Abstract: With the extensive applications of metallic-based nanomaterials (MNs), concerns are growing of their potential impact on aquatic organisms. Unlike traditional metal pollutants, MNs have different surface properties and compositions, which may modify their impact on aquatic environments as well as their bioavailability to aquatic organisms. Kinetic processes of MNs, such as dissolution, stabilization, aggregation, and sedimentation, are important in determining their bioavailability and subsequent toxicity to aquatic organisms. Among all of the physicochemical kinetics, the dissolution of MNs attracts the most attention, due to their potential toxicity generated by dissolved ions. This review summarizes the dissolution behavior of three common MNs, i.e., ZnO nanoparticles (ZnO-NPs), Ag nanoparticles (Ag-NPs), and TiO₂ nanoparticles (TiO₂-NPs), in toxicological studies. A kinetic model was developed to evaluate the contribution of dissolved ion on the total MN accumulation. Finally, toxicological data of the MNs to algae, zooplankton, and fish are summarized and interpreted based on their kinetics. Different dissolution rates were observed for ZnO-NPs, Ag-NPs, and TiO₂-NPs, and their solubility also varied during different toxicological studies, leading to a variable but increasing waterborne ion concentration during exposure. The bioavailability of these MNs and corresponding ions also varied for different aquatic organisms (e.g., algae, zooplankton, and fish). Specifically, the MNs appeared to be more bioavailable to daphnids, rendering a minor contribution of ion during short-term exposure. Generally, dissolved ion contributed partially to toxicity of ZnO-NPs and Ag-NPs, while the toxicity of TiO₂-NPs was mainly due to the generated reactive oxygen species (ROS). Additionally, the role of dissolved ion in both MN bioaccumulation and toxicity intensified during chronic exposure as a result of dissolution, thus it is critical to monitor the dissolution of MNs in toxicological studies. This review emphasizes the importance of integrating physicochemical kinetics and uptake kinetics in evaluating the bioavailability and toxicity of both MNs and dissolved ions.

从金属纳米颗粒的理化性质以及生物吸收动力学角度探究金属纳米颗粒对水生生物的毒性

[1]Alsop, D.H., Wood, C.M., 1999. Influence of waterborne cations on zinc uptake and toxicity in rainbow trout, Oncorhynchus mykiss. Canadian Journal of Fisheries and Aquatic Sciences, 56(11):2112-2119.

[2]Aruoja, V., Dubourguier, H.C., Kasemets, K., et al., 2009. Toxicity of nanoparticles of CuO, ZnO and TiO₂ to microalgae Pseudokirchneriella subcapitata. Science of Total Environment, 407(4):1461-1468.

[3]Asghari, S., Johari, S., Lee, J., et al., 2012. Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna. Journal of Nanobiotechnology, 10(1):14.

[4]Asharani, P.V., Wu, Y.L., Gong, Z.Y., et al., 2008. Toxicity of silver nanoparticles in zebrafish models. Nanotechnology, 19(25):255102.

[5]Ates, M., Demir, V., Adiguzel, R., et al., 2013. Bioaccumulation, subacute toxicity, and tissue distribution of engineered titanium dioxide nanoparticles in goldfish (Carassius auratus). Journal of Nano-materials, 2013: 460518.

[6]Auffan, M., Bottero, J.Y., Chaneac, C., et al., 2010. Inorganic manufactured nanoparticles: how their physicochemical properties influence their biological effects in aqueous environments. Nanomedicine, 5(6):999-1007.

[7]Bai, W., Zhang, Z., Tian, W., et al., 2010. Toxicity of zinc oxide nanoparticles to zebrafish embryo: a physicochemical study of toxicity mechanism. Journal of Nanoparticle Research, 12(5):1645-1654.

[8]Barron, M.G., Albeke, S., 2000. Calcium control of zinc uptake in rainbow trout. Aquatic Toxicology, 50(3):257-264.

[9]Baun, A., Hartmann, N.B., Grieger, K., et al., 2008. Ecotoxicity of engineered nanoparticles to aquatic invertebrates: a brief review and recommendations for future toxicity testing. Ecotoxicology, 17(5):387-395.

[10]Bian, S.W., Mudunkotuwa, I.A., Rupasinghe, T., et al., 2011. Aggregation and dissolution of 4 nm ZnO nanoparticles in aqueous environments: influence of pH, ionic strength, size, and adsorption of humic acid. Langmuir, 27(10):6059-6068.

