and desorption of hexazinone, metribuzin, and quinclorac in a tropical soil. The sorption-desorption was evaluated using the batch equilibrium method at five concentrations of hexazinone, metribuzin, and quinclorac. Soil was amended with eucalyptus, rice hull, and native bamboo biochar at a rate of 0 (control-unamended) and 1% (w w-1), corresponding to 0 and 12 t ha-1, respectively. The amount of sorbed herbicides in the unamended soil followed the decreasing order: quinclorac (65.9%) > metribuzin (21.4%) > hexazinone (16.0%). Native bamboo biochar provided the highest sorption compared to rice hull and eucalyptus biochar-amended soils for the three herbicides. The amount of desorbed herbicides in the unamended soil followed the decreasing order: metribuzin (18.35%) > hexazinone (15.9%) > quinclorac (15.1%). Addition of native bamboo biochar provided the lowest desorption among the biochar amendments for the three herbicides. In conclusion, the biochars differently affect the sorption and desorption of hexazinone, metribuzin, and quinclorac mobile herbicides in a tropical soil. The addition of eucalyptus, rice hull, and native bamboo biochars is a good alternative to increase the sorption of hexazinone, metribuzin, and quinclorac, thus, reducing mobility and availability of these herbicides to nontarget organisms in soil.

Effects Caused by the Ingestion of Microplastics: First Evidence in the Lambari Rosa (Astyanax altiparanae)

Microplastics are a class of contaminants that pose a threat to aquatic biota, as they are easily found in aquatic ecosystems and can be ingested by a wide variety of organisms, such as fish. The lambari rosa (Astyanax altiparanae) is a microphage fish, which feeds on microscopic beings and particles, making it potentially susceptible to ingesting MPs discarded in the environment. In addition, this fish is of great economic and food importance, as it is used for human consumption. This study aimed to evaluate the accumulation and possible toxicological effects caused to lambari rosa (n = 450) by the ingestion of polyethylene (PE) and polyethylene terephthalate (PET) MPs, since the MPs of these polymers in the form of granules, fragments, and fibers are the most commonly reported in the aquatic environment. The parameters investigated here were the quantitative analysis of ingested MPs using microscopic and staining techniques, as well as the mortality rate, malformations/injuries, and impaired weight gain. At the end of the experiment, it was concluded that MPs from both polymers accumulated in the gastrointestinal tract of the lambari rosa, and that dietary exposure, especially to the PET polymer, was responsible for increasing the mortality rate in this species.

Bioaccumulation and Depletion of the Antibiotic Sulfadiazine 14C in Lambari (Astyanax bimaculatus)

Antibiotics are present in the environment, primarily due to their release through wastewater treatment plants, agricultural practices, and improper disposal of unused medications. In the environment, these drugs can be bioaccumulated by organisms and transferred along the food chain. This is a problem when considering the consumption of fish meat. In the United States, legislation stipulates that the maximum residue limit for sulfadiazine (SDZ) should not exceed 100 μg kg-1. Lambari fishes have potential economic importance in aquaculture, as they are relatively easy to breed and can be raised in small-scale operations. Finally, studying the biology and ecology of lambari could provide valuable information about freshwater ecosystems and their inhabitants. The current work aimed to measure the bioaccumulation and depletion of the antibiotic SDZ 14C in lambari (Astyanax bimaculatus). For this purpose, the tests were divided into two stages; seven days of exposure and seven days of depletion, where one fish was randomly selected and sampled every day. In the exposure phase, the fish were fed the medicated feed three times a day at a concentration of 2.5 mg·g-1. The control fish were fed uncontaminated feed. For the depletion phase, the remaining lambari were transferred to clean tanks and fed uncontaminated feed three times a day. The fish samples were burned in the Oxidizer and the reading of radioactivity was performed in a liquid scintillation spectrometer. It is worth noting that on day 7 and day 14, the water in the aquariums was filtered through filter paper to collect the metabolic excrement. SDZ concentrations increased over the days and accumulation occurred in the fish, with day seven presenting the maximum accumulation value of 91.7 ng·g-1 due to feeding uptake. After the depletion phase on day 13, the value found was 0.83 ng·g-1. The bioconcentration factor calculated was 20 L·kg-1. After the bioaccumulation period, the concentrations of SDZ in the water and excreta were 4.5 µg·L-1 and 363.5 ng·g-1, respectively. In the depletion period, the concentrations in the water and excreta were 0.01 µg·L-1 and 5.96 ng·g-1, respectively. These results imply that there was little SDZ bioaccumulation in the fish, but that it was distributed in larger amounts in the water. This is due to the physicochemical properties of the molecule with the low Log P value. Regarding the maximum residue limit, the value was below the established value. This study contributes to understanding SDZ dynamics in an aquatic species native to Brazil.

Egeria densa remediates the aquatic environment and reduces 14C-deltamethrin bioaccumulation in Danio rerio

Deltamethrin is an insecticide with high toxicity to non-target aquatic organisms. Environment-friendly alternatives to removing insecticides from water bodies, like phytoremediation, require species to uptake and/or dissipate pesticides from water. Our research investigated the ability of Egeria densa plants to absorb and dissipate ¹⁴C-deltamethrin from water, and bioaccumulation in Danio rerio. The variables were four densities of E. densa (0, 234, 337, and 468 g dry weight m^-3), in tanks with seven adults of D. rerio, with three replicates. Dissipation was evaluated at 0, 24, 48, 72, and 96 h after application (HAA). After 96 HAA, the uptake of ¹⁴C-deltamethrin by plants and accumulation in fish were assessed. The E. densa increased ¹⁴C-deltamethrin dissipation and reduced bioaccumulation in zebrafish. The DT₅₀ decreased 3-fold in treatments with 337 and 468 g m^-3 of E. densa. The plants absorbed 32% of the ¹⁴C-deltamethrin applied, regardless of plant density. The bioaccumulation in fish was 8.21% without E. densa and only 1% in treatments with 468 g m^-3 of plants. These results suggest phytoremediation using E. densa is a possible alternative to removing deltamethrin from water and reducing the accumulation in non-target organisms, reducing the environmental impact of insecticides in aquatic ecosystems.

Diuron, hexazinone, and sulfometuron-methyl applied alone and in mixture in soils: Distribution of extractable residue, bound residue, biodegradation, and mineralization

Biodegradation studies of herbicides applied to the soil alone and in a mixture are required since herbicides are often used in combinations to control weeds. When herbicides are applied in mixtures, interactions may affect their environmental fate. Thus, the objective of this study was to evaluate the distribution of extractable residue, bound residue, biodegradation, and mineralization of diuron, hexazinone, and sulfometuron-methyl when applied alone and in a mixture in two agricultural soils. Biometric flasks filled with two types of soil (clay and sandy) collected from an area cultivated with sugarcane and treated with ¹⁴C-radiolabeled solutions of the herbicides were incubated for 70 d. More ¹⁴C-CO₂ was released when sulfometuron-methyl and hexazinone were applied in a mixture compared to when applied alone. Being used in a combination did not affect the mineralization of diuron. The soil texture directly influenced the mineralization, bound residue, and extractable residue of the three herbicides. The percentage of extractable residue decreased over time for all herbicides. Hexazinone and sulfometuron-methyl had the highest residue extracted on sandy soil when applied alone. Diuron showed the highest percentage of bound residue. The degradation of the three herbicides was higher in the clay soil regardless of the mode of application, which is related to the higher potential of the bacterial community in the clay soil to mineralize the herbicides.

