Assessment of water quality and identification of priority areas for intervention in Guanabara Bay basin, Rio de Janeiro, Brazil, using nonparametric and multivariate statistical methods.

The Guanabara Bay hydrographic region (GBHR) has served as a central hub for human settlement and resource utilization throughout Brazil's history. However, the region's high population density and intense industrial activity have come at a cost, leading to a significant decline in water quality. This work aimed to identify homogeneous regions in GBHR according to water quality parameters in dry and rainy periods.

Multi-experiment assessment of soil nitrous oxide emissions in sugarcane.

Unlabelled: Soil nitrous oxide (NO) fluxes comprise a significant part of the greenhouse gas emissions of agricultural products but are spatially and temporally variable, due to complex interactions between climate, soil and management variables. This study aimed to identify the main factors that affect NO emissions under sugarcane, using a multi-site database from field experiments. Greenhouse gas fluxes, soil, climate, and management data were obtained from 13 field trials spanning the 2011-2017 period.

Assessment of trends, variability and impacts of droughts across Brazil over the period 1980-2019.

Unlabelled: Drought indices are a numerical representation of drought conditions aimed to provide quantitative assessments of the magnitude, spatial extent, timing, and duration of drought events. Since the adverse effects of droughts vary according to the characteristics of the event, the socioeconomic vulnerabilities, exposed communities or environments, there is a profusion of drought indicators to assess drought impacts in different sectors. In this study, we evaluated the performance of two drought indices, the Standardized Precipitation Index-SPI and Standardized Precipitation Evapotranspiration Index-SPEI over Brazil derived from gridded meteorological information over the period 1980-2019.

The influence of drought and heat stress on long-term carbon fluxes of bioenergy crops grown in the Midwestern USA.

Perennial grasses are promising feedstocks for bioenergy production in the Midwestern USA. Few experiments have addressed how drought influences their carbon fluxes and storage. This study provides a direct comparison of ecosystem-scale measurements of carbon fluxes associated with miscanthus (Miscanthus × giganteus), switchgrass (Panicum virgatum), restored native prairie and maize (Zea mays)/soybean (Glycine max) ecosystems.

Greenness indices from digital cameras predict the timing and seasonal dynamics of canopy-scale photosynthesis.

The proliferation of digital cameras co-located with eddy covariance instrumentation provides new opportunities to better understand the relationship between canopy phenology and the seasonality of canopy photosynthesis. In this paper we analyze the abilities and limitations of canopy color metrics measured by digital repeat photography to track seasonal canopy development and photosynthesis, determine phenological transition dates, and estimate intra-annual and interannual variability in canopy photosynthesis. We used 59 site-years of camera imagery and net ecosystem exchange measurements from 17 towers spanning three plant functional types (deciduous broadleaf forest, evergreen needleleaf forest, and grassland/crops) to derive color indices and estimate gross primary productivity (GPP).