Novel flocking materials as biocarriers in moving bed biofilm reactor for improving simultaneous nitrification and denitrification performance.

Biocarrier is the key factor for the stable operation of moving bed biofilm reactor (MBBR). To achieve efficient simultaneous nitrification and denitrification (SND), this study provided novel flocking materials as biocarriers. The biofilm formation experiment showed that longer flocking carrier was more conducive to biomass accumulation, resulting in greater oxygen uptake rate. The continuous operation results showed that the total nitrogen removal and SND performance of the MBBR with the addition of 5.0 mm flocking carriers reached 52.0 % and 70.5 %, respectively, which were 29.1 % and 33.3 % greater than those of the control. Compared with those in suspended sludge, the extracellular polymeric substances and protein components in the biocarrier were more abundant. Furthermore, the relative abundance of genera related to denitrification and the nitrogen metabolic sequence improved with the addition of the novel flocking biocarriers. This study demonstrated the effectiveness of novel flocking fillers in improving the performance of MBBR.

Virtual group photography based on scene and person perception.

Group photos have become indispensable in various gathering scenarios, such as family reunions, friends' gatherings, competitions, conferences, store openings, and school graduation ceremonies. The researchers tried automatically adding people who could not participate in the group photo. However, the current research on generating the pose or position of the person by context prediction of the group photo ignores the individual attributes (such as height and body shape) of the target person and does not consider the pose and boundary of the person at the same time. To address these issues, we propose a virtual group photography model that combines the global context of a group photo and the individual attributes of the target person. The model is divided into two stages. The first stage is to predict the person's position, pose, and boundary in the new group photo based on the context of the input group photo and the person's characteristics. The second stage generates new group photos based on the first stage's pose and boundary results. The experimental results show that our method can significantly improve the harmony and authenticity of the synthesis of people in group photos and synthesize the characters that should exist in the group photo, which is very suitable for the field of group photos.

Simultaneous denitrification enhancement and sludge reduction based on novel suspended carrier modified using activated carbon and magnetite at low carbon/nitrogen ratio.

A novel suspended carrier was prepared by sticking activated carbon (AC) and magnetite (Fe3O4) onto polypropylene slices. Although this carrier could not reverse the decreased denitrification capacity trends under anoxic conditions at an influent carbon/nitrogen (C/N) ratio of 2, it enhanced denitrification by stimulating sludge reduction and accelerating electron transfer to certain extent. The carrier stuck by mixed AC/Fe3O4 exhibited better performance in terms of sludge reduction, extracellular polymeric substances (EPS) secretion, and denitrification than that merely stuck by AC and Fe3O4 at an influent C/N ratio of 2. The carrier stuck by mixed AC/Fe3O4 increased the total nitrogen removal efficiency by 24.6 % ± 12.5 % in a 72-h denitrification batch experiment compared to the common polypropylene carrier. Moreover, the carrier improved EPS secretion and nitrogen metabolism and promoted the growth of Trichococcus and some denitrifying genera. This study provides a reference for the treatment of low C/N ratio sewage.

Dendrobium Officinale Polysaccharide Alleviates Hepatic Fibrosis via Epithelial-Mesenchymal Transition / 中山大学学报(医学科学版)

ObjectiveTo investigate the effect of Dendrobium officinale polysaccharide （DOP）on CCl4-induced hepatic fibrosis（HF）and its mechanism. MethodsA total of 56 male SD rats were randomly divided into seven groups： normal group（NG），model group（MG），colchicine group（CG， 0.1 mg/kg）， Fuzheng Huayu group（FG， 0.45 g/kg），low-dose DOP group（LDG， 0.05 g/kg），middle-dose DOP group（MDG， 0.1 g/kg）and high-dose DOP group（HDG，0.2 g/kg），with 8 rats in each group. HF rat model was established by subcutaneous injection with 40% CCl4 olive oil mixture， every 3-day for 10 weeks. At the end of the sixth week， the drug groups were treated with colchicine， Fuzheng Huayu and DOP solution by gavage respectively， once a day for 4 weeks. NG and MG groups were similarly handled with an equal amount of 0.9 % normal saline. Liver histopathology was detected using hematoxylin-eosin （HE）， Masson and Sirius red staining； blood biochemistry was tested for liver function and four indicators of HF； RT-qPCR and Western Blot were used to measure the expression of α-SMA， Col-I， E-cadherin， and ZEB1 genes and proteins in the liver tissues of rats， respectively. ResultsHE， Masson， and Sirius red staining showed that the liver tissue of MG rats had typical pathologic features of HF， and the degree of HF was alleviated in LDG， MDG， and HDG rats， respectively. Liver function test results showed that the serum AST， TBIL， and AKP levels were significantly lower in LDG， MDG， and HDG， compared with those of the MG （P < 0.05 or < 0.01）. Meanwhile， ALT levels in serum deceased remarkably except in LDG （P < 0.05 or < 0.01）. The four results of HF showed that the serum HA， LN， PC-Ⅲ， and COL-Ⅳ levels in LDG， MDG， and HDG rats were significantly decreased compared with those of the MG （P < 0.05 or < 0.01）. The relative expressions of α-SMA， COL-I， and ZEB1 genes and proteins were significantly decreased in the liver tissues of LDG， MDG， and HDG （P < 0.05 or < 0.01）， and the relative expression of E-cadherin gene and protein increased （P < 0.05 or < 0.01）. In addition， the expressions of HA， α-SMA， COL-I， ZEB1 and E-cadherin were dependent on the dose of DOP. ConclusionDOP alleviated the degree of CCl4 induced HF in rats by inhibiting the epithelial-mesenchymal transition in liver tissue.