The role of land use, management, and microbial diversity depletion on glyphosate biodegradation in tropical soils

Land use and management changes affect the composition and diversity of soil bacteria and fungi, which in turn may alter soil health and the provision of key ecological functions, such as pesticide degradation and soil detoxification. However, the extent to which these changes affect such services is still poorly understood in tropical agroecosystems. Our main goal was to evaluate how land-use (tilled versus no-tilled soil), soil management (N-fertilization), and microbial diversity depletion [tenfold (D1 = 10^-1) and thousandfold (D3 = 10^-3) dilutions] impacted soil enzyme activities (β-glycosidase and acid phosphatase) involved in nutrient cycles and glyphosate mineralization. Soils were collected from a long-term experimental area (35 years) and compared to its native forest soil (NF). Glyphosate was selected due to its intensive use in agriculture worldwide and in the study area, as well as its recalcitrance in the environment by forming inner sphere complexes. Bacterial communities played a more important role than the fungi in glyphosate degradation. For this function, the role of microbial diversity was more critical than land use and soil management. Our study also revealed that conservation tillage systems, such as no-tillage, regardless of nitrogen fertilizer use, mitigates the negative effects of microbial diversity depletion, being more efficient and resilient regarding glyphosate degradation than conventional tillage systems. No-tilled soils also presented much higher β-glycosidase and acid phosphatase activities as well as higher bacterial diversity indexes than those under conventional tillage. Consequently, conservation tillage is a key component for sustaining soil health and its functionality, providing critical ecosystem functions, such as soil detoxification in tropical agroecosystems.

Availability of Metribuzin-Loaded Polymeric Nanoparticles in Different Soil Systems: An Important Study on the Development of Safe Nanoherbicides

Nanoformulations have been used to improve the delivery of fertilizers, pesticides, and growth regulators, with a focus on more sustainable agriculture. Nanoherbicide research has focused on efficiency gains through targeted delivery and environmental risk reduction. However, research on the behavior and safety of the application of these formulations in cropping systems is still limited. Organic matter contained in cropping systems can change the dynamics of herbicide−soil interactions in the presence of nanoformulations. The aim of this study was to use classical protocols from regulatory studies to understand the retention and mobility dynamics of a metribuzin nanoformulation, compared to a conventional formulation. We used different soil systems and soil with added fresh organic material. The batch method was used for sorption−desorption studies and soil thin layer chromatography for mobility studies, both by radiometric techniques. Sorption parameters for both formulations showed that retention is a reversible process in all soil systems (H~1.0). In deep soil with added fresh organic material, nanoformulation was more sorbed (14.61 ± 1.41%) than commercial formulation (9.72 ± 1.81%) (p < 0.05). However, even with the presence of straw as a physical barrier, metribuzin in nano and conventional formulations was mobile in the soil, indicating that the straw can act as a barrier to reduce herbicide mobility but is not impeditive to herbicide availability in the soil. Our results suggest that environmental safety depends on organic material maintenance in the soil system. The availability can be essential for weed control, associated with nanoformulation efficiency, in relation to the conventional formulation.

Development of a Preemergent Nanoherbicide: From Efficiency Evaluation to the Assessment of Environmental Fate and Risks to Soil Microorganisms

Nanoparticles based on biodegradable polymers have been shown to be excellent herbicide carriers, improving weed control and protecting the active ingredient in the crop fields. Metribuzin is often found in natural waters, which raises environmental concerns. Nanoencapsulation of this herbicide could be an alternative to reduce its losses to the environment and improve gains in its efficiency. However, there is a paucity of information about the behavior of nanoformulations of herbicides in environmental matrices. In this study, the stability of nanoencapsulated metribuzin in polymeric nanoparticles (nanoMTZ) was verified over time, as well as its dissipation in different soils, followed by the effects on soil enzymatic activity. The physiological parameters and control effects of nanoMTZ on Ipomoea grandifolia plants were investigated. No differences were verified in the half-life of nanoencapsulated metribuzin compared to a commercial formulation of the herbicide. Moreover, no suppressive effects on soil enzymatic activities were observed. The retention of nanoMTZ in the tested soils was lower compared to its commercial analogue. However, the mobility of nanoencapsulated metribuzin was not greatly increased, reflecting a low risk of groundwater contamination. Weed control was effective even at the lowest dose of nanoMTZ (48 g a.i. ha^-1), which was consistent with the higher efficiency of nanoMTZ compared to the conventional herbicide in inhibiting PSII activity and decreasing pigment levels. Overall, we verified that nanoMTZ presented a low environmental risk, with increased weed control.

Land use and roles of soil bacterial community in the dissipation of atrazine

Atrazine (ATZ) is one of the most widely used herbicides in the world even though it is classified as a carcinogenic endocrine disruptor. This study focused on how land use (grazing versus cultivation in parallel soils, the latter under no-till with a seven-year history of ATZ application) and bacterial community diversity affected ATZ dissipation. Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Acidobacteria, Verrucomicrobia, Planctomycetes, and Gemmatimonadetes were the dominant phyla in both soils. The mineralization of ATZ was much higher in soils under cultivation up to the onset of moderate diversity depletion (dilution =10^-3), corresponding to 44-52% of the amount applied (< 5% in the grazed soil). This was attributed to the higher diversity and complexity of the soils´ bacterial communities which consist of microbial groups that were more adapted as a result of previous exposure to ATZ. In these cases, ATZ dissipation was attributed mainly to mineralization (DT₅₀ = 4-11 d). However, formation of non-extractable ATZ residues was exceptionally important in the other cases (DT₅₀ = 17-44 d). The cultivated soils also presented a higher number of bacterial genera correlated with ATZ dissipation, in which Acidothermus, Aquicela, Arenimonas, Candidatus_Koribacter, Hirschia, MND1, Nitrospira, Occallatibacter, OM27_clade, and Ralstonia are suggested as potential ATZ-degraders. Finally, ATZ dissipation was mostly associated with an abundance of microbial functions related to energy supply and N-metabolism, suggesting co-metabolism is its first biodegradation step.

Accessing biochar's porosity using a new low field NMR approach and its impacts on the retention of highly mobile herbicides

Agrowaste biochars [sugarcane straw (SS), rice husk (RH), poultry manure (PM), and sawdust (SW)] were synthesized at different pyrolysis temperatures (350, 450, 550, and 650 °C) to evaluate their potential to retain highly mobile herbicides, such as hexazinone and tebuthiuron that often contaminate water resources around sugarcane plantations. A new low field nuclear magnetic resonance approach based on decay due to diffusion in internal magnetic field (NMR-DDIF) was successfully used to determine biochar's porosity and specific surface area (SSA) to clear the findings of this work. SSA of pores with diameters >5.0 μm increased with pyrolysis temperatures and seemed to dictate biochar's retention, which was >70% of the applied amounts at 650 °C. These macropores appear to act as main arteries for herbicide intra-particle diffusion into smaller pores, thus enhancing herbicides retention. Biochar granulometry had little, but herbicide aging had a significant effect on sorption, mainly of tebuthiuron. However, soils amended with 10,000 kg ha^-1 of the biochars showed low sorption potential. Therefore, higher than usual biochar rates or proper incorporation strategies, i.e., surface incorporation, will be needed to remediate areas contaminated with these highly mobile herbicides, thus precluding their leaching to groundwaters.

