Description: The rate of non-oxidative galena dissolution in seawater compositions over the pH range of 2–4.5 was determined from batch reactor experiments. The derivative at zero time of a polynomial fit of the Pb concentration versus time data for the first 30 min was used to determine the rate. A plot of R Gn (rate of galena dissolution) versus pH for data from six experiments is linear ( R 2  = 0.96), with a slope of 0.5. The rate equation describing the rate of galena dissolution as a function of hydrogen ion activity is $$R_{\text{Gn}} = - \,10^{ - 10.72} \left( {a_{{{\text{H}}^{ + } }} } \right)^{0.50}$$ Varying the concentration of dissolved oxygen produced no significant effect on the measured rates. The activation energy, based on four experiments carried out over the temperature range of 7–30 °C, is 61.1 kJ/mol.

Description: In the original publication of the article, Figs. 3 and 4 were interchanged. Now the correct figures have been provided in this erratum.

Description: The source, quantity and quality of sedimentary organic matter (SOM) were investigated in the surface sediments of Lake Fuxian, a deep oligotrophic lacustrine system in China. Granulometry, biochemical organic composition, bulk organic proxies and their stable isotopes were determined in the surface sediments (0–4 cm). The values of δ 13 C, δ 15 N and atomic ratio of total organic carbon to total nitrogen (TOC/TN) indicated that the sediments in the large partial lake were influenced by autochthonous organic matter. The concentrations of TOC, protein (PRT) and total hydrolysable amino acids may be mainly modulated by phytodetritus sinking from euphotic zones since they correlated significantly with chlorins. Otherwise, the lack of correlation between chlorins concentrations and carbohydrate (CHO) and lipid (LIP) indicated that the latter may have an additional terrestrial source. The highest sediment quantity was found in the deepest station NC owing to its fine sediment. Stations near northwestern shore accumulated more SOM than other littoral stations, which was in accordance with sewage discharge strength. Degradation quality indices, such as chlorin index, degradation index, PRT/CHO, and LIP/CHO, were in general agreement in showing the degraded status of SOM in Lake Fuxian. No clear spatial patterns were found in sediment degradation quality, which may be influenced by bottom oxygen concentration in the deep stations.

Description: Maharlu Lake with Na–Cl water type is the terminal point of a closed basin in southern Iran. A total of 10 water samples from two rivers discharging to the lake and 78 water samples of surface and pore brine of Maharlu Lake have been collected from different depths (surface, 20, 50 and 100 cm) of four sampling stations along the lake during a period of lake water-level fluctuation (November 2014–July 2015). To investigate chemical interaction between lake surface water and shallow pore water and to understand the major factors governing chemical composition of Maharlu brine, concentrations of major and minor (boron, bromide and lithium) solutes, pH and total dissolved solids have been measured in collected water samples. Saturation indices of evaporite minerals in collected water samples have been also calculated. The chemical behavior of dissolved solutes and evaporative evolution of the lake brine during a hydrological period have been simulated using PHREEQC. The results of our investigations indicated that chemical composition of lake surface water and pore brine of Maharlu Lake are mainly connected with lake water-level fluctuations and distance from input rivers (and depth), respectively. Hydrochemical investigations and statistical analysis showed that the brines chemistry of Maharlu is mainly controlled by three processes: brine evaporative evolution, dissolution–precipitation and diagenetic evolution of secondary carbonates.

Description: The chemical and isotope compositions of slab dehydration fluids from convergent margins have been theorized by many authors who have adopted several approaches. A direct collection of natural water is possible only in an oceanic environment, despite several difficulties in estimating the deepest component due to the mixing with seawater or hydrothermal fluids from the ridge. Accordingly, the study of melt inclusions is a valuable alternative. However, the latter mainly represents high temperature/pressure conditions in deep magmatic or metamorphic settings. Here, we present new H, O, Li and B isotope along with a revision of previously published chemical data from a potential natural example of slab dehydration water, sampled in a forearc region and affected by low-temperature metamorphism and serpentinization processes (Aqua de Ney, Northern California). Its extreme composition challenges the understanding of its origin and deep temperature, but this work is a further step on a topic of increasing interest for several scientists from different academic disciplines.

Description: In this study, the experimental results from long-term solubility experiments up to 1146 days on micro-crystalline neodymium hydroxide, Nd(OH) 3 (micro-cr), in high ionic strength solutions at 298.15 K under well-constrained conditions, are presented. Hydrogen ion concentrations in our experiments are controlled by the dissolution of Nd(OH) 3 (micro-cr) without artificial adjustment with addition of either an acid or a base, preventing the possibility of phase change that could be induced especially by addition of a base. Such an experimental design also provides the information about the hydrogen ion concentrations buffered by the dissolution of Nd(OH) 3 , which is currently lacking. The solubility data produced in this work, applicable to geological repositories in high ionic strength environments, are compared with the solubilities of Am(OH) 3 (s) predicted by using the Waste Isolation Pilot Plant (WIPP) thermodynamic model. The predicted values for Am(OH) 3 (s) are in good agreement with the experimental values for Nd(OH) 3 (micro-cr) obtained in this work. Our experimental data indicate that the pH m (negative logarithm of hydrogen ion concentration on a molal scale) buffered by dissolution of Nd(OH) 3 (micro-cr) ranges from ~ 9.5 to ~ 9.9. As the equilibrium constant for amorphous neodymium hydroxide, Nd(OH) 3 (am), is useful for several fields, the equilibrium constant regarding the dissolution of Nd(OH) 3 (am) for the following reaction, $$ {\text{Nd}}\left( {\text{OH}} \right)_{3} \left( {\text{am}} \right) + 3{\text{H}}^{ + } = {\text{Nd}}^{3 + } + 3{\text{H}}_{2} {\text{O}}\left( {\text{l}} \right) $$ is also obtained by evaluating the experimental data in a wide range of ionic strengths from the literature by using the WIPP thermodynamic model. The \( \log_{10} K_{{{\text{s}}0}}^{0} \) at 298.15 K for the above reaction obtained in this work is 16.85 ± 0.20 (2 σ ), which is similar to, but slightly lower than, the values in the literature evaluated in the low ionic strength range. This value can be applied to amorphous americium hydroxide, Am(OH) 3 (am), using Nd(III) as an analog to Am(III).

