Global metrics of land cover and land use provide a fundamental basis to examine the spatial variability of human-induced impacts on freshwater ecosystems. However, microscale processes and site ...specific conditions related to bank vegetation, pollution sources, adjacent land use and water uses can have important influences on ecosystem conditions, in particular in smaller tributary rivers. Compared to larger order rivers, these low-order streams and rivers are more numerous, yet often under-monitored. The present study explored the relationship of nutrient concentrations in 150 streams in 57 hydrological basins in South, Central and North America (Buenos Aires, Curitiba, São Paulo, Rio de Janeiro, Mexico City and Vancouver) with macroscale information available from global datasets and microscale data acquired by trained citizen scientists. Average sub-basin phosphate (P-PO4) concentrations were found to be well correlated with sub-basin attributes on both macro and microscales, while the relationships between sub-basin attributes and nitrate (N-NO3) concentrations were limited. A phosphate threshold for eutrophic conditions (>0.1 mg L-1 P-PO4) was exceeded in basins where microscale point source discharge points (eg. residential, industrial, urban/road) were identified in more than 86% of stream reaches monitored by citizen scientists. The presence of bankside vegetation covaried (rho = -0.53) with lower phosphate concentrations in the ecosystems studied. Macroscale information on nutrient loading allowed for a strong separation between basins with and without eutrophic conditions. Most importantly, the combination of macroscale and microscale information acquired increased our ability to explain sub-basin variability of P-PO4 concentrations. The identification of microscale point sources and bank vegetation conditions by citizen scientists provided important information that local authorities could use to improve their management of lower order river ecosystems.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
According to the World Health Organization (WHO), the definition of water quality indicators, including contaminants of emerging concern (CECs), associated with the development of multi-barrier ...approaches for wastewater treatment, are crucial steps towards direct potable reuse of water. The aims of this study were 1) quantifying twelve CECs (including pharmaceutical, stimulant, and artificial sweetener compounds) in both untreated and treated wastewater samples in a Brazilian wastewater treatment plant (WWTP) using bidimensional liquid chromatography coupled with tandem mass spectrometry, allowing the selection of five marker (i.e., priority) CECs; 2) evaluating the adsorption potential of such selected CECs caffeine, hydrochlorothiazide, saccharin, sucralose (SUC), and sulfamethoxazole (SMX) onto coconut-shell granular activated carbon (GAC); and 3) investigating the removal of the same CECs by a multi-barrier system (pilot-scale, 350 L h−1) treating the effluent of the WWTP and composed of reverse osmosis (RO), photoperoxidation (UV/H2O2), and filtration with GAC. Such technologies were tested separately and in binary or ternary combinations. Eleven and eight CECs were detected and quantified on the untreated and treated wastewater samples of the Brazilian WWTP, respectively. For the treated wastewater, the concentrations ranged from 499 ng L−1 (SMX) to 87,831 ng L−1 (SUC). The adsorption onto AC data fitted the Sips isotherm model, indicating monolayer chemisorption, which was also suggested by the mean adsorption energy values (>16 kJ mol−1). SMX and SUC were the most and the least adsorbed CECs (4.33 and 1.21 mg g−1, respectively). Concerning the pilot-scale treatment plant, the ternary combination (RO + UV/H2O2+GAC) removed >99% of the five marker CECs and promoted reductions on water color, turbidity, as well as on nitrogen and phosphorus concentrations. Further studies on water reuse could prioritize the selected marker CECs as quality indicators. While the removal of marker CECs is one of the WHO performance requirements, the RO + UV/H2O2+GAC system showed promising results as a first approach to direct potable reuse of water.
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•Sucralose was found ranging from 23,810 to 87,831 ng L−1 on the treated effluent.•Sulfamethoxazole had an adsorption capacity 3.6-fold higher than sucralose.•The adsorption capacity on real effluent compared to water was 49.1% lower for caffeine.•The mean adsorption energy was higher than 16 kJ mol−1, indicating hydrogen bonding.•The scheme RO + UV/H2O2+GAC removed >99% of the selected emerging contaminants.
