Emission rates of nitrogen and phosphorus in a tropical coastal river basin: a strategic management approach.

Watershed studies that account for nutrient loadings are crucial for suitable river basin and estuarine management. This study aims to contribute to the environmental planning and decision making regarding nitrogen and phosphorus loadings for the watershed of the Vitória Bay Estuarine System (VBES; 1925 km2) in southeast Brazil. Here, we estimate that the VBES had annual loadings (in 2016) from ten tributary river basins of 5480 and 10,784 t for P and N, respectively, based on emission factors for natural and anthropogenic sources. The main contribution sources were related to livestock farming (4801 t of P and 8000 t of N) and domestic wastewater (492 t of P and 1706 t of N). However, urban loadings have higher expressions when considering the input by watershed area (0.25 and 0.87 t km-2 year-1 of P and N yields, respectively), which are mainly due to wastewater since 70% of the sewage is untreated. Urban emissions play a prominent role and have a tendency to be aggravated due to Brazilian population growth (0.8% annual rate). If the current wastewater emissions continue, P and N loadings will likely increase by 1.316% to totals of 713 and 2474 t year-1 in 2050 for P and N, respectively. Considering that the wastewater tertiary treatment cost is US$ 0.50 m-3, and that in the future 70% of all wastewater will be collected, the P and N loadings will drop to 18.4 and 424.1 t year-1, respectively, with a treatment cost of 25 million USD year-1. The model holds well for non-regulated watersheds. However, for regulated basins, such as the Santa Maria de Vitória, the model overestimates the loadings mainly due to the damming systems in these watersheds (accounting for 49% retention of P and 0.13% retention of N).

Molecular variability of cowpea mild mottle virus infecting soybean in Brazil.

Molecular variability was assessed for 18 isolates of cowpea mild mottle virus (CPMMV, genus Carlavirus, family Betaflexiviridae) found infecting soybean in various Brazilian states (Bahia, Goiás, Maranhão, Mato Grosso, Minas Gerais, Pará) in 2001 and 2010. A variety of symptoms was expressed in soybean cv. CD206, ranging from mild (crinkle/blistering leaves, mosaic and vein clearing) to severe (bud blight, dwarfing, leaf and stem necrosis). Recombination analysis revealed only one CPMMV isolate to be recombinant. Pairwise comparisons and phylogenetic analysis were performed for partial genomes (ORF 2 to the 3' terminus) and for each ORF individually (ORFs 2 to 6), showing the isolates to be distinct. The topology of the phylogenetic tree could be related to symptoms, but not to the year of collection or geographical origin. Additionally, the phylogenetic analysis supported the existence of two distinct strains of the virus, designated CPMMV-BR1 and CPMMV-BR2, with molecular variations between them.