Ecotoxicological evaluation of sediments applied to environmental forensic investigation / Avaliação ecotoxicológica de sedimentos aplicada à perícia criminal ambiental

Abstract The present study aimed to evaluate the potential for using toxicity assays with sediment samples for the detection of water pollution caused by the discharge of tannery effluents into water bodies and its application to environmental forensic investigation. The study included ecotoxicological evaluation of sediments, survey of benthic organisms in the field, as well as chromium, cadmium and lead dosage which provided data for a sediment quality triad evaluation. The sediment samples showed acute and chronic toxicity to the bioindicators, low biodiversity of benthic macrofauna and high chromium concentration, reaching up to 4365 mg.Kg–1. A close relationship was observed between the separate results of ecotoxicological sediment evaluation and the sediment quality triad. The sediment ecotoxicological assessment proved to be applicable to tracking sources of contamination related to tanneries and similar activities in environmental forensics.

Resumo O objetivo do presente estudo foi avaliar o potencial de aplicação de ensaios de toxicidade com amostras de sedimento para constatação de poluição aquática causada por lançamentos de efluentes de curtumes em cursos d’água e seu emprego na perícia criminal ambiental. O estudo incluiu avaliação ecotoxicológica de sedimentos, avaliação da fauna bentônica local e dosagem de cromo, cádmio e chumbo que forneceram dados para avaliação da tríade de qualidade dos sedimentos. As amostras de sedimentos mostraram efeito de toxicidade aguda e crônica aos bioindicadores, baixa biodiversidade da macrofauna bentônica e altas concentrações de cromo que chegaram a 4365 mg.Kg–1. Houve uma estreita relação entre os resultados isolados da avaliação ecotoxicológica e a tríade de qualidade de sedimentos. A avaliação ecotoxicológica demonstrou ser aplicável na identificação de fontes de contaminação relacionadas a curtumes e atividades similares em perícias ambientais.

The effect of the glyphosate, 2,4-D, atrazine e nicosulfuron herbicides upon the Edaphic collembola (Arthropoda: Ellipura) in a no tillage system

The use of herbicides is a common and intensive practice in no tillage systems. The herbicides can influence, directly or indirectly, the population of edaphic arthropods. Collembola is a group that functions as a bio-indicator of soil conditions. The degree of abundance and diversity of Collembola provides the level of soil disturbance provoked by agricultural practices. This experiment was designed to compare the influence of herbicides on the population fluctuation of Collembola in a no-till soil preparation system. The work was conducted in a non irrigated no-till area at the Núcleo Experimental de Ciências Agrárias of the Universidade Federal de Mato Grosso do Sul (UFMS), Campus de Dourados, in soil planted with corn as a surface covering, during the period of December, 2002 to December, 2003. The data were analyzed according to a completely randomized model, in a split plot design. The plots received four types of herbicides: glyphosate, atrazine, 2,4-D and nicosulfuron. A fifth plot did not receive any herbicide (control), for a total of five treatment types. The sub plots were represented by their collection times (10, 20, 30 and 40 days after the herbicide applications). Both the type of herbicide and the time of data sampling influenced the Collembola population fluctuaction. The treatments with atrazine and 2,4-D caused the most reduction of the population of Collembola, depending on the time of application.

No plantio direto o uso de herbicidas é uma prática comum e intensiva, que influencia direta ou indiretamente a população de artrópodes da mesofauna edáfica. O grau de abundância e diversidade de Collembola comumente é indicado para comprovar a extensão de distúrbios de várias práticas agrícolas, pois esse grupo serve como bioindicador das condições do solo. Esta pesquisa teve como objetivo comparar a influência de alguns herbicidas na flutuação populacional de Collembola, em solo sob o sistema de plantio direto. O trabalho foi realizado em uma área de plantio direto de sequeiro, do Núcleo Experimental de Ciências Agrárias da Universidade Federal de Mato Grosso do Sul (UFMS), Campus de Dourados, em latossolo roxo distroférrico com cobertura de milho, durante os meses de outubro de 2002 a janeiro de 2003. Os dados obtidos foram analisados segundo o modelo inteiramente casualizado constituído de tratamentos dispostos no esquema de parcelas subdivididas, onde as parcelas são representadas por uma testemunha mais quatro herbicidas: glifosate, atrazina, 2,4-D e nicosulfuron (totalizando cinco tratamentos) e as subparcelas pelas épocas de cada coleta (10, 20, 30 e 40 dias após aplicação dos herbicidas). Tanto os herbicidas testados quanto as épocas de coleta influenciaram a população de Collembola. Dependente do período de degradação dos herbicidas no solo, os tratamentos com 2,4-D, Atrazina, foram os que mais influenciaram a abundância de Collembola reduzindo sua população.

Biomonitoring insecticide pollution using non-target soil microarthropods.

The scope of biomonitoring insecticide pollution in soil is discussed with the help of field and laboratory findings on the density, prey-predator ratio and fecundity of non-target microarthropod fauna. Field experiments were conducted in small plots with mustard, wheat and lady's finger crops and insecticides namely heptachlor 20EC (3.25 kg ai/ha = 16.25 lit/ha) and endosulfan 35EC (0.875 kg ai/ha = 2.5 lit/ha) applied at the seedling stages. Soil microarthropod population estimated at fortnightly intervals in the treated and untreated control plots revealed a general trend of adverse effect of the insecticides, prominently on the density and relative abundance of major prey groups like Collembola and Acari leading to notable decline in prey-predator ratio. Comparison of the percentage reductions of major taxonomic and trophic groups between pre-treatment and post-treatment intervals also demonstrated the ill effect of both heptachlor and endosulfan, notably on Collembola and the prey category. In the laboratory the survival success and fecundity of Cyphoderus javanus (Collembola) and Archegozetes longisetosus (Acari) were compared by exposing freshly emerged adults to sub-lethal concentrations of heptachlor and endosulfan for varying durations. The untreated control sets recorded high fecundity for both C. javanus and A. longisetosus, but chronic toxicity of the insecticides on adults confined to the treated soil resulted into very low fecundity. Even short duration exposure to heptachlor and endosulfan treated soil for 24 or 72 hours only was found to delay the egg-laying and decrease the fecundity of both the species. It is concluded that population responses and reproductive sensitivity in non-target soil microarthropods are potential eco-toxicological parameters for detecting pesticide pollution in soil and for ecological health assessment since the results are based on the bioactivity of toxicants.

Diversity of ground arthropod community at organic and chemically intensive tea plantation of Darjeeling terai.

Tea in Darjeeling foothills and terai are grown conventionally, with application of chemical fertilizers and pesticides, as well as organically without these inputs. Ground level arthropod community was collected from the above two types of tea plots using pitfall traps. Catches from these environments showed variation in the arthropod faunal structure with numerically and taxonomically greater abundance in the organic than that of the conventional plot. Coleopterans were more diverse with largest number of families and Recognizable Taxonomic Units (or morphospecies) in the organic tea plot. The diversity and similarity indices for coleopterans were comparable, in organic and conventional tea plots at species and family levels. The close relationship of the indices suggested that diversity study at family level could be used as surrogate for species level diversity; thus alleviating the laborious and expertise job of taxonomic identification of arthropod species. Faunal diversity study at ground level gave the clue that soil of the organic plantation was healthier than that of the conventional tea plot.