The COVID-19 pandemic required a wide range of adaptations to the way that water sector operated globally. This paper looks into the impact of the COVID-19 pandemic on Brazilian water sector and ...evaluates the water sector's organisational resilience from the lens of water professionals. This study uses British Standard (BS 65000:2014)'s Resilience Maturity Scale method to evaluate organisational resilience in water sector under two defined scenarios of before and during the pandemic. For this purpose, the self-assessment framework developed by Southern Water in the United Kingdom (based on BS 65000:2014), comprising of the core resilience elements of Direction, Awareness, Alignment, Learning, Strengthening, and Assurance, are used for evaluations. A qualitative-quantitative surveying method is used for data collection. A total of 14 responses to the whole questionnaire were received from May 2021 to August 2021, each representing one water company in Brazil (four local companies and ten state-owned ones). The analyses identified COVID-19 as a threat multiplier particularly to already existing financial challenges due to the pre-existing threats in water sector. Bad debt and the COVID-19 emergency measures are recognised as the main challenges by 21 % and 14 % of the survey respondents. The state-owned and local companies scored an almost similar maturity level 3, 35 % and 34 % respectively, while the local companies scored much lower at maturity level 4 i.e., 26 % as opposed to 47 % in state-owned sector. This indicates that COVID-19 has a greater impact on local companies and the needs to increase preparedness. This study replicates an international experience to raise awareness on water sector's resiliency in Brazil and how it can be improved to withstand future external shocks. It sheds light on how and what existing challenges can be exacerbated facing a global shock and proposes opportunities for improvement of resilience maturity in water sector in Brazil.
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•COVID-19 globally exacerbated pre-existing challenges in water sector.•COVID-19 has been a threat multiplier for water sector financial issues.•Brazilian water companies were assessed in relation to their resilience maturity.•State-owned companies had higher level of resilience maturity than local companies.•Water companies can learn from their response to COVID-19 to strengthen resilience.
•Forested areas provide better raw water quality for drinking purposes.•Trihalomethane potential formation was 24% lower in protected watersheds.•Treatment costs were lowest in impacted ...basins.•Factors other than raw water quality influenced treatment costs.•Water utilities should consider raw water characteristics for technology selection.
Anthropogenic disturbances to the environment can compromise valuable ecosystem services, including the provision of potable water. These disturbances decrease water quality, potentially increasing treatment costs for producing drinking water. We investigated the land use influence on raw surface water quality for drinking supply in the most populous state in Brazil (São Paulo). We analyzed a long-term dataset (2000–2014) to assess the raw water quality for drinking purposes in more than 50 river/stream sites located in predominantly industrial/urban, agriculture or forested watersheds. Temporal, seasonal and land cover influences were assessed through Analysis of Covariance (ANCOVA). Infrastructure and operating costs of the Water Treatment Plants (WTPs) were estimated. We found significantly better water quality (p<0.01, ANCOVA) in forested watersheds (e.g., mean turbidity and true color: 10 NTU and 14mgPt/L versus 48–56 NTU and 38–49mgPt/L in industrial/urban and agriculture areas). THMPF and TOC were greater in altered basins (304μg/L and 5.8mg/L, respectively), especially in the rainy season. Drinking water outputs varied across WTPs located in industrial/urban (average: 525L/s), agriculture (392L/s) and forest (167L/s) watersheds. Infrastructure and operating costs, shown as cost per unit of capacity, were greater for plants located in forested areas (US$ 98,208 per L/s), as compared to industrial/urban (US$ 78,230 per L/s) and agriculture (US$ 75,332 per L/s) basins. This was probably because treatment costs in these locations were greater in spite of plants starting with higher quality water. We recommend upgrades in the existing WTPs and the construction of new water utilities consider treatment costs related to predicted changes in land use in supply watersheds. Watershed conservation practices, water demand management, remediation and adaptation actions could also lower treatment costs and alter optimal treatment technology choice.
•A new trophic state index is proposed for tropical/subtropical reservoirs (TSItsr).•Trophic state categories are defined based on total phosphorus and chlorophyll a.•Indexes for temperate water ...bodies overestimate enrichment status of tropical/subtropical ones.•The TSItsr may help sustainable water management in the tropics/subtropics.
