Zn Loading Research Articles

One-pot, solid-state loading of Zn into g-C3N4 for increasing the population of photoexcited electrons and the rate of photocatalytic hydrogen evolution

In this research, we load g-C3N4 with Zn through a simple, one-pot solid-state route that results in appreciably improved photocatalytic activity for H2 evolution under visible light. X-ray photoelectron spectroscopy and synchrotron X-ray absorption near edge structure spectroscopy confirm that the Zn species are present in the +2 oxidation state, coordinated to O atoms in the form of nanoclusters. Following the Zn loading, the host g-C3N4 absorbs more light in the UV and visible regions, while its physical features are almost unaltered. In the absence of any co-catalysts, a H2 evolution rate as high as 26.3 μmol/g·h can be achieved by g-C3N4 loaded with 0.2 atomic% of Zn, more than 8 times higher than that of g-C3N4 (3 μmol/g·h). Our results then provide strong evidences that the photocatalytic activity of Zn-loaded g-C3N4 for H2 evolution is directly controlled by the population of photoexcited electrons.

Zn2+ Ion Surface Enrichment in Doped Iron Oxide Nanoparticles Leads to Charge Carrier Density Enhancement.

Here, we report the development of monodisperse Zn-doped iron oxide nanoparticles (NPs) with different amounts of Zn (ZnxFe3–xO4, 0 < x < 0.43) by thermal decomposition of a mixture of zinc and iron oleates. The as-synthesized NPs show a considerable fraction of wüstite (FeO) which is transformed to spinel upon 2 h oxidation of the NP reaction solutions. At any Zn doping amounts, we observed the enrichment of the NP surface with Zn2+ ions, which is enhanced at higher Zn loadings. Such a distribution of Zn2+ ions is attributed to the different thermal decomposition profiles of Zn and Fe oleates, with Fe oleate decomposing at much lower temperature than that of Zn oleate. The decomposition of Zn oleate is, in turn, catalyzed by a forming iron oxide phase. The magnetic properties were found to be strongly dependent on the Zn doping amounts, showing the saturation magnetization to decrease by 9 and 20% for x = 0.05 and 0.1, respectively. On the other hand, X-ray photoelectron spectroscopy near the Fermi level demonstrates that the Zn0.05Fe2.95O4 sample displays a more metallic character (a higher charge carrier density) than undoped iron oxide NPs, supporting its use as a spintronic material.

Contaminant loading and competitive access of Pb, Zn and Mn(III) to vacancy sites in biogenic MnO2

The scavenging properties of MnO2 are largely attributed to sorption on layer vacancy sites. However, co-occurrence of Mn(II, III) with MnO2 can change mineral reactivity by modifying its Mn(III) content or number of free vacancy sites. These processes are critical in biogenic MnO2 because nascent precipitates are in contact with aqueous Mn(II) and redox processes involving the biomass can modify the Mn(III) content of the oxide. Here we studied the mechanism of Zn(II) and Pb(II) sorption by the biogenic MnO2 precipitated by Pseudomonas putida GB-1. Sorption isotherms on biogenic MnO2 at pH 5.2 ± 0.3 showed considerably higher loadings for Pb(II) (0.49 mol Pb mol−1 Mn) than for Zn(II) (0.12 mol Zn mol−1 Mn). For loadings above 0.1 mol mol−1 Mn, Zn(II) and Pb(II) sorption was concomitant, albeit to different extents, with Mn(II) accumulation in solution. Wet chemical measurements and analysis of Zn K–edge and Pb L3-edge EXAFS spectra showed that the difference in metal loadings on the oxide and extent of Mn(II) release to solution originates from the ability of the cations to displace interlayer Mn(III), which then undergoes disproportionation and accumulates as Mn(II) in solution. In addition, the formation of nanoscale precipitates rich in Pb-P-Cl in the biomass matrix, as shown by energy dispersive X-ray analysis, leads to greater accumulation of Pb than Zn on the biomass. Our findings show how the reactivity of biogenic MnO2 towards co-occurring trace or contaminant metals in natural systems depends directly on the mineral Mn(III) content and competitive sorption processes.

