Zn Loading Research Articles

Transesterification of Litsea cubeba kernel oil to biodiesel over zinc supported on zirconia heterogeneous catalysts

An effective approach for synthesizing green and sustainable biodiesel fuel from low-value vegetable oils has been explored. Herein, a series of catalysts of zinc supported on zirconia (xZn/ZrO2) were successfully synthesized, characterized, and applied for the production of biodiesel from Litsea cubeba kernel oil (LCKO) through the transesterification process. The results showed that the monoclinic phase structure of the prepared catalysts transformed to the more stable tetragonal phase structure after supporting different Zn loadings (≥5%). Compared with the pure ZrO2, the highly dispersed Zn species on the surface of xZn/ZrO2 could be divided into Zn oxide and ZnOH+, which could promote the transesterification of LCKO. Thus, the 7%Zn/ZrO2 catalyst exhibited the best catalytic activity of the LCKO conversion 82.5%, which was attributed to the positive effects of both the ZrO2 support and Zn species. Furthermore, the various reaction parameters (such as reaction time, stirring rate, nCH3OH:nLCKO, catalyst amount, and reaction temperature) were investigated systematically and optimized carefully. And a possible mechanism of the transesterification process catalyzed by Zn/ZrO2 catalysts was also proposed. Finally, the physical properties of the as-synthesized biodiesel accorded with the current international biodiesel standards.

Effect of Land Reclamation on Soil Properties, Mineralogy and Trace-Element Distribution and Availability: The Example of Technosols Developed on the Tailing Disposal Site of an Abandoned Zn and Pb Mine

Land reclamation is a common practice leading to the restoration of areas affected by industrial activity. Soil studies in reclaimed areas are very useful to determine the effectiveness of reclamation works. The goal of the study was to investigate soil properties, mineral composition, total concentrations of Zn, Pb, Cd and As and chemical forms of these elements in order to assess the success of land reclamation of the abandoned mine tailing disposal site of the “Trzebionka” Zn-Pb mine in Trzebinia, southern Poland. The disposal site was reclaimed by covering tailings with a layer of inert material with a thickness up to 25 cm. The topsoil of the studied soil profiles was comprised of sandy loamy/loamy materials and the subsoil was comprised of sandy tailing materials. The soils were characterized by a neutral or slightly alkaline reaction due to the high content of carbonates. The dominant mineral in the subsoil was dolomite. The studied soils were considerably contaminated with Zn, Pb, Cd and As. A high load of mobile Zn, Pb and Cd was typical of the subsoil material. The reclamation layer does not provide sufficient isolation of toxic tailings from the environment and there is still a high risk of element uptake by plants.

Geochemistry of natural acid rock drainage in the Judith Mountains, Montana, part 2: Seasonal and spatial trends in Chicago Gulch

Three streams radially draining Red Mountain, a prominent peak in the Judith Mountains of central Montana, are naturally acidic in their headwaters and experience a rise in pH as they transition from hydrothermally altered quartz monzonite to sedimentary bedrock in their lower reaches. A previous study (Williams et al., 2015) examined the geochemistry of two of these streams, Armells Creek and Collar Gulch, using detailed synoptic sampling with continuous tracer-injection. Here we present results of two synoptic sampling events in the third stream, Chicago Gulch. Data are compared between the three watersheds, and estimates of solute flux (load divided by watershed area) are presented.Filtered and unfiltered metal concentrations and loads are quantified with distance downstream in Chicago Gulch under low-flow (August) and high-flow (May) conditions. Headwater streams in the watershed have pH < 4 and extensive deposits of ferricrete and Fe-bog deposits. Weakly acidic springs (pH > 4) contain >10 mg/L of Fe2+ which quickly oxidizes and precipitates as hydrous ferric oxide (HFO), releasing protons that lower the pH of the stream. Geochemical modeling suggests the actively forming HFO is a mix of schwertmannite and ferrihydrite, both of which are slowly converting to goethite which cements the ferricrete deposits. White, hydrous aluminum oxide (HAO) flocs form where stream pH transitions from <5 to >5, and a comparison of filtered and unfiltered samples indicates strong partitioning of Cu and Pb into the suspended particles. Dissolved loads of Zn, Cd, Mn, and Tl (thallium) diminish slightly in the lower reaches of Chicago Gulch where pH rises above 7.All water samples collected in the upper reaches of Chicago Gulch exceed the US-EPA water quality standards for protection of aquatic life for Pb, Cd, Zn, and Cu, and human health standards for Tl. Lead concentrations are especially high in the headwaters of Chicago Gulch, indicating the possible presence of an unmined Pb-sulfide deposit. Estimates of the load of dissolved sulfate at baseflow conditions in each stream on Red Mountain, normalized to their respective surface areas of hydrothermally altered bedrock, are remarkably similar, and indicate a steady state pyrite oxidation rate of 11.9 mol FeS2/h/km2. Prediction of pre-modern pH using the methods of Nimick et al. (2009) indicates that the current pH regimes of all three streams draining Red Mountain are broadly similar to conditions when ancient ferricretes were deposited. Because the Judith Mountains were never glaciated in the Pleistocene, it is possible that similar hydro-geochemical conditions have existed in the area for 10's to 100's of thousands of years.