Use of magnetic powder to effectively improve the denitrification employing the activated sludge fermentation liquid as carbon source.

Nitrogen removal is often limited in municipal wastewater treatment due to the lack of sufficient carbon source. Utilizing volatile fatty acids (VFAs) from waste activated sludge (WAS) fermentation broth as a carbon source is an ideal alternative to reduce the cost for wastewater treatment plants (WWTPs) and improve denitrification efficiency simultaneously. In this study, an anaerobic system was applied for simultaneous denitrification and WAS fermentation and the addition of magnetic microparticles (MMP) were confirmed to enhance both denitrification and WAS fermentation. Firstly, the addition of MMP increased the nitrate reduction rate by over 25.36% and improve the production of N2. Additionally, the equivalent chemical oxygen demand (COD) of the detected VFAs increased by 7.06%-14.53%, suggesting that MMP promoted the WAS fermentation. The electron transfer efficiency of denitrifies was accelerated by MMP via electron-transporting system (ETS) activity and cyclic voltammetry (CV) experiments, which might result in the promotional denitrification and WAS fermentation performance. Furthermore, the high-throughput sequencing displayed that, MMP enriched key microbes capable of degrading the complex organics (Chloroflexi, Synergistota and Spirochaetota) as well as the typical denitrifies (Bacteroidetes_vadinHA17 and Denitratisoma). Therefore, this study provides a novel strategy to realize simultaneous WAS utilization and denitrification for WWTPs.

Characterization of the microbial community and prediction of metabolic functions in an anaerobic/oxic system with magnetic micropolystyrene as a biocarrier.

Polystyrene (PS) and magnetic polystyrene (MPS) materials have been used extensively in wastewater treatment. In this research, a 55-day anaerobic/oxic process was carried out to evaluate the effects of PS and MPS on microorganisms under aerobic and anaerobic conditions. Scanning electron microscopy results revealed differences in the entanglement state of the sludge with the biocarrier due to differences in surface morphology. High-throughput sequencing analysis showed that the microbial communities differed considerably in the presence of PS and MPS addition under both aerobic and anaerobic conditions. The highest abundance and diversity were observed in the PS reactor, with 929 observed species and a PD_whole_tree index of 91.58 under anaerobic conditions. MPS promoted the enrichment of bacteria related to nitrogen recycling such as Nitrospirota which increased from 1.13% in the seeding sludge to 3.48% and 10.07% in the aerobic reactors with PS and MPS, respectively. Moreover, advanced analysis showed that PS inhibited many microbial functions (e.g., protein export, nitrogen metabolism), and MPS alleviated this inhibition. This study provides significant insights into the microbial effects of PS and MPS and may shed light on biocarrier selection in future studies.

Long-term effect of acetate and biochar addition on enrichment and activity of denitrifying anaerobic methane oxidation microbes.