Trophic state is an important property of the aquatic ecosystems as it reflects the anthropogenic influence on water quality and the ecological functioning of rivers, lakes and reservoirs. Trophic state indexes provide an insight on how nutrient and light availability controls phytoplankton development. We analyzed data on total phosphorus (TP, N=931), chlorophyll a (Chl a, N=848) and Secchi disk depth (SDD, N=204) monitored in 18 tropical/subtropical reservoirs from 1996 to 2009 by the Environmental Protection Agency of São Paulo State (Brazil) in a bimonthly basis. Through linear regression with paired data on “TP×Chl a” and “Chl a×SDD”, we proposed a new trophic state index for tropical/subtropical reservoirs (TSItsr). Based on the annual geometric mean concentrations of TP and Chl a, we also assessed the risk of occurrence of individual episodes (e.g. Chl a≥30μg/L or TP≥50μg/L) within six categories: ultraoligotrophic (U), oligotrophic (O), mesotrophic (M), eutrophic (E), supereutrophic (S) and hypereutrophic (H). The upper boundaries (as annual geometric means) are (μg/L): 15.9 (U), 23.8 (O), 36.7 (M), 63.7 (E) and 77.6 (S) for TP and 2.0 (U), 3.9 (O), 10.0 (M), 20.2 (E) and 27.1 (S) for Chl a. The lower boundaries for the hypereutrophic state were (μg/L) 77.7 (TP) and 27.2 (Chl a). Comparisons with criteria available in the literature suggested that trophic state limits established for temperate systems are not suitable for tropical/subtropical reservoirs and may overestimate their enrichment condition. Restrictions of the TSItsr are discussed in light of the limiting-nutrient concept, the spatial and temporal water quality variability and the use of Chl a as an indicator of phytoplankton density and biomass. The TSItsr may aid in reservoirs management as a starting point for analyzing data on water quality in the tropics/subtropics since this issue is of paramount importance worldwide.
Trophic state indexes (TSI) guide management strategies regarding eutrophication control worldwide. Such indexes usually consider chlorophyll-a (Chl-a), total phosphorus (TP), and Secchi disk depth ...(SDD) as independent variables for estimating aquatic productivity and the degree of impairment. TSIs for each of these components are frequently averaged to produce a single TSI value associated with a trophic state classification (e.g., oligotrophic, mesotrophic, or eutrophic). The potential divergence among equations and classification systems originally developed for temperate lakes or tropical/subtropical reservoirs might be particularly relevant in the tropics, where there is a lack of data and the use of equations originally developed for temperate systems may be inappropriate. We calculated two widely used TSIs for temperate lakes (TSI
temp
) or tropical reservoirs (TSI
trop
) and explored the deviations among TSI components in Brazilian reservoirs. When applied to our tropical/subtropical reservoirs, the TSI
temp
provided a conservative approach, with lower limits anticipating increasing trophic state classification. TSI components for Chl-a and SDD significantly deviated for both sets of equations, and these discrepancies were related to turbidity, water temperature, and cyanobacterial biomass. For TSI
temp
, but not for TSI
trop
, TSI values in relation to Chl-a and TP were also significantly different. All such deviations have important management implications especially when Chl-a, TP, and SDD are averaged in a single TSI, representing loss of information and less useful trophic state classifications. Our results demonstrate that tropical water bodies may respond to drivers of eutrophication differently than temperate systems, highlighting the need for more data to better inform management of these understudied ecosystems. As managers collect data from more tropical water bodies, regional models may offer even better understanding of factors influencing trophic state.
Freshwater ecosystems are severely threatened by urban development and agricultural intensification. Increased occurrence of algal blooms is a main issue, and the identification of local dynamics and ...drivers is hampered by a lack of field data. In this study, data from 13 cities (250 water bodies) were used to examine the capacity of trained community members to assess elevated phytoplankton densities in urban and peri-urban freshwater ecosystems. Coincident nutrient concentrations and land use observations were used to examine possible drivers of algal blooms. Measurements made by participants showed a good relationship to standard laboratory measurements of phytoplankton density, in particular in pond and lake ecosystems. Links between high phytoplankton density and nutrients (mainly phosphate) were observed. Microscale observations of pollution sources and catchment scale estimates of land cover both influenced the occurrence of algal blooms. The acquisition of environmental data by committed and trained community members represents a major opportunity to support agency monitoring programmes and to complement field campaigns in the study of catchment dynamics.
