Phytoremediation: A green and low-cost technology to remediate herbicides in the environment.

Pesticide dependence is one of the main disadvantages of agriculture. Despite the advances in biological control and integrated management of plant pests and diseases in recent years, herbicides are still essential for weed control and constitute the main class of pesticides worldwide. Herbicide residues in water, soil, air, and non-target organisms are among the biggest agricultural and environmental sustainability obstacles. Therefore, we suggest an environmentally viable alternative to reduce the harmful effects of herbicide residues, a technology called phytoremediation. Remediating plants were grouped into herbaceous, arboreal, and aquatic macrophytes. Phytoremediation can reduce the loss of at least 50% of all herbicide residues to the environment. Among the herbaceous species reported as phytoremediators of herbicides, the Fabaceae family was mentioned in more than 50% of reports. This family is also among the main species of trees reported. Regarding the most reported groups of herbicides, it is observed that most of them, regardless of the group of plants, are triazines. Processes such as extraction or accumulation are the best known and reported for most herbicides. The phytoremediation may be effective against chronic or unknown herbicide toxicity. This tool can be included in proposals for management plans and specific legislation in countries, guaranteeing public policies to maintain environmental quality.

Arbuscular mycorrhizal fungi activity in the rhizosphere of tree seedlings subjected to residual herbicides / Atividade de fungos micorrízicos arbusculares na rizosfera de mudas de árvores submetidas a herbicidas residuais

Abstract Trees occurring on the margins of agricultural areas can mitigate damage from residual herbicides. Rhizospheric microbial activity associated with trees is one of the main remedial capacity indicators. The objective of this study was to evaluate the rhizospheric microbiological activity in tree species subjected to the herbicides atrazine and sulfentrazone via the rhizosphere. The experiment was designed in four blocks and a 6 × 3 factorial scheme. The first factor consisted of six tree species from Brazil and the second of atrazine, sulfentrazone, and water solutions. Four herbicide applications were performed via irrigation. The total dry mass of the plants, mycorrhizal colonization, number of spores, basal respiration of the rhizospheric soil, and survival rate of bioindicator plants after phytoremediation were determined. Trichilia hirta had higher biomass when treated with atrazine and sulfentrazone. Herbicides decreased the microbial activity in Triplaris americana and did not affect the microbiological indicators of Myrsine gardneriana, Schizolobium parahyba, and Toona ciliata. Fewer bioindicator plants survived in soil with Triplaris americana and sulfentrazone. Microbiological indicators were influenced in different ways between species by the presence of herbicides in the rhizosphere.

Resumo As árvores que ocorrem nas margens das áreas agrícolas podem mitigar os danos dos herbicidas residuais. A atividade microbiana rizosférica associada às árvores é um dos principais indicadores de capacidade corretiva. O objetivo deste trabalho foi avaliar a atividade microbiológica rizosférica em espécies arbóreas submetidas aos herbicidas atrazina e sulfentrazone via rizosfera. O experimento foi estruturado em quatro blocos e esquema fatorial 6 × 3. O primeiro fator consistiu em seis espécies de árvores do Brasil e o segundo em soluções de atrazine, sulfentrazone e água. Quatro aplicações de herbicidas foram realizadas via irrigação. Foram determinados a massa seca total das plantas, colonização micorrízica, número de esporos, respiração basal do solo rizosférico e taxa de sobrevivência de plantas bioindicadoras após fitorremediação. Trichilia hirta apresentou maior biomassa quando tratada com atrazina e sulfentrazone. Os herbicidas diminuíram a atividade microbiana em Triplaris americana e não afetaram os indicadores microbiológicos de Myrsine gardneriana, Schizolobium parahyba e Toona ciliata. Menos plantas bioindicadoras sobreviveram no solo com Triplaris americana e sulfentrazone. Os indicadores microbiológicos foram influenciados de formas distintas entre as espécies pela presença dos herbicidas na rizosfera.

