Mercury methylation along a lake-forest transect in the Tapajós river floodplain, Brazilian Amazon: seasonal and vertical variations

The seasonal and spatial variations of net methylmercury production in sediments, soils and other sites were evaluated by assays with 203Hg at different depths and locations along a lake-forest transect at lake Enseada Grande, Tapajós river. Soil and sediment samples were taken at the surface and at different depths up to 9 cm. Fresh samples and acidified controls (1-3 g dry wt.) were slurried with local water and incubated in the dark at 25-28 degrees C for 3 days with 0.5-1.6 microg Hg g(-1) (dry wt.) added as 203HgCl2. CH3 203Hg was extracted and measured in scintillation cocktail after acid leaching. Methylmercury production varied by orders of magnitude among sites and among sediment or soil layers. Seasonal variations were smaller than those with sample depth and location. In both seasons, MeHg formation in sediment and soil or flooded soil decreased with depth and was, in the top layers, one order of magnitude higher in the C-rich littoral macrophyte zone (2.3-8.9%) and flooded forest (3.2-4.5%) than in the center of the lake (0.2-0.56%). Similar MeHg production was found in slurried dry soils (dry season) and in soils already flooded for months. In the macrophyte zone soil (dry season), methylation was mainly associated with the thin Paspalum sp. rootlet layer. In the forest site, vertical variation in methylation was less pronounced in flooded than in dry soils and during the inundation the higher methylation rate was found in the flocculent sediment settled over the litter layer. The roots of floating Paspalum sp. were an important Hg methylation site, particularly those heavily colonized with periphyton (3.4-5.4%). Methylation in surface or near-bottom water was undetectable (< 3 x 10(-2)%) at all sites. Flooded forests and macrophyte mats are specific features of the Amazon and are important links between Hg inputs from natural and manmade sources and MeHg exposure of local populations through fish intake.     

Evaluation of total mercury concentrations in fish consumed in the municipality of Itaituba, Tapajós River Basin, Pará, Brazil

The environmental exposure to mercury by riverine and Indian communities can occur through the ingestion of fish and products contaminated by mercury compounds. The present study aims to evaluate the total mercury concentration in the different fish species most consumed in the municipality of Itaituba, Tapajós river basin, where there are intense gold-mining activities. These fish samples were analyzed by atomic absorption spectrophotometry by cold vapor technique, Automatic Mercury Analyzer HG-3500. The largest mercury concentrations were found in the carnivorous species ranging from 112.4 to 2250 microg/g, while the detritivorous, herbivorous and omnivorous species presented total mercury levels ranging from 3.2 to 309.8 microg/g, which is below the limit established by the World Health Organization. This paper also reports and identifies which species are more polluted and present a statistical relationship among concentration and weight of the carnivorous species studied in detail, Brachyplatystoma flavicans (dourada) (r2 = 0.691) and Pseudoplatystoma sp. (surubim) (r2 = 0.654).     

Evaluation of mercury pollution in cultivated and wild plants from two small communities of the Tapajós gold mining reserve, Pará State, Brazil

This study examines the total Hg contamination in soil and sediments, and the correlation between the total Hg concentration in soil and vegetables in two small scale gold mining areas, S?o Chico and Creporizinho, in the State of Para, Brazilian Amazon. Total Hg values for soil samples for both study areas are higher than region background values (ca. 0.15 mg/kg). At S?o Chico, mean values in soils samples are higher than at Creporizinho, but without significant differences at alpha<0.05 level. S?o Chico's aboveground produce samples possess significantly higher values for total Hg levels than samples from Creporizinho. Creporizinho's soil-root produce regression model were significant, and the slope negative. Creporizinho's soil-aboveground and root wild plants regression models were also significant, and the slopes positives. Although, aboveground:root ratios were >1 in all of S?o Chico's produce samples, soil-plant parts regression were not significant, and Hg uptake probably occurs through stomata by atmospheric mercury deposition. Wild plants aboveground:root ratios were <1 at both study areas, and soil-plant parts regressions were significant in samples of Creporizinho, suggesting that they function as an excluder. The average total contents of Hg in edible parts of produces were close to FAO/WHO/JECFA PTWI values in S?o Chico area, and much lower in Creporizinho. However, Hg inorganic small gastrointestinal absorption reduces its adverse health effects.     