Foliar absorption and field herbicidal studies of atrazine-loaded polymeric nanoparticles

Nanoparticles loaded with atrazine show weed control efficacy even with lower application doses of the active ingredient. Changes in the mode of action of the herbicide through the nanoformulation are key to understanding the efficiency of post-emergence activity of nanoatrazine. Here, we report the leaf absorption and translocation of nanoatrazine and atrazine employing radiometric techniques and compare their herbicidal effects in greenhouse and field conditions. Compared to the commercial formulation, nanoatrazine showed greater and faster absorption rates in mustard leaves (40% increment in the absorbed herbicide 24 h after application), inducing higher inhibition of photosystem II activity. Assays with fusicoccin-treated leaves indicated that the stomatal uptake of nanoparticles might be involved in the improved activity of nanoatrazine. Nanoencapsulation potentiated the post-emergent herbicidal activity of atrazine and the gain provided by nanoencapsulation was higher in the field compared to greenhouse conditions. Regardless of the dose, nanoatrazine provided two-fold higher weed control in the field compared to commercial atrazine. Thus, the design of this carrier system enables improvements in the performance of the herbicide in the field with less risk of environmental losses of the active ingredients due to faster absorption.

Using 14C-glyphosate to investigate the distribution of two formulations in transgenic glyphosate-resistant soybean

Glyphosate residues in grain can be explained by the concentrations and formulations of glyphosate products. This study aimed to evaluate the residues from glyphosate formulations labeled with 14C-glyphosate applied to leaves of glyphosate-resistant soybean (GRS) in two life cycles by liquid scintillation spectrometry. Different plant tissues were analyzed after the end of the plants' life cycles. The experimental design was four repetitions of three treatments: Roundup® Original, Roundup Ready®, and unformulated glyphosate (control). The application of the dosing solution was 120 µL on the first four trifoliate leaves (10 µL per leaflet) of each plant, deposited manually with a 1-µL dispenser. All treatment solutions were calculated at a 1.2 kg a.e ha-1 of glyphosate. Glyphosate formulations of Roundup® Original and Roundup Ready® increased 14C-glyphosate distribution in GRS compared to the unformulated herbicide, regardless of the experiment (first or second cycle). Overall, the percentages of total radioactivity applied (18.33 kBq) found in grains were less than 5%. Grains, stems, and leaves showed the highest levels of herbicide residues compared to other parts of the plant. Despite the Roundup Ready® formulation having increased residues, the highest value found in grains, 1.95 mg kg-1, was less than 10 mg kg-1, the maximum residue limit (MRL) in Brazil.

Indaziflam sorption-desorption and its three metabolites from biochars- and their raw feedstock-amended agricultural soils using radiometric technique

This study aimed to characterize the effect of amending soils with biochars derived from soybean residues, sugarcane bagasse, and wood chips on the sorption-desorption of indaziflam and indaziflam-triazinediamine (FDAT), indaziflam-triazine-indanone (ITI), and indaziflam-carboxylic acid (ICA) metabolites applied to soils from three Midwestern U.S. states, a silt loam and a silty clay loam. Biochars produced from different feedstock were used as soil amendments and compared with raw feedstock. Sorption-desorption experiments of indaziflam and its three metabolites were performed using the batch equilibration method and analyzed for ¹⁴C activity by liquid scintillation counting (radiometric technique). In all soils, the use of organic amendments promoted greater sorption and less desorption of indaziflam and ITI. The addition of biochar to soils promoted greater sorption of the four tested chemical products compared with the corresponding raw materials. Among the biochars, grape wood chips showed greater potential in sorb indaziflam and ITI. In general, none of the biochars affected the sorption and desorption of FDAT and ICA. Characterization of biochar to be used as a soil amendment (immobilizer) is highly recommended prior to field addition to optimize the sorption process and to prevent increased soil and water contamination of indaziflam and its metabolites following biochar addition.

Potential of Egeria densa and Pistia stratiotes for the phytoremediation of water contaminated with saflufenacil

Saflufenacil is an herbicide that is leachable in soil and has the potential to contaminate groundwater, besides having moderate toxicity to aquatic organisms. Some macrophyte species may interfere with the availability of herbicides in water, increasing dissipation in this environment. Thus, the objective of this work was to evaluate the absorption and dissipation of ¹⁴C-saflufenacil in water by Egeria densa and Pistia stratiotes. Dissipation was performed with ¹⁴C-saflufenacil applied directly in water and quantified by liquid scintillation spectrometry (LSS). The evaluation times were 0, 3, 6, 24, 48, 72 and 96 h after application (HAA) for E. densa and 0, 12, 24, 36, 48, 60, 84 and 108 HAA for P. stratiotes. Absorption was analyzed through plant combustion in a biological oxidizer. The presence of the macrophytes increased the dissipation of ¹⁴C-saflufenacil in water. The half-life time (DT₅₀) of the herbicide decreased by 82.6% in the presence of E. densa at 96 HAA. For P. stratiotes, the reduction in DT₅₀ was 94.8% at 108 HAA. The absorption of ¹⁴C-saflufenacil was low for both macrophytes during the evaluated time. However, the macrophytes E. densa and P. stratiotes showed potential for the phytoremediation of water contaminated with saflufenacil.

Sulfadiazine dissipation as a function of soil bacterial diversity

Antibiotic residues in the environment are concerning since results in dispersion of resistance genes. Their degradation is often closely related to microbial metabolism. However, the impacts of soil bacterial community on sulfadiazine (SDZ) dissipation remains unclear, mainly in tropical soils. Our main goals were to evaluate effects of long-term swine manure application on soil bacterial structure as well as effects of soil microbial diversity depletion on SDZ dissipation, using "extinction dilution approach" and ¹⁴C-SDZ. Manure application affected several soil attributes, such as pH, organic carbon (OC), and macronutrient contents as well as bacterial community structure and diversity. Even minor bacterial diversity depletion impacted SDZ mineralization and non-extractible residue (NER) formation rates, but NER recovered along 42 d likely due to soil diversity recovery. However, this period may be enough to spread resistance genes into the environment. Surprisingly, the non-manured natural soil (NS-S1) showed faster SDZ dissipation rate (DT₉₀ = 2.0 versus 21 d) and had a great number of bacterial families involved in major SDZ dissipation pathways (mineralization and mainly NER), such as Isosphaeraceae, Ktedonobacteraceae, Acidobacteriaceae_(Subgroup_1), Micromonosporaceae, and Sphingobacteriaceae. This result is unique and contrasts our hypothesis that long-term manured soils would present adaptive advantages and, consequently, have higher SDZ dissipation rates. The literature suggests instantaneous chemical degradation of SDZ in acidic soils responsible to the fast formation of NER. Our results show that if chemical degradation happens, it is soon followed by microbial metabolism (biodegradation) performed by a pool of bacteria and the newly formed metabolites should favors NER formation since SDZ presented low sorption. It also showed that SDZ mineralization is a low redundancy function.

Spatial distribution of sorption and desorption process of 14C-radiolabelled hexazinone and tebuthiuron in tropical soil

The understanding of the interaction between soil physicochemical attributes and herbicide behavior is fundamental for optimizing the efficient use of PRE-emergence herbicides in a more sustainable approach. However, it is still a poorly studied area within precision agriculture. Thus, the objective of this research was to evaluate the correlation of soil physicochemical attributes with the sorption and desorption processes of hexazinone and tebuthiuron to support application maps considering the field level variability. Soil samples from an agricultural area had their physicochemical attributes analyzed and were submitted to sorption and desorption studies of ¹⁴C-tebuthiuron and ¹⁴C-hexazinone using the batch equilibrium method. The values of sorption and desorption apparent coefficients (K_d), sorption and desorption percentage and bioavailability were correlated with soil attributes by Pearson's correlation. The K_d values of tebuthiuron and hexazinone sorption ranged from 1.2 to 2.9 mL g^-1 and 0.4-0.6 mL g^-1, respectively. For desorption of tebuthiuron and hexazinone, K_d values ranged from 3.4 to 4.4 mL g^-1 and 2.6-3.0 mL g^-1, respectively. A positive correlation among clay content, soil organic matter (OM), and tebuthiuron and hexazinone sorption K_d values were found. Both herbicides had variable retention according to geographic position in the area. The recommendation of application of PRE herbicides, such as tebuthiuron and hexazinone, observing the physicochemical attributes of the soil is an alternative to increase efficiency in weed control and decrease the risk of environmental contamination.