The denitrifying anaerobic methane oxidation (DAMO) process plays a crucial role in the global carbon/nitrogen cycles and methane emission control, and also has application potential in biological wastewater treatment. However, given that DAMO microbes are susceptible to external conditions such as additional carbon source in the system, it is essential to evaluate the effect of alternative carbon substance on the enrichment efficiency and metabolic activity of DAMO microbes. To this end, this study investigated the effect of acetate (0.1 mmol/L-R2, 0.5 mmol/L-R3) and biochar addition (R4) on the enrichment and activity of DAMO microbes. The long-term operation showed that the NO2--N and CH4 consumption rates in the reactors almost presented the sequence of R4>R2>R3>R1. However, the short-term activity test with isotope labelling showed the sequence of R2>R4>R1>R3. Furthermore, the addition of acetate and biochar improved the electrochemical activity and extracellular polymeric substance (EPS) secretion in the systems. In R4 reactor, the proportion of DAMO bacteria was the highest (7.20%), indicating that the addition of biochar could promote the enrichment of DAMO bacteria, and Thauera was co-enriched with the proportion increasing from 0.26% to 6.73%. While in R1, R2 and R3 reactors, DAMO bacteria were enriched with relatively low abundances (0.10%, 0.23%, 0.15%, respectively), together with methanogens and denitrifiers. This study showed that biochar and acetate with appropriate concentration could enhance the enrichment and activity of DAMO bacteria, the results can provide reference for the enrichment of DAMO microbes and its application in the biological nitrogen removal of wastewater.

Selective Oxidation of Triethylamine Catalyzed by Mn-Ce/ZSM-5.

The selective catalytic oxidation (SCO) of triethylamine (TEA) to harmless nitrogen (N2), carbon dioxide (CO2), and water (H2O) is of green elimination technology. In this paper, Mn-Ce/ZSM-5 with different proportions of MnOx/CeOx were studied for the selective catalytic combustion of TEA. The catalysts were characterized by XRD, BET, H2-TPR, XPS, and NH3-TPD and their catalytic activities were analyzed. The results showed that MnOx was the main active component. The addition of a small amount of CeOx promotes the generation of high-valence Mn ions, which reduces the reduction temperature of the catalyst and increases the redox capacity of the catalyst. In addition, the synergistic effect between CeOx and MnOx significantly improves the mobility of reactive oxygen species on the catalyst, thus improving the catalytic performance of the catalyst. The catalytic oxidation performance of TEA over 15Mn5Ce/ZSM-5 is the highest. TEA can be completely converted at 220 °C, and the selectivity for N2 is up to 80%. The reaction mechanism was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS).

Magnetic Charge Model for Leakage Signals from Surface Defects in Ferromagnetic Material.

A novel three-dimensional theoretical model of magnetic flux leakage (MFL) is proposed in this paper based on the magnetic dipole model. The magnetic dipole model assumes that a ferromagnetic specimen with defects is exposed to a uniform external magnetic field that causes a uniform magnetization around the defect surface. Under this assumption, the MFL can be regarded as arising from magnetic charges on the defect surface. Previous theoretical models were mostly used to analyze simple crack defects such as cylindrical and rectangular cracks. In this paper, we developed a magnetic dipole model for more complex defect shapes such as circular truncated holes, conical holes, elliptical holes, and double-curve-shaped crack holes to complement the existing defect shapes. Experimental results and comparisons with previous models demonstrate that the proposed model provides a better approximation of complex defect shapes.

Contextual Relevance of Sustainable Supply Chain: Recycling, Philanthropy, or Both?

Many firms have already been actively or passively involved in sustainable supply chain management with the objective of improving the triple bottom line (TBL). But whether the limited funds should be allocated to both community responsibility activities (e.g., corporate philanthropy) and environmental protection activities (e.g., recycling) is a confusing question. This paper provides deep insights into the combination strategy of two corporate social responsibility (CSR) types in a two-tier sustainable supply chain by modeling analysis. The decision models in eight scenarios with different combinations of CSR types are proposed and applied for the determination of equilibrium scenarios. The paper's findings highlight: under certain conditions, (1) the supply chain with two types of CSR is the equilibrium scenario and improves the TBL; (2) counter-intuitively, balancing short- and long-term benefits, firms are more willing to cooperate with partners with relatively low consumers sensitivity of CSR activities; (3) it is wise for the manufacturer to allocate more funding to environmental responsibility than to community responsibility. In addition, considering both short- and long-term benefits, comparing with the manufacturer, the retailer has a stronger incentive to improve recycling efficiency.

Enhanced bio-affinity of magnetic QD-P(St-GMA)@Fe3O4 micro-particles via surface-quaternized modification.