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, δ¹³C, δ¹⁵N and bacterial heterotrophic production as ³H-leucine incorporation rate. THg concentration varied from 67 to 198 ng/g and the potential of Me²⁰³Hg formation was expressive (1-23%) showing that periphyton is an important matrix both in the accumulation of Hg and in MeHg production. The concentration of MeHg varied from 1 to 6 ng/g DW and was positively correlated with Me²⁰³Hg formation. Though methylmercury formation is mainly a bacterial process, no significant correlation was observed between the methylation potentials and bacterial production. The multiple regressions analyses suggested a negative correlation between THg and %C and %N and between methylation potential and δ¹³C. The discriminant analysis showed a significant difference in periphyton δ¹⁵N, δ¹³C and THg between seasons, where the rainy season presented higher δ¹⁵N and the wet period lighter δ¹³C, lower THg values and higher Me²⁰³Hg formation. This exploratory study indicates that the flooding cycle could influence the periphyton composition, mercury accumulation and methylmercury production.     

Mercury concentrations of fish, river water, and sediment in the Río Ramis-Lake Titicaca watershed, Peru

This study reports the first set of data on the concentration of mercury in muscle tissue of several varieties of fish from Lake Titicaca, including the pejerrey (Basilichthyes bonariensis), the carachi (Orestias), and 2 types of indigenous catfish (Trichomycterus). Approximately 27% of the pejerrey and 75% of the carachi exceeded the US EPA fish tissue-based water quality criterion level of 0.30 microg g(-1). Mercury levels of pejerrey increased with fish size, although this relationship was less apparent for the smaller carachi. The pejerrey and carachi are important food fish for local residents. A synoptic sampling of the Río Ramis--the largest tributary to Lake Titicaca--was conducted in an attempt to determine if mercury releases from artisanal gold mining could be an important source of Hg contamination to Lake Titicaca. Although highly elevated concentrations of Hg and other heavy metals were documented in headwater streams near the mining centers of La Rinconada and Cecilia, the quantity of Hg entering Lake Titicaca that could be attributed to mining in the Ramis watershed was below the quantifiable limit in our July 2002 study. This does not diminish the localized threat to mercury exposure for the artisanal gold miners themselves, as well as their families. Further studies of mercury dynamics in Lake Titicaca are recommended, as well as in the rivers draining into the lake. It is probable that most of the downgradient transport of Hg and other trace metals from the headwater mining centers occurs as suspended sediment during seasonal periods of high-flow.     

Microbial polymers in the aquatic environment—III: Isolation from river,potable and underground water and analysis

Organic substances from three river waters, one tap and one underground water were concentrated by vacuum distillation and the polymers with molecular weights > 10,000 were isolated by dialysis and lyophilization. The COD of the lyophilisates amounted to 19.8, 28.9 and 23.9% of the total COD in river waters, and to 13.9 and 13.1% of the total COD in tap and underground water, respectively. All isolated polymers contained sugars, amino sugars and amino acids, which indicates their microbial origin. The sum of these compounds amounted to 5.6, 6.8, and 9.0% of all organic substances present in river waters, and to 1.9 and 0.8% of those present in tap and underground water, respectively. It is concluded that the microbial polymers are ubiquitous and form part of the organic background of the aquatic environment.     

The Line of Beauty in River Designs: Hogarth’s Aesthetic Theory on Capability Brown’s Eighteenth-Century River Design and Twentieth-Century River Restoration Design

William Hogarth (1697–1764) was an influential eighteenth-century philosopher whose theory of beauty (1753) held that the “serpentine” line was the ideal “line of beauty.” Contemporary with Hogarth, the landscape architect Capability Brown (1716–1783) designed landscapes in England and Wales, creating sinuous water features by damming and reshaping small streams, perhaps the earliest examples of stream restoration. Prior authors suggested that Brown’s designs reflected the influence of Hogarth. Twentieth-century stream restoration projects in North America have been characterised by highly sinuous and symmetrical curves. Comparing the sinuosity and symmetry of Brown’s eighteenth-century water features, twentieth-century stream restoration projects, and Hogarth’s line of beauty, we found Brown’s features matched Hogarth’s line in sinuosity but were asymmetrical, while the recent stream restoration project designs had higher sinuosities and were nearly perfectly symmetrical.     

Elevated mercury concentrations in soils, sediments, water, and fish of the Madeira River basin, Brazilian Amazon: a function of natural enrichments?