Effect of Fertiactyl® on the absorption and translocation of 14C-glyphosate in young eucalyptus plants

Fertiactyl® is a foliar fertilizer with the potential to minimize the phytotoxicity effects caused by glyphosate drift in eucalyptus plants. As the interactions of the glyphosate and Fertiactyl® in tank mix on the plant behavior are not yet known, the objective was to evaluate the absorption and translocation of 14C-glyphosate, applied isolated and mixed in tank with Fertiactyl®, in young eucalyptus plants (clone I-144, Eucalyptus urophylla x E. grandis). The addition of Fertiactyl® to the mixture of 14C-glyphosate reduced the absorption by 94.3% in relation to the total absorbed at the end of the evaluation compared to plants treated only with 14C-glyphosate, i.e., Fertiactyl® protected the eucalyptus plants of the glyphosate intoxication by drift. The translocation rates from the treated leaves to the rest of the shoots and roots were low (<2% of the total recovered) in both treatments, suggest that restricted translocation is a mechanism of natural tolerance to glyphosate in plants of clone I-144. It is concluded that Fertiactyl®, mixed in the solution with glyphosate, protects young eucalyptus plants against glyphosate drift by reducing the amount of herbicide absorbed.

Sorption-desorption and biodegradation of sulfometuron-methyl and its effects on the bacterial communities in Amazonian soils amended with aged biochar

Sulfometuron-methyl is a broad-spectrum herbicide, used throughout Brazil; however, its environmental impacts in biochar (BC) amended soils is not fully understood. Biochar is known to enhance soil quality but can also have undesired effects such as altering the bioavailability and behavior of herbicides. Microbial communities can degrade herbicides such as sulfometuron-methyl in soils; however, they are known to be affected by BC. Therefore, it is important to understand the tripartite interaction between these factors. This research aimed to evaluate the sorption-desorption and biodegradation of sulfometuron-methyl in Amazonian soils amended with BC, and to assess the effects of the interactions between BC and sulfometuron-methyl on soil bacterial communities. Soil samples were collected from field plots amended with BC at three doses (0, 40 and 80 t ha^-1) applied ten years ago. The herbicide sorption and desorption were evaluated using a batch equilibrium method. Mineralization and biodegradation studies were conducted in microcosms incubated with ¹⁴C-sulfometuron-methyl for 80 days. Systematic soil sampling, followed by DNA extraction, quantification (qPCR) and 16S rRNA amplicon sequencing were performed. The presence of BC increased the sorption of the herbicide to the soil by 11% (BC40) and 16% (BC80) compared to unamended soil. The presence of BC also affected the degradation of ¹⁴C-sulfometuron-methyl, reducing the mineralization rate and increasing the degradation half-life times (DT50) from 36.67 days in unamended soil to 52.11 and 55.45 days in BC40 and BC80 soils, respectively. The herbicide application altered the bacterial communities, affecting abundance and richness, and changing the taxonomic diversity (i.e., some taxa were promoted and other inhibited). A tripartite interaction was found between BC, the herbicide and soil bacterial communities, suggesting that it is important to consider the environmental impact of soil applied herbicides in biochar amended soils.

Sorption and desorption of pendimethalin alone and mixed with adjuvant in soil and sugarcane straw

Sugarcane straw may work as a physical barrier for pre-emergent herbicides and interact with their molecules, increasing sorption process. Adjuvants may change herbicides dynamics in the environment and improve their efficiency for weed control. The objective of this work was to evaluate sorption and desorption of pendimethalin alone and in mixture with adjuvant in soil and sugarcane straw. Sorption experiments were performed using pendimethalin alone and in mixture with vegetable oil with herbicide solution concentrations ranging between 2.5 and 40 μg mL^-1 for both conditions. Sorption distribution coefficient (K_d) for soil was 18.48 mL g^-1 using pendimethalin alone. K_d value was not determined when pendimethalin was in mixture with adjuvant due to the complete retention of the herbicide in the soil regardless of the initial aqueous phase concentration. Sugarcane straw sorption experiment had K_d values corresponding to 355.52 and 27.24 mL g^-1 for pendimethalin alone and in mixture with adjuvant, respectively, indicating the addition of vegetable oil may significantly decrease pendimethalin retention in the straw and could improve weed control. Besides all desorption coefficients were higher than the respective sorption coefficients, which means that the sorption process may be considered irreversible.

Fertiactyl® in mixture with glyphosate decreases herbicide absorption and translocation in coffee seedlings

The application of glyphosate to coffee crops can cause injuries to plants. Fertiactyl® foliar fertilizer reduces injuries when mixed with glyphosate; however, it is important to establish which mechanisms are responsible for this protective action. This study aimed to evaluate the absorption and translocation of glyphosate applied separately and in mixture with Fertiactyl® in coffee seedlings. Absorption and translocation were performed with 14C-glyphosate applied separately and in mixture with Fertiactyl® at 0, 6, 12, 24, 48, 96, and 144 hours after application (HAA). Most of the 14C-glyphosate applied to coffee seedlings was not absorbed. The 14C-glyphosate applied separately had a higher absorption by coffee seedlings (6.5%) than in a mixture with Fertiactyl® (2.7%) at 144 HAA. The maximum translocation of the 14C-glyphosate applied separately was 0.69% at 81.2 HAA and in mixture with Fertiactyl® was 0.41% at 41.2 HAA. The treated leaves retained a higher percentage of 14C-glyphosate when applied separately (5.6% at 144 HAA) than in a mixture with Fertiactyl® (2.2% at 144 HAA). Low translocation (<1%) for the rest of the plant shoots was observed both for the 14C-glyphosate applied separately and in combination with Fertiactyl®. Therefore, Fertiactyl® decreased the absorption and translocation of 14C-glyphosate in coffee seedlings.

Phytoextraction of diuron, hexazinone, and sulfometuron-methyl from the soil by green manure species

The herbicides diuron, hexazinone, and sulfometuron-methyl present a potential risk of environmental contamination and are widely used for weed control in sugarcane cultivation. Our objectives were to measure the tolerance of Canavalia ensiformes (L.) DC., Stilizobium aterrimum L., Raphanus sativus L., Crotalaria spectabilis Röth, Lupinus albus L., and Pennisetum glaucum (L.) R. Br. To the herbicides diuron, hexazinone, and sulfometuron-methyl to assess the capacity of these species to extract and accumulate the herbicides in their tissues. Before sowing the green manure species, the soils were individually contaminated with the three ¹⁴C-radiolabeled herbicides. ¹⁴C-diuron and ¹⁴C-sulfometuron-methyl showed higher values remaining in the soil (>90%) for all species of green manure compared to hexazinone (<80%). The green manure species analyzed showed greater potential to remedy soils contaminated with hexazinone than the other herbicides. C. ensiformes showed high phytoextraction of hexazinone when compared to the other species, removing 11.2% of the pollutant from the soil, followed by L. albus (8.6%), S. aterrimum (7.3%), R. sativus (4.8%), C. spectabilis (2.5%), and P. glaucum (1.1%). The results indicate that the phytoextraction of diuron, hexazinone and sulfometuron-methyl is dependent on the species of green manure and can be an important tool for the decontamination of areas polluted by these herbicides.