[11]Blaise, C., Gagné, F., Férard, J.F., et al., 2008. Ecotoxicity of selected nano-materials to aquatic organisms. Environmental Toxicology, 23(5):591-598.

[12]Blinova, I., Niskanen, J., Kajankari, P., et al., 2013. Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus. Environmental Science and Pollution Research, 20(5):3456-3463.

[13]Brantley, S.L., 2008. Kinetics of mineral dissolution. Brantley, S.L., Kubicki, J.D., White, A.F. (Eds.), Kinetics of Water-Rock Interaction. Springer, New York, p.151-210.

[14]Bury, R.N., Galvez, F., Wood, M.C., 1999. Effects of chloride, calcium, and dissolved organic carbon on silver toxicity: comparison between rainbow tout and fathead minnows. Environmental Toxicology and Chemistry, 18(1):56-62.

[15]Cho, E.C., Xie, J., Wurm, P.A., et al., 2009. Understanding the role of surface charges in cellular adsorption versus internalization by selectively removing gold nanoparticles on the cell surface with a I2/KI etchant. Nano Letters, 9(3):1080-1084.

[16]Clément, L., Hurel, C., Marmier, N., 2013. Toxicity of TiO₂ nanoparticles to cladocerans, algae, rotifers and plants– effects of size and crystalline structure. Chemosphere, 90(3):1083-1090.

[17]Clemente, Z., Castro, V.L., Feitosa, L.O., et al., 2013. Fish exposure to nano-TiO₂ under different experimental conditions: Methodological aspects for nanoecotoxicology investigations. Science of Total Environment, 463-464:647-656.

[18]Clift, M.J.D., Rothen-Rutishauser, B., Brown, D.M., et al., 2008. The impact of different nanoparticle surface chemistry and size on uptake and toxicity in a murine macrophage cell line. Toxicology and Applied Pharmacology, 232(3):418-427.

[19]Conner, S.D., Schmid, S.L., 2003. Regulated portals of entry into the cell. Nature, 422(6927):37-44.

[20]Das, P., Xenopoulos, M., Metcalfe, C., 2013. Toxicity of silver and titanium dioxide nanoparticle suspensions to the aquatic invertebrate, Daphnia magna. Bulletin of Environmental Contamination and Toxicology, 91(1):76-82.

[21]David, C.A., Galceran, J., Rey-Castro, C., et al., 2012. Dissolution kinetics and solubility of ZnO nanoparticles followed by AGNES. The Journal of Physical Chemistry C, 116(21):11758-11767.

[22]Delay, M., Dolt, T., Woellhaf, A., et al., 2011. Interactions and stability of silver nanoparticles in the aqueous phase: influence of natural organic matter (NOM) and ionic strength. Journal of Chromatography A, 1218(27):4206-4212.

[23]Dokoumetzidis, A., Macheras, P., 2006. A century of dissolution research: from Noyes and Whitney to the biopharmaceutics classification system. International Journal of Pharmaceutics, 321(1-2):1-11.

[24]Fabrega, J., Luoma, S.N., Tyler, C.R., et al., 2011. Silver nanoparticles: behaviour and effects in the aquatic environment. Environment International, 37(2):517-531.

[25]Farré, M., Gajda-Schrantz, K., Kantiani, L., et al., 2009. Ecotoxicity and analysis of nanomaterials in the aquatic environment. Analytical and Bioanalytical Chemistry, 393(1):81-95.

[26]Franklin, N.M., Rogers, N.J., Apte, S.C., et al., 2007. Comparative toxicity of nanoparticulate ZnO, bulk ZnO, and ZnCl₂ to a freshwater microalga (Pseudokirchneriella subcapitata): the importance of particle solubility. Environmental Science & Technology, 41(24):8484-8490.

[27]Garnham, G., Codd, G., Gadd, G., 1992. Kinetics of uptake and intracellular location of cobalt, manganese and zinc in the estuarine green alga Chlorella salina. Applied Microbiology and Biotechnology, 37(2):270-276.

[28]Griffitt, R.J., Luo, J., Gao, J., et al., 2008. Effects of particle composition and species on toxicity of metallic nanomaterials in aquatic organisms. Environmental Toxicology and Chemistry, 27(9):1972-1978.