Previous site-specific investigations have found that mercury concentrations in water, sediments, and biota of the Brazilian Amazon are elevated above global averages, and that these concentrations are a direct result of widespread mercury amalgamation mining operations conducted by non-organized prospectors. In order to assess the regional impacts of Hg contamination from these non-organized gold mining activities, water, sediments, and fish were systematically collected in 1997 along a 900-km reach of the Madeira River. The sampling program extended from the Amazon River upstream to Porto Velho, the site of historic and ongoing mercury amalgamation mining. Mercury concentrations were found to be elevated above global averages in all sampled media. However, the geochemical data suggest that the high mercury levels are due largely to natural sources and natural biogeochemical processes, and that the impacts of anthropogenically released mercury from mine sites is relatively localized.     

Use of terrain evaluation techniques in the study of drainage network changes in microbasins of the Capivari River Basin, state of São Paulo, Brazil

In this paper the drainage network is considered as a geo-indicator of the environmental changes that haven taken place over a period of 23 years in three hydrographic microbasins in the São Paulo State (Brazil). The verification of the natural conditions of the physical environment was based on terrain evaluation for homogeneity of landforms and the materials associated with them. In order to identify the alterations, a temporal analysis of the drainage network morphometric variables and land use was made. The morphometric analysis indicates a decrease in the number of first-order channels and in the total length of all channels, with a consequential modification of the drainage and hydrographic densities. The losses and gains of the first-order channels were influenced by the slope, type of bedrock and presence of unconsolidated material. The catalyst for these changes was mainly the inadequate control of urban expansion and the intensive agricultural activities.Résumé Dans cet article le réseau de drainage est considéré comme un géo-indicateur de changements environnementaux qui se sont réalisés durant 23 années dans trois micro-bassins hydrographiques de létat de Sao Paulo (Brésil). Les caractéristiques du milieu physique ont été obtenues à partir dune étude des différentes unités géomorphologiques et des formations géologiques corrélatives. Afin de mettre en évidence les modifications du milieu, une analyse temporelle de loccupation des sols et des paramètres morphométriques du réseau de drainage a été réalisée. Lanalyse morphométrique indique une diminution du nombre de sections de premier ordre et de la longueur totale du réseau de drainage. Il en résulte une modification de la densité de drainage des bassins. Les diminutions ou augmentations de sections de premier ordre ont été influencées par la pente, le type de substratum et la présence de matériaux meubles. Une expansion urbaine mal contrôlée et le développement dune agriculture intensive sont les causes de ces modifications.     

European urban culture,Javier de Mesones-Cabello’s planning practice and its legacy in city of Valladolid

Javier de Mesones-Cabello was an influential and active planner of the 1960s and 1970s in Spain, who passed away in December, 2016. His professional career as a self-taught urban planner was extensively linked to his academic and institutional activities. These connections supported the establishment of relationships with prestigious professionals working in urban planning practice. In planning the 1969 masterplan for the city of Valladolid, in Spain, de Mesones-Cabello made several intellectual references to the Greek urban planner Doxiadis. This masterplan covers a relatively unknown example of directional city growth in a European context. My findings elucidate the extent to which de Mesones-Cabello was influenced by Doxiadis, and the circumstances in which these ideas have continued to dominate thinking about Valladolid's urban development.     

An integrated approach to public’s perception of urban water use and ownership of water companies during a period of economic crisis. Case study in Athens,Greece

ABSTRACT

This study applies an integrated approach to investigate public perception of residential water issues during a period of economic crisis. The study investigates the perceptions and practices of Athenians in water conservation, their satisfaction with the supplied water, their opinion on the privatization of Water Company and their willingness for additional payment for the improvement of water services. A survey was conducted using a structured questionnaire. Results indicate that the respondents have adopted water conservation practices, but there is still room for further saving. Most of the respondents declared to be satisfied with the supplied water and do not agree to the privatization of water companies. Women, older participants and those having lower income are less willing for additional payment. Research findings are useful tool for policymakers to design policies and make decisions regarding water management, ownership of water companies and changes in behavior of water use.     

