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.

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.

Soil chemical attributes and initial growth of corn crop by adding domestic and industrial sewage sludge / Atributos químicos do solo e crescimento inicial de milho pela adição de lodos de esgoto doméstico e industrial

In recent decades, organic and/or inorganic nonconventional waste such as sewage sludge, agroindustrial or industrial waste, inorganic waste, steel slag, etc., have become some of the most promising alternatives to commercial fertilizer shortages or rising prices. Hence, the aim was to evaluate morphological changes in corn plants and variations in chemical properties of cohesive Yellow Latosol (Oxisol), after the incorporation of sewage sludge doses from domestic waste and the dairy industry. The experimental units were randomised blocks designed with four repetitions. The treatments consisted of five doses of each sewage sludge incorporated into the soil, that is: Domestic Sewage Sludge (DSS) in doses of 0.0; 3.1; 4.6; 6.1 and 9.2 Mg ha-1 (on a dry basis ), and Industrial Sewage Sludge (ISS) in doses of 0.0; 5.2; 7.8; 10.4 e 15.6 Mg ha-1 (on a dry basis), all equivalent to 0; 100; 150; 200 and 300 kg of total N ha-1. Doses equivalent to 150 - 300 kg total N ha-1 led to greater gains in stem diameter, number of leaves, fresh and dry mass of leaves. Increasing doses of both sewage sludges enable gains in the morphological variables studied, except for root length. Positive linear increments occur in the pH and phosphorus content of soils when the doses of sewage sludge are increased. The exchangeable aluminium and potential acidity are reduced, from the first dose of industrial sewage sludge, with no significant difference for domestic sewage sludge.

Nas últimas décadas a utilização de resíduos orgânicos e/ou inorgânicos não convencionais, como lodo de esgoto, resíduos agroindustriais ou industriais, rejeitos inorgânicos, escórias siderúrgicas, dentre outros, surgem como alternativas promissoras a escassez ou encarecimento dos fertilizantes comerciais. Diante do exposto, objetivou-se avaliar alterações morfológicas em plantas de milho e alterações nos atributos químicos de um Latossolo Amarelo coeso, após a incorporação de doses de lodos esgoto doméstico e da indústria de laticínios. Os experimentos foram instalados em um delineamento em blocos casualizados, com quatro repetições. Os tratamentos consistiram de cinco doses de cada lodo incorporadas ao solo, sendo: Lodo de esgoto doméstico (LD) nas doses de 0,0; 3,1; 4,6; 6,1 e 9,2 Mg ha-1 (em base seca) e Lodo de esgoto industrial (LI) nas doses de 0,0; 5,2; 7,8; 10,4 e 15,6 Mg ha-1 (em base seca), equivalentes a 0; 100; 150; 200 e 300 kg de nitrogênio total ha-1. As doses equivalentes de 150 a 300 kg de N ha-1 propiciaram maiores ganhos de diâmetro de colmo, número de folhas, massa fresca e massa seca de folhas. Aumentos nas doses de ambos os lodos de esgotos propiciam ganhos nas variáveis morfológicas estudadas, exceto para o comprimento de raízes. Incrementos lineares positivos ocorrem no pH e no teor de fósforo dos solos com o aumento das doses de lodos. O alumínio trocável e a acidez potencial são reduzidos, a partir da primeira dose de lodo de esgoto industrial, não havendo diferença significativa para o lodo doméstico.

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.

Lodos de esgoto doméstico e industrial no crescimento inicial e qualidade de mudas de pinhão-manso / Urban and industrial sewage sludge in the initial growth and quality of physic nut seedlings

Na região Nordeste do país o pinhão-manso surge como uma planta promissora para a produção de biodiesel devido ao alto teor de óleo nas sementes. O presente trabalho objetivou avaliar o comportamento e a qualidade de mudas do pinhão-manso, em função de doses de lodos de esgoto doméstico e industrial. Os experimentos foram conduzidos em casa de vegetação com cinco tratamentos, consistindo de cinco doses de ambos os lodos de esgoto (equivalentes a 0, 100, 150, 200 e 300 kg N total ha-1), no delineamento em blocos casualizados, com quatro repetições. As variáveis analisadas foram: comprimento da parte aérea, comprimento da raiz, número de folhas, diâmetro do caule, massa fresca da parte aérea, massa fresca da raiz, massa seca da parte aérea, massa seca da raiz e índice de qualidade de mudas de Dickson (IQD). O lodo de esgoto industrial favorece as variáveis relacionadas à raiz até a dose de 200 kg N total ha-1 e o lodo de esgoto doméstico as variáveis relacionadas à parte aérea na dose de 200 kg N total ha-1, exceto para a massa seca da parte aérea e raiz de mudas de pinhão-manso. O lodo de esgoto industrial não alterou a quantidade de massa seca da parte aérea de mudas de pinhão-manso. O índice de qualidade de Dickson caracteriza as mudas de pinhão-manso como de boa qualidade, contudo não apresenta diferença significativa entre os tratamentos.