Precisely regulating acid density and types to promote the stable two-step conversion of methanol to aromatics via light hydrocarbons

Acidic properties of ZSM-5 zeolites for the aromatization of light hydrocarbons strongly determined the final catalytic selectivity and stability for two-step methanol conversions of aromatics via light hydrocarbons. Herein, the density and types of acid sites of ZSM-5 were precisely adjusted to explore their influences on the final catalytic performance. Different from the indistinctive effect of SiO2/Al2O3 ratios on traditional one-step methanol conversion to aromatics, decreasing acid density by increasing SiO2/Al2O3 ratios from 36 to 70 decelerated coke formation and significantly extended the catalytic lifetime from 46.5 to 190.8 h. Further modification with low Zn loading decreased B/L ratio from 19.0 to 1.7 and established a good catalytic synergy between Zn-Lewis and Brønsted acid sites for aromatization of light hydrocarbons, which increased the aromatics selectivity from 27.5% to 31.4%. The decreased catalytic stability after introducing Zn species was attributed to the coke coverage on acid sites but not the final blockage of pore channels as mentioned in previous studies, which was indicated by the similar coke rate of the deactivated catalyst and their gradually increased surface area with increasing Zn content. This work provides more insights into the regulation of acid properties for aromatization catalyst to boost the conversion of methanol to aromatics.

Coupling effects of Zn single atom and high curvature supports for improved performance of CO2 reduction

Single-atom catalysts (SACs) have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions, thanks to their maximum atom economy, unique electronic and geometric structures. However, the role of SACs supports on the catalytic performance does not receive enough research attentions. Here, we report an efficient route for synthesis of single atom Zn loading on the N-doped carbon nano-onions (ZnN/CNO). ZnN/CNO catalysts show an excellent high selectivity for CO2 electro-reduction to CO with a Faradaic efficiency of CO (FECO) up to 97% at −0.47 V (vs. reversible hydrogen electrode, RHE) and remarkable durability without activity decay. To our knowledge, ZnN/CNO is the best activity for the Zn based catalysts up to now, and superior to single atom Zn loading on the two-dimensional planar and porous structure of graphene substrate, although the graphene with larger surface area. The exact role of such carbon nano-onions (CNO) support is studied systematically by coupling characterizations and electrochemistry with density functional theory (DFT) calculations, which have attributed such good performance to the increased curvature. Such increased curvature modifies the surface charge, which then changes the adsorption energies of key intermediates, and improves the selectivity for CO generation accordingly.

Oxide-derived Cu-Zn nanoparticles supported on N-doped graphene for electrochemical reduction of CO2 to ethanol

The oxide-derived Cu and Zn nanoparticles (prepared by co-precipitation method) supported on N-doped graphene (CuZnx/NGN) were prepared and ZnO loading was optimized for efficient electrochemical CO2 reduction (ECR) to multi-carbon products. The ECR experiments were performed in aqueous 0.1 M KHCO3 electrolyte at ambient pressure. Results suggest that the Faradaic efficiency (FE) for multicarbon products could be tuned by varying the loading of Zn in the CuZnx/NGN. The catalyst with 20 wt% ZnO loading (CuZn20/NGN) gives the highest FE of 34.25% for ethanol production and 12.38% for N-propanol at −0.8 V (vs. RHE) with the total current density of 3.95 mA cm−2. The CuZn20/NGN electrode shows long term stability of at least 24 h at optimized conditions. It is suggested that CO generated at the reduced ZnO nanoparticles increases the local surface coverage of *CO on the reduced CuO, which improves the C-C coupling rate, facilitating the multi-carbon production (i.e. ethanol).

