Groundwater quality regarding major anions and cations in the Birjand Plain located in the largest desert in Eastern Iran was monitored in this study. Fifteen boreholes were considered as sampling stations and the parameters pH, TDS, EC and major anions and cations were measured in groundwater samples. The dominant groundwater types can be introduced as sodium-chloride and magnesium-sulphate. The majority of samples were within the not-suitable category for drinking uses. Regarding agricultural use, around 80 and 50 per cent of samples indicated a very high salinity hazard and a very high sodium alkali hazard, respectively. Spatial distribution of salinity was also monitored within the study area. If the study area was considered to be a semicircle, the centre appeared to be the least polluted area, while towards the peripheral surroundings, an increasing behaviour was observed. Intrusion of salt water from eastern and western parts of the study area caused severe groundwater degradation. The relatively better quality of groundwater in southern areas may be attributed to a chain of mountains located along south of the study area. The prevention of uncontrolled groundwater withdrawal must be regarded to cease the salinization trend and to prepare the required infrastructure for implementing the artificial recharge projects.

Appalachian surface coal mine overburden affects water quality as drainage percolates through spoil disposal fills. This study evaluated leaching potentials of 15 spoils from south-central Appalachia. Most bulk samples were non acid-forming, all were low in total-S, (≤0.34%), and initial saturated paste specific conductance (SC) ranged from 264 to 3560 μS cm−1. Samples were leached unsaturated (40 cycles) and leachates analyzed for pH, SC, and ion composition. Overall, leachates from unweathered spoils were higher in pH and SC than leachates from weathered spoils. Fine-textured spoils generally produced higher SCs than more coarsely textured spoils. Mean SC for all spoils decreased rapidly from an initial peak of 1468 μS cm−1 (±150) to 247 μS cm−1 (±23). Release patterns for most major ions reflected declining SC. Bicarbonate typically increased with successive leaches, replacing sulfate as the dominant anion. Column SC values were comparable to relevant published field data.

The application of constructed wetlands (CWs) has significantly expanded to treatment of various industrial effluents, but knowledge in this field is still insufficiently summarized. This review is accordingly necessary to better understand this state-of-the-art technology for further design development and new ideas. Full-scale cases of CWs for treating various industrial effluents are summarized, and challenges including high organic loading, salinity, extreme pH, and low biodegradability and color are evaluated. Even horizontal flow CWs are widely used because of their passive operation, tolerance to high organic loading, and decolorization capacity, free water surface flow CWs are effective for treating oil field/refinery and milking parlor/cheese making wastewater for settlement of total suspended solids, oil, and grease. Proper pretreatment, inflow dilutions through re-circulated effluent, pH adjustment, plant selection and intensifications in the wetland bed, such as aeration and bioaugmentation, are recommended according to the specific characteristics of industrial effluents.

The increasing use of silver nanoparticles (AgNPs) as a biocidal agent and their potential accumulation in sediments may threaten non-target natural environmental bacterial communities. In this study a microcosm approach was established to investigate the effects of well characterized OECD AgNPs (NM-300) on the function of the bacterial community inhabiting marine estuarine sediments (salinity 31‰). The results showed that a single pulse of NM-300 AgNPs (1 mg L−1) that led to sediment concentrations below 6 mg Ag kg−1 dry weight inhibited the bacterial utilization of environmentally relevant carbon substrates. As a result, the functional diversity changed, but recovered after 120 h under the experimental conditions. This microcosm study suggests that AgNPs under environmentally relevant experimental conditions can negatively affect bacterial function and provides an insight into the understanding of the bacterial community response and resilience to AgNPs exposure, important for informing relevant regulatory measures.

The distribution and fate of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) were investigated in the water and sediment of Bohai Bay, China, during 2011–2013. A total of 360 water samples and 60 sediment samples were collected from 20 locations. The median concentrations of PFOS and PFOA were 4.8 and 12.15 ng/L in the water, and 2.65 and 0.62 ng/g-dry in the sediment, respectively. Significant enrichment were observed for PFOS and PFOA in water of sea surface microlayer. The concentrations of these two compounds showed an apparent gradient from nearshore to offshore stations. The correlation analysis and the distribution tendencies indicated that freshwater inflowing to the bay was the main source of PFOS and PFOA. The salinity of seawater and the total organic carbon (TOC) content of sediment heavily affected the spatial distribution and the partitioning of PFOS and PFOA in the sediment-water system.