Long-term effects of the Aznalcóllar mine spill-heavy metal content and mobility in soils and sediments of the Guadiamar river valley (SW Spain)

In 1998, a toxic spill from a pyrite mine (Aznalcóllar, SW Spain) contaminated some 40 km2 of the Agrio and Guadiamar river valley with heavy metal-enriched tailings sludge and acidic mine water. The aim of this study is to describe the long-term effects of heavy metal migration particularly with respect to the extent of vertical redistribution of As, Cd, Cu, Fe, Pb, S, Sb and Zn in soils and sediments of the river Guadiamar 4 years after the accident. For an assessment of the mobility behaviour, chemical associations of Cu, Pb, Sb and Zn in depth profiles polluted by tailings were determined by using sequential extraction procedures. In 2002, residues of toxic tailings were found in several places along the river Guadiamar. Heavy weathering has accelerated heavy metal displacement and contamination of the surrounding soil. Two element groups of contrary mobility can be distinguished: Cd and Zn are highly mobile and show strong displacements in acidic surroundings. Accumulation zones for Cd and Zn develop in less acidic soil layers due to the occurrence of Fe oxides, which constitute retaining fractions for these elements. The immobile elements Pb and Sb represent the second group. Highest concentrations of Pb and Sb are found in the tailings sludge. Cu and As show a variable distribution pattern. As a consequence of the heavy metal migration, an accumulation zone has formed up to 30 cm into the underlying soil at the time of investigation. In the future, there may be further penetration of heavy metals to greater depths.     

Quality,Quantity and Origin of PAHs （Polycyclic Aromatic Hydrocarbons） in Lotic Ecosystem of Al-Hilla River,Iraq

The Euphrates River is one of the major rivers in Iraq. When it reaches north of Hilla city, it will be divided in two branches. One of these braches flows toward Hilla city. On this branch, six locations were studied for the water quality of the Euphrates water. The present paper is aimed to fill the gap of information of the presence of PAHs （poly aromatic hydrocarbons） in water and sediment of AI-Hilla River, as well as to determine the quality and quantity of some PAHs. The depth of the river ranges from 2 m to 6 m. The quality, quantity and the origin of PAHs were studied in the water and sediment of Al-Hilla River. In addition, some physical and chemical properties were studied at six sites along the studied area, for the period March, 2010 to February, 2011. Sixteen PAHs that are listed by USEPA （US Environmental Protection Agency） as priority pollutants （Nap （naphthalene）, Acpy （acenaphthylene）, Acp （acenaphthene）, Flu （fluorine）, Phen （phenanthrene）, Ant （anthracene）, Flur （fluoranthene）, Py （pyrene）, B（a）A （benzo（a）anthracene）, Chry （chrysene）, B（b）F （benzo（b）fluoranthene）, B（k）F （benzo（k）fluoranthene）, B（a）p （benzo（a）pyrene）, BbA （dibenzo（a,h）anthracene）, B（ghi）P （benzo（ghi）perylene） and Ind （indeno （1,2,3-cd） pyrene）） were detected in Al-Hilla river. High concentrations of PAHs were detected in the sediment relative to that within the water. The present study revealed that the origin of PAHs in water and sediment might be the pyrogenic origin.     

Behaviour of alkylphenol polyethoxylate surfactants in the aquatic environment—III. Occurrence and elimination of their persistent metabolites during infiltration of river water to groundwater

The behaviour of various persistent metabolites derived from nonylphenol polyethoxylate (NPnEO) surfactants was studied during infiltration of river water to groundwater at two field sites situated in the northern part of Switzerland (Glatt River and Sitter River). Nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), nonylphenoxy acetic acid (NP1EC) and nonylphenoxy(ethoxy) acetic acid (NP2EC) were observed in the two investigated rivers at relatively high concentrations with average values of the individual types of nonylphenolic compounds ranging from 1.8 to 25 μg/l. The average concentrations of NP, NP1EO and NP2EO in groundwater were significantly lower (range <0.1–1 μg/l) suggesting an efficient elimination of these compounds during infiltration. In contrast, the elimination of nonylphenoxy carboxylic acids was less efficient. Most of the observed elimination occurred in the first 2.5 m of the aquifer, while further decrease in concentration was rather slow. In one sampling period, residual concentrations of nonylphenolic compounds up to 7.2 μg/l were detected in a pumping station used for drinking water supply which is situated 130 m from the Glatt River bed. Concentrations of NP, NP1EO and NP2EO in both river water and groundwater showed a pronounced seasonal variability with higher values observed during winter. The data suggest that low temperatures, which prevail in winter, significantly reduce the elimination efficiency of NP and to a lesser extent of NP1EO, while the behaviour of NP2EO was not affected. Such a behaviour indicates biogical transformation as the responsible elimination process. A comparison of average elimination efficiences of nonylphenolic compounds with those of pentachlorphenol (PCP) and nitrilotriacetate (NTA) gives the following sequence: NTA ≧ NP2EO > NP1EO > NP > PCP > NP1EC = NP2EC.     