Pesticides can cause harmful effects to aquatic communities, even at concentrations below the threshold limit established as guidelines for the water bodies by environmental agencies. In this ...research, an input of the herbicide 2,4-dichlorophenoxyacetic acid (i.e., 2,4-D) was simulated under controlled conditions in a 500-m-long reach of a first-order tropical stream in Southeastern Brazil. Two water samplings at eight stations investigated the stream longitudinal contamination profile. The ecotoxicological effects were analyzed using
Eruca sativa
L. seed germination assays and the acute and chronic toxicity tests with the neotropical cladoceran
Ceriodaphnia silvestrii
. Physicochemical parameters of water quality were evaluated to characterize the study area and quantify 2,4-D concentrations along the stream to assess pesticide retention. The 2,4-D concentration was reduced by approximately 50% downstream in the samplings, indicating that the herbicide was retained along the stream. Moreover,
C. silvestrii
reproduction in long-term assays decreased approximately 50% in the stations with higher concentrations of 2,4-D than the laboratory control. After contamination,
E. sativa
L. showed a lower average root growth (1.0 cm), statistically different from the control (2.2 cm). On the other hand, similar growth values were obtained among the background and the most downstream stations. Our study highlighted the relevance of reviewing and updating herbicide guidelines and criteria to prevent possible ecological risks.
Toxic cyanobacterial blooms in aquatic ecosystems are associated to both public health and environmental concerns worldwide. Depending on the treatment technologies used, the removal capacity of ...cyanotoxins by drinking water treatment plants (DWTPs) is not sufficient to reach safe levels in drinking water. Likewise, controlling these blooms with algaecide may impair the efficiency of DWTPs due to the possible lysis of cyanobacterial cells and consequent release of cyanotoxins. We investigated the effects of three commercial algaecides (cationic polymer, copper sulfate, and hydrogen peroxide) on the growth parameters of the cyanobacterium
Microcystis aeruginosa
and the release of microcystin-LR (MC-LR). The potential interference of each algaecide on the MC-LR removal by adsorption on activated carbon (AC) was also tested through adsorption isotherms and kinetics experiments. Most algaecides significantly decreased the cell density and biovolume of
M. aeruginosa
, as well as increased the release of MC-LR. Interestingly, the presence of the algaecides in binary mixtures with MC-LR affected the adsorption of the cyanotoxin. Relevant adsorption parameters (e.g., maximum adsorption capacity, adsorption intensity, and affinity between MC-LR and AC) were altered when the algaecides were present, especially in the case of the cationic polymer. Also, the algaecides influenced the kinetics (e.g
.
, by shifting the initial adsorption and the desorption constant), which may directly affect the design and operation of DWTPs. Our study indicated that algaecides can significantly impact the fate and the removal of MC-LR in DWTPs when the adsorption process is employed, with important implications for the management and performance of such facilities.
This paper attempts to understand and explore the problem of eutrophication in the context of agriculture with the help of a nexus perspective. Eutrophication is significantly linked to water and ...energy resources with theoretically well-defined trade-offs and threshold levels. While looking at the linkages between water and land resources comprehensively, our paper questions the present approach to designing and implementing watershed management, and analyses the effects of agricultural intensification, especially in dry regions. Eutrophication is the process by which excessive nutrient loads in water bodies lead to undesirable water-quality problems and the degradation of the overall aquatic ecosystem. Due to limited information and knowledge on water and soil quality in most countries, farmers continue to use fertilizers at an increasing rate and agricultural run-off has been carrying ever more nitrogen and phosphorus into water bodies. This is likely to become a vicious cycle of eutrophication affecting food and water security. Of late, soil- and water-conservation interventions, like watershed development, are further reducing run-off. It is argued that there is a need to rethink the assumptions under which watershed interventions are designed and implemented.
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