Heavy metal concentrations in water and sediment of the Steelpoort River, Olifants River System, South Africa

Steelpoort River has been adversely affected by human activities in the catchment. Water and sediment quality of the river was assessed in 2015. The concentrations of some of the metals in water were found to be high and exceeded the guideline values and the concentrations of metals in sediment were found exceeding the guideline values for Cr, Cu and Zn. The high concentrations of Cu and Zn at Site 1 and Site 2 (upstream) could have originated from anthropogenic sources, such as fertilisers and pesticides from discharge of agricultural wastes, whereas the high concentrations of Cr at Site 3, Site 4 (midstream) and Site 5 (downstream) could have originated from the mine waste, and from domestic/ industrial wastes respectively. The principal component analysis results showed two main components: PC-1 with high positive loading of Cu and Mn, and PC-2 with high positive loading of Zn. These findings indicate the presence of pollution. Therefore, control measures should be implemented to reduce river contamination from anthropogenic sources.

Pt-Zn/HZSM-5 as a highly selective catalyst for the Co-aromatization of methane and light straight run naphtha

Selectivity of catalysts has become increasingly important in the petrochemical industry in order to reduce waste, maximize efficiency, and reduce costs. Reported here is a catalyst in the form of Pt-Zn/HZSM-5 with low acidity to reduce over cracking and maximize selectivity of benzene, toluene, and xylene (BTX) during the aromatization of naphtha under methane environment. The Pt-Zn combination when coupled with HZSM-5 support over light straight run naphtha (LSR) and methane, is capable of BTX selectivity of 94.4% with no formation of detrimental polyaromatics and olefins. Such a performance is attributed to the appropriate distribution of acid sites (seen via NH3-TPD and pyridine DRIFT) with regards to strength and type because of loading Pt and Zn as well as Zn’s ability to reduce coke formation as seen via TGA-DSC (1 μg coke/(g cat·h) for Zn/HZSM-5 and 5.9 μg coke/(g cat·h) for HZSM-5). TEM imaging shows that a methane environment effectively suppresses metal particle agglomeration (1.4 nm average metal nanoparticle diameter) compared to nitrogen (2.1 nm average metal nanoparticle diameter) with XRD showing Pt’s ability to maintain catalyst crystallinity during moderate temperature and moderate pressure as well as reaction time of 1 h. It has been seen here that by employing Zn and Pt in tandem over HZSM-5, catalytic performance can be greatly increased (22.4% BTX yield) when compared to sole loading of Zn (13.4%) or Pt (13.1%), thus a positive synergetic effect is witnessed. Such a selective and coke resistant catalyst shows great promise for the future of LSR reformation to valuable products with methane as a very feasible co-reactant capable of contributing to positive liquid products.

Cucumber Golgi protein CsMTP5 forms a Zn-transporting heterodimer with high molecular mass protein CsMTP12

Heterodimeric complexes formed by members of the cation facilitator (CDF) family catalyse the import of Zn into the secretory pathway of yeast and vertebrate cells. Orthologous proteins AtMTP5 and AtMTP12 from Arabidopsis have also been shown to form a heterodimeric complex at the Golgi compartment of plant cells that possibly transport Zn. In this study we show that cucumber proteins CsMTP5 and CsMTP12 form a functional heterodimer that is involved in the loading of Zn into the ER lumen under low Zn, and not in the detoxification of yeast from Zn excess through vesicle-mediated exocytosis. Using specific antibodies, we demonstrate that CsMTP5 is localized at the Golgi compartment of cucumber cells and is markedly up-regulated upon Zn deficiency. The level of CsMTP5 transcript in cucumber is also significantly elevated in Zn-limiting conditions, whereas the expression of CsMTP12 is independent of the availability of Zn. Therefore we propose that the cucumber heterodimeric complex CsMTP5-CsMTP12 functions to deliver Zn to Zn-dependent proteins of the Golgi compartment and is regulated by zinc at the level of CsMTP5 transcription.

