Volcanic rock is a potential adsorbent for metallic ions from wastewater. This study determined the capacity of Gisenyi volcanic rock found in Northern Rwanda to adsorb Cd, Cu, Pb and Zn using laboratory scale batch experiments under a variety of experimental conditions (initial metal concentration varied from 1 to 50 mg/L, adsorbent dosage 4 g/L, solid/liquid ratio of 1:250, contact time 120 h, particle size 250–900 μm). The adsorbent had a surface area of 3 m2/g. The adsorption process was optimal at near-neutral pH 6. The maximal adsorption capacity was 6.23, 10.87, 9.52 and 4.46 mg/g for Cd, Cu, Pb and Zn, respectively. The adsorption process proceeded via a fast initial metal uptake during the first 6 h, followed by slow uptake and equilibrium after 24 h. Data fitted well the pseudo second-order kinetic model. Equilibrium experiments showed that the adsorbent has a high affinity for Cu and Pb followed by Cd and Zn. Furthermore, the rock is a stable sorbent that can be reused in multiple sorption–desorption–regeneration cycles. Therefore, the Gisenyi volcanic rock was found to be a promising adsorbent for heavy metal removal from industrial wastewater contaminated with heavy metals.

The characteristics (natural, socioeconomic and administrative/institutional) of Alfeios River basin, in Greece, are identified and presented, incorporating and critically reviewing all possibly found literature. The Alfeios River is a water resources system of great natural, ecological, social and economic importance for Western Greece, since it has the longest and highest flow rate watercourse in the Peloponnisos region. Moreover, the river basin was exposed in the last decades to a plethora of environmental stresses (such as hydrogeological alterations, intensively irrigated agriculture, surface and groundwater overexploitation and infrastructure developments), resulting in the degradation of its quantitative and qualitative characteristics. It is therefore necessary for the development of an integrated river basin management plan for this basin, to study and analyse the interplay between the river components and the exerted environmental stresses, taking into account the puzzle of various and conflicting water uses, including water supply, irrigation, hydropower generation, lignite thermal power production and recreation. Mitigative, preventive and control measures for the analysed environmental stresses are epigrammatically depicted. Focusing on the problematic features, the present work provides a concrete foundation for the determination and conceptualisation of management objectives and possible sustainable alternatives.

2-Methylisoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin) are two commonly observed taste and odor compounds present in drinking water sources. The effects of pH on the analysis of the two chemicals are investigated using a gas chromatograph and mass spectrometric detector (GC/MSD) coupled with three pre-concentration methods, namely solid-phase micro-extraction (SPME), purge-and-trap concentration (PTC), and liquid–liquid extraction (LLE). At neutral and alkaline pH conditions, the concentrations detected for both compounds remain constant. However, a substantial reduction of concentration for both chemicals is observed when the water solution pH is less than 5. Under acidic conditions (pH ≅ 2.5), the 2-MIB concentrations detected by GC/MSD coupled with SPME, PTC, and LLE are 87%, 16%, and 37% lower than those measured at pH 6–7, respectively. For geosmin, a decrease in concentration is only observed when using GC/MSD-SPME, presumably due to the higher extraction temperature compared to the other two techniques. The pH-dependent behavior was attributed to dehydration of the tertiary alcohols of 2-MIB and geosmin under acidic conditions. The dehydration for 2-MIB and geosmin is reversible, and the analysis can be mitigated by adjusting the water solution pH back to a neutral condition.

