Site properties, environmental factors, and crop identify influence soil bacterial communities more than municipal biosolid application.

Reducing the environmental impact of Canadian field crop agriculture, including the reliance on conventional synthesised fertilisers, are key societal targets for establishing long-term sustainable practices. Municipal biosolids (MSB) are an abundant, residual organic material, rich in phosphate, nitrogen and other oligo-nutrients, that could be used in conjunction with conventional fertilisers to decrease their use. Though MBS have previously been shown to be an effective fertiliser substitute for different crops, including corn and soybean, there remain key knowledge gaps concerning the impact of MBS on the resident soil bacterial communities in agro-ecosystems.

Fertilisation of agricultural soils with municipal biosolids: Glyphosate and aminomethylphosphonic acid inputs to Québec field crop soils.

Municipal biosolids (MBS) are suggested to be abundant, sustainable, inexpensive fertilisers, rich in phosphorus and nitrogen. However, MBS can also contain glyphosate and phosphonates that can degrade to AMPA. Glyphosate-based herbicides (GBH) are used in field crops all over the world.

Rural development and shifts in household dietary practices from 1999 to 2010 in the Tapajós River region, Brazilian Amazon: empirical evidence from dietary surveys.

Background: Research on changing dietary practices is rare in lower and middle income countries, and understanding the impact of global economic processes on population health and nutrition is important, especially of rural communities. We analyzed the diet of 22 families in Brasília Legal, a riverside community in the Tapajós River region of the Brazilian Amazon, using nonparametric tests to compare dietary surveys taken in 1999 and 2010.

Results: Data from the two surveys show that food obtained through commercial supply chains became more frequent in household diets, corresponding to significant increases in daily consumption of food items rich in energy, protein, and sugar.

Glyphosate and Aminomethylphosphonic Acid Content in Glyphosate-Resistant Soybean Leaves, Stems, and Roots and Associated Phytotoxicity Following a Single Glyphosate-Based Herbicide Application.

Glyphosate-based herbicide (GBH) applications were reported to induce physiological damages to glyphosate-resistant (GR) soybean, which were mainly attributed to aminomethylphosphonic acid (AMPA). In order to study glyphosate and AMPA dynamics in plants and associated phytotoxic effects, a greenhouse experiment was set where GR soybeans were exposed to GBH (0.7 to 4.

Potential Efficiency of Grassy or Shrub Willow Buffer Strips against Nutrient Runoff from Soybean and Corn Fields in Southern Quebec, Canada.

Riparian buffer strips (RBS) are encouraged to control agricultural diffuse pollution. In Quebec Province, Canada, a policy promotes 3-m-wide RBS. Abiding farmers minimally maintain herbaceous vegetation, but nutrient retention efficiency could be improved with woody biomass.

Effects of low concentrations of glyphosate-based herbicide factor 540 on an agricultural stream freshwater phytoplankton community.

Residual glyphosate from glyphosate based herbicides (GBH) are ubiquitously detected in streams draining agricultural fields, and may affect phytoplankton communities present in these ecosystems. Here, the effects of the exposure (96 h) of a phytoplankton community collected in an agricultural stream to various glyphosate concentrations (1, 5, 10, 50, 100, 500 and 1000 μg l) of Factor 540 GBH were investigated. The lowest GBH concentration of 1 μg l reduced chlorophyll a and carotenoid contents.

Phytoplankton growth and PSII efficiency sensitivity to a glyphosate-based herbicide (Factor 540).

The use of glyphosate-based herbicides in agriculture has increased steadily since the mid 90's and there is now evidence of glyphosate leaching and contamination of aquatic ecosystems. The aim of this study was to evaluate the effects of a glyphosate-based herbicide (Factor 540) on growth and photosynthetic capacity of algae and cyanobacteria. Six algal and three cyanobacterial species/strains, of three different taxonomic groups, were exposed to five glyphosate concentrations (10, 50, 100, 500 and 1000μgl) during 48h.

Reduction of soil erosion and mercury losses in agroforestry systems compared to forests and cultivated fields in the Brazilian Amazon.

In addition to causing physical degradation and nutrient depletion, erosion of cultivated soils in the Amazon affects aquatic ecosystems through the release of natural soil mercury (Hg) towards lakes and rivers. While traditional agriculture is generally cited as being among the main causes of soil erosion, agroforestry practices are increasingly appreciated for soil conservation. This study was carried out in family farms of the rural Tapajós region (Brazil) and aimed at evaluating soil erosion and associated Hg release for three land uses.