[29]Griffitt, R.J., Hyndman, K., Denslow, N.D., et al., 2009. Comparison of molecular and histological changes in zebrafish gills exposed to metallic nanoparticles. Toxicological Sciences, 107(2):404-415.

[30]Gunawan, C., Sirimanoonphan, A., Teoh, W.Y., et al., 2013. Submicron and nano formulations of titanium dioxide and zinc oxide stimulate unique cellular toxicological responses in the green microalga Chlamydomonas reinhardtii. Journal of Hazardous Materials, 260:984- 992.

[31]Han, J., Qiu, W., Gao, W., 2010. Potential dissolution and photo-dissolution of ZnO thin films. Journal of Hazardous Materials, 178(1-3):115-122.

[32]Handy, R.D., Eddy, F.B., 2004. Transport of solutes across biological membranes in eukaryotes: an environmental perspective. van Leeuwen, H.P., Köster, W. (Eds), Physicochemical Kinetics and Transport at Biointerfaces. John Wiley & Sons, Ltd., USA, p.337-356.

[33]Handy, R.D., Kammer, F., Lead, J., et al., 2008a. The ecotoxicology and chemistry of manufactured nanoparticles. Ecotoxicology, 17(4):287-314.

[34]Handy, R.D., Henry, T., Scown, T., et al., 2008b. Manufactured nanoparticles: their uptake and effects on fish—a mechanistic analysis. Ecotoxicology, 17(5):396-409.

[35]Hartmann, N.B., von der Kammer, F., Hofmann, T., et al., 2010. Algal testing of titanium dioxide nanoparticles—testing considerations, inhibitory effects and modification of cadmium bioavailability. Toxicology, 269(2-3):190-197.

[36]He, C., Hu, Y., Yin, L., et al., 2010. Effects of particle size and surface charge on cellular uptake and biodistribution of polymeric nanoparticles. Biomaterials, 31(13):3657- 3666.

[37]Heinlaan, M., Ivask, A., Blinova, I., et al., 2008. Toxicity of nanosized and bulk ZnO, CuO and TiO₂ to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus. Chemosphere, 71(7):1308-1316.

[38]Heng, D., Cutler, D., Chan, H.K., et al., 2008. What is a suitable dissolution method for drug nanoparticles? Pharmaceutical Research, 25(7):1696-1701.

[39]Hirota, K., Terada, H., 2012. Endocytosis of particle formulations by macrophages and its application to clinical treatment. Brian, C. (Ed.), Molecular Regulation of Endocytosis. InTech, Rijeka, Croatia, p.413-428.

[40]Hofmeister, H., Thiel, S., Dubiel, M., et al., 1997. Synthesis of nanosized silver particles in ion-exchanged glass by electron beam irradiation. Applied Physics Letters, 70(13):1694-1696.

[41]Hou, W.C., Westerhoff, P., Posner, J.D., 2013. Biological accumulation of engineered nanomaterials: a review of current knowledge. Environmental Science: Processes & Impacts, 15:103-122.

[42]Hund-Rinke, K., Simon, M., 2006. Ecotoxic effect of photocatalytic active nanoparticles (TiO₂) on algae and daphnids. Environmental Science and Pollution Research, 13(4):225-232.

[43]Hunter, R.J., 2001. Foundations of Colloid Science, 2nd Edition. Oxford University Press, Oxford, p.45-80.

[44]Ji, J., Long, Z., Lin, D., 2011. Toxicity of oxide nanoparticles to the green algae Chlorella sp. Chemical Engineering Journal, 170(2-3):525-530.

[45]Kennedy, A.J., Hull, M.S., Bednar, A.J., et al., 2010. Fractionating nanosilver: importance for determining toxicity to aquatic test organisms. Environmental Science & Technology, 44(24):9571-9577.

[46]Kettler, K., Veltman, K., van de Meent, D., et al., 2014. Cellular uptake of nanoparticles as determined by particle properties, experimental conditions, and cell type. Environmental Toxicology and Chemistry, 33(3):481-492.

[47]Kim, M.S., Louis, K.M., Pedersen, J.A., et al., 2014. Using citrate-functionalized TiO₂ nanoparticles to study the effect of particle size on zebrafish embryo toxicity. The Analyst, 139(5):964-972.

[48]Kittler, S., Greulich, C., Diendorf, J., et al., 2010. Toxicity of silver nanoparticles increases during storage because of slow dissolution under release of silver ions. Chemistry of Materials, 22(16):4548-4554.