We assessed the suitability of two nonnative poeciliid fishes—western mosquitofish (Gambusia affinis) and sailfin mollies (Poecilia latipinna)—for monitoring selenium exposure in desert pupfish (Cyprinodon macularius). Our investigation was prompted by a need to avoid lethal take of an endangered species (pupfish) when sampling fish for chemical analysis. Total selenium (SeTot) concentrations in both poeciliids were highly correlated with SeTot concentrations in pupfish. However, mean SeTot concentrations varied among fish species, with higher concentrations measured in mosquitofish than in mollies and pupfish from one of three sampled agricultural drains. Moreover, regression equations describing the relationship of selenomethionine to SeTot differed between mosquitofish and pupfish, but not between mollies and pupfish. Because selenium accumulates in animals primarily through dietary exposure, we examined fish trophic relationships by measuring stable isotopes (δ 13C and δ 15N) and gut contents. According to δ 13C measurements, the trophic pathway leading to mosquitofish was more carbon-depleted than trophic pathways leading to mollies and pupfish, suggesting that energy flow to mosquitofish originated from allochthonous sources (terrestrial vegetation, emergent macrophytes, or both), whereas energy flow to mollies and pupfish originated from autochthonous sources (filamentous algae, submerged macrophytes, or both). The δ 15N measurements indicated that mosquitofish and mollies occupied similar trophic levels, whereas pupfish occupied a slightly higher trophic level. Analysis of gut contents showed that mosquitofish consumed mostly winged insects (an indication of terrestrial taxa), whereas mollies and pupfish consumed mostly organic detritus. Judging from our results, only mollies (not mosquitofish) are suitable for monitoring selenium exposure in pupfish.

The historical trend of heavy metal pollution recorded in sediment cores from Lake Shinji, western Japan, was investigated to evaluate the contribution of increasing long-range transport of heavy metals from the Asian continent in recent years. The concentrations of Cd, Co, Cr, Cu, Ni, Pb, Sb, and Zn and lead isotope ratios were determined for sediment cores collected at two sites in the lake. Among the metals, Cd, Sb, and Zn showed markedly high concentrations since the 1970s. Moreover, a high Pb concentration and less radiogenic lead isotope ratios have been observed since the 1980s in the core from a site close to the mouth of a major river. Air masses from the Asian continent, including China, Russia, and South Korea, have less radiogenic lead isotope ratios than those from Japan. This suggests that the recent increase in Pb concentration in the sediment core is primarily due to the long-range transport of heavy metals from the Asian continent, followed by their deposition in the catchment area of the river. The concentration ratios of Pb/Cd, Pb/Sb, and Pb/Zn of the sediment around 2000 were calculated on the basis of the metal concentrations in excess of those before 1940. They were then compared with the volume-weighted annual average concentration ratios of Pb/Cd, Pb/Sb, and Pb/Zn of rain samples collected on the shore of the lake for 1999–2001. The result showed that the ratios of the former to the latter are 1.0 for Cd, 0.69 for Sb, and 0.31 for Zn. Thus, it is likely that the long-range transport of Cd and Sb from the Asian continent also contributes significantly to the recent increase in the concentrations of these metals in the sediment core from Lake Shinji. For Zn, however, the contribution from the Asian continent was evaluated to be small, suggesting the importance of local sources such as effluent discharges.

Specific activity of tritium (³H) in precipitation and specific activity of ¹³⁷Cs in ground-level air were monitored at three locations in Belgrade (Meteorological Station of Belgrade at Zeleno Brdo (ZB), Meteorological Station Usek (USEK), and Vinča Institute of Nuclear Sciences (VINS)). Data presented cover the period 1985–1997 for ¹³⁷Cs for all locations and 1985–2009 (ZB), 1988–1997 (USEK), and 1988–2009 (VINS) for ³H. Concentrations of ³H in precipitation have been determined using electrolytic enrichment and liquid scintillation spectrometer LKB-Wallac 1219 RackBeta. The activity of ¹³⁷Cs in air was determined on an HPGe detector (Canberra, relative efficiency 23 %). ³H concentrations in precipitation ranged from 0.40 ± 0.08 to 74.6 ± 5.2 Bq l⁻¹ decreasing with distance from the nuclear facilities. Significantly higher tritium levels were measured in samples in VINS compared with those from an off-site location. The observed seasonal variations of tritium concentration indicate the stratospheric source of tritium. Increases in activity concentration of ¹³⁷Cs in the atmosphere were observed after the nuclear plant accident at Chernobyl in April 1986. The concentrations obtained for ¹³⁷Cs in 1986 were compared with the integrated air concentrations of ¹³⁷Cs in the region. The increases of ¹³⁷Cs air concentrations in 1987 and 1988 were attributed to local resuspensions from the ground. Since 1989, the activity level before the accident has been obtained. The average monthly concentrations of ¹³⁷Cs in ground-level air were shown spread maximum in spring–summer period and pronounced maximum during winter. The obtained results were statistically analyzed, i.e., the following parameters were determined: tritium deposition, monthly activities of ³H and ¹³⁷Cs, seasonal indices, radionuclide loading indices, and linear correlation coefficients.

