Minimizing disruptions caused by damming and ensuring the health of downstream ecosystems

In view of the Brazilian Ten‐Year Energy Expansion Plan 2021, this article presents a discussion on environmental flow (e‐flow). The authors analyze the literature to show the evolution of publications concerning e‐flow releases from the perspective of ecosystems services preservation considering results from different case studies from throughout the world. Finally, two main recommendations are drawn regarding e‐flow are: (1) performing a holistic approach to e‐flow planning, including hydrological, hydraulic, water quality, habitat, and riparian zone considerations; and (2) installing in new structures adequate bottom outlets to allow a range of adjustable e‐flow from reservoir dams to reproduce natural flow variations.     

Overview of surface measurements and spatial characterization of submicrometer particulate matter during the DISCOVER-AQ 2013 campaign in Houston,TX

The sources of submicrometer particulate matter (PM₁) remain poorly characterized in the industrialized city of Houston, TX. A mobile sampling approach was used to characterize PM₁ composition and concentration across Houston based on high-time-resolution measurements of nonrefractory PM₁ and trace gases during the DISCOVER-AQ Texas 2013 campaign. Two pollution zones with marked differences in PM₁ levels, character, and dynamics were established based on cluster analysis of organic aerosol mass loadings sampled at 16 sites. The highest PM₁ mass concentrations (average 11.6 ± 5.7 µg/m³) were observed to the northwest of Houston (zone 1), dominated by secondary organic aerosol (SOA) mass likely driven by nighttime biogenic organonitrate formation. Zone 2, an industrial/urban area south/east of Houston, exhibited lower concentrations of PM₁ (average 4.4 ± 3.3 µg/m³), significant organic aerosol (OA) aging, and evidence of primary sulfate emissions. Diurnal patterns and backward-trajectory analyses enable the classification of airmass clusters characterized by distinct PM sources: biogenic SOA, photochemical aged SOA, and primary sulfate emissions from the Houston Ship Channel. Principal component analysis (PCA) indicates that secondary biogenic organonitrates primarily related with monoterpenes are predominant in zone 1 (accounting for 34% of the variability in the data set). The relevance of photochemical processes and industrial and traffic emission sources in zone 2 also is highlighted by PCA, which identifies three factors related with these processes/sources (~50% of the aerosol/trace gas concentration variability). PCA reveals a relatively minor contribution of isoprene to SOA formation in zone 1 and the absence of isoprene-derived aerosol in zone 2. The relevance of industrial amine emissions and the likely contribution of chloride-displaced sea salt aerosol to the observed variability in pollution levels in zone 2 also are captured by PCA.

Implications: This article describes an urban-scale mobile study to characterize spatial variations in submicrometer particulate matter (PM₁) in greater Houston. The data set indicates substantial spatial variations in PM₁ sources/chemistry and elucidates the importance of photochemistry and nighttime oxidant chemistry in producing secondary PM₁. These results emphasize the potential benefits of effective control strategies throughout the region, not only to reduce primary emissions of PM₁ from automobiles and industry but also to reduce the emissions of important secondary PM₁ precursors, including sulfur oxides, nitrogen oxides, ammonia, and volatile organic compounds. Such efforts also could aid in efforts to reduce mixing ratios of ozone.     

In situ chemical oxidation: Lessons learned at multiple sites

This paper compiles a detailed set of in situ chemical oxidation (ISCO) lessons learned pertaining to design, execution, and safety based on global experiences over the last 20 years. While the benefits of a “correct” application are known (e.g., cost effectiveness, speed, permanence of treatment), history also provides examples of a variety of “incorrect” applications. These provide an opportunity to highlight recurring themes that resulted in failures. ISCO is, and will continue to provide, an important remedial tool for site remediation, particularly as a component of a multifaceted approach for addressing large and complex sites. Future success, however, requires an objective understanding of both the benefits and the limitations of the technology. The ability to learn from the mistakes of the past provides an opportunity to eliminate, or at least minimize, them in the future. Over the last 25 years of ISCO application, process understanding and knowledge have improved and evolved. This paper combines a thorough discussion of lessons learned through decades of ISCO implementation throughout all aspects of ISCO projects with an analysis of changes to the ISCO remediation market. By discussing the interplay of these two themes and providing recommendations from collective lessons learned, we hope to improve the future of safe, cost‐effective, and successful applications of ISCO.     

Prevalence of chromosomal aberrations in Argentinean agricultural workers

Environmental Science and Pollution Research - Little is known about biosecurity measures and toxic effects during pesticide application in the province of Jujuy, Argentina, particularly concerning...     

Ecotoxicity interspecies study of ionic liquids based on phosphonium and ammonium cations

Environmental Science and Pollution Research - This work studies the effects of different bromide-based ionic liquids, with phosphonium and ammonium cations, towards several environmental...     

