Removal Of Trace Elements Research Articles

Degradation of the AMP/PZ-based solvent CESAR1 and effects of solvent management in two longtime pilot plant tests

Two 24/7 longtime testing campaigns at the CO2 capture pilot plant at Niederaussem with an accumulated testing time of more than 40,000 h with the CESAR1 solvent, an aqueous solution of 26.7 wt% 2-amino-2-methylpropan-1-ol (AMP) and 12.9 wt% piperazine (PZ), provide a unique data base for the development of solvent management technologies and the evaluation of hypotheses on amine degradation. In the first campaign with a testing time of 34,000 h without replacement of the solvent inventory, three solvent management strategies with different effect mechanisms were investigated: adsorptive removal of trace elements from the solvent by two kinds of active carbon, removal of ionic contaminants by ion exchange using cation and anion exchange resins, and removal of NO2 from the flue gas by treatment with a thiosulfate/sulfite solution. After replacement of the solvent inventory the second campaign was conducted, in which none of the solvent management technologies mentioned have been applied for 10,000 h. The results of the two campaigns allow a direct comparison of the solvent degradation behavior. It is shown that active carbon does not significantly affect the accumulation rate of degradation products in CESAR1, and that an inappropriate kind of active carbon can cause foaming. Anionic degradation products, metal complexes, trace components and cationic contaminants can be effectively removed from the aged solvent by ion exchange. However, after their removal, accelerated formation of oxidative degradation products by a factor of up to 3 higher than before the anion exchange was observed. Removal of NO2 from the flue gas did not affect the NH3 emissions from the CO2 absorber, but it led to the highest observed increase rate of the accumulation of acidic degradation products for aged CESAR1. The results show that exaggerated efforts for solvent management are contra-productive and that a reassessment of the effect mechanisms of solvent management technologies is necessary.

Wastewater-contaminated treatment with heavy metals by using a sustainable green nanomaterial

The current research included treating wastewater with sustainable nanotechnology to remove some trace elements (arsenic, copper, baron, lead, and chromium) by using a nanomaterial extracted from potato plant waste in a sustainable, green, environmentally friendly way, with two different additions, the first adding 0.5 grams and the second adding 1 gram of nanocellulose. For two different periods (6 hours and 12 hours) for both quantities of nanocellulose. The results showed that nanocellulose has a great ability to remove the studied elements from wastewater after comparing their original concentrations that were in the water before treatment with nanocellulose. The results showed that increasing the amount of nanocellulose and increasing the time led to an increase in the removal rate, and this was clear from the results of the statistical analysis, which showed the presence of a positive significant correlation between the rate of removal of trace elements from waste water with increasing the amount of nanocellulose and increasing the time. When comparing the removal rates of the studied elements from wastewater with the PH values, it was found that the pH is the control of these rates, as the highest removal rates were at the neutral or close to acidic level, the pH between 5.5 and 7.5, and when the pH tends towards basicity (8 - 9.5) The removal rate decreased. The results also showed that the removal rate varies between the elements and this depends on the concentration of the element present in the water, its chemical composition, and the degree of its binding to the substance used for treatment.

Synergistic effect by Sorghum bicolor L., citric acid, biochar, and vermiwash amendment for the remediation of a mine-contaminated soil.

Phytoremediation is an in situ remediation and eco-friendly technique employing accumulator plant species to remove trace elements (TEs) from contaminated sites. Moreover, it has been demonstrated that both natural and synthetic amendments can enhance trace elements (TEs) phytoremediation from polluted soils through bioenergy crops. This work assessed the synergistic impact of two tested biochar (BC) from data palm (B1) and Prosopis (B2) (1.5%/ kg), citric acid (CA, 1.5 mmol/kg) and vermiwash (VW, 20 ml/kg) to enhance the remediation of tested TEs (Mn, Zn, Cd, Pb, Ni, Cu, and Fe) from Mahad AD'Dahab mine-contaminated soil by sorghum (Sorghum bicolor L.). The BC and CA amendments alone and combined with VW significantly augmented the proliferation and survival of sorghum grown in mine-contaminated soil. Considering the individual and combined applications of VW and BC, the influence on plant growth followed this order: K < VW < B2 < B1 < B1 + VW < B2 + VW < CA < CA + VW. Applying tested BC/CA and VW significantly increased chlorophyll compared to unamended soil. The outcomes revealed a substantial elevation in TE absorption in both shoot and root (p ≤ 0.05) with all tested treatments compared to the untreated soil (K). The combined application of CA and VW resulted in the most significant TE uptake of TEs at both the root and the shoot. Furthermore, adding CA or VW as a foliar spray enhanced the bioaccumulation factor (BCF) and translocation factor (TF) of studied metals. The combined addition of CA and foliar spraying of VW was more effective than the sole addition of CA or VW. Such increase reached 20.0%, 15.6%, 19.4%, 14.3%, 14.0%, and 25.6% of TF, and 13.7%, 11.9%, 8.3%, 20.9%, 20.5%,18.7%, and 19.8% of BCE for Cd, Cu, Fe, Mn, Ni, Pb, and Zn, respectively. This study highlights the efficiency of combining CA/BC with VW as a more viable option for remediating mine-contaminated soil than individual amendments. However, future research should prioritize long-term field trials to assess the efficiency of using citric acid and vermiwash for restoring contaminated mining soils.