Arbuscular mycorrhizal fungi activity in the rhizosphere of tree seedlings subjected to residual herbicides

Abstract Trees occurring on the margins of agricultural areas can mitigate damage from residual herbicides. Rhizospheric microbial activity associated with trees is one of the main remedial capacity indicators. The objective of this study was to evaluate the rhizospheric microbiological activity in tree species subjected to the herbicides atrazine and sulfentrazone via the rhizosphere. The experiment was designed in four blocks and a 6 × 3 factorial scheme. The first factor consisted of six tree species from Brazil and the second of atrazine, sulfentrazone, and water solutions. Four herbicide applications were performed via irrigation. The total dry mass of the plants, mycorrhizal colonization, number of spores, basal respiration of the rhizospheric soil, and survival rate of bioindicator plants after phytoremediation were determined. Trichilia hirta had higher biomass when treated with atrazine and sulfentrazone. Herbicides decreased the microbial activity in Triplaris americana and did not affect the microbiological indicators of Myrsine gardneriana, Schizolobium parahyba, and Toona ciliata. Fewer bioindicator plants survived in soil with Triplaris americana and sulfentrazone. Microbiological indicators were influenced in different ways between species by the presence of herbicides in the rhizosphere.

Resumo As árvores que ocorrem nas margens das áreas agrícolas podem mitigar os danos dos herbicidas residuais. A atividade microbiana rizosférica associada às árvores é um dos principais indicadores de capacidade corretiva. O objetivo deste trabalho foi avaliar a atividade microbiológica rizosférica em espécies arbóreas submetidas aos herbicidas atrazina e sulfentrazone via rizosfera. O experimento foi estruturado em quatro blocos e esquema fatorial 6 × 3. O primeiro fator consistiu em seis espécies de árvores do Brasil e o segundo em soluções de atrazine, sulfentrazone e água. Quatro aplicações de herbicidas foram realizadas via irrigação. Foram determinados a massa seca total das plantas, colonização micorrízica, número de esporos, respiração basal do solo rizosférico e taxa de sobrevivência de plantas bioindicadoras após fitorremediação. Trichilia hirta apresentou maior biomassa quando tratada com atrazina e sulfentrazone. Os herbicidas diminuíram a atividade microbiana em Triplaris americana e não afetaram os indicadores microbiológicos de Myrsine gardneriana, Schizolobium parahyba e Toona ciliata. Menos plantas bioindicadoras sobreviveram no solo com Triplaris americana e sulfentrazone. Os indicadores microbiológicos foram influenciados de formas distintas entre as espécies pela presença dos herbicidas na rizosfera.

Mabea fistulifera and Zeyheria tuberculosa can be indicated for phytoremediation programs of soils contaminated with hormonal herbicides.

Hormone-like herbicides, used for large crops, can contaminate non-target areas with their waste. The objective of this study was to evaluate the tolerance of Mabea fistulifera and Zeyheria tuberculosa to 2,4-D + picloram herbicides by means of morphological and anatomical evaluations. The experiment was performed in a greenhouse in a 4 × 2 factorial scheme. The first factor was the control (without herbicide) and three doses (0.166; 0.333, and 0.666 L ha-1) of the herbicide Tordon® (402 g L-1 2,4-D + 103.6 g L-1 picloram) and the second factor, the species Mabea fistulifera and Zeyheria tuberculosa. The number of M. fistulifera leaves was lower after treatment with the highest dose of the 2,4-D + picloram mixture. The herbicide rates did not influence the number of Z. tuberculosa leaves. The higher dose of 2,4-D + picloram caused a more than 50% reduction in leaf area. Toxicity increased linearly as a function of the doses of the 2,4-D + picloram mixture. Changes in the leaf anatomy of the two species treated with herbicides were observed; however, the roots did not show any changes. Mabea fistulifera and Zeyheria tuberculosa can be recommended for phytoremediation programs in areas contaminated by the herbicides 2,4-D + picloram.