[49]Klaine, S.J., Alvarez, P.J.J., Batley, G.E., et al., 2008. Nanomaterials in the environment: behavior, fate, bioavailability, and effects. Environmental Toxicology and Chemistry, 27(9):1825-1851.

[50]Knauss, K.G., Dibley, M.J., Bourcier, W.L., et al., 2001. Ti(IV) hydrolysis constants derived from rutile solubility measurements made from 100 to 300 °C. Applied Geochemistry, 16(9-10):1115-1128.

[51]Laban, G., Nies, L., Turco, R., et al., 2010. The effects of silver nanoparticles on fathead minnow (Pimephales promelas) embryos. Ecotoxicology, 19(1):185-195.

[52]Lam, K.S., Wang, W.X., 2006. Accumulation and elimination of aqueous and dietary silver in Daphnia magna. Chemosphere, 64(1):26-35.

[53]Lee, D.Y., Fortin, C., Campbell, P.G.C., 2004. Influence of chloride on silver uptake by two green algae, Pseudokirchneriella subcapitata and Chlorella pyrenoidosa. Environmental Toxicology and Chemistry, 23(4):1012- 1018.

[54]Lee, W.M., An, Y.J., 2013. Effects of zinc oxide and titanium dioxide nanoparticles on green algae under visible, UVA, and UVB irradiations: no evidence of enhanced algal toxicity under UV pre-irradiation. Chemosphere, 91(4):536-544.

[55]Li, W.M., Wang, W.X., 2013. Distinct biokinetic behavior of ZnO nanoparticles in Daphnia magna quantified by synthesizing ⁶⁵Zn tracer. Water Research, 47(2):895-902.

[56]Li, X., Lenhart, J.J., Walker, H.W., 2012. Aggregation kinetics and dissolution of coated silver nanoparticles. Langmuir, 28(2):1095-1104.

[57]Liu, J., Hurt, R.H., 2010. Ion release kinetics and particle persistence in aqueous nano-silver colloids. Environmental Science & Technology, 44(6):2169-2175.

[58]Lopes, S., Ribeiro, F., Wojnarowicz, J., et al., 2014. Zinc oxide nanoparticles toxicity to Daphnia magna: size-dependent effects and dissolution. Environmental Toxicology and Chemistry, 33(1):190-198.

[59]Lu, F., Wu, S.H., Hung, Y., et al., 2009. Size effect on cell uptake in well-suspended, uniform mesoporous silica nanoparticles. Small, 5(12):1408-1413.

[60]Lubick, N., 2008. Nanosilver toxicity: ions, nanoparticles or both? Environmental Science & Technology, 42(23):8617-8617.

[61]Ma, H., Williams, P.L., Diamond, S.A., 2013. Ecotoxicity of manufactured ZnO nanoparticles–a review. Environmental Pollution, 172:76-85.

[62]Ma, R., Levard, C., Marinakos, S.M., et al., 2012. Size- controlled dissolution of organic-coated silver nanoparticles. Environmental Science & Technology, 46(2):752- 759.

[63]MacInnis, I.N., Brantley, S.L., 1992. The role of dislocations and surface morphology in calcite dissolution. Geochimica et Cosmochimica Acta, 56(3):1113-1126.

[64]Manzo, S., Miglietta, M.L., Rametta, G., et al., 2013. Toxic effects of ZnO nanoparticles towards marine algae Dunaliella tertiolecta. Science of The Total Environment, 445-446:371-376.

[65]Marambio-Jones, C., Hoek, E.V., 2010. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment. Journal of Nanoparticle Research, 12(5):1531-1551.

[66]Matranga, V., Corsi, I., 2012. Toxic effects of engineered nanoparticles in the marine environment: model organisms and molecular approaches. Marine Environmental Research, 76:32-40.

[67]Miao, A.J., Wang, W.X., 2004. Relationships between cell- specific growth rate and uptake rate of cadmium and zinc by a coastal diatom. Marine Ecology Progress Series, 275:103-113.

[68]Miao, A.J., Schwehr, K.A., Xu, C., et al., 2009. The algal toxicity of silver engineered nanoparticles and detoxification by exopolymeric substances. Environmental Pollution, 157(11):3034-3041.