Herbaceous or Salix miyabeana 'SX64' narrow buffer strips as a means to minimize glyphosate and aminomethylphosphonic acid leaching from row crop fields.

Glyphosate is the most widely used herbicide worldwide and is now frequently detected in surface waters of agricultural regions, notably in Quebec (Canada). Numerous legislations require vegetated riparian buffer strips (RBS) along agricultural streams. Quebec policy requires 3-meter-wide RBS.

Glyphosate-Dependent Inhibition of Photosynthesis in Willow.

We studied the physiological mechanisms involved in the deleterious effects of a glyphosate-based herbicide (Factor 540) on photosynthesis and related physiological processes of willow ( cultivar SX64) plants. Sixty-day-old plants grown under greenhouse conditions were sprayed with different rates (0, 1.4, 2.

Glyphosate Can Decrease Germination of Glyphosate-Resistant Soybeans.

We investigated the effects of different concentrations of glyphosate acid and one of its formulations (Roundup) on seed germination of two glyphosate-resistant (GR) and one non-GR variety of soybean. As expected, the herbicide affected the shikimate pathway in non-GR seeds but not in GR seeds. We observed that glyphosate can disturb the mitochondrial electron transport chain, leading to HO accumulation in soybean seeds, which was, in turn, related to lower seed germination.

Environmental and Anthropogenic Factors Influencing Mercury Dynamics During the Past Century in Floodplain Lakes of the Tapajós River, Brazilian Amazon.

In the Tapajós River region of the Brazilian Amazon, mercury (Hg) is a prevalent contaminant in the aquatic ecosystem. Few studies have used comprehensive chronological analyses to examine the combined effects of environmental and anthropogenic factors on Hg accumulation in sediments. Total mercury (THg) content was measured in sediments from eight floodplain lakes and 210 isotope analysis was used to develop a timeline of THg accumulation.

Differential effects of glyphosate and aminomethylphosphonic acid (AMPA) on photosynthesis and chlorophyll metabolism in willow plants.

We used a willow species (Salix miyabeana cultivar SX64) to examine the differential secondary-effects of glyphosate and aminomethylphosphonic acid (AMPA), the principal glyphosate by-product, on chlorophyll metabolism and photosynthesis. Willow plants were treated with different concentrations of glyphosate (equivalent to 0, 1.4, 2.

Climate and Physiography Predict Mercury Concentrations in Game Fish Species in Quebec Lakes Better than Anthropogenic Disturbances.

The fluctuations of mercury levels (Hg) in fish consumed by sport fishers in North-Eastern America depend upon a plethora of interrelated biological and abiological factors. To identify the dominant factors ultimately controlling fish Hg concentrations, we compiled mercury levels (Hg) during the 1976-2010 period in 90 large natural lakes in Quebec (Canada) for two major game species: northern pike (Esox lucius) and walleye (Sander vitreus). Our statistical analysis included 28 geographic information system variables and 15 climatic variables, including sulfate deposition.

Impact of phosphate on glyphosate uptake and toxicity in willow.

Phosphate (PO4(3-)) has been shown to increase glyphosate uptake by willow, a plant species known for its phytoremediation potential. However, it remains unclear if this stimulation of glyphosate uptake can result in an elevated glyphosate toxicity to plants (which could prevent the use of willows in glyphosate-remediation programs). Consequently, we studied the effects of PO4(3-) on glyphosate uptake and toxicity in a fast growing willow cultivar (Salix miyabeana SX64).

Consequences of phosphate application on glyphosate uptake by roots: Impacts for environmental management practices.

Phosphate (PO4(3-)) fertilization is a common practice in agricultural fields also targets for glyphosate application. Due to their chemical similarities, PO4(3-) and glyphosate compete for soil adsorbing sites, with PO4(3-) fertilization increasing glyphosate bioavailability in the soil solution. After PO4(3-) fertilization, its concentration will be elevated in the soil solution and both PO4(3-) and glyphosate will be readily available for runoff into aquatic ecosystems.

Alteration of plant physiology by glyphosate and its by-product aminomethylphosphonic acid: an overview.

It is generally claimed that glyphosate kills undesired plants by affecting the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme, disturbing the shikimate pathway. However, the mechanisms leading to plant death may also be related to secondary or indirect effects of glyphosate on plant physiology. Moreover, some plants can metabolize glyphosate to aminomethylphosphonic acid (AMPA) or be exposed to AMPA from different environmental matrices.