Phytoremediation of soils contaminated with herbicides is a recent and viable tool for environmental decontamination and for the protection of water resources. Mabea fistulifera and Zeyheria tuberculosa can be used to compose riparian forests and retain the arrival of herbicides in the water. Plant anatomy and morphological characteristics are viable tools to assess the tolerance and phytoremediation potential of plant species. Mabea fistulifera and Zeyheria tuberculosa are tolerant to the presence of hormonal herbicides. In this way, they can be used to recover natural areas close to the cultivation areas where the herbicides 2,4-D and picloram are used.

Arbuscular mycorrhizal fungi activity in the rhizosphere of tree seedlings subjected to residual herbicides.

Trees occurring on the margins of agricultural areas can mitigate damage from residual herbicides. Rhizospheric microbial activity associated with trees is one of the main remedial capacity indicators. The objective of this study was to evaluate the rhizospheric microbiological activity in tree species subjected to the herbicides atrazine and sulfentrazone via the rhizosphere. The experiment was designed in four blocks and a 6 × 3 factorial scheme. The first factor consisted of six tree species from Brazil and the second of atrazine, sulfentrazone, and water solutions. Four herbicide applications were performed via irrigation. The total dry mass of the plants, mycorrhizal colonization, number of spores, basal respiration of the rhizospheric soil, and survival rate of bioindicator plants after phytoremediation were determined. Trichilia hirta had higher biomass when treated with atrazine and sulfentrazone. Herbicides decreased the microbial activity in Triplaris americana and did not affect the microbiological indicators of Myrsine gardneriana, Schizolobium parahyba, and Toona ciliata. Fewer bioindicator plants survived in soil with Triplaris americana and sulfentrazone. Microbiological indicators were influenced in different ways between species by the presence of herbicides in the rhizosphere.

Tolerance and remedial potential of trees submitted to atrazine and sulfentrazone in the rhizosphere.

Residual herbicides are important for agricultural production but they may be lost underground. Trees capable of removing or degrading these products are interesting to the agro system. The objective was to evaluate the tolerance and remedial potential of trees in soil contaminated by atrazine and sulfentrazone. The experiment was arranged in a 7 × 3 factorial scheme. Factor one was composed of Inga edulis Mart., Myrsine gardneriana A.DC., Schizolobium parahyba (Vell.) Blake, Toona ciliata M. Roem., Trichilia hirta L. and Triplaris americana L. Factor two consisted of monthly solutions of atrazine (1000 g ha-1), sulfentrazone (150 g ha-1) and water only (control), applied through subgrade irrigation. The following parameters were evaluated: visual intoxication, plant growth, and biomass accumulation. Cucumber biomass was used as an indicator of herbicide residues in soil. Symptoms of intoxication were found only in S. parahyba and T. americana. Growth and biomass of the species were not affected by herbicides, except for T. americana. The herbicides provided higher biomass for T. hirta. Saplings of I. edulis, M. gardneriana, S. parahyba, T. ciliate, and T. hirta tolerate atrazine and sulfentrazone. Triplaris americana is sensitive to sulfentrazone. Inga edulis decreased sulfentrazone residues in the soil.

Shifted-excitation Raman difference spectroscopy for in vitro and in vivo biological samples analysis.

The contamination of the Raman scattering signal with luminescence is a well-known problem when dealing with biological media excited by visible light. The viability of the shifted-excitation Raman difference spectroscopy (SERDS) technique for luminescence suppression on Raman spectra of biological samples was studied in this work. A tunable Lithrow-configuration diode laser (λ = 785 and 830 nm) coupled (directly or by optical fiber) to a dispersive Raman spectrometer was employed to study two sets of human tissues (tooth and skin) in order to determine the set of experimental parameters suitable for luminescence rejection. It was concluded that systematic and reproducible spectra of biological interest can be acquired by SERDS.

Dental enamel irradiated with infrared diode laser and photo-absorbing cream: part 2--EDX study.