A review of crop residue-based biochar as an efficient adsorbent to remove trace elements from aquatic systems

AbstractCrop residue-based biochar (CRB) has shown great potential for removing trace elements (TEs) from aquatic matrices. Despite the increasing interest in this area, no review has focused specifically on the efficacy of CRB for TEs removal in aquatic environments. This comprehensive review examines the global TEs water contamination status with an emphasis on their sources, compositional metrics for crop residue feedstock (proximate, ultimate, and lignocellulosic properties), and the potential use of CRB for TEs removal in aquatic media. It also evaluates the factors that affect the ability of CRB to remove TEs, such as feedstock type, production conditions, water pH, background electrolytes, water temperature, CRB/water ratio, and underlying pollutant sorption mechanisms. This review also discusses the practical applications of CRB in real water samples and engineering considerations for designing CRB with improved physicochemical properties, treatment efficiencies, and regeneration abilities. Additionally, the cost–benefit and economic assessment of CRB, challenges, and future research directions related to CRB are highlighted to promote research on this sustainable source of biochar. By elucidating the prospects of CRB as an adsorbent, this review emphasizes the need for continued research on its practical implications for environmentally relevant pollutant concentrations. Graphical Abstract

An assessment of inorganic components in condensable particulate matter as a function of surface aggregation, spatial suspension state and particle size

Experimental studies assessed the removal efficiency and fine-size distribution of CPM coupled with compositional analysis across air pollution control device systems (APCDs) at an ultra-low emission (ULE) power plant. The findings indicated total CPM emissions were reduced to a minimum of 0.418 mg/m3 at the Wet Electrostatic Precipitator (WESP). The Wet Flue Gas Desulfurization (WFGD) showed the highest removal efficiency (98%) across all particle sizes, notably in the ultra-micron range. Selective Catalytic Reduction (SCR) demonstrated a mere 34% overall efficiency, with a negative removal rate in the ultra-fine particle range. The WESP effectively removed CPM only in sub-micron and ultra-micron sizes, but significantly increased water-soluble ions formation in ultra-fine spatially suspended CPM (CPMspa), leading to overall negative efficiency. Thus, the removal efficiency of the ultra-fine particle range was most affected among the three particle size ranges when the flue gas went through the APCDs. Major metal elements and water-soluble ions were more readily removed by APCDs due to their surface aggregation, while the removal of trace elements like Hg and Se was limited. Reducing SO42-/NH4+ formation in SCR, and optimizing WESP spray system operations based on flue gas components are essential steps in controlling CPM concentration in ULE power plants.

Effect of pH on Trace Elements Removal from Batteries and Compact Disks by Aspergillus terreus Pellets

Background: The aim of this study is the removal of three trace elements (Nickle Ni, Cadmium Cd and Lead Pb) by an environmentally friendly method from Batteries and compact discs. This study aimed to rapidly remove trace elements from E-waste (batteries) by filamentous fungi pellets. Methods: Aspergillus was the best heavy metal tolerated isolate under the following incubation parameters: pH (5), temperature (25°C), ground electronic waste powder doses (0.5, 1 and 1.5 g/L) absorbed by fungal pellets biomass 10 gm/L of wet weight. Result: The results showed the best removal percentage R% of Ni, Cd and Pb removal were (89,91and 96) observed at pH 5. Images from SEM showed accumulations of metal particles on the surface of the fungal hyphae and Fourier Transform Infra-Red Spectroscopy (FT-IR) was used to determine the effective groups in the fungal cell wall responsible of biosorption of trace elements and This study indicates that an application may be possible Aspergillus terreus as a promising candidate for biological sorption and recycling of trace elements and as an ecologically friendly and effective process in terms of time and cost.

