Nutrient baselines of Cerrado low-order streams: comparing natural and impacted sites in Central Brazil

Abstract

The aquatic systems responsible for water supply in the Brazilian Federal District (FD) have been threatened by anthropogenic pressures, especially considering the expressive demographic increase in the region during the last decades. The purposes of this research were: (a) to assess the water quality in streams located in the FD by monitoring physical-chemical variables; (b) to define baselines for these variables among different ecological status categories. The 14 investigated streams were sampled between 2006 and 2009, in the dry (August-September, 2006, 2008, 2009) and rainy (March-April, 2008, 2009) seasons. All sampling sites were classified in four categories ("very impacted", "impacted", "in transition" and "natural") using an adaptation of a rapid habitat assessment protocol. Differences in water quality among sites were generally well predicted in the four ecological status categories defined by the protocol, which showed a gradient in nutrient concentrations from reference sites classified as "natural" (medians: electrical conductivity = 7.3 μS cm(-1); nitrate = 0.040 mg L(-1); ammonium = 0.039 mg L(-1); soluble reactive phosphorus (SRP) = <0.001 mg L(-1); total phosphorus (TP) = 0.006 mg L(-1); ) to those classified as "very impacted" (medians: electrical conductivity = 87.7 μS cm(-1); nitrate = 0.247 mg L(-1); ammonium = 0.219 mg L(-1); SRP = 0.010 mg L(-1); TP = 0.035 mg L(-1)). Point sources inputs were the main factor for water quality deterioration. The nutrient baselines reported were relatively low when compared to data collected from reference areas in Brazil (e.g., São Paulo State) or temperate regions, especially for TP.

A Water–Energy–Food Nexus Perspective on the Challenge of Eutrophication

“…As watershed size increases, factors other than land use can also become important, such as natural features (e.g., intensity of extreme rainfall events) [39]. Similar findings can be deduced from trophic state indexes and nutrient criteria (e.g., reference/background concentrations) that have been developed in Brazil for eutrophication assessment [40][41][42][43].…”

Factors that drive zooplankton diversity in Neo-Tropical Savannah shallow lakes

“…These results can be explaining by the increase of system productivity, showing by chlorophyll dates on the shallow lakes (Marleau et al, 2015;Rezende et al, 2016). Also the correlation of most diversity shallow lakes (Bonita and Gansos) whit nitrogen and phosphorus (respectively) in CCA analysis suggest that these nutrients are limiting in savannah lentic systems for the zooplankton communities (Fonseca et al, 2014). Nutrient enrichment also explains the high turbidity by the increase of available ions in the water (Brandimarte et al, 2008).…”

“…This high variability on characteristics of aquatic environments has led to the recent studies on the alpha (number of species) and beta (species composition turnover among communities) diversity Lopes et al, 2014;Heino et al, 2015a, b). However, the lakes situated in Brazilian savannah (general characteristics) tend to be shallow, with transparent water and a dense bank of macrophytes, including a rich submerged and floating flora (Junk et al, 2014), but poor in nutrients (Fonseca et al, 2014). Therefore, our hypothesis is that i) shallow lakes systems that are more heterogeneous in their environmental…”

“…The neo-tropical savannah (Cerrado) has countless number of natural shallow lakes formed into wetlands areas by the upwelling of the groundwater (Fonseca et al, 2014). Studies done in these lentic systems have been scarce, despite their potential to increasing aquatic biodiversity in Brazilian savannah have been reported (Leibowitz, 2003), especially in protected areas with a pristine condition.…”

Bioindicators assessing water quality and environmental impacts of water treatment plant sludge

“…This inadequate disposal can have negative impacts, both by increasing the amount of solids and turbidity and introducing toxic agents into the water, as well as compromising the stability of aquatic life (Filho et al, 2013;Hoppen et al, 2006). Traditionally, the assessment of these environmental impacts is accomplished by measuring chemical and physical variables (CONAMA, 2005;Fonseca et al, 2014;WHO, 1996). However, many authors (Beneberu et al, 2014;Bere and Tundisi, 2012;Calderon et al, 2014;Rinaldi, 2007) state that the use of biological responses as environmental degradation indicators are more advantageous compared to chemical and physical parameters since these non-biological measurements only represent a snapshot of the moment they were collected.…”