Description: Polycyclic aromatic hydrocarbons (PAHs) released from diverse sources passing through water column carry information into the sediment where they can be used to assess the environmental status of an ecosystem over specified geologic time frame. The vertical distributions of PAHs in two recent sediment cores (RS and RC, 30 cm long) from Refome Lake, South–South Nigeria, were investigated using gas chromatography–mass spectrometry in order to evaluate their sources and historical trends of deposition over the last ca. century. The total PAHs (TPAHs—sum of parent and retene) concentrations ranged from 66.99 ng/g dry weight (dw) at the middle layer of RC core (RC3 10–15 cm) to 182.24 ng/g dw at the near-bottom layer of RS core (RS5 20–25 cm) with a mean of 102.21 ± 24.32 ng/g. The elevated TPAH level at the near-bottom layer of the RS core, corresponding to geologic time-frame ca. 1930–1947, coincided with the period of inhabitation of the European settlers along the lake’s catchments when utilization of coal and/or coal products for domestic/recreational activity was at its peak. A decline in TPAH levels up-cores thereafter reflected the periods of gradual evacuation of inhabitants of the lake area hinterland following the departure of the White after the Nigerian independence in 1960. Evaluation of PAH category according to ring size coupled with data from specific molecular ratios revealed inputs dominated by wood/coal combustion with a moderate contribution from petrochemical/liquid fossil fuel exhaust emissions and a minor diagenetic sources. Principal component analysis result not only distinctively separated RS from RC core samples but also revealed that the RS samples were more impacted by wood/coal combustion emissions than the RC, while liquid fossil fuel exhaust emission dominated the RC over the RS samples. Although short-range eolian transport did play a role in the delivery of PAHs to the lake, localization of source contamination was more important.

Description: In application at the Zlatna gold mining area (Apuseni Mountains, Romania), the correlation of water isotopes and geochemical data were successfully used to assess the genetic relationships between surface running water, groundwater and mine water, as well as to evaluate the mining effects on the surrounding environment after the cessation of mining operations. The majority of mine water sources display pH values between 4 and 5, i.e. acid mine water. The mine water characterized by slightly higher pH values (~6) interacts with ophiolitic rocks which have high pH buffering capacity. The neutral mine water (pH ~ 7) does not come into direct contact with reactive minerals, either because it is discharged from an exploration adit or because of the complete leaching of pyrite and other sulphides in old abandoned mining works. The later also shows low levels of heavy metals concentrations. Calcium is the dominant cation in mine water and in the majority of surface running water and groundwater sources, indicating the same mechanisms of mineralization. All mine water sources are \(\text{SO}_{4}^{2 - }\) type and show very high \(\text{SO}_{4}^{2 - }\) concentrations (6539 mg/l mean value). Surface and groundwater sources are classified either as \(\text{SO}_{4}^{2 - }\) or as \(\text{HCO}_{3}^{ - }\) type water. Linear correlation between δD and δ 18 O values indicates that all water sources belong to the meteoric cycle. Low δD and δ 18 O values of mine water (δD 〈 −70‰; δ 18 O 〈 −10‰) suggest snow melt and high-altitude precipitations as the main source of recharge. The mine water is less affected by the seasonal variation of temperature. In most cases, the variations in isotopic composition are within narrow limits (less than 1‰ for both δD and δ 18 O), and this result suggests well-mixed underground systems. Elevated concentration of sulphates, Zn and Fe in mine waters are the main issues of concern. For the study area, no relevant contamination of springs or phreatic water by mine water was revealed. On the contrary, surface running water is contaminated by mine water, and the negative effects of acid mine drainage occur mainly in the summer months when the flow of the surface running water decreases.

Description: Nitrogen inputs to Great Salt Lake (GSL), located in the western USA, were quantified relative to the resident nitrogen mass in order to better determine numeric nutrient criteria that may be considered at some point in the future. Total dissolved nitrogen inputs from four surface-water sources entering GSL were modeled during the 5-year study period (2010–2014) and ranged from 1.90 × 10 6 to 5.56 × 10 6  kg/year. The railroad causeway breach was a significant conduit for the export of dissolved nitrogen from Gilbert to Gunnison Bay, and in 2011 and 2012, net losses of total nitrogen mass from Gilbert Bay via the Causeway breach were 9.59 × 10 5 and 1.51 × 10 6  kg. Atmospheric deposition (wet + dry) was a significant source of nitrogen to Gilbert Bay, exceeding the dissolved nitrogen load contributed via the Farmington Bay causeway surface-water input by 〉100,000 kg during 2 years of the study. Closure of two railroad causeway culverts in 2012 and 2013 likely initiated a decreasing trend in the volume of the higher density Deep Brine Layer and associated declines in total dissolved nitrogen mass contained in this layer. The large dissolved nitrogen pool in Gilbert Bay relative to the amount of nitrogen contributed by surface-water inflow sources is consistent with the terminal nature of GSL and the predominance of internal nutrient cycling. The opening of the new railroad causeway breach in 2016 will likely facilitate more efficient bidirectional flow between Gilbert and Gunnison Bays, resulting in potentially substantial changes in nutrient pools within GSL.