Different Zn loading in Urea\u2013Formaldehyde influences the N controlled release by structure modification

Nitrogen fertilization has been a critical factor for high crop productivity, where urea is currently the most used N source due to its high concentration and affordability. Nevertheless, urea fast solubilization leads to frequent losses and lower agronomic efficiency. The modification of urea structure by condensation with formaldehyde has been proposed to improve nutrient uptake by plants and to reduce environmental losses. Herein we show that the co-formulation with Zn strongly modifies the N release (in lab conditions) and, more important, the Zn source—ZnSO4 or ZnO—has a critical role. Urea–formaldehyde (UF) served as a matrix for the zinc sources, and chemical characterizations revealed that Zn particles influenced the length of the polymeric chain formation. Release tests in an aqueous medium showed that the UF matrix favors ZnO release and, on the other hand, delays ZnSO4 delivery. Soil incubation with the fertilizer composites proved the slow-release of N from UF, is ideal for optimizing nutritional efficiency. Our results indicated that the ZnO-UF system has beneficial effects for both nutrients, i.e., reduces N volatilization and increases Zn release.

Bio-BTX production from the shape selective catalytic fast pyrolysis of lignin using different zeolite catalysts: Relevance between the chemical structure and the yield of bio-BTX

As the most abundant aromatic bio-polymer in nature, lignin can be converted into bio-BTX via the shape selective catalytic fast pyrolysis process (SS-CFP). In this work, three types of MWL were isolated from softwood (Chinese fir), hardwood (poplar), and herbaceous biomass (corn stover), namely CF-MML, P-MWL, and CS-MWL. The chemical structural of lignin was analyzed by gel permeation chromatography (GPC), 2D-HSQC-NMR, and 31P NMR. Five types of the parent zeolites (HZSM-5 (25), HZSM-5 (85), Al-MCM-41, HY, and USY) and the Zn modified HZSM-5 (25) with different loading amounts (1% to 4%) were screened. Results showed that CF-MWL had the highest carbon content (59.90%). P-MWL had highest content of β-O-4 linkage (53.90%) and Mw (2778 g/mol). Among the five parent zeolites, HZSM-5 (25) was the most effective catalyst to produce bio-BTX with the highest selective yield of 56.56% at the optimal operation parameters. As a bi-functional catalyst, the incorporation of Zn on zeolite promoted the formation of BTX, where metal promoted the reaction rates of de‑oxygenation reaction and aromatization reaction, while the HZSM-5 remains the ability of shape selectivity. The maximum selective yields of BTX were 65.02% (CF-MWL) > 63.77% (CS-MWL) > 63.41% (P-MWL) when the Zn loading amount was 2%.

Cattle manure loadings and legacy effects on copper and zinc availability under rainfed and irrigated conditions

Long-term cattle manure applications build up nutrient pools and can lead to trace element enrichments in soils. The objectives of this study were to evaluate copper (Cu) and zinc (Zn) loadings in the soil during continuous annual cattle manure applications and determine the time required for soil to return to its pre-manure available Cu and Zn levels after manure is discontinued. The manure application rates were 0, 30, 60, and 90 Mg·ha−1 for rainfed and 0, 60, 120, and 180 Mg·ha−1 (wet weight) for irrigated plots. Although manure was applied for 45 yr in some plots, applications were terminated in one subset of treatments after 14 yr and in another subset after 30 yr to study legacy effects after 31 and 15 yr, respectively. Soil samples were collected in the fall of 2003, 2008, 2013, and 2018 and analyzed for available Cu and Zn. Crops were grown in all years continuously with Cu and Zn concentrations measured in both silage and grains harvested. The regression model developed using data collected suggests long legacy effects with recovery time to pre-manure levels ranging from 10 to 20 yr for Cu and 23 to 41 yr for Zn at irrigated and 10–24 for Cu and 21–32 yr for Zn under rainfed, respectively. Long-term applications of cattle manure could lead to accumulation of Cu and Zn, creating long-lasting legacy effects in soils with the increased environmental risk of leaching to groundwater.

Cover Feature: A Single‐Flow Battery with Multiphase Flow (ChemSusChem 4/2021)

Widespread adoption of redox flow batteries (RFBs) for renewable energy storage is inhibited by a relatively high cost of storage. This is due largely to typical RFBs requiring two flows, two external tanks, and expensive ion-exchange membranes. Here, we propose a potentially inexpensive Zn-Br2 RFB which is membraneless and requires only a single flow. The flow is an emulsion consisting of a continuous, Br2 -poor aqueous phase and a dispersed, Br2 -rich polybromide phase, pumped through the channel separating anode and cathode. With our prototype cell, we explore the effect of polybromide-phase volume fraction and Br2 concentration on cell performance and plating efficiencies. We demonstrate high discharge currents of up to 270 mA/cm2 , plating efficiencies up to 88 %, and dendriteless plating up to the highest Zn loading investigated of 250 mAh/cm2 . We provide mechanistic insights into cell behavior and elucidate paths towards unlocking ultra-low-cost single-flow RFBs with multiphase flow.