In this work, a kind of bio-carrier quaternized-polystyrene-polyglycidyl methacrylate@Fe3O4 (QD-P(St-GMA)@Fe3O4, QD-PSGF) micro-particles was successfully prepared by modifying PSGF micro-particles through a hydrothermal method. The quaternary ammonium group and surface structure of QD-PSGF were confirmed through several characterization methods. We directly verified the efficacy of the quaternary ammonium group in promoting microbial activity due to QD-PSGF being synthesized by a hydrothermal method without changing the surface topography and pore. The bio-affinity of QD-PSGF microspheres was evaluated by bacterial adhesion and anaerobic digestion experiments. The results showed that a little quaternary ammonium group can increase bacterial adhesion by about 2-3 times and methane production by 40%. The novel developed QD-PSGF micro-particles can be a promising material as a biofilm carrier for bio-application.

Biochemical characteristics of point mutated Capra hircus lysosome α-mannosidase.

Locoweeds, a type of poisonous weedare, are widely distributed throughout the world and have a significant impact on the development of herbivore animal husbandry. Swainsonine (SW), the main toxin in locoweeds, can competitively inhibit lysosomes α-mannosidase (LAM) in animal cells, resulting in α-mannosidosis. However, the specifics of the interaction between SW and LAM are still unclear. Here, we used molecular docking to predicte the interaction points between SW and LAM, built mutated lysosomes α-mannosidase (LAMM), and analyzed its biochemical properties changes in presumption points. The Trp at the 28th position and the Tyr at the 599th position of the LAM were interaction point candidates, and the above two amino acids in Capra hircus LAM (chLAM), were successfully mutated to glycine by constructing recombinant yeast GS115/PIC9K- LAMM. The results showed that the sensitivity of Capra hircus LAMM (chLAMM), to SW decreased significantly compared with wild-type LAM, the enzyme activity of LAM decreased approximately threefold, the optimum temperature of LAMM decreased from 55°C to 50°C, the optimum pH value increased from 4.5 to 5.0, and the effects of Mn2+, Fe3+, Al3+, Co2+, Cr3+, and ethylenediaminetetraacetic acid (EDTA) on LAM enzyme activity before and after point mutation changed significantly. These findings help us better understanding the molecular mechanism of the interaction mechanism between SW and chLAM, and provide new reference for solving locoweeds poisoning.

[Influence of bronchopulmonary dysplasia on cerebral blood flow in preterm infants: a prospective study based on arterial spin labeling]. / åŸºäºŽåŠ¨è„‰è‡ªæ—‹æ ‡è®°æˆåƒæŠ€æœ¯æŽ¢è®¨æ”¯æ°”ç®¡è‚ºå‘è‚²ä¸è‰¯å¯¹æ—©äº§å„¿è„‘è¡€æµé‡å½±å“çš„å‰çž»æ€§ç ”ç©¶.

OBJECTIVES: To investigate local cerebral blood perfusion in preterm infants with bronchopulmonary dysplasia (BPD) based on cerebral blood flow (CBF) values of arterial spin labeling (ASL). METHODS: A prospective study was conducted on 90 preterm infants with a gestational age of <32 weeks and a birth weight of <1 500 g who were born in the Department of Obstetrics and admitted to the Department of Neonatology in the Third Affiliated Hospital of Zhengzhou University from August 2021 to June 2022. All of the infants underwent cranial MRI and ASL at the corrected gestational age of 35-40 weeks. According to the presence or absence of BPD, they were divided into a BPD group with 45 infants and a non-BPD group with 45 infants. The two groups were compared in terms of the CBF values of the same regions of interest (frontal lobe, temporal lobe, parietal lobe, occipital lobe, thalamus, and basal ganglia) on ASL image. RESULTS: Compared with the non-BPD group, the BPD group had a significantly lower 1-minute Apgar score, a significantly longer duration of assisted ventilation, and a significantly higher incidence rate of fetal distress (P<0.05). After control for the confounding factors such as corrected age and age at the time of cranial MRI by multiple linear regression analysis, compared with the non-BPD group, the BPD group still had higher CBF values of the frontal lobe, temporal lobe, parietal lobe, occipital lobe, basal ganglia, and thalamus at both sides (P<0.05). CONCLUSIONS: BPD can increase cerebral blood perfusion in preterm infants, which might be associated with hypoxia and a long duration of assisted ventilation in the early stage.

The relationship between zooplankton vertical distribution and the concentration of aqueous Hg in boreal lakes: A comparative field study.