Simultaneous Adsorption of Heavy Metals from Roadway Stormwater Runoff Using Different Filter Media in Column Studies

Stormwater runoff from roadways often contains a variety of contaminants such as heavy metals, which can adversely impact receiving waters. The filter media in stormwater filtration/infiltration systems play a significant role in the simultaneous removal of multiple pollutants. In this study, the capacity of five filter media—natural quartz sand (QS), sandy soil (SS) and three mineral-based technical filter media (TF-I, TF-II and TF-III)—to adsorb heavy metals (Cu, Pb and Zn) frequently detected in stormwater, as well as remobilization due to de-icing salt (NaCl), were evaluated in column experiments. The column breakthrough data were used to predict lifespan of the filter media. Column experiment operated under high hydraulic load showed that all technical filters and sandy soil achieved &gt;97%, 94% and &gt;80% of Pb, Cu and Zn load removals, respectively, while natural quartz sand (QS) showed very poor performance. Furthermore, treatment of synthetic stormwater by the soil and technical filter media met the requirements of the Austrian regulation regarding maximum effluent concentrations and minimum removal efficiencies for groundwater protection. The results showed that application of NaCl had only a minor impact on the remobilization of heavy metals from the soil and technical filter media, while the largest release of metals was observed from the QS column. Breakthrough analysis indicated that load removal efficiencies at column exhaustion (SS, TF-I, TF-II and TF-III) were &gt;95% for Cu and Pb and 80–97% for Zn. Based on the adsorption capacities, filtration systems could be sized to 0.4 to 1% (TF-I, TF-II and TF-III) and 3.5% (SS) of their impervious catchment area and predicated lifespan of each filter media was at least 35, 36, 41 and 29 years for SS, TF-I, TF-II and TF-III, respectively. The findings of this study demonstrate that soil—based and technical filter media are effective in removing heavy metals and can be utilized in full-stormwater filtration systems.

Application of hydrologic-tracer techniques to the Casargiu adit and Rio Irvi (SW-Sardinia, Italy): Using enhanced natural attenuation to reduce extreme metal loads

Hydrologic tracer techniques were applied to Rio Irvi (SW Sardinia), a stream affected by mine drainage, allowing the calculation of stream discharge and metal loads and comparison to other streams. The calculated discharge showed a continuous increase from near 21.2 L/s to 29.1 L/s. Cumulative loads of mine-related constituents, including the Casargiu adit inflow, were large, with more than 9900 kg/day of SO42−, 2370 kg/day of Zn, 550 kg/day of Fe and 172 kg/day of Mn. The greatest measurable inflow source of metals, other than the Casargiu adit, was an acidic tributary (L4), but most sources of instream metal load were related to dispersed groundwater inflows. Some of those groundwater inflows were related to non-flowing tributaries. Calculations of the cumulative instream metal load, excluding the Casargiu adit inflow, indicated increases of 1250 kg/day for SO42, 858 kg/day for Zn-, 137 kg/day gain for Fe and 60 kg/day for Mn.Rio Irvi Zn load was extreme for a stream of this size and discharge. A comparison with two other mine-affected rivers in Sardinia indicated the loading in Rio Irvi was two to three orders of magnitude greater. This difference was attributed to different geochemical conditions, but also to a lack of a biogeochemical barrier like that seen to be acting along and below the riverbed in Rio San Giorgio. Several years of intense vegetation growth in the river bed of Rio San Giorgio created a biogeochemical barrier to metal loading, and the cumulative Zn load there was near 8 kg/day, despite being a drainage with a greater mass of mine wastes to contribute to the load.

