Chemical dynamics of the Sava riverine system

Presented here is a study of the geochemical dynamics of the entire River Sava watershed, a major tributary of the River Danube which has not previously been investigated. The sampling was performed at 33 selected locations along the main channel of the stream and at its largest tributaries during three sampling seasons (fall 2005, spring 2006 and fall 2006), going from headwater locations to the mouth near the confluence with the Danube. Almost 80% of the solutes are derived from carbonate mineral weathering and represent over 50% of specific HCO(3)(-) flux normalized to unit basin area at the mouth of the Danube. Statistical analysis indicates that agricultural and industrial sources contribute significantly to increased Na(+), K(+), Cl(-), SO(4)(2-) and NO(3)(-) concentrations in tributary waters. Different processes control the water chemistry along the course of the Sava's drainage-the upper reaches are largely regulated by contributions from carbonate mineral weathering, the middle reaches are influenced by agricultural activity and biological processes related to eutrophication, while the lower reaches tend to have more pronounced parameters related to the industrial processing along with leakages from municipal sanitary systems of these higher population density areas.     

Fractionation of heavy metals and assessment of contamination of the sediments of Lake Titicaca

Chemical weathering is one of the major geochemical processes that control the mobilization of heavy metals. The present study provides the first report on heavy metal fractionation in sediments (8–156 m) of Lake Titicaca (3,820 m a.s.l.), which is shared by the Republic of Peru and the Plurinational State of Bolivia. Both contents of total Cu, Fe, Ni, Co, Mn, Cd, Pb, and Zn and also the fractionation of these heavy metals associated with four different fractions have been determined following the BCR scheme. The principal component analysis suggests that Co, Ni, and Cd can be attributed to natural sources related to the mineralized geological formations. Moreover, the sources of Cu, Fe, and Mn are effluents and wastes generated from mining activities, while Pb and Zn also suggest that their common source is associated to mining activities. According to the Risk Assessment Code, there is a moderate to high risk related to Zn, Pb, Cd, Mn, Co, and Ni mobilization and/or remobilization from the bottom sediment to the water column. Furthermore, the Geoaccumulation Index and the Enrichment Factor reveal that Zn, Pb, and Cd are enriched in the sediments. The results suggest that the effluents from various traditional mining waste sites in both countries are the main source of heavy metal contamination in the sediments of Lake Titicaca.     

The responses of the hepatosomatic index (HSI), 7-ethoxyresorufin-O-deethylase (EROD) activity and glutathione-S-transferase (GST) activity in sea bass (Dicentrarchus labrax, Linnaeus 1758) caged at a polluted site: implications for their use in environmental risk assessment

The present study investigates the response of three hepatic biomarkers in adult sea bass (Dicentrarchus labrax, Linnaeus 1758) caged at a wastewater outlet of an oil refinery with fish caged at a pristine site used as controls. The biomarkers that were investigated were the hepatosomatic index (HSI), 7-ethoxyresorufin-O-deethylase (EROD) activity and glutathione-S-transferase (GST) activity. In addition, we have measured the levels of polycyclic aromatic hydrocarbons (PAHs) and selected heavy metals (lead, cadmium, mercury, copper and zinc) in sediment samples at the polluted site. Although the polluted site had high environmental levels of PAHs and heavy metals, there was no difference in hepatic EROD activity and HSI between fish caged at the polluted site and controls. On the other hand, GST activity was significantly lower in fish caged at the polluted site compared to controls. Our results point out that the studied biomarkers have limited use in environmental risk assessment studies, at least when caged adult sea bass is used as the sentinel species and complex toxicant mixtures are involved.     

Effect of a reservoir in the water quality of the Reconquista River, Buenos Aires, Argentina

The lower portion of the Reconquista River is highly polluted. However, little is known about the state of the high and middle basins. The aims of this work were to assess the water quality on the high and middle Reconquista River basins and to determinate if the presence of a reservoir in the river has a positive effect on the water quality. We conducted a seasonal study between August 2009 and November 2010 at the mouth of La Choza, Durazno, and La Horqueta streams at the Roggero reservoir—which receives the water from the former streams—at the origin of the Reconquista River and 17 km downstream from the reservoir. We measured 25 physical and chemical parameters, including six heavy metal concentrations, and performed a multivariate statistical analysis to summarize the information and allow the interpretation of the whole data set. We found that the Durazno and La Horqueta streams had better water quality than La Choza, and the presence of the reservoir contributed to the improvement of the water quality, allowing oxygenation of the water body and processing of organic matter and ammonia. The water quality of the Reconquista River at its origin is good and similar to the reservoir, but a few kilometers downstream, the water quality declines as a consequence of the presence of industries and human settlements. Therefore, the Roggero reservoir produces a significant improvement of water quality of the river, but the discharge of contaminants downstream quickly reverses this effect.     