In reverse osmosis, a frequently used technology in water desalination processes, wastewater (RO concentrate) is generated containing the retained solutes as well as so-called antiscalants (AS), i.e. chemical substances that are commonly applied to prevent membrane-blocking. In this study, a risk assessment of a possible discharge of concentrate into a small stream was conducted. The acute toxicity of two concentrates containing two different ASs and of concentrate without AS to the amphipods Gammarus pulex and Gammarus roeseli was studied. Mortality of gammarids exposed to the concentrate without AS was not different to the control, whereas concentrates including ASs caused mortality rates up to 100% at the highest test concentrations after 168 h. Resulting EC50-values were 36.2–39.4% (v/v) after 96 h and 26.6–58.0% (v/v) after 168 h. These results suggest that the ecotoxicological relevance of antiscalants is greater than currently assumed.

A novel method for in situ determination of the polycyclic aromatic hydrocarbons (PAHs) adsorbed onto the root surface of Kandelia obovata seedlings was established using laser-induced time-resolved nanosecond fluorescence spectroscopy (LITRF). The linear dynamic ranges for the established method were 1.5–1240ng/spot for phenanthrene, 1.0–1360ng/spot for pyrene and 5.0–1220ng/spot for benzo[a]pyrene. Then, the mechanisms of PAHs transport from the Ko root surface to tissues were investigated. The three-phase model including fast, slow and very slow fractions was superior to the single or dual-phase model to describe the PAHs transport processes. Moreover, the fast fraction of PAHs transport process was mainly due to passive movement, while the slow and very slow fractions were not. Passive movement was the main process of B[a]P adsorbed onto Ko root surface transport to tissues. In addition, the extent of the PAHs transport to Ko root tissues at different salinity were evaluated.

Distribution and speciation of mercury (Hg) in the sediments from a tropical estuary (Godavari estuary) was influenced by the changing physico-chemical parameters of the overlying water column. The sediments from the upstream and downstream of the estuary were uncontaminated but the sediments from the middle of the estuary were contaminated by Hg. The concentrations of Hg became considerably less during the monsoon and post monsoon period. Total Hg concentrations and its speciation (at the middle of the estuary) were dependent on the salinity of the overlying water column. However, salinity had little or no effect on Hg association with organic phases in the sediments at downstream. Increasing pH of the overlying water column corresponded with an increase in the total Hg content in the sediments. Total organic carbon in the sediments played an important role in controlling Hg partitioning in the system. Uncomplexed Hg binding ligands were available in the sediments.

The influence of environmental parameters on the total and pathogenic Vibrio parahaemolyticus seasonal densities in American oysters (Crassostrea virginica) was evaluated for 1year. Harvesting site A yielded the highest mean densities of V. parahaemolyticus tlh+, tdh+/trh−, tdh−/trh+ and tdh+/trh+ during spring season at 2.57, 1.74, 0.36, and −0.40 log10MPN/g, respectively, and tdh+/orf8+ during winter season (0.90 log10MPN/g). V. parahaemolyticus tlh+ densities were associated to salinity (R2=0.372, P<0.022), tdh+/trh+ to turbidity (R2=0.597, P<0.035), and orf8+ to temperature, salinity, and pH (R2=0.964, P<0.001). The exposure to salinity and temperature conditions during winter and spring seasons regulated the dynamics of V. parahaemolyticus harboring potentially pathogenic genotypes within the oyster. The adaptive response of V. parahaemolyticus to seasonal environmental changes may lead to an increase in survival and virulence, threatening the seafood safety and increasing the risk of illness.

A 3-D prognostic baroclinic hydrodynamic model of the Arabian Gulf (AG) was developed using Delft3D-FLOW. The model was forced with long-term time averaged climatological data over the computational domain and long-term salinity and temperature boundary conditions applied at its tidal open boundary. The model simulation results were thoroughly validated against measured tides from 5 stations and measured currents at 4 locations in the central and southern parts. Water salinity and temperature were validated in space and time using observations spanning over 73years from 1923 to 1996 for the AG, the Strait of Hormuz and the Gulf of Oman. The bottom flow of the AG basin at the vicinity of the Strait of Hormuz was also validated against the available measurements. Seasonal evaporation and surface density spatial distribution maps were produced and compared with available records. The developed model setup successfully generated the AG seasonal stratification and hydrographic conditions.