Geochemical evaluation of soil, surface water and groundwater around the Tongon gold mining area, northern Côte d’Ivoire, West Africa

A comprehensive geochemical evaluation of soils and water resources around the largest gold mine in Côte d’Ivoire was conducted. The enrichment factors and statistical analysis of heavy metals revealed that the mining had greatly contributed to As, W, Hg, Sr and, to a lesser degree, Co, Ni and Zn loadings into the soils. In contrast, V, Zr, Hf, Sc, Cs, Mo and Fe were primarily derived from chemical weathering of the parent rock, whereas abundance of Th and U were related to heavy mineral dissolution. The influence of tailings on the surrounding soils was further highlighted by the similarities between rare earth element distribution patterns of the soils and that of the tailings. With pollution indices of soils greater than unity, the majority of the sites were classified as highly polluted. Because of their weak buffering capacity (pH 5–6.1), the soils could not be a major sink for heavy metals, and the tailings leachates are likely to migrate into surface water and groundwater. The highly mining-impacted surface waters were classified as Ca-SO4 and Na-Cl types with high pH values, whereas the slightly contaminated groundwaters as a Ca-Mg-HCO3 type, reflecting the influence of silicate and carbonate weathering. Although mining-impacted surface waters and groundwaters showed the highest concentrations of heavy metals, their relatively high pH values had favored adsorption of the metals onto precipitating Fe-oxyhydroxides. The findings of this study showed that the soils and water resources around the Tongon mine are vulnerable to mining operations.

CO2 sensing properties of electro-spun Ca-doped ZnO fibres

The availability of low-cost, high-performing sensors for carbon dioxide detection in the environment may play a crucial role for reducing CO2 emissions and limiting global warming. In this study, calcium-doped zinc oxide nanofibres with different Ca to Zn loading ratios (1:40 or 1:20) are synthesised via electro-spinning, thoroughly characterised and, for the first time, tested as an active material for the detection of carbon dioxide. The results of their characterisation show that the highly porous fibres consist of interconnected grains of oxide with the hexagonal wurtzite structure of zincite. Depending on the Ca:Zn loading ratio, calcium fully or partly segregates to form calcite on the fibre surface. The high response of the sensor based on the fibres with the highest Ca-doping level can be attributed to the synergy between the fibre morphology and the basicity of Ca-ion sites, which favour the diffusion of the gas molecules within the sensing layer and the CO2 adsorption, respectively.

Health risk assessment of heavy metals in atmospheric deposition in a congested city environment in a developing country: Kandy City, Sri Lanka

This research study which was undertaken in a congested city environment in a developing country provides a robust approach for the assessment and management of human health risk associated with atmospheric heavy metals. The case study area was Kandy City, which is the second largest city in Sri Lanka and bears the characteristics of a typical city in the developing world such as the urban footprint, high population density and traffic congestion. Atmospheric deposition samples were collected on a weekly basis and analyzed for nine heavy metals common to urban environments, namely, Al, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb. Health risk was assessed using hazard quotient (HQ) and hazard index (HI), while the cancer risk was evaluated based on life time daily cancer risk. Al and Fe were found to be in relatively high concentrations due to the influence of both, natural and anthropogenic sources. High Zn loads were attributed to vehicular emissions and the wide use of Zn coated building materials. Contamination factor and geo-accumulation index showed that currently, Al and Fe are at uncontaminated levels and other metals are in the range of uncontaminated to contaminated levels, but with the potential to exacerbate in the long-term. The health risk assessment showed that the influence of the three exposure pathways were in the order of ingestion > dermal contact > inhalation. The HQ and HI values for children for the nine heavy metals were higher than that for adults, indicating that children may be subjected to potentially higher health risk than adults. The study methodology and outcomes provide fundamental knowledge to regulatory authorities to determine appropriate mitigation measures in relation to HM pollution in city environments in the developing world, where to-date only very limited research has been undertaken.