Assessment of ecological health of Swarnamukhi river estuary, southeast coast of India, through AMBI indices and multivariate tools

A combination of biotic indices, geo-accumulation (Igeo) index, and a multivariate approach were applied to assess the anthropogenic influence on the benthic community at five stations from 2018 to 2019 in the Swarnamukhi river estuary, Nellore, India. Non-metric multidimensional scaling and cluster analysis indicated that the Buckingham canal (BC) station showed azoic conditions and formed a separate cluster. Strong positive factor loadings of Cd (0.96), Al (0.93), Zn (0.91), Fe (0.90), Co (0.89), Cu (0.89), Ni (0.87), Pb (0.85), Cr (0.77), organic matter (0.94), Silt (0.92), and clay (0.93) and negative loading of sand (−0.90) showed the variability in sediment. AMBI results illustrated the disturbance status of each station and classified BC station as ‘extremely disturbed’ class, and M-AMBI assessed the ecological status as ‘bad’. The Igeo index also revealed metal (Cd) contamination. The present study illustrated that the combined approach is effective for ecological assessment of coastal ecosystem.

Preparation of anisole in phenol by Zn/HZSM-5 catalyst from walnut shell catalyzed liquefaction

The promotional effect of Zn was investigated relative to the calcining activation of HZSM-5. It was found that the lignin separated from walnut shell could be liquefied into small molecular ethers such as anisole by the promotional effect of the modified catalyst. Experimental results showed that, after the loading of Zn, the HZSM-5 catalyst retained its original crystal structure, which exhibited good metal dispersion. Besides, due to the existence of two interactions respectively of Zn with Al and Zn with a Brønsted-Lowry acid on the Zn/HZSM-5 catalyst surface, the remaining catalyst intergranular distance increased, particularly for the 2% Zn/HZSM-5 catalyst. The inside of the catalyst was in a state of spherical particle aggregation with a narrow pore size distribution and uniform particle size. The peak intensity of the Si-O stretching vibration was affected by the content of Zn, which was least affected for the 2% Zn/HZSM-5 catalyst. The signal peak of this small molecule ether was not found in the absence of the metal ions, and the catalytic effect of 2% Zn/HZSM-5 was more distinct. Calculated by the mass difference method, the yield of the liquid via the 2% Zn/HZSM-5 catalyst was 59.8%, including phenol and small molecule ethers represented by anisole.

A highly-effective/durable metal-organic anti-corrosion film deposition on mild steel utilizing Malva sylvestris (M.S) phytoextract-divalent zinc cations

For the first time, a metal-organic film with high anti-corrosion potency was constructed over the mild steel surface using Malva sylvestris (M.S) and zinc cations (Zn2+). The mild steel panels were immersed in the simulated seawater solution (3.5%wt. NaCl solution) containing different loadings of Zn:M.S inhibitors. The electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) measurements were performed at a different time step up to 240h. The potentiodynamic polarization test was carried out to determine the inhibitor's inhibition mechanisms. The synergistic inhibition impact of the Zn:M.S before and after immersion was analyzed by Ultraviolet-Visible (UV–vis) spectroscopy. The protective film formed on the surface was studied by the Fourier transform infrared (FT-IR), Raman, grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), atomic force microscopy (AFM), and contact angle (CA) techniques. The EIS results evidenced that applying various ratios of Zn:M.S resulted in more than 98% corrosion inhibition efficiency (IE), which was stable up to 240h. Meanwhile, the outstanding corrosion resistance of 170kΩ.cm2 in 300:700ppm Zn:M.S was recorded.