Changes in the location and function of small water bodies in the upper Sanna River catchment—case study (SE Poland)

The article summarises the results of analyses of temporal and spatial changes in the location of small water bodies in the upper Sanna River catchment between the fifteenth and twenty-first centuries. The investigations were conducted on historical sources and cartographic data using GIS tools and inventory files. Natural (location of springs, groundwater depth, geomorphology of valleys), anthropogenic factors (quarries, excavations) and historical determinants of construction of the water reservoirs are presented. Additionally, changes in the economic (fish farming, mills), defence and industrial (paper and steel mills, bloomeries, fulleries) functions of the water bodies have been analysed. The changes in the functions of the water bodies were often influenced by the changing ownership. The results have application significance on a local and regional scale.     

Quantification and speciation of mercury in soils from the Tripuí Ecological Station, Minas Gerais, Brazil

Contents of total mercury, organic carbon, total sulfur, iron, aluminum and grain size and clay mineralogy were used along with Pearson's correlation and Hg thermal desorption technique to investigate the presence, distribution and binding behavior of Hg in soils from three depths from the Tripuí Ecological Station, located near Ouro Preto, Minas Gerais State, Brazil. The soils studied had predominantly medium and fine sand texture (0.59-0.062 mm), acid character and Hg contents ranging from 0.09 to 1.23 microg/g. The granulometric distribution revealed that Hg is associated with coarse sand (2-0.59 mm) and silt and clay (<0.062 mm) and presents similar Hg concentrations in both fractions. Mercury distribution in soil profiles showed that Hg was homogeneously distributed throughout the depths at most sites. Hg thermal desorption curves show that mercury occurs not only as Hg2+ predominantly bound to organic components in most of the samples, but also in the form of cinnabar in some. Pearson's correlation confirmed that mercury is associated with organic matter and sulfur and possibly with sulfur-bearing organic matter in most samples.     

Uncovering sexuality and gender: an intersectional examination of women’s experience in UK construction

UK employers have been broadening their equality and diversity activities to include the issue of sexual orientation; however, the construction industry has been slow to follow. Equally there is a lack of research on the experiences of lesbian, gay, bisexual and transgender (LGBT) workers in construction. While women’s sexuality soon becomes a focus of interest when they enter male-dominated work, little research has discussed how sexual minorities–and in particular lesbians–fare in such environments. This article examines how both gender and sexuality interact to shape women’s working lives within the UK construction sector, drawing on 22 interviews and a focus group with heterosexual women and lesbians in male-dominated occupations in construction. While women share common experiences of heightened interest and questioning, open lesbians can sometimes minimize the sexualized content of workplace interactions. However the potential for exclusion on the basis of minority sexuality also exists. Sexual harassment appears less prevalent for women in professional occupations than in the past, while women in the manual trades reported that the problem persists. Lesbians can experience different forms of harassment, however, from heterosexual women, while employers are less developed in their response to homophobic harassment.     

Challenges of Structure in Today＇s Architectural,Economic and Social Context

The recent establishment of a digital culture and society, together with current financial crisis and urgent energetic and climatic needs, has radically changed the architectural scene from the optimism of some years ago to a situation of uncertainty and huge social demands and challenges. In this context, it is suggested to rethink the role of structure in architecture, such as an enabler, a guide and a catalyst. The purpose of this paper is to present the economic, cultural and social context in which architecture develops nowadays. The method, to suggest a discussion on which role the structure may adopt in the architecture to come. The achievement, to highlight its potential to face current requirements and challenges.     

Sand and gravel extraction from piedmont and floodplain zones of Yamunanagar district in Haryana,India: Environmental tragedy or economic gain?

This study examines the environmental and economic consequences of sand and gravel extraction from piedmont and floodplain zones of Yamunanagar district in Haryana state of India. The study establishes that there have been significant changes in area under different crops, soil fertility, groundwater depth and its quality, employment and economy of the region. Estimates suggest that in a year nearly Rs 1.1 million ($16,213) worth of nitrogen, Rs 2.1 million ($30,953) worth of phosphorus and Rs 3.5 million ($51,588) worth of potassium are lost. A change in policy on sand and gravel extraction in the district appears to be necessary.