Appendix C. Results of all statistical tests.

Results of all statistical tests

Appendix A. Fitting survival models in an integral projection model for giant clams, Tridacna maxima.

Fitting survival models in an integral projection model for giant clams, Tridacna maxima

Appendix B. Elasticity of equilibrium abundance to recruitment in an open model sums to one.

Elasticity of equilibrium abundance to recruitment in an open model sums to one

Appendix A. Details of thermally matched temperature loggers and field temperature surveys.

Details of thermally matched temperature loggers and field temperature surveys

Toxicity of Nano-Zero Valent Iron to Freshwater and Marine Organisms

<div><p>We tested whether three commercial forms (uncoated, organic coating, and iron oxide coating) of nano zero-valent iron (nZVI) are toxic to freshwater and marine organisms, specifically three species of marine phytoplankton, one species of freshwater phytoplankton, and a freshwater zooplankton species (<em>Daphnia magna</em>), because these organisms may be exposed downstream of where nZVI is applied to remediate polluted soil. The aggregation and reactivity of the three types of nZVI varied considerably, which was reflected in their toxicity. Since levels of Fe²⁺ and Fe³⁺ increase as the nZVI react, we also evaluated their toxicity independently. All four phytoplankton species displayed decreasing population growth rates, and <em>Daphnia magna</em> showed increasing mortality, in response to increasing levels of nZVI, and to a lesser degree with increasing Fe²⁺ and Fe³⁺. All forms of nZVI aggregated in soil and water, especially in the presence of a high concentration of calcium ions in groundwater, thus reducing their transports through the environment. However, uncoated nZVI aggregated extremely rapidly, thus vastly reducing the probability of environmental transport and potential for toxicity. This information can be used to design a risk management strategy to arrest the transport of injected nZVI beyond the intended remediation area, by injecting inert calcium salts as a barrier to transport.</p> </div

Nanofer 25S and Nanofer STAR particle size as a function of ionic strength at 100 mg L⁻¹ and pH 7, over time.

<p>Nanofer 25S and Nanofer STAR particle size as a function of ionic strength at 100 mg L⁻¹ and pH 7, over time.</p

Summary of results of aggregation and toxicity studies.

*<p>Results are for observed statistically significant toxic effect.</p

Species Sensitivity Distributions for Engineered Nanomaterials

Engineered nanomaterials (ENMs) are a relatively new strain of materials for which little is understood about their impacts. A species sensitivity distribution (SSDs) is a cumulative probability distribution of a chemical’s toxicity measurements obtained from single-species bioassays of various species that can be used to estimate the ecotoxicological impacts of a chemical. The recent increase in the availability of acute toxicity data for ENMs enabled the construction of 10 ENM-specific SSDs, with which we analyzed (1) the range of toxic concentrations, (2) whether ENMs cause greater hazard to an ecosystem than the ionic or bulk form, and (3) the key parameters that affect variability in toxicity. The resulting estimates for hazardous concentrations at which 5% of species will be harmed ranged from <1 ug/L for PVP-coated n-Ag to >3.5 mg/L for CNTs. The results indicated that size, formulation, and the presence of a coating can alter toxicity, and thereby corresponding SSDs. Few statistical differences were observed between SSDs of an ENM and its ionic counterpart. However, we did find a significant correlation between the solubility of ENMs and corresponding SSD. Uncertainty in SSD values can be reduced through greater consideration of ENM characteristics and physiochemical transformations in the environment

Nanofer 25S particles imaged with SEM and Nanofer STAR particles imaged with TEM.

<p>Nanofer 25S particles imaged with SEM and Nanofer STAR particles imaged with TEM.</p

Growth Rate for <i>I. galbana</i> exposed to (a) Nanofer 25S, (b) Nanofer STAR, (c) Fe²⁺, and (d) Fe³⁺.

<p>Growth Rate for <i>I. galbana</i> exposed to (a) Nanofer 25S, (b) Nanofer STAR, (c) Fe²⁺, and (d) Fe³⁺.</p