Low tech photovoltaic panels (PVPs) installed in the early ’80s are now coming to the end of their life cycle and this raises the problem of their proper disposal. As panels contain potentially toxic elements, unconventional, complex and costly procedures are required to avoid environmental health risks and in countries where environmental awareness and economic resources are limited this may be especially problematic. This work was designed to investigate potential risks from improper disposal of these panels. To accomplish this aim an exhausted panel was broken into pieces and these were placed in water for 30 days. The resulting leached solution was analyzed to determine chemical release or used in toto, to determine its potential toxicity in established tests. The end points were seed germination (on Cucumis sativus and Lens culinaris) and effects on early development in three larval models: two crustaceans, Daphnia magna and Artemia salina, and the sea urchin Paracentrotus lividus. Our results show that the panels release small amounts of electrolytes (Na, Ca and Mg) into solution, along with antimony and manganese, with a concentration under the accepted maximum contaminant level, and nickel at a potentially toxic concentration. Developmental defects are seen in the plant and animal test organisms after experimental exposure to the whole solution leached from the broken panel. The toxic effects revealed in in vitro tests are sufficient to attract attention considering that they are exerted on both plants and aquatic animals and that the number of old PVPs in disposal sites will be very high.

To investigate the size distributions of chemical compositions and sources of particulate matter (PM) at ground level and from the urban canopy, a study was conducted on a 255 m meteorological tower in Tianjin from December 2013 to January 2014. Thirteen sets of 8 size-segregated particles were collected with cascade impactor at 10 m and 220 m. Twelve components of particles, including water-soluble inorganic ions and carbonaceous species, were analyzed and used to apportion the sources of PM with positive matrix factorization. Our results indicated that the concentrations, size distributions of chemical compositions and sources of PM at the urban canopy were affected by regional transport due to a stable layer approximately 200 m and higher wind speed at 220 m. The concentrations of PM, Cl− and elemental carbon (EC) in fine particles at 10 m were higher than that at 220 m, while the reverse was true for NO3− and SO42−. The concentrations of Na+, Ca2+, Mg2+, Cl− and EC in coarse particles at 10 m were higher than that at 220 m. The size distributions of major primary species, such as Cl−, Na+, Ca2+, Mg2+ and EC, were similar at two different heights, indicating that there were common and dominant sources. The peaks of SO42−, NH4+, NO3− and organic carbon (OC), which were partly secondary generated species, shifted slightly to the smaller particles at 220 m, indicating that there was a different formation mechanism. Industrial pollution and coal combustion, re-suspended dust and marine salt, traffic emissions and transport, and secondary inorganic aerosols were the major sources of PM at both heights. With the increase in vertical height, the influence of traffic emissions, re-suspended dust and biomass burning on PM weakened, but the characteristics of regional transport from Hebei Province and Beijing gradually become obvious.

Rigorous studies of recovery from soil acidification are rare. Hence, we resampled 97 old-growth beech stands in the Vienna Woods. This study exploits an extensive data set of soil (infiltration zone of stemflow and between trees area at different soil depths) and foliar chemistry from three decades ago. It was hypothesized that declining acidic deposition is reflected in soil and foliar chemistry. Top soil pH within the stemflow area increased significantly by 0.6 units in both H2O and KCl extracts from 1984 to 2012. Exchangeable Ca and Mg increased markedly in the stemflow area and to a lower extent in the top soil of the between trees area. Trends of declining base cations in the lower top soil were probably caused by mobilization of organic S and associated leaching with high amounts of sulfate. Contents of C, N and S decreased markedly in the stemflow area from 1984 to 2012, suggesting that mineralization rates of organic matter increased due to more favorable soil conditions. It is concluded that the top soil will continue to recover from acidic deposition. However, in the between trees areas and especially in deeper soil horizons recovery may be highly delayed. The beech trees of the Vienna Woods showed no sign of recovery from acidification although S deposition levels decreased. Release of historic S even increased foliar S contents. Base cation levels in the foliage declined but are still adequate for beech trees. Increasing N/nutrient ratios over time were considered not the result of marginally higher N foliar contents in 2012 but of diminishing nutrient uptake due to the decrease in ion concentration in soil solution. The mean foliar N/P ratio already increased to the alarming value of 31. Further nutritional imbalances will predispose trees to vitality loss.