Phytoremediation of quinclorac and tebuthiuron-polluted soil by green manure plants

Quinclorac and tebuthiuron are residual herbicides that may remain in the soil longer than for the cropping season. The objective of this research was to evaluate the use of green manure plants to remediate soils treated with quinclorac and tebuthiuron. Soils were separately treated with ¹⁴C-quinclorac and ¹⁴C-tebuthiuron at 266.4 and 132 g ha^-1, respectively. After 21 days, four green manure plants, namely Crotalaria spectabilis, Canavalia ensiformis, Stizolobium aterrimum, and Lupinus albus, were separately sown in the treated soils. Overall, all four species absorbed more ¹⁴C-tebuthiuron [C. ensiformes (22.49%), S. aterrimum (16.71%), L. albus (15%), and C. spectabilis (4.48%)] than ¹⁴C-quinclorac [C. ensiformis (13.44%), L. albus (10.02%), S. aterrimum (6.2%), and C. spectabilis (1.75%)]. Quinclorac translocation in all four plants was greater in young leaves compared to old leaves, cotyledons, or roots, and ¹⁴C-tebuthiuron translocation in all four plant species was greater in old leaves and cotyledons compared to young leaves or roots. Regardless of the differences in translocation between the two herbicides, the four green manure plants are capable to remediate soils that have been treated with quinclorac and tebuthiuron. However, C. ensiformis is more efficient for the remediation of tebuthiuron-treated soil compared to the other plants.

Sulfadiazine dissipation in acidic tropical soils

Sulfadiazine (SDZ) residues have been detected in manured soils as well as their adjacent water resources, but its behavior is still poorly understood in acidic tropical soils. This research aimed to evaluate sorption, leaching, and biodegradation of ¹⁴C-SDZ in four acidic soils from Brazil, using OECD guidelines. Except for the sand soil (K_d = 2.6 L kg^-1), SDZ sorption tended to be higher (K_d > 8.4 L kg^-1) and more hysteretic (ΔH >> 1) in acidic soils. When freshly applied, SDZ leaching was low (< 0.11% of applied radioactivity (AR)) and could not always be predicted by K_d values; but leaching was restricted when SDZ was aged for 62 days. SDZ mineralization was low (< 3%) but its dissipation was fast (DT₅₀ < 2.3 days and DT₉₀ < 6.3 days) due to fast initial degradation (an unknown metabolite was immediately formed, likely 4-hydroxysulfadiazine) and mainly to fast formation of non-extractable residues (NER) (> 78% of AR up to 7 days). For certain acidic soils, the abrupt breakdown of the SDZ suggests that degradation should be initially chemical and then followed by enzymatically driven reactions. The fast formation of NERs was attributed mostly to chemical bounding to soil humic substances (Type II-NER), but SDZ sequestration cannot be ruled out (Type I-NER). NERs represent a long-term environmental reservoir of SDZ that may cause deleterious effects on non-target organisms as well as promote antibiotic resistance to soil microbes.

Limited Diclosulam Herbicide Uptake and Translocation-Induced Tolerance in Crotalaria juncea

The study was to identify the potential tolerance of Crotalaria juncea to diclosulam uptake and translocation and its effects on the physiological metabolism of plants. Two experiments were carried out; I-Evaluation of uptake and translocation of ¹⁴C-diclosulam (35 g a.i. ha^-1) in C. juncea, at seven and 14 days after emergence. II-Evaluation of chlorophyll a transient fluorescence of dark-adapted C. juncea leaves when applied diclosulam in pre-emergence. Plants of C. juncea presented an anatomical/metabolic barrier to diclosulam translocation in the stem, which may confer tolerance to this herbicidal, besides reduced translocation due to low accumulation in the cotyledons. In addition, plants can maintain photosynthetic metabolism active when growing in soil with diclosulam by not changing the dynamics of energy dissipation. Thus, when cultivated in soil with residual of diclosulam, C. juncea can tolerate the herbicide to maintain plant growth.

Atrazine movement in corn cultivated soil using HYDRUS-2D: A comparison between real and simulated data

Atrazine is an herbicide that is applied in corn around the world and in sugarcane in Brazil. It is known to be hazardous for animals' health, mobile in the soil, and its analysis is considered expensive and onerous. Solute movement studies are essential to provide information about dangerous molecules movement, which can avoid contamination. While field investigations demand time and financial resources, numerical models are an alternative to describe water and solute distribution in the soil profile. Thus, the objective of this work was to use HYDRUS 2-D model for simulations of atrazine movement in containers packed with tropical soil cultivated with corn and to compare simulated and observed data through statistical parameters. The research was carried out in a greenhouse during 116 days after planting. Atrazine was analyzed in the soil solution at three different depths to validate HYDRUS-2D. Simulations were carried out using hydraulic properties fitted directly to measured retention data and parameters for corn growing and atmospheric characteristics. The mixed procedure analysis indicated that there are differences in atrazine concentration among depths and along time. In general, atrazine concentration is higher at shallow depths and right after application. However, it is possible to find atrazine in deeper soil layers, which might be a concern regarding contamination. RMSE, Willmott and Pearson coefficients indicated a favorable capacity of the model to simulate atrazine concentration on corn cultivation. HYDRUS-2D is a reliable tool to obtain trends in atrazine movement under these experiment's conditions. The uptake parameters, the crop root growth and distribution parameters depend on further specific studies to better describe the relationship between the plant and atrazine and meteorological parameters need to be updated.

Respiration induced by substrate and bacteria diversity after application of diuron, hexazinone, and sulfometuron-methyl alone and in mixture

After application, herbicides often reach the soil and affect non-target soil microorganisms, decreasing their population, diversity or affecting metabolic activity. Therefore, laboratory studies were performed to evaluate the effects of diuron, hexazinone and sulfometuron-methyl alone and mixed upon carbon transformation by soil microorganisms in clayey and sandy soils and the effect on bacterial diversity and structure. Control treatment without herbicide application was also performed. Sub-samples from the control and herbicide treatments (10 g - in triplicate) were collected before herbicide application and 7, 14, 28 and 42 days after treatment (DAT), then 1 mL of ¹⁴C-glucose solution was applied. The released ¹⁴CO₂ was trapped in 2 M NaOH solution and the radioactivity was analyzed by liquid scintillation counting (LSC), 12 h after glucose application. The effect of herbicides on bacterial diversity was evaluated by T-RFLP. The experiment was conducted in a complete randomized design. Hexazinone did not affect ¹⁴CO₂ evolution. Diuron showed a greater ¹⁴CO₂ evolution in sandy and clayey soil, while sulfometuron-methyl led to an increase in sandy soil, at 42 DAT. A greater evolution of carbon was observed in the treatment with herbicide mixture in sandy soil, compared with the same treatment in clayey soil or control. However, the herbicide mixture application did not affect the soil biological activity measured by the respiration rate induced by substrate. On the other hand, the herbicide mixtures affected the bacterial diversity in both soils, being the strongest effect to diuron and sulfometuron-methyl in clayey soil and hexazinone in sandy soil.