Timekeepers for Trace Elements in the Global Ocean: The Thorium Stopwatches

The various isotopes of thorium offer oceanographers tools for tracking particulate matter in the ocean across multiple timescales. To learn about the cycling of trace elements in the ocean, in this perspective we focus on the latest applications of thorium’s longest-lived naturally occurring isotopes: 232Th, 230Th, 228Th, and 234Th. From desert dust to marine snow to sediment porewaters, thorium measurements can be used to derive rates of trace element input and removal, using the assumptions of radioactive disequilibrium. Opportunities exist to fine tune and improve the application of these already versatile stopwatches, but GEOTRACES-era data clearly demonstrate their utility.

The arsenic-lowering effect of inulin-type prebiotics in end-stage renal disease: a randomized crossover trial.

Background: Circulatory imbalance of trace elements is frequent in end-stage renal disease (ESRD), leading to a deficiency of essential elements and excess of toxic elements. The present study aimed to investigate whether inulin-type fructans (ITFs) could ameliorate the circulatory imbalance by modulating gut microbiota and regulating the absorption and elimination of trace elements. Methods: Peritoneal dialysis patients were enrolled in a randomized crossover trial, undergoing interventions with ITFs (10 g d-1) and maltodextrin (placebo) over a 9-month period (with a 3-month washout). The primary outcomes included essential elements Mn, Fe, Co, Cu, Zn, Se, Sr, and Mo and potential toxic elements V, Cr, Ni, As, Cd, Ba, Tl, Pb, Th, and U in plasma. Secondary outcomes included the gut microbiome, short chain fatty acids (SCFAs), bile acids (BAs), and daily removal of trace elements through urine, dialysate and feces. Results: Among the 44 participants initially randomized, 29 completed the prebiotic, placebo or both interventions. The daily dietary intake of macronutrients and trace elements remained consistent throughout the study. The administration of 10 g d-1 ITFs significantly reduced plasma arsenic (As) by 1.03 μg L-1 (95%CI: -1.74, -0.33) (FDR-adjusted P = 0.045) down from the baseline of 3.54 μg L-1 (IQRs: 2.61-4.40) and increased the As clearance rate by urine and dialysis (P = 0.033). Positive changes in gut microbiota were also observed, including an increase in the Firmicutes/Bacteroidetes ratio (P = 0.050), a trend towards higher fecal SCFAs (P = 0.082), and elevated excretion of primary BAs (P = 0.035). However, there were no significant changes in plasma concentrations of other trace elements or their daily removal by urine, dialysis and feces. Conclusions: The daily administration of 10 g d-1 ITFs proved to be effective in reducing the circulating retention of As but demonstrated to be ineffective for other trace elements in ESRD. These sentences are ok to include but as "The clinical trial registry number is ChiCTR-INR-17013739 (https://www.chictr.org.cn/showproj.aspx?proj=21228)".

Synthesis and application of a new multi-functional biopolymer-based aerogel loaded with bistriazole derivative as highly efficient adsorbent and disinfectant

Herein, we exploited xanthan gum (XG) and cationic dextran (CD) in designing a novel porous aerogel (XCD) loaded with different concentrations of a new bistriazole derivative (CPSC). The CPSC was deposited into and onto the pores of aerogels. The neat aerogel removed both AB40 dye and Cu2+ efficiently. Adding 0.5 g of CPSC to the neat aerogel (XCD-0.50 sample) improved slightly the adsorption of Cu2+ and has no effect on the adsorption of AB40 dye. XCD-0.50 removed almost completely 10 mg/L of AB40 dye in 10 min using 0.5 g/L at pHi 6 while for Cu2+ longer contact time (90 min) and higher dosage (2.0 g/L) were required to remove 10 mg/L solution at pHi 5. Relative to literature, the Langmuir adsorption capacity of XCD-0.5 toward AB40 dye (436 mg/g) was the highest and toward Cu2+ (60 mg/g) was comparable to others. The aerogel XCD-0.50 was regenerable and reusable for three cycles with reasonable efficiency. By submerging a bacterial solution (106 CFU/mL) in the XCD-0.75 aerogel for 90 min, an impressive 6-log decrease in the number of bacteria was obtained under ideal circumstances. Crucially, toxicity test clearly confirmed that the prepared aerogels had non-toxic impact. Across all investigated bacterial species, XCD-0.75 continuously achieved a 6-log CFU decrease after 180 min, demonstrating its efficacy in the context of disinfection experiment. The results of the study highlight the extraordinary potential of the biopolymer aerogel loaded with CPSC as a potent adsorbent and disinfectant. They show significant removal of toxic trace elements and dyes, along with microbial reduction in industrial wastewater, underscoring the aerogel's potential use in water treatment.