Presence of Torque Teno Virus (TTV) in Tap Water in Public Schools from Southern Brazil

Torque teno virus (TTV) was surveyed in tap water collected in schools from three municipalities located in the south of Brazil. TTV genomes were found in 11.7 % (4/34) of the samples. TTV DNA was detected in 10.5 % (2/19) of the samples collected at the city of Caxias do Sul and in 25 % (2/8) of the samples from Pelotas. Those cities have a low rate of sewage treatment. All samples from Santa Cruz do Sul, which has nearly 92 % of its sewage treated, were negative. These results suggest that the amount of sewage treated may have an effect on the detection rates of TTV DNA in drinking water in a given urban area, showing a mild negative correlation (r = ?0.76), when comparing the percentage of sewage treatment to the detection of TTV genomes. The detection rate of TTV was also compared with Escherichia coli, showing a strong correlation (r = 0.97), indicating that TTV may be a suitable marker of fecal contamination.     

Recent Changes in Stream Flashiness and Flooding,and Effects of Flood Management in North Carolina and Virginia

The southeastern United States has undergone anthropogenic changes in landscape structure, with the potential to increase (e.g., urbanization) and decrease (e.g., reservoir construction) stream flashiness and flooding. Assessment of the outcome of such change can provide insight into the efficacy of current strategies and policies to manage water resources. We (1) examined trends in precipitation, floods, and stream flashiness and (2) assessed the relative influence of land cover and flow‐regulating features (e.g., best management practices and artificial water bodies) on stream flashiness from 1991 to 2013. We found mean annual precipitation decreased, which coincided with decreasing trends in floods. In contrast, stream flashiness, overall, showed an increasing trend during the period of study. However, upon closer examination, 20 watersheds showed stable stream flashiness, whereas 5 increased and 6 decreased in flashiness. Urban watersheds were among those that increased or decreased in flashiness. Watersheds that increased in stream flashiness gained more urban cover, lost more forested cover and had fewer best management practices installed than urban watersheds that decreased in stream flashiness. We found best management practices are more effective than artificial water bodies in regulating flashy floods. Flashiness index is a valuable and straightforward metric to characterize changes in streamflow and help to assess the efficacy of management interventions.     

Tillage system did not affect weed diversity in a 23-year experiment in Mediterranean dryland

This study investigated whether the choice of a tillage system (no-tillage, minimum tillage or traditional tillage) affected weed diversity in a 23 years cereal–leguminous rotation system in Spain. Weed diversity was assessed using common diversity indices: species richness, Shannon's index and Pieloús evenness. Linear mixed-effects models were employed to compare the tillage systems. It was found that after 23 years no large differences between tillage systems have arisen related to weed diversity. Only minimum tillage appeared to support, on average, more species than the two other tillage systems. Richness, Shannon diversity index and evenness varied largely through the years in all tillage systems but this variation was not related to type of crop sown (cereal or leguminous). Our results highlight that conservation tillage practices did not represent any concern for weed diversity conservation in cereal–leguminous rotations in the conditions of central Spain.     

Assessment of contamination by heavy metals and petroleum hydrocarbons in sediments of Montevideo Harbour (Uruguay)

As part of the first environmental assessment within Montevideo Harbour, in summer and winter of 1998, sediments samples were collected at eight locations to determine the spatial distribution of anthropogenic pollutants. Muddy sediments with high organic matter content dominate the study area. Heavy metal levels indicated that sediments were highly polluted with Zn (overall mean: 312+/-102 microg g(-1) dry sediment), Pb (85+/-31), Cu (89+/-25), Cr (162+/-62), and Hg (0.63+/-0.3) and moderately with Ni (30+/-2) and Ag (1.2+/-0.4). Depending on location and season, aliphatic hydrocarbons reached from 21 to 120 microg g(-1), while the unresolved complex mixture represented up to 76% of the total aliphatic fraction. Total PAH concentrations ranged from 1.56 to 90.44 microg g(-1); except at one location, petroleum derivatives were identified as main local source. The results pointed out that almost all the harbour area presented some substances that can cause adverse biological effects, especially in the inner region where all metals are above PEL levels. Principal components analysis confirmed that the inner harbour region is most severely affected by the pollutants and it was possible to differentiate three regions according to their environmental quality.     

Evaluation of the Impacts of Dock Structures and Land Use on Tidal Creek Ecosystems in South Carolina Estuarine Environments

Tidal creeks and their associated salt marshes are the primary link between uplands and estuaries in the southeastern region. They are also critical nursery and feeding grounds. In addition, the uplands surrounding creeks are preferred sites for homebuilding because of their natural beauty and the ability to access the estuary from a personal dock structure. The objective of this study was to evaluate the cumulative impacts of docks on tidal creek nursery habitats for both small and large tidal creeks. The number of docks was associated with the amount of impervious cover in both small and large creeks. The presence of docks had little measurable effect on sediment metal concentrations at the scale of small and large creeks. In small and large creeks, sediment polycyclic aromatic hydrocarbon (PAH) concentrations were related to the human activity in the upland that includes the presence of docks at the scale of small and large creeks. Some impacts on the benthic community were associated with docks and human activity in small creeks but not in large creeks. Suburban development may reduce fish and crustacean abundances, but the dock may potentially mediate the development effect. Individually, the harm to the marine environment resulting from dock shading, chrominated copper arsenate leachates, and PAH contamination was small at the scale of tidal creeks. However, impacts from dock structures could not be separated from anthropogenic watershed-scale effects. These results demonstrate that suburban development with its accompanying dock construction does represent a major source of environmental degradation to tidal creeks and associated salt marsh habitats.