Microbial metabolic activity in Amazon floodplain forest and agricultural soils.

Microorganisms play an essential role in ecosystem functions. An increasingly used method for conducting functional analyses of a soil microbial community is based on the physiological profile at the community level. This method allows the metabolic capacity of microorganisms to be assessed based on patterns of carbon consumption and derived indices. In the present study, the functional diversity of microbial communities was assessed in soils from seasonally flooded-forest (FOR) and -traditional farming systems (TFS) in Amazonian floodplains flooded with black, clear, and white water. The soils of the Amazon floodplains showed differences in the metabolic activity of their microbial communities, with a general trend in activity level of clear water floodplain > black water floodplain > white water floodplain. The redundancy analysis (RDA) indicated that soil moisture (flood pulse) was the most important environmental parameter in determining the metabolic activity of the soil microbial communities in the black, clear, and white floodplains. In addition, the variance partitioning analysis (VPA) indicated that the microbial metabolic activity of the soil was more influenced by water type (41.72%) than by seasonality (19.55%) and land use type (15.28%). The soil microbiota of the white water floodplain was different from that of the clear water and black water floodplains in terms of metabolic richness, as the white water floodplain was mainly influenced by the low substrate use during the non-flooded period. Taken together, the results show the importance of considering soils under the influence of flood pulses, water types, and land use as environmental factors when recognizing functional diversity and ecosystem functioning in Amazonian floodplains.

Assessment of Ecological Risk and Environmental Behavior of Pesticides in Environmental Compartments of the Formoso River in Tocantins, Brazil.

Anthropogenic interference the ecosystem unavoidably changes the physical and biological environment. The biodiversity of the Amazon region has been threatened by increased agricultural production and pesticide use. Considering that monitoring pesticides in environments close to their application is one of the ways to preserve the ecosystem, this study investigated the levels of pesticide residues in different environmental compartments (soil, sediment, and water samples). Thirty-one active ingredients of pesticides of different classes were analyzed by UHPLC-MS/MS. For this purpose, we performed quarterly collections in dry and rainy seasons in the region, which helped to evaluate the impact of pesticides on the biodiversity of the study site. Sampling points were the river banks in the area of an agricultural project in Formoso do Araguaia city, Tocantins State. After analysis, we detected the following substances in the water matrix: clomazone, fluazifop-p-butyl, flutolanil, metsulfuron-methyl, propanil, and imidacloprid. Nevertheless, we did not detect any active ingredient in sediment and soil matrices. The active ingredient clomazone was present in all points in the trials, with concentrations reaching up to 0.538 µg L-1. These substances have potential for groundwater contamination. Even at low concentrations in the aquatic ecosystem, these substances can damage human populations and wildlife species, given their toxicological classification. Thus, the study showed an environmental risk of bioaccumulation and/or biomagnification in the region, which may affect environmental biodiversity as well as human health.