The production of the highly toxic monomethylmercury (MeHg) is heterogenous throughout the water column. Multiple factors have been identified to significantly affect this process, such as an extended anoxic water layer and a deep-water phytoplankton maximum. However, the role of water column heterogeneity on mercury (Hg) cycling is still poorly known, especially concerning the role of zooplankton grazers. Here, four boreal lakes with contrasting characteristics were sampled (i.e., transparency and the presence/absence of fish) at both day and night in order to maximize the heterogeneity in zooplankton abundance both among and within lakes, and to investigate their potential links with Hg vertical heterogeneity. Diel variation of the concentrations of both dissolved total Hg (DTHg) and total Hg (THg) were observed, with night samples significantly higher than day samples. Although this pattern was not related to diel changes in the vertical distribution of zooplankton, results showed that the presence of large copepods (>1.2 mm) and medium-sized (0.6 to 1.2 mm) cladocerans was significantly associated with lower concentrations of DTHg in the water at a given depth, whereas the presence of medium-sized copepods was significantly associated with the concentration of THg. The presence of cladocerans was significantly associated with the ratio between the dissolved MeHg and DTHg (conventionally used as a proxy of methylation potential). Phytoplankton biomass was directly correlated with the concentration of both dissolved and total MeHg and the methylation potential. At the same time, phytoplankton biomass was inversely related to the fraction of DTHg. These results suggest a potential key role of the heterogeneity of biotic factors in the water column, especially of phytoplankton and zooplankton, in the cycling of total Hg and MeHg in boreal lakes.

Effect of Shengmai Yin on Epithelial-Mesenchymal Transition of Nasopharyngeal Carcinoma Radioresistant Cells / 中国结合医学杂志

OBJECTIVE@#To investigate the mechanism by which Chinese medicine Shengmai Yin (SMY) reverses epithelial-mesenchymal transition (EMT) through lipocalin-2 (LCN2) in nasopharyngeal carcinoma (NPC) cells CNE-2R.@*METHODS@#Morphological changes in EMT in CNE-2R cells were observed under a microscope, and the expressions of EMT markers were detected using quantitative real-time PCR (RT-qPCR) and Western blot assays. Through the Gene Expression Omnibus dataset and text mining, LCN2 was found to be highly related to radiation resistance and EMT in NPC. The expressions of LCN2 and EMT markers following SMY treatment (50 and 100 µ g/mL) were detected by RT-qPCR and Western blot assays in vitro. Cell proliferation, migration, and invasion abilities were measured using colony formation, wound healing, and transwell invasion assays, respectively. The inhibitory effect of SMY in vivo was determined by observing a zebrafish xenograft model with a fluorescent label.@*RESULTS@#The CNE-2R cells showed EMT transition and high expression of LCN2, and the use of SMY (5, 10 and 20 µ g/mL) reduced the expression of LCN2 and reversed the EMT in the CNE-2R cells. Compared to that of the CNE-2R group, the proliferation, migration, and invasion abilities of SMY high-concentration group were weakened (P<0.05). Moreover, SMY mediated tumor growth and metastasis in a dose-dependent manner in a zebrafish xenograft model, which was consistent with the in vitro results.@*CONCLUSIONS@#SMY can reverse the EMT process of CNE-2R cells, which may be related to its inhibition of LCN2 expression. Therefore, LCN2 may be a potential diagnostic marker and therapeutic target in patients with NPC.

GPER inhibitor increases tamoxifen-induced apoptosis in T-47DTR-resistant cells / 中国药理学通报

Aim To study the effect of G protein-coupled estrogen receptor(GPER)inhibitor G15 on the sensitivity of breast cancer tamoxifen-resistant cells to T-47DTR. Methods Experiments were carried out with 4-hydroxytamoxifen(4-OHT),the active form of tamoxifen in vivo. The sensitivity of tamoxifen-resistant breast cancer cell line T-47DTR and its parental cell line T-47D to tamoxifen was detected by MTT assay; the expression of GPER protein was analyzed by plasma separation of inhibitor G15; the effect of 4-OHT combined with G15 on the apoptosis of T-47DTR cells was analyzed by flow cytometry AnnexinV-FITC/PI double staining; the expression levels of apoptosis-related proteins Bax,Bcl-2,caspase-3,cleaved caspase-3,caspase-9,cleaved caspase-9 were analysed by Western blot. Results(1)Compared with the parental cell T-47D,the resistance of T-47DTR-resistant cells to 4-OHT was significantly enhanced.(2)When 4-OHT(2 μmol·L-1)was administered,the membrane distribution of GPER increased,indicating that GPER was activated in T-47DTR-resistant cells compared with the control group; Compared with OHT,the use of G15(5 μmol·L-1)and OHT significantly reduced the expression of GPER.(3)GPER inhibitor G15 could increase the apoptotic rate of T-47DTR-resistant cells while down-regulating the anti-apoptotic protein Bcl-2 and up-regulating the expression of pro-apoptotic proteins Bax,cleaved caspase-3,cleaved caspase-9. Conclusions The GPER inhibitor G15 increases the apoptosis of T-47DTR cells and restores the sensitivity of drug-resistant cells to tamoxifen.