Highly active Fe-Co-Zn/K-Al2O3 catalysts for CO2 hydrogenation to light olefins

CO2 hydrogenation to light olefins over Fe-Co-Zn/K-Al2O3 catalysts with different Zn loading contents (0–1.74 wt%) is studied. The addition of Zn improves the dispersion and the reducibility of iron oxides. The amount of CO adsorbed of the catalysts showed a volcanic trend as a function of Zn content with its maximum of 2.42 μmol g−1 at 0.58 wt% Zn, suggesting an increase of number of active sites. The 0.58 wt% Zn-promoted Fe-Co/K-Al2O3 catalyst shows superior activity for light olefins yield (19.9%) under the optimum operating conditions of 340 °C, 25 bar, 9,000 mL gcat−1 h−1 and H2 to CO2 ratio = 4. A gradual decrease in olefin to paraffin ratio with an almost constant CO2 conversion as a function of time-on-stream is observed, which is related to a continuous increase of iron carbide content, indicating that the iron carbide can be acted as the active site for paraffins production.

Co-precipitation of Cu and Zn in precipitation of struvite

Struvite recovered from wastewater can be used as a slow-release fertilizer. Nevertheless, hazardous metals easily precipitated with struvite would increase the ecological risk for its agricultural use. In this study, the influence of individual and coexistence of Cu and Zn on the precipitation of struvite was investigated. The loading of Cu and/or Zn in precipitates increased with the increase of initial metal concentrations (0.1–100 mg/L). Quantitative X-ray diffraction (QXRD) analysis revealed that the increase of Cu and/or Zn level in reaction solution disturbed crystal growth of struvite and promoted the formation of amorphous phase(s). Scanning electron microscopy (SEM) revealed the pit formation on struvite crystal surfaces, combined with X-ray photoelectron spectroscopy (XPS) data, the results indicated a surface interaction for the formation of Cu-OH and Cu-NH3 on struvite surface at Cu of 0.1–10 mg/L. With the increase of Cu to 25–100 mg/L, the precipitation of amorphous Cu phosphate(s) was confirmed by XPS and QXRD. At Zn of 0.1–10 mg/L, the enrichment of Zn-PO4 and Zn-OH on struvite surface was observed, whereas, the precipitation of amorphous Zn hydroxide(s) was confirmed at Zn of 25–100 mg/L. At Cu and Zn co-existed solution, the decrease of Cu-PO4 and increase of Zn-PO4 suggested the competitive binding of PO4 between Cu and Zn. In addition, the formation of amorphous Mg hydroxide(s) and phosphate(s) was detected regardless of the addition of Cu in solutions. The overall results revealed that the existence of Cu and Zn during struvite formation can greatly affect its content by formation of different metal-containing products.

A Single-Flow Battery with Multiphase Flow.

Widespread adoption of redox flow batteries (RFBs) for renewable energy storage is inhibited by a relatively high cost of storage. This is due largely to typical RFBs requiring two flows, two external tanks, and expensive ion-exchange membranes. Here, we propose a potentially inexpensive Zn-Br2 RFB which is membraneless and requires only a single flow. The flow is an emulsion consisting of a continuous, Br2 -poor aqueous phase and a dispersed, Br2 -rich polybromide phase, pumped through the channel separating anode and cathode. With our prototype cell, we explore the effect of polybromide-phase volume fraction and Br2 concentration on cell performance and plating efficiencies. We demonstrate high discharge currents of up to 270 mA/cm2 , plating efficiencies up to 88 %, and dendriteless plating up to the highest Zn loading investigated of 250 mAh/cm2 . We provide mechanistic insights into cell behavior and elucidate paths towards unlocking ultra-low-cost single-flow RFBs with multiphase flow.

Finding the active species: The conversion of methanol to aromatics over Zn-ZSM-5/alumina shaped catalysts

The Zn-loaded zeolite ZSM-5 is an active and promising catalyst for the conversion of methanol to aromatics with high yield. In this work, we have investigated the catalytic performance of shaped Zn-ZSM-5/alumina catalysts in this reaction at industrially relevant pressures. This has been combined with extensive characterization to identify the active Zn species. It is clear that the introduction of Zn leads to an improved catalyst lifetime when the reaction is carried out at elevated pressure. A clear shift from reaction pathways leading to alkane formation to pathways leading to molecular hydrogen formation during the production of aromatics is observed. For industrial catalysts, Zn incorporation is conveniently carried out by impregnation after shaping. A significant migration of Zn into the zeolite ion exchange positions is observed upon calcination of impregnated catalysts, and it is these species that are active for the reaction. At high Zn loadings, ZnAl2O4 species observable by X-ray absorption spectroscopy, but not detectable by diffraction, are formed in the alumina binder.