The Dissipative Potential of Gamma Irradiation in Residues of Imidacloprid and Thiamethoxam in the Postharvest of Common Beans

Gamma irradiation (⁶⁰ Co) in postharvest of common beans (Phaseolus vulgaris L.), has already proven beneficial, regarding the prolongation of shelf life and physical, chemical, and organoleptic aspects of grains. However, few prior studies have investigated the effect of gamma irradiation on the dissipation of pesticides in foods, especially insecticides in beans. This study aimed to evaluate the waste dissipation of two insecticides, imidacloprid and thiamethoxam, used in the cultivation of common bean, a variety of Carioca, using gamma irradiation. Ground bean samples were spiked each insecticide in the laboratory at 3, 4, and 5 mg/kg, and were then irradiated at 0, 1, and 2 kGy per irradiator with a ⁶⁰ Co source. Liquid chromatography-tandem mass spectrometry was used to quantify the insecticides. The irradiation promoted dissipation of thiamethoxam at 1 and 2 kGy doses, with the highest dissipation verified at 2 kGy. In general, at this higher dose of irradiation the reduction dissipation of thiamethoxam was 66% of the mean value found in the treatment without irradiation and ∼44% relative to the 1 kGy dose. Conversely, imidacloprid showed no effect of irradiation on waste dissipation, except in the treatment of 5 mg/kg at 2 kGy dose. From the results, it was concluded that the gamma irradiation might have applicability in dissipating thiamethoxam in real bean samples.

PRACTICAL APPLICATION

Pesticide residues remaining from bean cultivation, sensitive to optimal doses of gamma irradiation, can be transformed into other less harmful or nonharmful substances, increasing the quality of the beans before the food arrives at the consumer's table. Irradiation of the grains after harvest also eliminates the need for application of other pesticides to preserve the grains during storage, as the technique is capable of eradicating deteriorating agents, such as microorganisms and insects.

Absorption and translocation of sulfometuron-methyl in sugarcane (Saccharum officinarum L.) at different growth stages

In Brazil, weed management in sugarcane fields is mainly done with the use of selective herbicide formulations. For many years, diuron+hexazinone was one of the main herbicide mixture formulations used in sugarcane. Later, sulfometuron-methyl was included in the same mixture, which was marketed as a new herbicide formulation for residual in-season weed control in sugarcane. The mixture diuron+hexazinone+sulfometuron-methyl has been widely used in commercial sugarcane fields in Brazil. However, recent field observations have shown that sugarcane plants at different growth stages varied in their phytotoxicity levels after treatment with diuron+hexazinone+sulfometuron-methyl. Greenhouse and laboratory studies were conducted to determine ¹⁴Csulfometuron-methyl absorption and translocation, as well as ¹⁴C distribution in sugarcane at two growth stages, 2 to 3 leaves and 5 to 6 leaves. ¹⁴Csulfometuron-methyl absorption by sugarcane did not differ between the two growth stages. Different patterns of ¹⁴C accumulation were observed, which may explain variations in sulfometuron-methyl phytotoxic responses observed in the field.

Concentrations of polycyclic aromatic hydrocarbons in liver samples of juvenile green sea turtles from Brazil: Can these compounds play a role in the development of fibropapillomatosis?

Fibropapillomatosis (FP) poses a significant threat to the conservation of green sea turtles (Chelonia mydas). Polycyclic aromatic hydrocarbons-PAHs are considered mutagenic, carcinogenic and toxic, and can act as cofactor of this disease. In order to evaluate possible differences between green sea turtles with and without FP, we monitored 15 PAHs in liver samples of 44 specimens (24 with FP) captured in Brazil. We detected eight PAHs and quantified phenanthrene in all green sea turtles with FP. Specimens without FP presented lower values than the tumored ones (1.48 ng g^-1 and 17.35 ng g^-1, respectively; p < 0.0001). There were no significant differences between tumored and non-tumored specimens, among studied areas, or Southwest Atlantic Fibropapillomatosis Score. Even though we found higher concentrations in the liver samples of green sea turtles with FP, further studies are necessary to confirm if these pollutants are involved in the pathogenesis of the disease.

Role of soil physicochemical properties in quantifying the fate of diuron, hexazinone, and metribuzin

The physicochemical properties of soil are fundamental to quantification of the fate of herbicides. Thus, the aim of this research was to evaluate the fate of diuron, hexazinone, and metribuzin in five soils (Clay-1, Clay-2, Loam-1, Loam-2, and Sand), presenting variation in clay content, cation exchange capacity (CEC), pH, and organic carbon (OC). Herbicides radiolabeled with ¹⁴C were applied, and the ¹⁴C-CO₂ released from mineralization was trapped in 0.2 mol L^-1 sodium hydroxide solution. The degradation ratio, as well as herbicide-bound residues (non-extractable), transformation products, and residues extractable from soil, was also evaluated. Average ¹⁴C-CO₂ evolution accumulated for diuron mineralization was higher (22.24%) than hexazinone (7.73%) and metribuzin (3.20%). The degradation time half-life (DT50) values for hexazinone correlated with soil OC content. Although no correlation between soil properties and DT50 values was found for metribuzin, the degradation rate and total degree of mineralization were low in sand soil for metribuzin. Regarding diuron, OC content and CEC value appear to be related to mineralization and degradation rate, respectively. Differences in soil properties can influence the persistence and fate of herbicides, affecting their impact on the environment, weed control, and possible effects on subsequent crops.

The depleted mineralization of the fungicide chlorothalonil derived from loss in soil microbial diversity

There are lack of studies regarding the effects of microbial diversity on specific soil functions, such as pesticides degradation. This study evaluated the role of bacterial community diversity and biochar on chlorothalonil (CTN) degradation, using 'dilution to extinction' approach, PCR-DGGE/16S rRNA gene technique, and radiorespirometry (14C-CTN). Biochar and microbial community dilution affected structure of the microbial community. In spite of that, CTN mineralization was slow, but dissipation was very fast (D50 < 1.0 d) due to immediate chemical degradation and formation of non-extractable (bound) residues. However, any depletion on soil microbial diversity strongly affected CTN mineralization, suggesting that this function is related to less abundant but specific microbial groups (CTN degraders) or to soil microbial diversity. The extent of these effects will strongly depend on the compound nature (recalcitrance) and soil matrix/substrate (bioavailability). It can be corroborated by the fact that biochar affected CTN sorption, its bioavailability, and subsequently its mineralization rate in the NS. These data indicate a strong relationship between soil microbial diversity and pesticide degradation, which is an acting form to mitigate xenobiotics accumulation in the environment.

DETERMINATION OF ORGANOCHLORINE PESTICIDE RESIDUES IN HUMAN MILK IN PIRACICABA, SP

Worldwide, there is great concern with the issue of bioaccumulation of organochlorine compounds in human milk and their potential impact on health. Breastfeeding is recognized as essential for the proper development and protection of children’s health. In this study, we collected human milk samples from 40 donors in Piracicaba - SP, and analyzed to determine the levels of residues of organochlorine pesticides: hexachlorobenzene (HCB), lindane, heptachlor, aldrin, heptachlor epoxide, o,p’ DDE, a- endosulfan, p,p’ DDE, dieldrin, endrin, b-endosulfan, endosulfan sulfate, and methoxychlor. The analysis was performed by solid phase extraction (SPE) and quantification by gas chromatography using electron capture detector (ECD). Residues of organochlorine pesticides were detected in 65% of the donors evaluated.