[69]Miao, A.J., Zhang, X.Y., Luo, Z., et al., 2010. Zinc oxide-engineered nanoparticles: dissolution and toxicity to marine phytoplankton. Environmental Toxicology and Chemistry, 29(12):2814-2822.

[70]Mihranyan, A., Strømme, M., 2007. Solubility of fractal nanoparticles. Surface Science, 601(2):315-319.

[71]Misra, S.K., Dybowska, A., Berhanu, D., et al., 2012. The complexity of nanoparticle dissolution and its importance in nanotoxicological studies. Science of The Total Environment, 438:225-232.

[72]Mudunkotuwa, I.A., Rupasinghe, T., Wu, C.M., et al., 2012. Dissolution of ZnO nanoparticles at circumneutral pH: a study of size effects in the presence and absence of citric acid. Langmuir, 28(1):396-403.

[73]Navarro, E., Baun, A., Behra, R., et al., 2008a. Environmental behavior and ecotoxicity of engineered nanoparticles to algae, plants, and fungi. Ecotoxicology, 17(5):372-386.

[74]Navarro, E., Piccapietra, F., Wagner, B., et al., 2008b. Toxicity of silver nanoparticles to Chlamydomonas reinhardtii. Environmental Science & Technology, 42(23):8959-8964.

[75]Oukarroum, A., Bras, S., Perreault, F., et al., 2012. Inhibitory effects of silver nanoparticles in two green algae, Chlorella vulgaris and Dunaliella tertiolecta. Ecotoxicology and Environmental Safety, 78:80-85.

[76]Ovečka, M., Lang, I., Baluška, F., et al., 2005. Endocytosis and vesicle trafficking during tip growth of root hairs. Protoplasma, 226(1-2):39-54.

[77]Pan, Z., Tao, J., Zhu, Y., et al., 2010. Spontaneous growth of ZnCO₃ nanowires on ZnO nanostructures in normal ambient environment: unstable ZnO nanostructures. Chemistry of Materials, 22(1):149-154.

[78]Peng, X., Palma, S., Fisher, N.S., et al., 2011. Effect of morphology of ZnO nanostructures on their toxicity to marine algae. Aquatic Toxicology, 102(3-4):186-196.

[79]Piccapietra, F., Allué, C.G., Sigg, L., et al., 2012. Intracellular silver accumulation in Chlamydomonas reinhardtii upon exposure to carbonate coated silver nanoparticles and silver nitrate. Environmental Science & Technology, 46(13):7390-7397.

[80]Piccinno, F., Gottschalk, F., Seeger, S., et al., 2012. Industrial production quantities and uses of ten engineered nanomaterials in Europe and the world. Journal of Nanoparticle Research, 14(9):1-11.

[81]Podila, R., Brown, J.M., 2013. Toxicity of engineered nanomaterials: a physicochemical perspective. Journal of Biochemical and Molecular Toxicology, 27(1):50-55.

[82]Poynton, H.C., Lazorchak, J.M., Impellitteri, C.A., et al., 2011. Differential gene expression in Daphnia magna suggests distinct modes of action and bioavailability for ZnO nanoparticles and Zn ions. Environmental Science & Technology, 45(2):762-768.

[83]Reed, R.B., Ladner, D.A., Higgins, C.P., et al., 2012. Solubility of nano-zinc oxide in environmentally and biologically important matrices. Environmental Toxicology and Chemistry, 31(1):93-99.

[84]Reidy, B., Haase, A., Luch, A., et al., 2013. Mechanisms of silver nanoparticle release, transformation and toxicity: a critical review of current knowledge and recommendations for future studies and applications. Materials, 6(6):2295-2350.

[85]Rejman, J., Oberle, V., Zuhorn, I.S., et al., 2004. Size- dependent internalization of particles via the pathways of clathrin- and caveolae-mediated endocytosis. Biochemical Journal, 377(1):159-169.

[86]Schmidt, J., Vogelsberger, W., 2006. Dissolution kinetics of titanium dioxide nanoparticles: the observation of an unusual kinetic size effect. The Journal of Physical Chemistry B, 110(9):3955-3963.

[87]Scown, T.M., van Aerle, R., Tyler, C.R., 2010. Review: do engineered nanoparticles pose a significant threat to the aquatic environment? Critical Reviews in Toxicology, 40(7):653-670.

[88]Sharma, V.K., 2009. Aggregation and toxicity of titanium dioxide nanoparticles in aquatic environment—a review. Journal of Environmental Science and Health, Part A, 44(14):1485-1495.