Ecology of Rhodnius robustus Larrousse, 1927 (Hemiptera, Reduviidae, Triatominae) in Attalea palm trees of the Tapajós River Region (Pará State, Brazilian Amazon).

Background: The rising number of acute cases of Chagas disease in the State of Pará, reported in the past two decades, has been associated, in part, with the ingestion of juice of local palm tree fruits, mainly açaí berry and bacaba. Near the study area, in Santarém, Pará State, an outbreak of Chagas disease has been notified and investigations suggest the consumption of bacaba juice as the main source of infection with T. cruzi.

Impact of forested fallows on fertility and mercury content in soils of the Tapajós River region, Brazilian Amazon.

Recent research on slash-and-burn agriculture conducted in the Amazonian basin has suggested that soils must be left under forested fallows for at least 10 to 15 years to regain fertility levels comparable to non-disturbed forests in order to allow for short cycle crop cultivation. However, small scale farmers tend nowadays to re-burn secondary forests as soon as after 3 to 5 years, thus could contribute to further reduce soil fertility and could enhance the transfer of mercury (Hg) naturally present in soils of the region towards water courses. The present research project sets out to characterize the impact of forested fallows of differing age and land-use history on soils properties (fertility and Hg contents) in the region of the Tapajós River, an active pioneer front of the Brazilian Amazon.

Mercury and flooding cycles in the Tapajós River basin, Brazilian Amazon: the role of periphyton of a floating macrophyte (Paspalum repens).

Methylmercury (MeHg) increases mercury (Hg) toxicity and is biomagnified in the trophic chain contaminating riverine Amazon populations. Freshwater macrophyte roots are a main site of Hg methylation in different Brazilian environments. Paspalum repens periphyton was sampled in four floodplain lakes during the dry, rainy and wet seasons for measurement of total Hg (THg), MeHg, Hg methylation potentials, %C, %N, δ(13)C, δ(15)N and bacterial heterotrophic production as (3)H-leucine incorporation rate.

Mercury and methylmercury concentrations in high altitude lakes and fish (Arctic charr) from the French Alps related to watershed characteristics.

Total mercury (THg) and methylmercury (MeHg) concentrations were measured in the muscle of Arctic charr (Salvelinus alpinus) and in the water column of 4 lakes that are located in the French Alps. Watershed characteristics were determined (6 coverage classes) for each lake in order to evaluate the influence of watershed composition on mercury and methylmercury concentrations in fish muscle and in the water column. THg and MeHg concentrations in surface water were relatively low and similar among lakes and watershed characteristics play a major role in determining water column Hg and MeHg levels.

Early Hg mobility in cultivated tropical soils one year after slash-and-burn of the primary forest, in the Brazilian Amazon.

In the Brazilian Amazon, forest conversion to agricultural lands (slash-and-burn cultivation) contributes to soil mercury (Hg) release and to aquatic ecosystem contamination. Recent studies have shown that soil Hg loss occurs rapidly after deforestation, suggesting that Hg mobility could be related to the massive cation input resulting from biomass burning. The objective of this research was to determine the effects of the first year of slash-and-burn agriculture on soil Hg levels at the regional scale of the Tapajós River, in the state of Pará, Brazilian Amazon.

Ecosystem matters: fish consumption, mercury intake and exposure among fluvial lake fish-eaters.

Many studies use the number of fish meals as an estimate of Hg intake, although fish Hg concentrations, even within the same species, can greatly vary. Furthermore, most freshwater advisories only refer to local catch, while market fish advisories only focus on market fish, although both can contribute to Hg body burden. The present study, carried out in lakeside communities from 2 ecosystems in Quebec, Canada, sought to (i) estimate Hg intake from local freshwater sources, hunted waterfowl and market fish and seafood, and (ii) examine the relations between fish consumption, estimated Hg intake and biomarkers of exposure.

Emergence and robustness of a community discussion network on mercury contamination and health in the Brazilian Amazon.

Information exchanges, debates, and negotiations through community social networks are essential to ensure the sustainability of the development process initiated in participatory research. The authors analyze the structural properties and robustness of a discussion network about mercury issues in a community in the Brazilian Amazon involved in a participatory research aimed at reducing exposure to the pollutant. Most of the villagers are connected in a large network and are separated from other individuals by few intermediaries.