Widespread microplastic pollution in mangrove soils of Todos os Santos Bay, northern Brazil.

Microplastics have been studied in sediments from coastal and aquatic environments, but contamination of mangrove soils is still relatively unknown in most mangroves around the world. In this study, the presence of microplastics was investigated in six mangrove soils around the Todos Santos Bay (TSB), the largest and most important navigable bay on the Brazilian coast. Samples were collected at three depths (surface, 10 cm, and 30 cm) at three different distances from the lower tidal area. Ten grams of soil were sieved in a 150 µm mesh and centrifuged with ZnCl2 solution (density of 1.5 kg dm-3) for the extraction of microplastics. The microplastics were quantified, measured, and described using a systematic photographic method and the ImageJ program. Microplastics were abundant in all samples, with a mean of 10,782 ± 7,671 items kg-1 (max.: 31,087 items kg-1, only one sample <2,000 items kg-1), higher than any other value reported worldwide. The abundances varied among the six mangroves studied, with a predominance of fibers and mean size of 196 µm. Even remote mangroves were highly polluted, reflecting a large dispersion of the pollutants. The abundance did not differ significantly between soil depths, evidencing a continuous input and burial of microplastics in the soil up to 30 cm. The investigation of the source of microplastics and their presence in water and biota is urgent in this Brazilian region, and these results emphasize the need for global actions to protect coastal ecosystems.

Microplastics in surface waters of tropical estuaries around a densely populated Brazilian bay.

Brazil is the fourth largest producer of plastic waste in the world, but studies on pollution of rivers and estuaries by microplastics are still scarce. This study is located in the state of Bahia (Northeast region) in ten estuarine environments around Todos dos Santos Bay (TDB), the largest Brazilian bay, where more than 3 million Brazilians live. The aim of the study was the evaluation of the input of microplastics into the TSB by river. Microplastic abundance, size, morphology and water quality were determined during three sampling campaigns. All river samples were highly polluted with microplastics (mostly <150 µm), up to 33,000 items m-3, exceeding values observed in most estuaries worldwide. The poor quality of the river water reflect the deficient treatment of domestic wastewater in the state of Bahia (49% are not treated), and in this study is shown a correlation with the abundance of microplastics, indicating their possible main source. Artisanal fishing can also contribute locally to this pollution. Morover, the results highlight the importance of sampling small microplastics (<100 µm) to avoid important underestimation of this pollution. Based on these data, the three major rivers would discharge 3.88 trillion items into the Bay each year, equivalent to 4.75 × 105 m2 of plastic. Further research in surface water systems is essential, given that the average wastewater treatment rates in the country and in the Northeast and North regions are only 43%, 32%, and 12%, respectively.

Induced changes of pyrolysis temperature on the physicochemical traits of sewage sludge and on the potential ecological risks.

Biochar from sewage sludge is a low-cost sorbent that may be used for several environmental functions. This study evaluates the induced effects of pyrolysis temperature on the physicochemical characteristics of sewage sludge (SS) biochar produced at 350 (SSB350), 450 (SSB450) and 600 (SSB600), based on the metal enrichment index, metal mobility index (MMI), and potential ecological risk index (PERI) of Cd, Cu, Pb, and Zn. Increased pyrolysis temperature reduced the biochar concentration of elements that are lost as volatile compounds (C, N, H, O, and S), while the concentration of stable aromatic carbon, ash, alkalinity, some macro (Ca, Mg, P2O5, and K2O) and micronutrients (Cu and Zn), and toxic elements such as Pb and Cd increased. Increasing the pyrolysis temperature is also important in the transformation of metals from toxic and available forms into more stable potentially available and non-available forms. Based on the individual potential ecological risk index, Cd in the SS and SSB450 were in the moderate and considerable contamination ranges, respectively. For all pyrolysis temperature biochar Cd was the highest metal contributor to the PERI. Despite this, the potential ecological risk index of the SS and SSBs was graded as low.

Sewage sludges in physic nut seedlings macronutrient contents and chemical attributes of soil / Lodos de esgoto nos teores de macronutrientes em mudas de pinhão-manso e atributos químicos do solo

Ever since the government began providing incentives for biofuel production, physic nut has appeared to be a promising plant, due to the high oil content of the seeds. The purpose of this study was to evaluate the nutrition of physic nut seedlings and changes in the chemical attributes of soil, based on the doses of domestic and industrial sewage sludge. Two experiments were conducted in a design with casualized blocks with four replicates using samples of a "Latossolo Amarelo" that received five doses of each sludge, equivalent to 0; 100; 150; 200 and 300 kg N total ha-1. The domestic sewage sludge raised the calcium and magnesium contents in the dry mass of the aerial part and root, and nitrogen and phosphorus in the dry mass of the aerial part of physic nut seedlings, whereas the industrial sludge raised the calcium and nitrogen in the dry mass of the aerial part and root of the physic seedlings, but did not affect the phosphorus, nitrogen, magnesium and potassium contents in the dry mass of the aerial part and root. The domestic sludge did not alter the soil pH but raised the amounts of phosphorus, calcium + magnesium, cation exchange capacity, organic matter and reduced the exchangeable aluminum, while the industrial one raised the pH and the cation exchange capacity of the soil, increased the amounts of phosphorus, calcium + magnesium, and organic matter and reduced the exchangeable aluminum present in the soil. The domestic and industrial sludges may be used to produce physic nut seedlings; however is necessary studies to evaluate the presence of heavy metals or potentially pathogenic microorganisms.

Com os incentivos governamentais para produção de biocombustíveis, o pinhão-manso surgiu como uma planta promissora, devido ao alto teor de óleo nas sementes. Objetivou-se, com este estudo, avaliar a nutrição de mudas de pinhão-manso e alterações nos atributos químicos do solo, em função de doses de lodos de esgoto doméstico e industrial. Dois experimentos em um delineamento em blocos casualizados, com quatro repetições, foram conduzidos utilizando amostras de um Latossolo Amarelo que recebeu cinco doses de cada lodo, equivalentes a 0; 100; 150; 200 e 300 kg N total ha-1. O lodo de esgoto doméstico elevou os teores de cálcio e magnésio na massa seca da parte aérea e raiz e de nitrogênio e fósforo na massa seca da parte aérea das mudas de pinhão-manso, enquanto o lodo industrial elevou os teores de cálcio e nitrogênio na massa seca da parte aérea e raiz das mudas de pinhão-manso, porém não afetou os teores de fósforo, nitrogênio, magnésio e potássio na massa seca da parte aérea e raiz. O lodo doméstico não alterou o pH do solo, contudo elevou as quantidades de fósforo, cálcio + magnésio, a capacidade de troca catiônica, a matéria orgânica e reduziu o alumínio trocável, enquanto o industrial elevou o pH e a capacidade de troca catiônica do solo, aumentou as quantidades de fósforo, cálcio + magnésio e matéria orgânica e reduziu o alumínio trocável presentes no solo. Os lodos domésticos e industriais podem ser utilizados na produção de mudas de pinhão-manso, contudo é necessário estudos sobre a presença de metais pesados ou micro-organismos patogênicos.