The upper limit of fluoride concentration in water for human consumption is 1.5 ppm. Many studies have been carried out concerning the water fluoride concentration in wide areas around the world, but none have studied the change of fluoride concentration as a function of geographical coordinates and through time. This paper describes ‘microvariation’ of fluoride concentration among wells separated by less than 500 m in a month. On the other hand, ‘macrovariation’ is also studied describing changes among cities that are separated by more than 10 km and compared with fluoride concentrations measured 65 years ago. Fluoride concentration was measured in a wide geographical area of Argentina, which is 133,000 km². Samples of water were collected from different regions. Macrovariation: Differences in fluoride concentration in well water among regions were found, as well as an increase in water fluoride concentration during seven decades. Microvariation: Daily water fluoride concentration in a specific area displayed a great variation in the measurements through time. In addition, wells with no more than 500 m of separation were measured at the same time and were significantly different. These results indicate that in order to determine the fluoride concentration of a region, different samples of the same area should be obtained and a sampling through time should also be done.

After the accident in Fukushima reactors, a daily monitoring programme was initiated in two laboratories in Belgrade, one at the Vinčа Institute for Nuclear Sciences and the other at Institute for Occupational Health Karajovic. Samples of aerosol and fallout, as well as the random samples of food and water, were collected and analysed, using gross alpha/beta and gamma spectrometry, in order to establish the presence of traces of isotopes indicating Fukushima fallout. Gamma spectrometry measurement of these samples showed clear evidence of fission products ¹³¹I, ¹³⁴Cs and ¹³⁷Cs wtihin 2 weeks after the accident. The activity diminished with time due to dispersion in air and, in case of ¹³¹I, short half-life.

Biocovers are an alternative for mitigating fugitive and residual emissions of methane from landfills. In this study, we evaluated the performance of two experimental passive methane oxidation biocovers (PMOBs) constructed within the existing final cover of the St-Nicéphore landfill (Quebec, Canada). The biocovers were fed in a controlled manner with raw biogas and surface fluxes were obtained using static chambers. This enabled calculating mass balances of CH₄ and oxidation efficiencies (f ₒ_MB). Most of the time, f ₒ_MB ≥ 92 % were obtained for loadings as high as 818 g CH₄ m⁻² day⁻¹ (PMOB-2) and 290 g CH₄ m⁻² day⁻¹ (PMOB-3B). The lowest efficiencies (f ₒ_MB = 45.5 % and 34.0 %, respectively) were obtained during cold days (air temperature ~0 °C). Efficiencies were also calculated using stable isotopes (f ₒ_SI); the highest f ₒ_SI were 66.4 % for PMOB-2 and 87.3 % for PMOB-3B; whereas the lowest were 18.8 % and 23.1 %, respectively. However, f ₒ_SI values reflect CH₄ oxidation up to a depth of 0.10 m, which may partly explain the difference in regards to mass balance-derived efficiencies. Indeed, it is expected that a significant fraction of the total CH₄ oxidation occurs within the zone near the surface, where there is greater O₂ availability. The influence of the values of fractionation factors α ₒₓ and α ₜᵣₐₙₛ were also evaluated in this paper.