[89]Shaw, B.J., Handy, R.D., 2011. Physiological effects of nanoparticles on fish: a comparison of nanometals versus metal ions. Environment International, 37(6):1083-1097.

[90]Smith, C.J., Shaw, B.J., Handy, R.D., 2007. Toxicity of single walled carbon nanotubes to rainbow trout, (Oncorhynchus mykiss):respiratory toxicity, organ pathologies, and other physiological effects. Aquatic Toxicology, 82(2):94-109.

[91]Sotiriou, G.A., Meyer, A., Knijnenburg, J.T.N., et al., 2012. Quantifying the origin of released Ag⁺ ions from nanosilver. Langmuir, 28(45):15929-15936.

[92]Tan, Q.G., Wang, W.X., 2008. The influences of ambient and body calcium on cadmium and zinc accumulation in Daphnia magna. Environmental Toxicology and Chemistry, 27(7):1605-1613.

[93]Tan, Q.G., Wang, W.X., 2012. Two-compartment toxicokinetic- toxicodynamic model to predict metal toxicity in Daphnia magna. Environmental Science & Technology, 46(17):9709-9715.

[94]Ting, Y.P., Lawson, F., Prince, I.G., 1989. Uptake of cadmium and zinc by the alga Chlorella vulgaris: Part 1. Individual ion species. Biotechnology and Bioengineering, 34(7):990-999.

[95]Tinke, A.P., Vanhoutte, K., de Maesschalck, R., et al., 2005. A new approach in the prediction of the dissolution behavior of suspended particles by means of their particle size distribution. Journal of Pharmaceutical and Biomedical Analysis, 39(5):900-907.

[96]Varela-Valencia, R., Gómez-Ortiz, N., Oskam, G., et al., 2014. The effect of titanium dioxide nanoparticles on antioxidant gene expression in tilapia (Oreochromis niloticus). Journal of Nanoparticle Research, 16(4):1-12.

[97]Wang, J., Flanagan, D.R., 2002. General solution for diffusion-controlled dissolution of spherical particles. 2. Evaluation of experimental data. Journal of Pharmaceutical Sciences, 91(2):534-542.

[98]Wang, J., Wang, W.X., 2014. Salinity influences on the uptake of silver nanoparticles and silver nitrate by marine medaka (Oryzias melastigma). Environmental Toxicology and Chemistry, 33(3):632-640.

[99]Wang, J., Zhang, X., Chen, Y., et al., 2008. Toxicity assessment of manufactured nanomaterials using the unicellular green alga Chlamydomonas reinhardtii. Chemosphere, 73(7):1121-1128.

[100]Wang, W.X., 2011. Ecotoxicology and Biogeochemistry of Trace Metals. Science Press, Beijing, China, p.118-119 (in Chinese).

[101]Wang, W.X., 2013. Dietary toxicity of metals in aquatic animals: recent studies and perspectives. Chinese Science Bulletin, 58(2):203-213.

[102]Wang, W.X., Fisher, N., 1997. Modeling metal bioavailability for marine mussels. Ware, G. (Ed.), Reviews of Environmental Contamination and Toxicology. Springer, New York, p.39-65.

[103]Wang, W.X, Fisher, N.S., Luoma, S.N., 1996. Kinetic determinations of trace element bioaccumulation in the mussel, Mytilus edulis. Marine Ecology Progress Series, 140:91-113.

[104]Wang, Y., Miao, A.J., Luo, J., et al., 2013. Bioaccumulation of cdte quantum dots in a freshwater alga Ochromonas danica: a kinetics study. Environmental Science & Technology, 47(18):10601-10610.

[105]Ward, J.E., Kach, D.J., 2009. Marine aggregates facilitate ingestion of nanoparticles by suspension-feeding bivalves. Marine Environmental Research, 68(3):137-142.

[106]Ward, T.J., Kramer, J.R., 2002. Silver speciation during chronic toxicity tests with the mysid, Americamysis bahia. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 133(1-2):75-86.

[107]Warheit, D.B., Hoke, R.A., Finlay, C., et al., 2007. Development of a base set of toxicity tests using ultrafine TiO₂ particles as a component of nanoparticle risk management. Toxicology Letters, 171(3):99-110.