OBJECTIVE: The effects of laser-induced compositional changes on the enamel were investigated by energy-dispersive X-ray fluorescence spectrometry (micro-EDX). After cariogenic challenge, we administered treatment of low-level infrared diode laser and a photo-absorbing cream (used to intensify the superficial light absorption). BACKGROUND DATA: Dental caries is considered the most prevalent oral disease. A simple and noninvasive caries preventive regimen is treating tooth enamel with a laser, either alone or in combination with fluoride, which reduces enamel solubility and dissolution rates. High power lasers are still not widely used in private practice. Low-power near-infrared lasers may be an alternative approach. Energy-dispersive micro-EDX is a versatile and nondestructive spectroscopic technique that allows for a qualitative and quantitative elemental analysis of inorganic enamel components, such as calcium and phosphorus. MATERIALS AND METHODS: Twenty-four extracted or exfoliated caries-free deciduous molars were divided into six groups: 1) control group (CTR-no treatment); 2) infrared laser treatment (L) (lambda = 810 nm, 100 mW/cm(2), 90 sec, 4.47 J/cm(2), 9 J); 3) infrared laser irradiation and photo-absorbing agent (CL); 4) photo-absorbing agent alone (C); 5) infrared laser irradiation and fluoridated photo-absorbing agent (FCL); and 6) fluoridated photo-absorbing agent alone (FC). Samples were analyzed using micro-EDX after two sets of treatments and pH cycling cariogenic challenges. RESULTS: The CL group showed statistically significant increases in calcium and phosphorus (wt%) compared with the CTR group. The Ca/P ratio was similar in the FCL and CTR groups. There was a significant laser-induced reduction compared with the CTR group, and there was a possible modification of the organic balance content in enamel treated with laser and cream. CONCLUSION: micro-EDX may be able to detect compositional changes in mineral phases of lased enamel under cariogenic challenge. Our results suggest that with a combined laser and photo-absorbing agent (CL) treatment, there was a possible disorganization of organic content in the tooth enamel with hydroxyapatite crystal reordering and reorganization.

Dental enamel irradiated with infrared diode laser and photoabsorbing cream: Part 1 -- FT-Raman Study.

OBJECTIVE: The aim of this FT-Raman study was to investigate laser-induced compositional changes in enamel after therapy with a low-level infrared diode laser and a photoabsorbing cream, in order to intensify the superficial light absorption before and after cariogenic challenge. BACKGROUND DATA: Dental caries remains the most prevalent disease during childhood and adolescence. Preventive modalities include the use of fluoride, reduction of dietary cariogenic refined carbohydrates, plaque removal and oral hygiene techniques, and antimicrobial prescriptions. A relatively simple and noninvasive caries preventive regimen is treating tooth enamel with laser irradiation, either alone or in combination with topical fluoride treatment, resulting in reduced enamel solubility and dissolution rates. Due to their high cost, high-powered lasers are still not widely employed in private practice in developing countries. Thus, low-power red and near-infrared lasers appear to be an appealing alternative. MATERIALS AND METHODS: Twenty-four extracted or exfoliated caries-free deciduous molars were divided into six groups: control group (no treatment; n = 8); infrared laser treatment (L; n = 8) (810 nm at 100 mW/cm(2) for 90 sec); infrared diode laser irradiation (810 nm at 100 mW/cm(2) for 90 sec) and photoabsorbing cream (IVL; n = 8); photoabsorbing cream alone (IV; n = 8); infrared diode laser irradiation (810 nm at 100 mW/cm(2) for 90 sec) and fluorinated photoabsorbing agent (IVLF; n = 8); and fluorinated photoabsorbing agent alone (IVF; n = 8). Samples were analyzed using FT-Raman spectroscopy before and after pH cycling cariogenic challenge. RESULTS: There was a significant laser-induced reduction and possible modification of the organic matrix content in enamel treated with the low-level diode laser (the L, IVL, and IVFL groups). CONCLUSION: The FT-Raman technique may be suitable for detecting compositional and structural changes occurring in mineral phases and organic phases of lased enamel under cariogenic challenge.