Sedimentary metals in developing tropical watersheds in relation to their urbanization intensities

The spatial distribution of seven metals (Pb, Hg, Cd, Cr, Ni, Cu, and Zn) and As in the surface sediments from three major tributaries of a tropical urbanizing river network (i.e., Chao Phraya River, Thachin River, and Pasak River) was investigated. An obvious metal concentration gradient in response to the intensity of urbanization was found at inter-watershed and intra-watershed scales. Sediment Quality Guidelines (SQGs) exceedances of several metals (Pb, Cr, Ni, Cu, and Zn) and high ecological risk were primarily identified at the down streams of Chao Phraya and Thachin watersheds, where the social-economic center of the country with intensive industries is located. Stepwise multiple linear regression revealed significant correlations between studied metals and catchment land use pattern (with p < 0.0001 except for Ni and Cr). Particularly, urban land use showed remarkable effect on sedimentary Pb, Cd, Cu, and Zn loads with high coefficients over 0.65. The results of cluster analysis and principal component analysis indicated the dominated urban/industrial sources for Pb, Cd, Cu, and Zn, mixed natural and industrial sources for Cr and Ni, and diffuse sources for Hg and As in the watersheds, respectively.

Bioavailability and risk assessment of trace metals in sediments of a high-altitude eutrophic lake, Ooty, Tamil Nadu, India.

Ooty lake, in the southern part of India, has raised huge concern about the role of metals in a lake due to increasing anthropogenic activities. Present study is aimed at understanding fate of trace metals in a lake's sediment. Sixteen sediment samples collected from bottom of the lake at various locations during March 2017 were analysed for trace metals cobalt, chromium, copper, iron, lead, manganese, nickel and zinc. Fe and Mn dominate total metal concentration followed by Ni and Cr. A high concentration of Cr, Cu, Ni and Zn in residual fraction indicates weathering as the source for these metals. A significant concentration of metals in exchangeable, reducible and oxidisable fraction indicates adsorbtion/chelation of these metals with oxides and organic matter due to change in oxic state. Geo-accumulation index for metals show unpolluted to moderate nature of sediments at all sampling locations. Moderate to significant enrichment factor of Cr, Ni and Zn indicates influence of anthropogenic sources. Co, Pb and Zn show a high amount of bioavailability for aquatic life. Other metals (Cr, Ni, Fe and Mn) show scarce to moderate bioavailability. On the other hand, a global contamination factor denotes moderate to high metal contamination of sediments in the entire lake. Statistical analysis of metals shows good inter-element correlation among metals Fe, Cr, Ni, Co, Cu and Zn indicating natural source. Influence of domestic sewage and recreational activities as the main/additional source is revealed by negative loading of Pb and Zn in principal component analysis. The present study, in essence, has identified rock weathering, as a major source of trace meals in the sediments of Ooty lake entering through stream and surface runoff from an adjacent forest area. The study has also identified high bioavailability of Pb and Zn, which is derived through the recreational activities (boating) causing permanent adverse impact.

Baltic Sea sediments record anthropogenic loads of Cd, Pb, and Zn

The unsustainable settlement and high industrialization around the catchment of the Baltic Sea has left records of anthropogenic heavy metal contamination in Baltic Sea sediments. Here, we show that sediments record post-industrial and anthropogenic loads of Cd, Zn, and Pb over a large spatial scale in the Baltic Sea. We also demonstrate that there is a control on the accumulation of these metals in relation to oxic/anoxic conditions of bottom waters. The total concentrations of Cd, Zn, and Pb were obtained with the near-total digestion method in thirteen cores collected from the Bothnian Bay, the Bothnian Sea, and the west and central Baltic Proper. The lowest average concentrations of Cd, Zn, and Pb were observed in Bothnian Bay (0.4, 125, 40.2 mg kg−1 DW, respectively). In contrast, the highest concentrations were observed in the west Baltic Proper (5.5, 435, and 56.6 mg kg−1 DW, respectively). The results indicate an increasing trend for Cd, Zn, and Pb from the early nineteenth century until the 1970s, followed by a decrease until 2000–2008. However, surface sediments still have concentrations above the pre-industrial values suggested by the Swedish EPA (Cd is 0.2, Zn is 85, and Pb is 31 mg kg−1 DW). The results also show that the pre-industrial Cd, Zn, and Pb concentrations obtained from 3 cores with ages < 1500 B.C. were 1.8, 1.7, and 1.2 times higher, respectively, than the pre-industrial values suggested by the Swedish EPA. To conclude, accumulations of metals in the Baltic Sea are governed by anthropogenic load and the redox conditions of the environment. The significance of correct environmental governance (measures) can be illustrated with the reduction in the pollution of Pb, Zn, and Cd within the Baltic Sea since the 1980s.