[108]Webb, N.A., Wood, C.M., 2000. Bioaccumulation and distribution of silver in four marine teleosts and two marine elasmobranchs: influence of exposure duration, concentration, and salinity. Aquatic Toxicology, 49(1-2):111-129.

[109]Wessels, J.G.H., 1993. Wall growth, protein excretion and morphogenesis in fungi. New Phytologist, 123(3):397- 413.

[110]Wiench, K., Wohlleben, W., Hisgen, V., et al., 2009. Acute and chronic effects of nano- and non-nano-scale TiO₂ and ZnO particles on mobility and reproduction of the freshwater invertebrate Daphnia magna. Chemosphere, 76(10):1356-1365.

[111]Wong, S.Y., Leung, P.Y., Djurišić, A.B., et al., 2010. Toxicities of nano zinc oxide to five marine organisms: influences of aggregate size and ion solubility. Analytical and Bioanalytical Chemistry, 396(2):609-618.

[112]Wood, C.M., Grosell, M., Hogstrand, C., et al., 2002. Kinetics of radiolabelled silver uptake and depuration in the gills of rainbow trout (Oncorhynchus mykiss) and European eel (Anguilla anguilla): the influence of silver speciation. Aquatic Toxicology, 56(3):197-213.

[113]Wood, C.M., McDonald, M.D., Walker, P., et al., 2004. Bioavailability of silver and its relationship to ionoregulation and silver speciation across a range of salinities in the gulf toadfish (Opsanus beta). Aquatic Toxicology, 70(2):137- 157.

[114]Xu, Y., Wang, W.X., 2002. Exposure and potential food chain transfer factor of Cd, Se and Zn in marine fish Lutjanus argentimaculatus. Marine Ecology Progress Series, 238: 173-186.

[115]Yang, X., Gondikas, A.P., Marinakos, S.M., et al., 2012. Mechanism of silver nanoparticle toxicity is dependent on dissolved silver and surface coating in Caenorhabditis elegans. Environmental Science & Technology, 46(2):1119-1127.

[116]Zemke-White, W.L., Clements, K.D., Harris, P.J., 2000. Acid lysis of macroalgae by marine herbivorous fishes: effects of acid pH on cell wall porosity. Journal of Experimental Marine Biology and Ecology, 245(1):57-68.

[117]Zhang, L., Wang, W.X., 2007. Waterborne cadmium and zinc uptake in a euryhaline teleost Acanthopagrus schlegeli acclimated to different salinities. Aquatic Toxicology, 84(2):173-181.

[118]Zhang, W., Yao, Y., Sullivan, N., et al., 2011. Modeling the primary size effects of citrate-coated silver nanoparticles on their ion release kinetics. Environmental Science & Technology, 45(10):4422-4428.

[119]Zhao, C.M., Wang, W.X., 2010. Biokinetic uptake and efflux of silver nanoparticles in Daphnia magna. Environmental Science & Technology, 44(19):7699-7704.

[120]Zhao, C.M., Wang, W.X., 2011. Comparison of acute and chronic toxicity of silver nanoparticles and silver nitrate to Daphnia magna. Environmental Toxicology and Chemistry, 30(4):885-892.

[121]Zhao, C.M., Wang, W.X., 2012a. Importance of surface coatings and soluble silver in silver nanoparticles toxicity to Daphnia magna. Nanotoxicology, 6(4):361-370.

[122]Zhao, C.M., Wang, W.X., 2012b. Size-dependent uptake of silver nanoparticles in Daphnia magna. Environmental Science & Technology, 46(20):11345-11351.

[123]Zhu, X., Zhu, L., Duan, Z., et al., 2008. Comparative toxicity of several metal oxide nanoparticle aqueous suspensions to zebrafish (Danio rerio) early developmental stage. Journal of Environmental Science and Health, Part A, 43(3):278-284.

[124]Zhu, X., Zhu, L., Chen, Y., et al., 2009a. Acute toxicities of six manufactured nanomaterial suspensions to Daphnia magna. Journal of Nanoparticle Research, 11(1):67-75.

[125]Zhu, X., Wang, J., Zhang, X., et al., 2009b. The impact of ZnO nanoparticle aggregates on the embryonic development of zebrafish (Danio rerio). Nanotechnology, 20(19):195103.

[126]Zhu, X., Chang, Y., Chen, Y., 2010. Toxicity and bioaccumulation of TiO₂ nanoparticle aggregates in Daphnia magna. Chemosphere, 78(3):209-215.