Leaching of Diuron, Hexazinone, and Sulfometuron-methyl Applied Alone and in Mixture in Soils with Contrasting Textures

When herbicides are applied in mixture, interactions among them could potentially promote changes in herbicide behavior in the soil. Thus, application mode (isolated or in mixture) and soil texture (sandy or clayey) were investigated in the total leaching of the commercial mixture diuron + hexazinone + sulfometuron-methyl, and of each isolated compound. Experiments in soil columns also evaluated the movement of each herbicide and mixtures across soil layers. In the sandy soil, the greatest total leaching was observed with hexazinone compared to diuron and sulfometuron. Most of the applied diuron remained at the top layer of the soil, indicating that this herbicide has low soil mobility. Overall, our results show that hexazinone has greater leaching potential and mobility along the soil profile compared to diuron and sulfometuron. Our data can be used in assessing the fate of diuron, hexazinone, and sulfometuron alone or in mixture on natural ecosystems, under different soil types and application modes.

Quantification of the fate of mesotrione applied alone or in a herbicide mixture in two Brazilian arable soils

The effects of mesotrione, S-metolachlor, and terbuthylazine, applied in mixture, on soil biodegradation remain insufficiently researched. However, herbicide mixtures have been a common practice in agricultural systems in the last years. Understanding the fate of soil-applied herbicides may help on planning weed management tactics towards more sustainable and efficient weed control. Therefore, this study evaluated the fate of mesotrione alone and in mixture with S-metolachlor and terbuthylazine when applied to two contrasting arable Brazilian soils. Mineralization and degradation experiments were conducted using ¹⁴C-mesotrione alone or in mixture. From the 49-day laboratory incubation data, increased mineralization half-life of mesotrione was observed for the mixture of herbicides, ranging from a 4-day increase for the sandy loam soil to a 1-day increase in the sandy clay texture soils. Mesotrione degradation rate had a twofold increase in the sandy loam compared to the sandy clay soil. Two metabolites can be identified from mesotrione degradation, 4-methyl-sulfonyl-2-nitrobenzoic acid (MNBA) and 2-amino-4-methylsulfonyl benzoic acid (AMBA). Indices for the score of ubiquity in groundwater indicated mesotrione possesses leaching potential for both soils. Applying mesotrione alone or in mixture did not influence the amount of bound residues from mesotrione. However, mesotrione degradation rate was influenced by soil texture regardless if applied alone or in mixture. Mesotrione biotransformation was relatively quick, indicating that this herbicide has low persistence and, consequently, low residual effect on crops and weeds when present in similar soils to this present study.

Microcystin-LR bioaccumulation and depuration kinetics in lettuce and arugula: Human health risk assessment

Microcystin-LR (MC-LR) is one of the most toxic and common microcystins (MCs) variant found in aquatic ecosystems. Little is known about the possibility of recovering microcystins contaminated agricultural crops. The objectives of this study were to determine the bioaccumulation and depuration kinetics of MC-LR in leaf tissues of lettuce and arugula, and estimate the total daily intake (ToDI) of MC-LR via contaminated vegetables by humans. Arugula and lettuce were irrigated with contaminated water having 5 and 10μgL(-1) of MC-LR for 7days (bioaccumulation), and subsequently, with uncontaminated water for 7days (depuration). Quantification of MC-LR was performed by LC-MS/MS. The one-compartment biokinetic model was employed for MC-LR bioaccumulation and depuration data analysis. MC-LR was only accumulated in lettuce. After 7days of irrigation with uncontaminated water, over 25% of accumulated MC-LR was still retained in leaf tissues of plants treated with 10μgL(-1) MC-LR. Total daily toxin intake by adult consumers (60kg-bw) exceeded the 0.04μgMC-LRkg(-1) limit recommended by WHO. Bioaccumulation was found to be linearly proportional to the exposure concentration of the toxin, increasing over time; and estimated to become saturated after 30days of uninterrupted exposure. On the other hand, MC-LR depuration was less efficient at higher exposure concentrations. This is because biokinetic half-life calculations gave 2.9 and 3.7days for 5 and 10μgL(-1) MC-LR treatments, which means 29-37days are required to eliminate the toxin. For the first time, our results demonstrated the possibility of MC-LR decontamination of lettuce plants.

Fate of Tebuthiuron and Hexazinone in Green-Cane Harvesting System

In Brazil, fire prior to sugar cane harvesting has to be phased out by 2017, but it has already been phased out in up to 85-90% of the cropped area. The new system is called green cane and has entirely changed weed management practices. The main goal of this study was to evaluate the effects of the straw presence as well as humic acid (HA), formulation, soil type, and aging on the sorption and leaching of (14)C-tebuthiuron and hexazinone. Both herbicides presented low sorption for all treatments (Kd,app ≤ 3.25 L kg(-1)), but it was higher for tebuthiuron in the clayer soil (LVd). Straw and aging only slightly enhanced sorption. The HA effects were not clear. Sorption was mostly affected by herbicide and soil type. Straw may promote physical trapping (∼40% of applied amount), which cannot be accessed by "batch" sorption (∼15% of the applied amount is sorbed), attenuating leaching of highly mobile herbicides in green-cane systems. To properly assess leaching through straw residues under laboratory condition, rainfall distribution is very important.

Determining organochlorine pesticides in samples of green sea turtles by QuEChERS approach

Alguns Pesticidas organoclorados (OCPs) podem causar numerosos efeitos adversos na biota. As tartarugas marinhas enfrentam diversas ameaças, em especial aquelas relacionadas às atividades antropogênicas, por isso o desenvolvimento de melhorias nos métodos para monitorar compostos químicos são tarefas importantes. Neste trabalho foi desenvolvida uma metodologia baseada na extração QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) para a detecção de doze OCPs, por cromatografia gasosa com captura de elétrons, em amostras de gordura e fígado de tartarugas verdes. Os limites de quantificação ficaram abaixo de 5.3 ng g-1; com taxas de recuperação aceitáveis para a maioria de compostos; efeito matriz médio; calibração da matriz com linearidade variando de 1.0 a 200 ng g-1. Esta metodologia traz contribuições ao estudo de resíduos com efeito adverso na saúde das tartarugas marinhas, sendo importante instrumento para novas direções em temas de conservação. 

Effects of the exposure to atrazine on bone development of Podocnemis expansa (Testudines, Podocnemididae)

The use of pesticides is a widely spread practice in Brazilian agriculture, and dispersion of these substances is an important factor for the fauna and flora. Atrazine is an endocrine disruptor in the xenoestrogen class that is used worldwide in agricultural practices. In Brazil, its use is permitted in several crops. Podocnemis expansa is a representative of the Testudines order that is the largest freshwater reptile of South America. Its distribution enables it to get in contact with molecules that are commonly used as pesticides, which may cause deleterious effects in target populations. In order to evaluate the possible effects of the exposure to atrazine on bone ontogeny of this species, eggs were artificially incubated in sand moistened with water contaminated with atrazine at concentrations equal to 0, 2, 20 or 200 μg/L. Embryos were collected throughout incubation and submitted to diaphanization of soft tissues with potassium hydroxide (KOH); bones were stained with Alizarin red S and cartilages by Alcian blue. Embryos were evaluated for the presence of abnormalities during the different stages of pre-natal development of skeletal elements. No effect of atrazine was observed on bone development during the embryonic phase in P. expansa individuals, in the conditions of this study.