Relative grain zinc loading ability of cereals (rice, wheat, maize) and a grain legume (chickpea)

Data from field experiments conducted at the ICAR-Indian Agricultural Research Institute, New Delhi, India during the last few years on Zn biofortification of the cereals, viz. wheat (Triticum asestivum L.), rice (Oryza sativa L.) and maize (Zea mays L.) and a grain legume (chickpea) were utilized in studying the comparative efficiency of these crops in grain Zn loading. Although Zn uptake per tonne of grain produced was the highest, the grain Zn loading was the lowest in rice. Zn concentration in grain (an intensity factor) was the highest in wheat at 46.8 mg/kg, closely followed by maize at 45.1 mg/kg, chickpea at 41.8 mg/kg and was the least for rice kernels at 21.2 mg/kg. ZnHI (a capacity factor for measuring grain Zn loading) was also the highest for wheat at 51%, followed by chickpea at 39.3%, maize at 35.9% and was the least for rice at 17.9%. Further, rice grain contains husk (about one-third by weight) and only kernel is consumed, for which ZnHI was only 6.3%; a major part of Zn loaded on grain in rice goes to the husk. Thus, from the Zn nutrition point of view rice is the poorest cereal. However, rice deserves utmost attention, because it is the staple food in South, Southeast and East Asia, where about 62.5% of the world’s people live and hunger and malnutrition is rampant. Since most grain Zn loading in rice is from the Zn absorbed by the roots through xylem in contrast to other crops, where it is mostly achieved through mobilization of Zn in the vegetative tissue through phloem, it is suggested that rice plant types using grain Zn loading through phloem be developed. It is necessary, because applied Zn gets fixed or precipitated in soil through several mechanisms and its availability to rice plants gets reduced as it reaches grain filling stage.

Cinnamon Gulch revisited: Another look at separating natural and mining-impacted contributions to instream metal load

Baseline, premining data for streams draining abandoned mine lands is virtually non existent, and indirect methods for estimating premining conditions are needed to establish realistic, cost effective cleanup goals. One such indirect method is the proximal analog approach, in which premining conditions are estimated using data from nearby mineralized areas that are unaffected by mining. In this paper, we combine the proximal analog approach with a quantitative mass balance framework using data from a spatially-detailed synoptic sampling campaign. The combined approach is applied to Cinnamon Gulch, a headwater stream with numerous draining adits. Synoptic sampling results indicate that three of the top five metal sources are affected by mining activities, and stream segments draining these sources account for a large percentage of overall metal loading within the study reach. These initial calculations overestimate the effects of mining, as the affected stream segments were likely acidic and metal rich prior to mining. Premining loads and concentrations were therefore determined through a replacement approach in which the chemistry of each mining-affected stream segment is revised based on proximal analog concentrations. The revised loading profiles indicate that 15–17% of the Al, Cd, Cu, Mn, Ni, and Zn loads are attributable to mining, whereas the mining contribution for Pb is 40%. Premining concentrations of Al, Cd, Cu, Mn, and Zn are estimated to be in excess of aquatic life standards over the length of the study reach.

High Zn/Al ratios enhance dehydrogenation vs hydrogen transfer reactions of Zn-ZSM-5 catalytic systems in methanol conversion to aromatics

Two series of Zn-ZSM-5 catalysts were prepared by ion exchanging two commercial zeolites with different Si/Al ratios (40 and 15) with increasing Zn loadings. The nature of the Zn sites in the zeolite was studied by spectroscopy using laboratory and synchrotron techniques. All the evidences suggest that catalytic activity is associated with [Zn(H2O)n(OH)]+ species located in the exchange positions of the materials with little or no contribution of ZnO or metallic Zn. The effect of Zn/Al ratio on their catalytic performance in methanol conversion to aromatics has been investigated. In all cases, higher Zn content causes an increase in the yield of aromatics while keeping the production of alkanes low. For similar Zn contents, high densities of Al sites favour the hydrogen transfer reactions and alkane formation whereas in samples with low Al contents, and thus higher Zn/Al ratio, the dehydrogenation reactions in which molecular hydrogen is released are favoured.

