Metal Pollution Assessment of Surface Sediments Along a New Gas Pipeline in the Niger Delta (Nigeria)

Chromium, nickel, copper, zinc and cadmium were determined in sediments of the Niger Delta (Nigeria) in order to discriminate between natural metal sources and anthropogenic ones. Surface sediments were collected at seven sites along a new gas pipeline near Port Harcourt, between the New Calabar River and the Bonny River towards Bonny town. Chemical characterisation is obtained by hydrofluoric–nitric acid digestion procedure, providing the ‘total’ (‘residual’) metal contents. Information about the anthropogenic metal fraction was obtained by cold diluted hydrochloric acid extraction procedure. This ‘labile’ acid soluble fraction of metals, perhaps due to relatively recent inputs in the sediments, constitutes the fraction more likely to be available to marine organisms, and furnishes a first evaluation of the possible toxicity of sediments of this sensitive ecosystem. Zinc appears to be the most available of all the heavy metals: its ‘labile’ fraction attains 40–50% of the ‘total’ zinc in sediment. Sites near Port Harcourt city are the most contaminated. All the examined metals are one order of magnitude below the respective values proposed as a limit for toxicity and are comparable with those observed by other authors in similar Niger Delta areas. Some anomalous data found near Port Harcourt city suggest that zinc and cadmium are the metals that require further monitoring. Their anthropogenic source could be derived from urban and industrial sewage.     

Benthic vegetation,chlorophyllα and physical-chemical variables in a protected zone of a Mediterranean coastal lagoon (Lesina,Italy)

Phytoplankton and benthic vegetation biomass undergoes spatial-temporal changes in relation to their life cycle, but also to meteorological conditions, physical-chemical variables, organic input and internal dynamism. The main aim of this work was to observe the effect of all environmental variables on the vegetative dynamic process in a protected zone of a Mediterranean costal lagoon (Lesina lagoon, SE Italy). Seven samplings were performed from 2010 to 2012 at 30 sites for nutrient and chlorophyll analyses, while TOC measurements and wet biomass evaluation were performed at 10 sites. Temperature, salinity and oxygen saturation were also measured by multiparametric probe and a visual census for vegetation was performed. Sites close to freshwater inflow were characterized by lower temperature and salinity, and high nitrate, with maxima of 191.05 μM in May 2010 and more than 250 μM in October 2010. Silicates drastically decreased from May 2010 (87.57 μM) to July 2010 (6.15 μM) and increased again in October (74.99 μM). Chl a concentrations were not on average higher than 6 mg m^?3, but peaks of 20 mg m^?3 were observed during May 2011 and May 2012. Benthic vegetation wet biomass collected in 2010 was approximately twice that collected in 2012, with a maximum of 27,554 g m^?2 and a dominance of macroalgae (70 % in May 2010 and 40 % in August 2010). During period 2010, a simultaneous and drastic decreasing of both mean values of wet biomass and chl a was observed from May to October 2010. During period 2012 a shift of vegetation biomass was shown from May (phytoplankton prevalence) to August 2012, with angiosperm prevalence (more than 30 %).     

Nutrient distribution in locations of the Gulf of Trieste (northern Adriatic sea) suspected of pollution

Nutrients (ammonium‐nitrogen, nitrite, nitrate, orthophosphate and dissolved silica) as well as some chemical‐physical parameters (temperature, pH, salinity, dissolved oxygen and total suspended matter) were determined in filtered seawater samples taken at the surface, at middle depth and at the bottom, in 6 open‐sea locations of the Gulf of Trieste (northern Adriatic Sea) close to pipeline exits that discharge wastewaters from treatment plants. The collected data allow a comparison of the quality of these open‐sea waters with coastal waters and constitute a reference for successive monitoring in these locations suspected of pollution. A multivariate statistical analysis by the principal component method shows that the considered ecosystem can be modeled with two factors: the first one is referenced to the marine environment, in particular to the decomposition of the organic debris in deep water; whereas the second factor is referenced to the input of freshwaters in the Gulf, driving nitrates from agricultural lands.     

Temperature and discharge variations in natural mineral water springs due to climate variability: a case study in the Piedmont Alps (NW Italy)

Environmental Geochemistry and Health - In the context of global climate change, understanding the relationships between climate and groundwater is increasingly important. This study in the NW Alps...