Removal and emission characteristics of hazardous trace elements in total and graded particulate matters: A case study of a typical ultra-low emission coal-fired power plant

Particulate matters (PMs) and hazardous trace elements (HTEs) emitted from coal-fired power plants (CFPPs) have raised serious environmental and human issues. Herein, total PMs and graded PMs including PM<1, PM1–2.5 and PM2.5–10 at the inlet/outlet of air pollution control devices (APCDs) were collected from a representative ultra-low emission (ULE) CFPP in China. The removal efficiencies of total PMs by selective catalytic reduction (SCR), electrostatic precipitator (ESP), wet flue gas desulfurization (WFGD) and wet electrostatic precipitator (WESP) were 0.40 %, 99.9 %, 38.1 % and 85.3 %, respectively. PM2.5–10 was robustly removed by WFGD, while PM<1 and PM1–2.5 were readily removed by WESP. The removal efficiencies of As, Cd, Cr and Pb in total PMs by APCDs followed an order: ESP > WESP > WFGD > SCR. SCR significantly decreased Se concentration by 42.8 %, contrasting to the removal of As, Cd, Cr and Pb (10.8–20.8 %). As, Cd, Cr, Pb and Se concentrations in graded PMs at the outlets of ESP, WFGD and WESP decreased with particle size increasing. All As, Cd, Cr, and Pb contents in PM<1, PM1–2.5 and PM2.5–10 at WFGD outlet increased, surpassing their analogues at ESP and WESP outlets. However, the concentration of Se declined in PM<1 at WFGD outlet. The atmospheric emission factors (EFs) of As, Cd, Cr, Pb and Se in the studied ULE CFPP were respectively 7.32, 1.27, 6.05, 122.5 and 6.42 mg/t, in line with Monte Carlo simulations. This study would not only provide a basis for emission control of PMs and HTEs in CFPPs, but also promote the improvement of respective environmental policy.

Conclusions from 3 years of continuous capture plant operation without exchange of the AMP/PZ-based solvent at Niederaussem – insights into solvent degradation management

A many times heard mantra of solvent degradation management in amine-based post combustion capture is “keep the solvent clean” to minimize solvent consumption. It is assumed that the amine losses would decrease by the removal of metals, degradation products, and reactive trace components which are captured from the flue gas, like NO2 (as potentially driving components of the amine degradation besides dissolved O2). However, this theoretical hypothesis – based on results from laboratory experiments typically generated with fresh amines – disregards the complexity of the solvent matrix, interaction of potential metal catalysts with degradation products and oxidizing agents, and specific chemical requirements which must be fulfilled before a degradation mechanism can proceed. Degradation of the solvent CESAR1 (aqueous solution of 3.0 molar 2-amino-2-methylpropan-1-ol (AMP) and 1.5 molar piperazine (PZ)) is investigated in a unique long-time test campaign (testing time up to now 40 months; 24/7 operation) without replacement of the solvent inventory at the capture pilot plant at the lignite-fired power plant in Niederaussem. Three solvent management strategies with different effect mechanisms are investigated and evaluated: (a) removal of only anionic compounds and trace elements (within 75 days solvent inventory treated two times) and anionic as well as cationic compounds and trace elements (114 days, inventory treated four times) from the solvent by ion exchange, (b) adsorptive removal of trace elements from the solvent by active carbon in 35% of the operating time, and (c) removal of >80% NO2 by flue gas pretreatment with thiosulfate/sulfite solution (dosing for 2,000 h). The results of the testing program clearly show that “solvent cleanliness” is not a well-defined parameter and that results from laboratory tests, tests without fully representative industrial flue gasses, and short-term testing of monoethanolamine cannot be generalized for other solvents and industrial application. These results showcase that specific degradation management considering solvent, capture plant and flue gas quality is reasonable. Overshooting efforts for solvent management are contra-productive and produce unnecessary waste streams, efficiency losses and costs.