Metals geochemistry and mass export from the Mississippi-Atchafalaya River system to the Northern Gulf of Mexico

Discharging 680 km3 of freshwater annually to the Northern Gulf of Mexico (NGOM), the Mississippi-Atchafalaya River System (MARS) plays a significant role in transporting major and trace elements to the ocean. In this study, we analyzed total recoverable concentrations of thirty-one metals from water samples collected at five locations along the MARS during 2013–2016 to quantify their seasonal mass exports. The Atchafalaya River flows through a large swamp floodplain, allowing us to also test the hypothesis that floodplains function as a sink for metals. We found that the seven major elements (Ca, Na, Mg, Si, K, Al, and Fe) constituted 99% of the total annual mass load of metals (7.38 × 107 tons) from the MARS. Higher concentrations of Al, Ba, B, Ca, Fe, Mg, Mn, Ag, and Ti were found in the Mississippi River, while significantly higher Si and Na concentrations were found in the Atchafalaya River. Significant relationships were found between daily discharge and daily loads of Ba, Ca, Fe, K, Sr, and Ti in both rivers, while significant relationships were also found for Al, Mg, Mn, V, and Zn in the Atchafalaya River and B in the Mississippi River. Overall, the Mississippi River contributed 64–76% of the total annual loading of metals from the MARS to the NGOM. Daily loads of Al, Ba, B, Fe, Li, Mn, P, K, Si, Ag, Ti, V, and Zn regularly decreased upstream to downstream in the Atchafalaya River, partially accepting the initial hypothesis on metals transport in river floodplains.

Emission of heavy metals from an urban catchment into receiving water and possibility of its limitation on the example of Lodz city

Heavy metals are among the priority pollutants which may have toxic effects on receiving water bodies. They are detected in most of samples of stormwater runoff, but the concentrations are very variable. This paper presents results of study on the amount of heavy metals discharged from urban catchment in Lodz (Poland) in 2011–2013. The research was carried out to identify the most important sources of their emission and to assess the threats to receiving water quality and opportunities of their limitation. The city is equipped with a combined sewerage in the center with 18 combined sewer overflows and with separate system in other parts. Stormwater and wastewater from both systems are discharged into 18 small urban rivers. There is a need of restoration of water bodies in the city. Research results indicate that the main issue is high emission of heavy metals, especially zinc and copper, contained in stormwater. Annual mass loads (g/ha/year) from separate system were 1629 for Zn and 305 for Cu. It was estimated that about 48% of the annual load of Zn, 38% of Cu, 61% of Pb, and 40% of Cd discharged into receiving water came from separate system, respectively 4% of Zn and Cu, 10% of Pb and 11% of Cd from CSOs, and the remaining part from wastewater treatment plant. Effective reduction of heavy metals loads discharged into receiving water requires knowledge of sources and emissions for each catchment. Obtained data may indicate the need to apply centralized solution or decentralized by source control.

The Supramolecular and Coordination Chemistry of Cobalt(II) Extraction by Phosphinic Acids

A combination of mass spectrometry, DFT calculations and 31P{1H} NMR spectroscopy has been used to define the mode of action of the commercial cobalt extractant, bis(2,4,4‐trimethylpentyl)phosphinic acid (CYANEX®272, L1H) in Co recovery. The nature of the CoII complexes formed in the water‐immiscible phase is determined largely by the propensity of phosphinates to form strong interligand H‐bonds in the outer coordination sphere and also to form stable µ2‐Co–O–P–O–Co bridges. At low Co loading levels, the predominant species is the 4:1 complex, [Co(L1·L1H)2], in which coordinated neutral phosphinic acid ligands form strong H‐bonds to adjacent anionic phosphinates. At higher Co loading, oligomers such as [(L1·L1H)Co(L12Co)n(L1·L1H)] are formed with µ2‐phosphinate bridging, resulting in a substantial increase in the viscosity of the water‐immiscible phase. The presence of tris(2,4,4‐trimethylpentyl)phosphine oxide (L2) in the commercial formulation reduces the viscosity because its incorporation into oligomeric complexes such as [(L2)Co{L13CoL1CoL13Co}mL1] can terminate chains, resulting in a lower average molecular weight. The uptake of Zn by L1H shows a very similar dependence of viscosity on loading, and DOSY spectra and mass spectrometry demonstrate that higher molecular weight species are present at high Zn loading.