In the Northeast region of the country the physic nut emerges as a promising plant for the biodiesel production, due its high oil content in seeds. This study aimed to evaluate the behavior and seedlings quality of physic nut, depending on the dose of domestic and industrialsewage sludge. The experiments were conducted in a greenhouse with five treatments, consisting in five doses for both sewage sludge (equivalent to 0, 100, 150, 200 and 300 kg total N ha-1), in complete randomized blocks, with four replications. The variables analyzed were: shoot length, root length, leaf number, stem diameter, shoot fresh weight, root fresh weight, shoot dry weight, root dry mass and index of seedlings quality of Dickson. The industrial sewage sludge increases the variables related to the root until level of 200 kg total N ha-1 and domestic sewage sludge increases variables related to shoot at a dose of 200 kg total N ha-1, except for the dry matter of shoot and root system of physic nut seedlings. The industrial sewage sludge did not change the amount of dry matter of shoots of physic nut seedlings. The Dickson quality index (DQI) characterizes the seedlings of physic nut as good quality, however no significant difference was found between treatments.

Rhizosphere characteristics of two arsenic hyperaccumulating Pteris ferns.

Better understanding of the processes controlling arsenic bioavailability in the rhizosphere is important to enhance plant arsenic accumulation by hyperaccumulators. This greenhouse experiment was conducted to evaluate the chemical characteristics of the rhizosphere of two arsenic hyperaccumulators Pterisvittata and Pterisbiaurita. They were grown for 8 weeks in rhizopots containing arsenic-contaminated soils (153 and 266 mg kg(-1) arsenic). Bulk and rhizosphere soil samples were analyzed for water-soluble As (WS-As) and P (WS-P), pH, and dissolved organic carbon (DOC). Comparing the two plants, P.vittata was more tolerant to arsenic and more efficient in arsenic accumulation than P.biaurita, with the highest frond arsenic being 3222 and 2397 mg kg(-1). Arsenic-induced root exudates reduced soil pH (by 0.74-0.92 units) and increased DOC concentrations (2-3 times) in the rhizosphere, resulting in higher WS-P (2.6-3.8 times higher) compared to the bulk soil. Where there was no difference in WS-As between the rhizosphere and bulk soil in soil-153 for both plants, WS-As in the rhizosphere was 20-40% higher than those in bulk soil in soil-266, indicating that the rate of As-solubilization was more rapid than that of plant uptake. The ability to solubilize arsenic via root exudation in the rhizosphere and the ability to accumulate more P under arsenic stress may have contributed to the efficiency of hyperaccumulator plants in arsenic accumulation.

Three new arsenic hyperaccumulating ferns.

Phytoremediation, an emerging, plant-based technology for the removal of toxic contaminants from soil and water, has been receiving increased attention. The prerequisite for successful phytoremediation is the existence of hyperaccumulator plants. Designed to search for new arsenic (As) hyperaccumulators, an experiment was conducted under greenhouse conditions in a completely randomized design with four replications. This experiment identified Pteris biaurita L., P. quadriaurita Retz and P. ryukyuensis Tagawa as new hyperaccumulators of As and re-confirmed Pteris cretica as a hyperaccumulator. The average As concentration ranged from 1770 to 3650 mg kg(-1) DW in the fronds and 182 to 507 mg kg(-1) DW in the roots of P. cretica, P. biaurita, P. quadriaurita and P. ryukyuensis after having been grown in 100 mg As kg(-1) soil. There was a greater percentage of As(III) as compared to As (V) in the fronds of these plants. Based on our study, P. ryukyuensis is the most promising candidate to phytoremediate As contaminated soils compared to the other three species. The nutrient requirements or distributions within the Pteris species were altered distinctly when the plants were exposed to As.