Phytoremediation as an Effective Remedy for Removing Trace Elements from Ecosystems.

The pollution of soil by trace elements is a global problem. Conventional methods of soil remediation are often inapplicable, so it is necessary to search intensively for innovative and environment-friendly techniques for cleaning up ecosystems, such as phytoremediation. Basic research methods, their strengths and weaknesses, and the effects of microorganisms on metallophytes and plant endophytes resistant to trace elements (TEs) were summarised and described in this manuscript. Prospectively, bio-combined phytoremediation with microorganisms appears to be an ideal, economically viable and environmentally sound solution. The novelty of the work is the description of the potential of "green roofs" to contribute to the capture and accumulation of many metal-bearing and suspended dust and other toxic compounds resulting from anthropopressure. Attention was drawn to the great potential of using phytoremediation on less contaminated soils located along traffic routes and urban parks and green spaces. It also focused on the supportive treatments for phytoremediation using genetic engineering, sorbents, phytohormones, microbiota, microalgae or nanoparticles and highlighted the important role of energy crops in phytoremediation. Perceptions of phytoremediation on different continents are also presented, and new international perspectives are presented. Further development of phytoremediation requires much more funding and increased interdisciplinary research in this direction.

Efficient detoxification of textile wastewater by applying Chenopodium album nanoparticles and its application in simulated metal-bearing effluents removal.

Large-scale pollution of water and soils bodies is associated with the discharge of the untreated textile industry effluents. Halophytes grows on saline lands and accumulate secondary metabolites and other stress protective compounds. Utilization of Chenopodium album (halophytes) to synthesize zinc oxide (ZnO) and their efficiency to treat different concentrations of textile industry waste water is proposed in this study. Potential of nanoparticles textile industry waste water effluents was also analyzed by exposing different concentrations of nanoparticles (0 (control), 0.2, 0.5, 1mg) and time intervals of 5, 10, and 15days. The absorption peaks by UV region, FTIR and SEM analysis were used characterized on ZnO NPs for the first time. FTIR analysis showed the preens of various functional groups and vital phytochemicals that can play its role in the formation of nanoparticles that can be used for trace elements removal and bioremediation. SEM analysis indicated that the pure ZnO NPs synthesis ranged from 30 to 57nm. Results shows that the green synthesis of halophytic nanoparticles presents maximum removal capacity after 15days exposure to 1mg of ZnO NPs. Hence, the prepared ZnO Nps from halophytes can be a viable solution for treating the textile industry effluents before they are discharged into water bodies for sustainable environmental growth and environmental safety.

Influence of biodeposition by suspended cultured oyster on the distributions of trace elements in multiple media in a semi-enclosed bay of China

It remains unclear how the suspended non-fed bivalve mariculture will alter the coastal transfer and cleaning process of trace elements, the non-degradable contaminants, which have been reported to accumulate in sediment from bivalve mariculture areas. Herein, we set up a field in situ comparative test in the suspended oyster (Crassostrea plicatula) farming area (OF) and reference area (RA) of Xiangshan Bay to verify our hypothesis that the biodepositon of suspended oysters would consolidate trace elements from the water column and transport them to the sediment. Distribution of trace elements in multiple media of biodeposits (BDs), settling particles (SPs), sediments (SEs), and seawater demonstrate that the accelerated deposition of BDs which enriched trace elements from the water column by oysters filtering suspended particles led to trace elements accumulation in SEs from OF. Additionally, As, Cd, Co, Cr, Cu, Ni, V, and Zn were strongly regulated by this process with significant (p<0.05) higher concentrations in SEs from OF (10.96, 0.20, 13.98, 82.40, 38.47, 38.22, 108.57, and 111.20μg/g, repectively) than those from RA (9.43, 0.13, 11.76, 63.30, 30.34, 29.55, 86.59, and 100.24μg/g, repectively), but the extent was different for Mn, Mo, Pb, and W with concentrations in SEs from OF (737.37, 0.81, 30.98, and 3.96μg/g, repectively) and RA (765.25, 0.69, 31.27, and 3.34μg/g, repectively), especially for Rb and Sr with concentrations in SEs from OF (131.13 and 96.24μg/g, repectively) and RA (142.21 and 161.10μg/g, repectively), due to their geochemical and geophysical properties. Moreover, the harvest of hyper-accumulated oysters as a sink for removing trace elements from water column cannot hide the impact of this process.