Environmentally Relevant Concentrations of Atrazine and Ametrine Induce Micronuclei Formation and Nuclear Abnormalities in Erythrocytes of Fish

A rapid and sensitive method using liquid chromatography coupled with mass spectrometry triple quadrupole direct aqueous injection for analysis of atrazine and ametrine herbicides in surface waters was developed. According to the validation method, water samples from six different locations in the Piracicaba River were collected monthly from February 2011 to January 2012 and injected into a liquid chromatographer/dual mass spectrometer without the need for sample extraction. The method was validated and shown to be precise and accurate; limits of detection and quantification were 0.07 and 0.10 µg L(-1) for atrazine and 0.09 and 0.14 µg L(-1) for ametrine. During the sampling period, concentrations of atrazine ranged from 0.11 to 1.92 µg L(-1) and ametrine from 0.25 to 1.44 µg L(-1). After analysis of the herbicides, Danio rerio were exposed a range of concentrations found in the river water to check the induction of micronuclei and nuclear abnormalities (NAs) in erythrocytes. Concentrations of atrazine and ametrine >1.0 and 1.5 µg L(-1), respectively, induced MN formation in D. rerio. Ametrine was shown to be more genotoxic to D. rerio because a greater incidence of NAs was observed compared with atrazine. Therefore, environmentally relevant concentrations of atrazine and ametrine found in the Piracicaba River are dangerous to the aquatic biota.

Genotoxic responses of juvenile tilapia (Oreochromis niloticus) exposed to florfenicol and oxytetracycline

Florfenicol (FLC) and oxytetracycline (OTC) are the two most commonly used antibiotics for bacterial treatment in fish farming in Brazil, and because of their intensive use, the potential harmful effects on aquatic organisms are of great concern. This study evaluated the effects of environmental concentrations of FLC and OTC on the genetic material of juvenile tilapia (Oreochromis niloticus) erythrocytes by using the comet assay and the occurrence of micronuclei (MN) and other erythrocytic nuclear abnormalities (ENAs) after exposure to 96hour. The comet assay showed that fish erythrocytes exhibited significantly higher DNA damage after exposure to environmental concentrations of FLC and OTC. Although MN was not observed, ENAs were significantly higher after exposure to FLC, indicating that ENAs are a better biomarker for FLC than MN. The results showed that environmental concentrations of FLC and OTC were genotoxic to erythrocytes of O. niloticus; however, future studies on DNA damage recovery are needed.

Detection of hormones in surface and drinking water in Brazil by LC-ESI-MS/MS and ecotoxicological assessment with Daphnia magna

The growing use of pharmaceutical drug is mainly due to several diseases in human and in animal husbandry. As these drugs are discharged into waterways via wastewater, they cause a major impact on the environment. Many of these drugs are hormones; in which even at low concentrations can alter metabolic and physiological functions in many organisms. Hormones were found in surface water, groundwater, soil, and sediment at concentrations from nanograms to milligrams per liter of volume--quantities known to cause changes in the endocrine system of aquatic organisms. This study aimed to develop a methodology for hormone detection (estriol, estrone, 17β-estradiol, 17α-ethinylestradiol, progesterone, and testosterone) on surface and treated water samples. Sample toxicity was assessed by ecotoxicology tests using Daphnia magna. A liquid chromatograph coupled to a mass spectrometer with an electrospray ionization source (LC-ESI-MS/MS) was used for the analysis. The results showed that samples were contaminated by the hormones estriol, estrone, progesterone, 17β-estradiol, and 17α-ethinylestradiol during the sampling period, and the highest concentrations measured were 90, 28, 26, 137, and 194 ng · L(-1), respectively. This indicates the inflow of sewage containing these hormones at some points in the Piracicaba River in the State of Sao Paulo-Brazil. Results indicated little toxicity of the hormone estriol in D. magna, indicating that chronic studies with this microcrustacean are necessary.

Sorption of fluoroquinolones and sulfonamides in 13 Brazilian soils

Animal production is a leading economic activity in Brazil and antibiotics are widely used. However, the occurrence, behavior, and impacts of antibiotics in Brazilian soils are still poorly known. We evaluated the sorption behavior of four fluoroquinolones (norfloxacin, ciprofloxacin, danofloxacin, and enrofloxacin) and five sulfonamides (sulfadiazine, sulfachloropyridazine, sulfamethoxazole, sulfadimidine, and sulfathiazole) in 13 Brazilian soils with contrasting physical, chemical, and mineralogical properties. Fluoroquinolone sorption was very high (Kd≥544 L kg(-1)) whereas sulfonamide sorption ranged from low to high (Kd=0.7-70.1 L kg(-1)), consistent with previous reports in the literature. Soil texture and cation exchange capacity were the soil attributes that most affected sorption. Cation exchange was the most important sorption mechanism for the fluoroquinolones in highly weathered tropical soils, although cation bridging and ion pairing could not be ruled out. Hydrophobic partition played an important role in the sorption of the sulfonamides, but sorption was also affected by non-hydrophobic interactions with organic and/or mineral surfaces. Sorption for both compound classes tended to be higher in soils with high Al and Fe oxihydroxide contents, but they were not correlated with Kd values. No direct effect of soil pH was seen. The fluoroquinolones are not expected to leach even in worst-case scenarios (soils rich in sand and poor in organic carbon), whereas soil attributes dictate leaching potential for the sulfonamides.

Evaluation of surface water quality using an ecotoxicological approach: a case study of the Piracicaba River (São Paulo, Brazil)

A long-term study was conducted to evaluate Piracicaba River water (São Paulo state, Brazil) using different methodologies and organisms. During 1 year (February 2011 to January 2012), water samples were collected monthly at six different locations and exposed under laboratory conditions to the microcrustaceans Ceriodaphnia dubia and Ceriodaphnia silvestrii for 7 days and to the fish Danio rerio for 4 days to evaluate effects on reproduction and on gill morphology, respectively. Physical-chemical parameters of the water were also measured. Physical-chemical characteristics demonstrated decreasing water quality from upstream to downstream of the river. Effects on the reproduction of C. dubia and C. silvestrii were observed in 3 months (February and March 2011 and January 2012) and occurred in samples collected close to industrialized cities like Americana and Piracicaba. Evaluation of the gills showed normal function of the organ during all months, except in February, September, and October for some locations.

Occurrence and sorption of fluoroquinolones in poultry litters and soils from São Paulo State, Brazil

Animal production is one of the most expressive sectors of Brazilian agro-economy. Although antibiotics are routinely used in this activity, their occurrence, fate, and potential impacts to the local environment are largely unknown. This research evaluated sorption-desorption and occurrence of four commonly used fluoroquinolones (norfloxacin, ciprofloxacin, danofloxacin, and enrofloxacin) in poultry litter and soil samples from São Paulo State, Brazil. The sorption-desorption studies involved batch equilibration technique and followed the OECD guideline for pesticides. All compounds were analyzed by HPLC, using fluorescence detector. Fluoroquinolones' sorption potential to the poultry litters (K(d) ≤65 L kg(-1)) was lower than to the soil (K(d) ~40,000 L kg(-1)), but was always high (≥69% of applied amount) indicating a higher specificity of fluoroquinolones interaction with soils. The addition of poultry litter (5%) to the soil had not affected sorption or desorption of these compounds. Desorption was negligible in the soil (≤0.5% of sorbed amount), but not in the poultry litters (up to 42% of sorbed amount). Fluoroquinolones' mean concentrations found in the poultry litters (1.37 to 6.68 mg kg(-1)) and soils (22.93 μg kg(-1)) were compatible to those found elsewhere (Austria, China, and Turkey). Enrofloxacin was the most often detected compound (30% of poultry litters and 27% of soils) at the highest mean concentrations (6.68 mg kg(-1) for poultry litters and 22.93 μg kg(-1) for soils). These results show that antibiotics are routinely used in poultry production and might represent one potential source of pollution to the environment that has been largely ignored and should be further investigated in Brazil.