Development of slow release Zn fertilizer using nano-zeolite as carrier

ABSTRACTZinc (Zn) use efficiency hardly exceeds 2–3% and major portion of added Zn gets fixed in the soil. In order to improve the Zn use efficiency by crops, a laboratory study was undertaken at the Department of Nano Science and Technology, Tamil Nadu Agricultural University, Coimbatore, India, to develop Zn fertilizer using nano-zeolite as a substrate. The natural zeolite (clinoptilolite) was ball milled to achieve nano-dimension (90–110 nm) and fortified with Zn by loading Zinc sulphate (ZnSO4). The zeolite was characterized before and after loading of Zn using particle size analyzer, Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-ray Diffraction, Scanning Electron Microscope and Transmission Electron Microscope. The data clearly indicated that the nano-zeolite was loaded successfully loaded with Zn to the tune of 14% and Zn presence in the substrate was confirmed by Energy dispersive X-ray spectroscopy and Atomic Force Microscopy. After the synthesis, sorption and desorption pattern of Zn of the nano-zeolite was examined using a percolation reactor. The results showed that Zn release from the nano-zeolite substrate has prolonged for a period of 1,176 hrs, while the Zn release from the ordinary ZnSO4 ceased to exist within 216 hrs. The data suggest that the nano-sized zeolite is capable of retaining Zn and slowly release into the soil solution, which may be served as a slow release Zn fertilizer and improve use efficiency by crops.

HEAVY METALS CONTENT IN THE SPROUTS OF Glyceria maxima (Hartm.) Holmb. AND IN RIVER SEDIMENTS (NORTHERN POLAND)

The aim of this study was to evaluate the content of Zn, Mn, Cu and Ni in the aboveground and underground shouts of Glyceria maxima and in the bottom sediments of the Slupia River. These studies allow for assessment of the existing and potential hazards resulting from toxic influence of heavy metals on water environment and human health. The concentration of research elements was determined by atomic absorption spectrometry (AAS). Results indicate that the concentration of heavy metals in the examined bottom sediments remained within the limits of the geochemical background for majority of the determined elements. The concentrations of Zn and Cu, sporadically exceeded the level of the geochemical background at the stations in the central part of the city, and in the case of Ni in all researched positions. Following the LAWA classification, the bottom sediments within the Slupsk area were classified in the first class, as slightly contaminated. It was found the G. maxima underground sprouts accumulated several times more of Zn, Mn, Cu and Ni than their aboveground sprouts. The indices of quality of the tested bottom sediments and the enrichment factors of the sprouts with heavy metals indicate that the Slupia River is the least contaminated along the segments of the river with a low or moderate transformation of the river bed and the largest load of Zn, Mn, Cu and Ni is found at the stations with a high transformation of the river bed. The strong positive correlations between the concentrations of Mn in bottom sediments and the level this element in aboveground and underground sprouts indicate that the sprouts of Glyceria maxima are potentially useful in biomonitoring environmental contamination with Mn.

Influence of elevated Zn (II) on Anammox system: Microbial variation and zinc tolerance

Nitrogen removal by anaerobic ammonium oxidation (Anammox) has attracted increasing attention in nowadays. An Anammox biofilter was subjected to a continuous loading of elevated Zn (II). The influence of Zn (II) on the nitrogen removal, microbial community and biofilm property was investigated in the condition of 23–26 °C and 3.5 h HRT. The nitrogen removal greatly decreased to 0.054 from the initial 0.502 kg m−3 d−1, with the Zn (II) addition. Anaerobic ammonia-oxidizing bacteria (AAOB) had self-adaption to Zn (II) in 1–10 mg L−1 and was significantly enhanced after long-term acclimatization, while the suppression threshold was 20 mg L−1. Soluble microbial products (SMP) increased correspondingly with Zn (II), while extracellular polymeric substance (EPS) climbed up initially and then decreased. Anammox biofilm performed the highest zinc adsorption as 158.27 mg g−1 SS in biofilm. High Zn (II) improved the microbial diversity and lowered the Candidatus Kuenenia abuandance to 1.38% from 20.89%.