Bibliometric Analysis and Comprehensive Review of Stormwater Treatment Wetlands: Global Research Trends and Existing Knowledge Gaps

Stormwater treatment wetlands are widely recognized as efficient and cost-effective solutions to growing stormwater problems. This study presented a new approach to evaluating the current status and trends in stormwater treatment wetlands research. The annual scientific productivity of different states was identified using a bibliometric analysis approach. The number of publications related to stormwater treatment wetlands has exhibited an increasing trend since the earliest record of publication. USA and China were among the states that had the most number of stormwater treatment wetlands-related publications and international collaborations. In terms of the population-to-publication ratio, Australia, Canada, and South Korea were found to have a higher level of scientific productivity. Analysis of frequently used keywords and terms in scientific publications revealed that the efficiency of stormwater treatment wetlands and the processes involved in the removal of nutrients and trace elements were adequately investigated; however, inquiries on the removal of organic micropollutants and emerging pollutants, such as pharmaceuticals and personal care products, microplastics, and industrial compounds, among others, are still lacking. Through the comprehensive review of related scientific works, the design, components, and primary factors affecting the performance of stormwater treatment wetlands were also identified. Future works that address the aforementioned knowledge gaps are recommended to optimize the benefits of stormwater treatment wetlands.

Plant species contribution to bioretention performance under a temperate climate

Bioretention systems are green infrastructures increasingly used to manage urban stormwater runoff. Plants are an essential component of bioretention, improving water quality and reducing runoff volume and peak flows. However, there is little evidence on how this contribution varies between species, especially in temperate climates with seasonal variations and plant dormancy. The aim of our study was to compare the performance of four plant species for bioretention effectiveness during the growing and dormant periods in a mesocosm study. The species selected (Cornus sericea, Juncus effusus, Iris versicolor, Sesleria autumnalis) are commonly used in bioretention and cover a wide range of biological forms and functional traits.All bioretention mesocosms were effective in reducing water volume, flow and pollutant levels in both of the studied periods. Plants decreased runoff volume and increased contaminant retention by reducing water flow (up to 2.7 times compared to unplanted systems) and increasing water loss through evapotranspiration during the growing period (up to 2.5 times). Plants improved removal of macronutrients, with an average mass removal of 55 % for TN, 81 % for TP and 61 % for K compared to −6 % (release), 61 % and 22 % respectively for the unplanted systems. Except for Sesleria, mass removal of trace elements in planted mesocosms was generally higher than in unplanted ones (up to 8.7 %), regardless of season. Between-species differences in exfiltration rate and improved water quality followed the same order as their evapotranspiration rate and overall size, measured in terms of plant volume, leaf biomass, total leaf area and maximum average root density (Cornus > Juncus > Iris > Sesleria). By increasing evapotranspiration, plants decreased runoff volume and increased contaminant retention. Nutrient removal was partly explained by plant assimilation. Our study confirms the importance of plant species selection for improving water quality and reducing runoff volume during bioretention under a temperate climate.

Role of terrestrial versus marine sources of humic dissolved organic matter on the behaviors of trace elements in seawater

We investigated the behaviors of dissolved trace elements (Mn, Fe, Ni, Cu, Zn, and Cd) associated with humic dissolved organic matter (DOMH) of varying origins in the surface waters of two Korean coastal regions (Jinhae Bay [JH] and offshore Tongyeong [TY]). Both regions displayed intensive scavenging and settling of the particle-reactive Ce and 234Th tracers. However, in JH, where DOMH is mainly terrestrial-derived, the concentrations of trace elements (Fe, Ni, and Cu) were negatively correlated with salinity and positively correlated with DOMH. This indicates that terrestrial DOMH could form complexes with dissolved trace elements, and this complexation likely deters the adsorptive removal of trace elements by settling particles. Similar interactions between trace elements (Mn, Fe, and Cu) and DOMH were also discovered in TY, where most DOMH originated from marine biological production. Our study reveals that both terrestrial and marine DOMH would complex with dissolved trace elements, stabilizing them in the dissolved phase in coastal waters. Therefore, DOMH-trace element complexation in coastal waters could play a key role in regulating the cycling and transport of trace elements in the ocean.