DDT, DDE, and 1-hydroxypyrene levels in children (in blood and urine samples) from Chiapas and Oaxaca, Mexico

The aim of this study was to evaluate the DDT, DDE, and 1-hydroxypyrene exposure levels of children living in communities located in southeastern Mexico. The study communities were Lacanja and Victoria in Chiapas state and Ventanilla in Oaxaca state. Children living in Lacanja had total blood DDT levels (mean?±?SD, 29,039.6?±?11,261.4 ng/g lipid) that were significantly higher than those of children in Victoria (10,220.5?±?7,893.1 ng/g lipid) and Ventanilla (11,659.7?±?6,683.7 ng/g lipid). With respect to the 1-hydroxypyrene levels in urine samples, the levels in Lacanja (4.8?±?4.1 μg/L or 4.5?±?3.9 μmol/mol creatinine) and Victoria (4.6?±?3.8 μg/L or 3.9?±?3.0 μmol/mol Cr) were significantly higher than levels found in Ventanilla (3.6?±?1.4 μg/L or 2.5?±?0.5 μmol/mol Cr). In conclusion, our data indicate high levels of exposure in children living in the communities studied in this work. The evidence found in this study could be further used as a trigger to revisit local policies on environmental exposures.     

Changes in the trade in native medicinal plants in Brazilian public markets

Plants continue to be an important source of new bioactive substances. Brazil is one of the world’s mega-diverse countries, with 20 % of the world’s flora. However, the accelerated destruction of botanically rich ecosystems has contributed to a gradual loss of native medicinal species. In previous study, we have observed a fast and intensive change in trade of medicinal plants in an area of Amazon, where human occupation took place. In this study, we surveyed 15 public markets in different parts of Brazil in search of samples of 40 plants used in traditional medicine and present in first edition of Brazilian Official Pharmacopoeia (FBRAS), published in 1926. Samples of plants commercialized as the same vernacular name as in Pharmacopoeia were acquired and submitted to analysis for authentication. A total of 252 plant samples were purchased, but the laboratory analyses showed that only one-half of the samples (126, 50.2 %) were confirmed as the same plant species so named in FBRAS. The high number of unauthenticated samples demonstrates a loss of knowledge of the original native species. The proximity of the market from areas in which the plant occurs does not guarantee that trade of false samples occurs. The impact of the commerce of the substitute species on their conservation and in public health is worrying. Strategies are necessary to promote the better use and conservation of this rich heritage offered by Brazilian biodiversity.     

Pollution by organochlorine pesticides in Navachiste-Macapule,Sinaloa, Mexico

The lagoon system of Navachiste-Macapule is located in northern Mexico, in the state of Sinaloa, with an area of 24,000 ha. The main economic activity in the area is agriculture, and the lagoon lies next to the irrigation district ID-063 which covers 116,615 ha. The purpose of this study is to evaluate the levels of pollution generated by organochlorine pesticides (OC) in the surface sediments of the lagoon and in the agricultural drains of the ID-063 that are supposedly transported into the system as a result of agricultural activities and runoff from adjacent land. For this, between 2006 and 2007, 45 surface sediment samples were collected (warm dry, rainy and cold dry) from 15 sampling sites, during the three climatic seasons. Of these, eight were located inside the lagoon in marine conditions (salinity >31 PSU) and seven in the agricultural drains of the ID-063 in freshwater conditions (salinity <5 PSU). The average concentration of the OC in the sediments was 44.75 ng g^− 1, among which the group of the alicyclic compounds presented the greatest concentrations. The average value of the total organic carbon (TOC) in the sediments of the system was 0.90%. The sediments collected inside the lagoon had an average OC concentration of 18.97 ng g^− 1, and the predominant type of sediment was fine to very fine sand. The average OC concentration in the sediments collected in the agricultural drains was 75.69 ng g^− 1, where fine sediments (silt) were predominant. The presence of methoxychlor, endrin and heptachlor suggested that these compounds were continuously used in the system, even though their use is forbidden in Mexico.     

Impact of water quality on bacterioplankton assemblage along Cértima River Basin (central western Portugal) assessed by PCR–DGGE and multivariate analysis

The information on bacterial community composition (BCC) in Portuguese water bodies is very scarce. Cértima River (central western Portugal) is known to have high levels of pollution, namely organic. In the present work, the BCC from a set of 16 water samples collected from Cértima River Basin and its main tributaries was characterized using 16S rDNA–denaturing gradient gel electrophoresis, a culture-independent molecular approach. Molecular data were related to environmental parameters through multivariate analysis to investigate potential impact of water pollution along the river. Principal component analysis using environmental data showed a water quality gradient from more pristine waters (at the mountain tributaries) to waters with increasingly eutrophic potential (such as Fermentelos Lake). This gradient was mainly defined by factors such as organic and inorganic nutrient sources, electrical conductivity, hydrogen carbonate concentration, and pH. Molecular results showed variations in BCC along Cértima River Basin but in the main river section, a Bacteroidetes phylotype (Flavobacterium sp.) proved to be dominant throughout the river course. Multivariate analysis suggests that spatial variation of BCC along the Cértima River Basin depended mainly on parameters such as Chl a, total suspended solid (TSS), total organic carbon, electrical conductivity, and HCO _boxclose^-_{3}^{-} levels. Bacteroidetes phylotypes were all related to higher electrical conductivity and HCO₃^-_{3}^{-} levels although some of these were also correlated with high SO₄^2-_{4}^{2-} and others with high soluble reactive phosphorus, nitrate, TN, and Kjeld-N levels. The Gammaproteobacteria occurrence was correlated with high SO₄^2-_{4}^{2-} levels. One of the Betaproteobacteria phylotypes showed to correlate with low redox potential (E_h) and high temperature, pH, TSS, and Chl a levels while another one showed a negative correlation with Chl a values.