[1] The upper basin of Effingham Inlet possesses permanently anoxic bottom waters, with a water column redox transition zone typically occurring at least 40 m above the sediment-water interface. During our sampling campaign in April and July 2007, this redox transition zone was associated with sharp peaks in a variety of parameters, including soluble reactive phosphorus (SRP) and total particulate phosphorus (TPP). Based on sequential extraction results, TPP maxima exhibited preferential accumulation of an operationally defined class of loosely adsorbed organic phosphorus (P), which may contain a substantial fraction of polyphosphate (poly-P). This poly-P may furthermore be involved in the redox-dependent remobilization of SRP. For example, direct fluorometric analysis of poly-P content revealed that particulate inorganic poly-P was present at concentrations ranging from 1 to 9 nM P within and several meters above the TPP maximum. Below the depth of 1% oxygen saturation, however, particulate inorganic poly-P was undetectable (<0.8 nM in situ). Assuming this concentration profile reflects the remineralization of inorganic poly-P to SRP across the redox transition, inorganic poly-P degradation accounted for as much as 4 AE 3% (average AE standard deviation) to 9 AE 8% of the vertical turbulent diffusive SRP flux. This finding is a conservative estimate due in part to sample storage effects associated with our analysis of poly-P content. By comparison, iron-linked P cycling accounted for at most 65 AE 33% of the diffusive SRP flux, leaving $25% unaccounted for. Thus, while redox-sensitive poly-P remineralization in Effingham Inlet appears modest based on our direct conservative estimate, it may be higher from a mass balance viewpoint. Poly-P cycling may therefore be an overlooked mechanism for the redox-sensitive cycling of P in some hypoxic/anoxic boundaries, especially iron-poor marine oxygen minimum zones.

The vast range of C₆₀ derivatives makes it difficult to assess the potential environmental impact of this class of materials, while past environmental studies mostly focused only on pristine C₆₀. Central to derivatized C₆₀'s potential to negatively impact (micro)biological receptors upon unintended release is its unique property of mediating the transfer of light energy to ambient oxygen, producing ¹O₂. To initiate the process of establishing a thorough understanding of the photoinduced adverse biological effects of functionalized fullerenes and their aqueous dispersions, the photochemical properties relevant to ¹O₂ production were evaluated using three selected series of mono-, bis-, and tris-adducted fullerene materials. Differential ¹O₂ production of derivatives in toluene were explained by spectral variations under visible and UVA light conditions. Of the nine functionalities studied only aggregates of two positively charged derivatives showed significant photoactivity under experimental conditions. Laser flash photolysis revealed a triplet excited state in the photoactive aggregates with a sufficiently long lifetime to be quenched by ³O₂. Dynamic light scattering, transmission electron microscopy, and electron diffraction patterns revealed aggregates with sizes typical of aqueous C₆₀ colloids that varied in crystallinity based on functionality. Results raised questions about our current understanding of the photoactivity of fullerene aggregates.

Of the many fullerene derivatives that have been examined, cationic functionalization has proven to be most promising for aqueous or biological applications. Until recently, however, no cationic colloidal fullerene aggregates in the nanosize regime have been characterized in the aqueous phase. The results presented here represent the most rapid and efficient, to the best of our knowledge, viral inactivation reported for any colloidal fullerene aggregates. Tris-adducted fulleropyrrolidinium aggregates are prepared and analyzed for concentration-dependent singlet oxygen (1O2) production and MS2 bacteriophage inactivation. Experiments are performed under visible, UVA, and sunlight irradiation with the addition of natural organic matter (NOM) to simulate environmental conditions. Viral inactivation was observed at sensitizer concentrations in the nanomolar range. A 5-log inactivation of MS2 was observed after 4 or 1 min of sunlight exposure with 250 nM fullerenes with or without NOM, respectively. The environmental implications of these results are discussed in the context of previously reported 1O2-mediated MS2 inactivation.

We herein report the first instance of using pristine C70 as a heavy-atom free organic sensitizer for efficient triplet-triplet annihilation upconversion (UC) for both green-to-blue and red-to-green UC using 9,10-bis(phenylethynyl)anthracene and perylene as acceptors, respectively. C70 achieved quantum yields of 8% and 0.8% for green-to-blue and red-to-green UC, 25 to 35 times higher than C60, and showed improved stability under continuous laser irradiation compared to the benchmark platinum(II)-octaethylporphyrin.

The nature of fullerene-water interactions has been the subject of much research and debate. Specifically, the presence of a stabilizing, negative surface potential on colloidal aggregates of C60 in water is unexpected, given the neutral nature of pure carbon, and is not well understood. Previous simulation efforts have focused on the C60-water interaction using molecular dynamics simulations that lacked the ability to account for charge transfer and distribution interactions. In this study, first-principles density functional theory was used to analyze the fundamental electronic interactions to elucidate the polarization and charge transfer between water and C60. Simulations show that charge is inductively transferred to the C60 from water molecules, with subsequent polarization of the C60 molecule. In a case with two neighboring C60 molecules, the charge polarization induces a charge onto the second C60. Simulation suggests that this charge transfer and polarization may contribute at least partly to the observed negative surface potential of fullerene aggregates and, combined with hydrogen bonding network formation around C60, provides a fundamental driving force for aggregate formation in water.