Insufficient understanding of the hydrogeochemistry of aquifers makes it necessary to conduct a preliminary water quality assessment in the southern region of Ordos Basin, an arid area in the world. In this paper, the major ions of groundwater have been studied aiming at evaluating the hydrogeochemical processes that probably affect the groundwater quality using 150 samples collected in 2015. The two prevalent hydrochemical facies, HCO3Mg·Na·Ca and HCO3Mg·Ca·Na type water, have been identified based on the hydrochemical analysis from Piper trilinear diagram. Compositional relations have been used to assess the origin of solutes and confirm the predominant hydrogeochemical processes responsible for the various ions in the groundwater. The results show that the ions are derived from leaching effect, evaporation and condensation, cation exchange, mixing effect and human activities. Finally groundwater quality was assessed with single factor and set pair methods, the results indicate that groundwater quality in the study region is generally poor in terms of standard of national groundwater quality. The results obtained in this study will be useful to understand the groundwater quality status for effective management and utilization of the groundwater resource.

Biochar is a porous carbonaceous material with high alkalinity and rich minerals, making it possible for CO2 capture. In this study, biochars derived from pig manure, sewage sludge, and wheat straw were evaluated for their CO2 sorption behavior. All three biochars showed high sorption abilities for CO2, with the maximum capacities reaching 18.2–34.4 mg g−1 at 25 °C. Elevating sorption temperature and moisture content promoted the transition of CO2 uptake from physical to chemical process. Mineral components such as Mg, Ca, Fe, K, etc. in biochar induced the chemical sorption of CO2 via the mineralogical reactions which occupied 17.7%–50.9% of the total sorption. FeOOH in sewage sludge biochar was transformed by sorbed CO2 into Fe(OH)2CO3, while the sorbed CO2 in pig manure biochar was precipitated as K2Ca(CO3)2 and CaMg(CO3)2, which resulted in a dominant increase of insoluble inorganic carbon in both biochars. For wheat straw biochar, sorbed CO2 induced CaCO3 transformed into soluble Ca(HCO3)2, which led to a dominant increase of soluble inorganic carbons. The results obtained from this study demonstrated that biochar as a unique carbonaceous material could distinctly be a promising sorbent for CO2 capture in which chemical sorption induced by mineralogical reactions played an important role.

Modified clay-based solid-phase phosphorous (P) sorbents are increasingly used as lake geoengineering materials for lake eutrophication control. However, some still dispute the feasibility of using these materials to control internal P loading from shallow eutrophic lakes. The lack of information about P behavior while undergoing frequent sediment resuspension greatly inhibits the modified minerals’ use. In this study, a sediment resuspension generating system was used to simulate the effect of both moderate winds (5.1 m/s) and strong winds (8.7 m/s) on the stability of sediment treated by two geoengineering materials, Phoslock® (a lanthanum modified bentonite) and thermally-treated calcium-rich attapulgite. This study also presents an analysis of the P dynamics across the sediment-water interface of two shallow eutrophic lakes. In addition, the effect of wind velocity on P forms and P supply from the treated sediment were studied using chemical extraction and diffusive gradients in thin films (DGT) technique, respectively. Results showed that adding geoengineering materials can enhance the stability of surface sediment and reduce the erosion depth caused by wind accordingly. All treatments can effectively reduce soluble reactive phosphorus (SRP) concentration in overlying water when sediment is capped with thermally-treated calcium-rich attapulgite, which performs better than sediment mixed with modified attapulgite but not as well as sediment treated with Phoslock®. However, their efficiency decreased with the increase in occurrences of sediment resuspension. The addition of the selected geoengineering materials effectively reduced the P fluxes across sediment-water interface and lowered P supply ability from the treated sediment during sediment resuspension. The reduction of mobile P and enhancement of calcium bound P and residual P fraction in the treated sediment was beneficial to the long-term lake internal P loading management. All of the results indicated that the studied geoengineering materials are suitable for application in shallow eutrophic lakes with frequent sediment resuspension activity.

