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The article presents information on the war of the Guaikuru-Kadiwéu against Paraguay in the nineteenth century with respect to the relations of the Indians with Portugal and Spain. The strategies of the indigenous people are required for the purpose of analysing the involvement of the Indians in conflicts with the Brazilian Empire. Information on the requirement of the interfacing anthropology with history for the indigenous issues is also presented.

Microplastic pollution is becoming a major challenge with the growing use of plastic. In recent years, research about microplastic pollution in the environment has become a field of study with increased interest, with ever expanding findings on sources, sinks and pathways of microplastics. Wastewater treatment plants effectively remove microplastics from wastewater and concentrate them in sewage sludge which is often used to fertilise agricultural fields. Despite this, quantification of microplastic pollution in agricultural fields through the application of sewage sludge is largely unknown. In light of this issue, four wastewater treatment plants and 16 agricultural fields (0–8 sewage sludge applications of 20–22 tons ha−1 per application), located in the east of Spain, were sampled. Microplastics were extracted using a floatation and filtration method, making a distinction between light density microplastics (ρ < 1 g cm−3) and heavy density microplastics (ρ > 1 g cm−3). Sewage sludge, on average, had a light density plastic load of 18,000 ± 15,940 microplastics kg−1 and a heavy density plastic load of 32,070 ± 19,080 microplastics kg−1. Soils without addition of sewage sludge had an average light density plastic load of 930 ± 740 microplastics kg−1 and a heavy density plastic load of 1100 ± 570 microplastics kg−1. Soils with addition of sewage sludge had an average light density plastic load of 2130 ± 950 microplastics kg−1 and a heavy density plastic load of 3060 ± 1680 microplastics kg−1. On average, soils' plastic loads increased by 280 light density microplastics kg−1 and 430 heavy density microplastics kg−1 with each successive application of sewage sludge, indicating that sewage sludge application results in accumulation of microplastics in agricultural soils. Image 1 • 4 WWTPs and 16 fields in Spain were evaluated for microplastic pollution. • Fields without application of sludge had an average of 2030 microplastics kg−1. • Fields with application of sludge had an average of 5190 microplastics kg−1. • Soils' microplastic content increased with the number of sewage sludge applications. Microplastics concentrations in soils are highly proportional to the number of sludge applications. [ABSTRACT FROM AUTHOR]