The mass transfer of chemical elements and of their compounds in agrocenoses

The analysis of publications on the mass transfer of chemical elements in agrocenosis in the soil – plant system was carried out. Methods for estimating the content of mobile forms of chemical compounds coming from the soil into plants are considered. The phenomena of antagonism and synergism are characterized, and the necessity to consider them while planning fertilizer application is indicated. It is shown that the phenomena of synergism and antagonism of elements can be used in agriculture to regulate the flow of heavy metals or radionuclides into agricultural products. A balance model for mass transfer of chemical elements in agrocenosis is analyzed. It is shown that the introduction of organic fertilizers in soil mostly leads to a positive balance of microelements in the agrosystem. To characterize the efficiency of fertilizer use an assessment of the balance of nutrients in the agrosystem is required. The removal of trace elements by agricultural crops increases with the use of mineral fertilizers in doses that are optimal for the cultivation of crops in the region. In some cases, the input of heavy metals with technogenic fallout may exceed the removal of metals by plants from the soil. It may cause the accumulation of metals in the system. In uncontaminated background areas, the levels of microelement intake from fertilizers and atmospheric fallout in agrocenoses are comparable.

Field assessment of trace element phytoextraction by different Populus clones established on brownfields in southern Quebec (Canada)

Fast-growing hybrid poplars have been tested for their potential to remove trace elements (TE) from polluted soil in several temperate regions. Despite their potential, they have rarely been tested in countries with a cold temperate climate. The current study screened four different Populus hybrids for phytoextraction of four TEs (i.e., As, Cu, Pb, and Zn) on an abandoned brownfield site in southern Quebec (Canada). The main results showed that under the current experimental conditions, the most important traits determining the actual phytoextraction rate are Biological Concentration Factor (BCF) and TE accumulation in the aboveground biomass, rather than biomass productivity. Although the overall performance of the chosen hybrids was rather poor, the presence of poplar stands enhanced the movement of mobile contaminants in soil, which led to an increase in their concentration in the root zone. This aspect suggests possible strategies for using these plants with high transpiration rates in future phytoremediation projects, including either possible rotation with more effective TE phytoextractor plants (e.g., hyperaccumulators) that can remove high TE amounts that have migrated from the deeper soil layers following poplar plantation, or phytostabilization.

Shallow Depth, Substantial Change: Fluid-Metasomatism Causes Major Compositional Modifications of Subducted Volcanics (Mariana Forearc)

Mass transfer at shallow subduction levels and its ramifications for deeper processes remain incompletely constrained. New insights are provided by ocean island basalt (OIB) clasts from the Mariana forearc that experienced subduction to up to ∼25–30 km depth and up to blueschist-facies metamorphism; thereafter, the clasts were recycled to the forearc seafloor via serpentinite mud volcanism. We demonstrate that the rocks were, in addition, strongly metasomatized: they exhibit K2O contents (median = 4.6 wt%) and loss on ignition (median = 5.3 wt%, as a proxy for H2O) much higher than OIB situated on the Pacific Plate, implying that these were added during subduction. This interpretation is consistent with abundant phengite in the samples. Mass balance calculations further reveal variable gains in SiO2 for all samples, and increased MgO and Na2O at one but losses of MgO and Fe2O3* at the other study site. Elevated Cs and Rb concentrations suggest an uptake whereas low Ba and Sr contents indicate the removal of trace elements throughout all clasts. The metasomatism was likely induced by the OIBs’ interaction with K-rich fluids in the subduction channel. Our thermodynamic models imply that such fluids are released from subducted sediments and altered igneous crust at 5 kbar and even below 200°C. Equilibrium assemblage diagrams show that the stability field of phengite significantly increases with the metasomatism and that, relative to not-metasomatized OIB, up to four times as much phengite may form in the metasomatized rocks. Phengite in turn is considered as an important carrier for K2O, H2O, and fluid-mobile elements to sub-arc depths. These findings demonstrate that mass transfer from the subducting lithosphere starts at low P/T conditions. The liberation of solute-rich fluids can evoke far-reaching compositional and mineralogical changes in rocks that interact with these fluids. Processes at shallow depths (&amp;lt;30 km) thereby contribute to controlling which components as well as in which state (i.e., bound in which minerals) these components ultimately reach greater depths where they may or may not contribute to arc magmatism. For a holistic understanding of deep geochemical cycling, metasomatism and rock transformation need to be acknowledged from shallow depths on.