The Diffusive Gradients in Thin Films (DGT) technique using PIWBA resin (The Dow Chemical Company) was developed and validated for the measurement of uranium (U) concentration in natural and uranium mining influenced waters. The U uptake on the PIWBA resin gel was 97.3 ± 0.4% (batch method; Vsol = 5 mL; [U] = 20 μg L−1; 0.01 M NaNO3; pH = 7.0 ± 0.2). The optimal eluent was found to be HNO3conc/70 °C with an elution efficiency of 88.9 ± 1.4%. The laboratory DGT investigation demonstrated that the PIWBA resin gel exhibits a very good performance across a wide range of pH (3–9) and ionic strength (0.001–0.7 M NaNO3) at different time intervals. Neither effect of PO43− (up to 1.72 × 10−4 M), nor of HCO3− (up to 8.20 × 10−3 M) on the quantitative measurement of uranium by DGT-PIWBA method were observed. Only at very high Ca2+ (2.66 × 10−4 M), and SO42− (5.55 × 10−4 M) concentration, the U uptake on DGT-PIWBA was appreciably lessened. In-situ DGT field evaluation was carried out in the vicinity of three former uranium mining sites in France (Loire-Atlantique and Herault departments), which employ different water treatment technologies and have different natural geochemical characteristics. There was a similar or inferior U uptake on DGT-Chelex®-100 in comparison with the U accumulation on a DGT-PIWBA sampler. Most likely, the performance of Chelex®-100 was negatively affected by a highly complex matrix of mining waters. The high concentration and identity of co-accumulating analytes, typical for the mining environment, did not have a substantial impact on the quantitative uptake of labile U species on DGT- PIWBA.The use of the polyphenol impregnated anion exchange resin leads to a significant advancement in the application and development of the DGT technique for determination of U in the vicinity of the former uranium mining sites.

Heavy metal pollution is a global issue severely constraining aquaculture practices, not only deteriorating the aquatic environment but also threatening the aquaculture production. One promising solution is adopting aquaponics systems where a synergy can be established between aquaculture and aquatic plants for metal sorption, but the interactions of multiple metals in such aquatic plants are poorly understood. In this study, we investigated the absorption behaviors of Cu(II) and Cd(II) in water by water hyacinth roots in both single- and binary-metal systems. Cu(II) and Cd(II) were individually removed by water hyacinth roots at high efficiency, accompanied with release of protons and cations such as Ca2+ and Mg2+. However, in a binary-metal arrangement, the Cd(II) sorption was significantly inhibited by Cu(II), and the higher sorption affinity of Cu(II) accounted for its competitive sorption advantage. Ionic exchange was identified as a predominant mechanism of the metal sorption by water hyacinth roots, and the amine and oxygen-containing groups are the main binding sites accounting for metal sorption via chelation or coordination. This study highlights the interactive impacts of different metals during their sorption by water hyacinth roots and elucidates the underlying mechanism of metal competitive sorption, which may provide useful implications for optimization of phytoremediation system and development of more sustainable aquaculture industry.

Graphene oxide (GO) and reduced graphene oxide (RGO) materials contain a variety of surface O-functional groups that are chemically reactive. When released into the environment these materials may significantly affect the abiotic transformation of organic contaminants, and therefore, may alter their fate and risks. We found that two GO and five RGO materials that varied in C/O ratio, hydrophobicity, and type/distribution of surface O-functionality all had catalytic effects on the dehydrochlorination of 1,1,2,2-tetrachloroethane (TeCA). Even though the catalytic effects of the materials originated from their deprotonated surface O-functional groups, which served as conjugated bases to catalyze the reaction, the catalytic efficiencies of the materials did not correlate strongly with their surface O contents. The spectroscopic evidence (X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy), surface charge data, and adsorption experiments demonstrated that the catalytic efficiencies of the GO/RGO materials were controlled by a complex interplay of the type and distribution of surface O-functionality, as well as adsorption affinity of the materials. Both Ca2+ and Mg2+ inhibited the catalytic efficiency of the materials by binding to the surface O-functional groups, and consequently, decreasing the basicity of the functional groups. At an environmentally relevant concentration of 10 mg/L, Suwannee River humic acid (used as a model dissolved organic matter) alone had little effect on the dehydrochlorination of TeCA. However, it could inhibit the catalytic efficiency of the GO/RGO materials by coating on their surface and thus, decreasing the adsorption affinity of these materials for TeCA. The findings further underline the potentially important impacts of nanomaterials on contaminant fate and effects in the environment.

This study evaluated concentrations of main air pollutants in a Portuguese preschool (indoors/outdoors) environment, with emphasis on elemental characterization of different PM fractions, and estimated risks for the pupils (aged 3–5 years). With exception to total volatile organic compounds, levels of PM10, PM2.5, CO, CO2, and formaldehyde were below legislative guidelines. Calcium, sodium, aluminium, and potassium were the most abundant elements in indoor PM (82–84% of the analysed content) resulting mainly from crustal sources. Carcinogenic elements (1–2% of the indoor analysed content) were mostly PM2.5-bound (83–91%). Indoor-to-outdoor ratios of individual elements indicated contributions of indoor origin and from penetration of outdoor emissions indoors; trace metals were associated with ambient anthropogenic emissions (namely traffic). Non-carcinogenic and carcinogenic risks from overall preschool exposure were acceptable for children; for adults carcinogenic risks exceeded (4–11 times) the USEPA recommend value of 10−6, being 8–40 times higher than for children.