Nitro-oleic acid ameliorates erectile dysfunction in a streptozotocin-induced rat model of diabetes by inhibiting oxidative stress and apoptosis and activating the NO/cGMP pathway / 亚洲男科学杂志(英文版)

The major vascular complications associated with diabetes make the management of diabetic mellitus erectile dysfunction (DMED) a challenging endeavor. Notable factors contributing to DMED include oxidative stress, nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway activation, and apoptosis, while nitro-oleic acid (NO2-OA) has been shown to be beneficial in treating these aspects of this condition. We, herein, investigated the effects and possible mechanisms of NO2-OA on erectile function as assessed in a streptozotocin-induced rat model of diabetes. Our results revealed that the erectile function of DMED rats was significantly impaired compared with that of the control group. However, in response to 4 weeks of NO2-OA treatment, there was an improvement in erectile function. The expression of oxidative stress-related indicators was significantly increased and the NO/cGMP pathway was impaired in the DMED group. The expression of proapoptotic factors was increased, while that of antiapoptotic factors was decreased in the DMED group. Moreover, the cell morphology in the cavernous tissue of the DMED group also changed adversely. NO2-OA treatment significantly reversed all these changes observed in the DMED group. In conclusion, NO2-OA treatment partially improved erectile function in DMED rats through mechanisms that included inhibition of oxidative stress, activation of the NO/cGMP pathway, and a reduction in apoptosis.

Enhancement of biological nitrogen removal performance from low C/N municipal wastewater using novel carriers based on the nano-Fe3O4.

The aim of this work was to study the effects of the magnetic microparticles (MMP) on nitrogen removal under low C/N conditions. A 30-day anaerobic/oxic progress illustrated that nitrification and denitrification were promoted in the presence of MMP. MMP could facilitate the production of extracellular polymeric substances (EPS) and act as pH buffering in aerobic conditions. The high-throughput sequencing displayed that, compared with the sludge without MMP, the relative abundance of Dokdonella and Comamonas which are capable of both nitrifying and denitrifying were 8.7% and 1.29% higher in anaerobic sludge and 7.11% and 0.97% higher in aerobic sludge with MMP, respectively. The relative abundance of Pseudomonas with the excellent capability of EPS secretion was also observed 4.33 times higher than that without MMP in the aerobic sludge. Based on the superior performance above, MMP is a promising additive to enhance nitrogen removal efficiency for low C/N wastewater.

Grazer-mediated regeneration of methylmercury, inorganic mercury, and other metals in freshwater.

Whereas it is well established that zooplankton can transfer various pollutants such as mercury (Hg) from primary producers to higher trophic levels, less is known on the effects of their activities on the recycling of Hg in aquatic ecosystems. Here, the impact of zooplankton grazing efficiency and excretion/egestion processes on metal concentrations in freshwater was investigated. Isotopically labeled algae (200HgCl2, Me198HgCl) was used as a food source and the transfer of the selected isotopes to the culture medium during grazing was measured. In parallel, the potential for the recycling of major ions and metals, including selected essential and non-essential metals, was investigated for this could help to track the effects of sloppy feeding. To highlight the role of feeding behavior, a large filter-feeder (Daphnia magna) was compared to a smaller selective feeder zooplankton taxon (calanoid copepods), with the latter being expected to cause more sloppy feeding than the former. The experiments demonstrated that zooplankton grazing of both taxa significantly influenced the concentrations of the particulate portion of both inorganic Hg (IHg) and monomethylmercury (MeHg) in water. In contrast, only Daphnia significantly increased the concentration of dissolved IHg, whereas the concentration of dissolved MeHg was not affected by either grazer. The results also suggested that both taxa affected the concentrations of dissolved Fe, Zn, SO42- and rare earth elements via sloppy feeding, whereas only Daphnia significantly increased the concentration of dissolved Cu via this mechanism. The effects of excretion/egestion were negligible except for dissolved IHg and Cu in Daphnia treatment. These results highlight a neglected pathway of IHg and MeHg recycling in the water column in freshwater ecosystems with potentially important consequences for trophic transfer.