This study for the first time reports a quantitative analysis of phthalates and spatial distribution of phthalates in Lake Pontchartrain, Louisiana, USA using solid phase micro-extraction (SPME) coupled with gas chromatography mass spectroscopy (GC-MS). During 2008–2009, di-n-butylphthalate (DnBP) along with its congener (DiBP) and di(2-ethylhexyl) phthalate (DEHP) were detected in Lake Pontchartrain. Concentrations of these phthalates in the lake were monitored in different areas before and after the opening of the Bonnet Carré Spillway that occurred from April to May in 2008. The concentration of Σ₃PAEs (DnBP, DiBP and DEHP) ranged from 0 to 20 μg/L in the surface water of the lake from March 2008 to June 2009. The distribution of the three phthalates varied with locations in the lake. An increase trend of Σ₃PAEs was observed after the opening of the Bonnet Carré Spillway in the central lake area. The observed increase of the phthalates could be correlated to the opening of the spillway. The SPME followed by GC-MS employed in this study has been proved to be a rapid, sensitive and practical method to quantitatively analyse and evaluate phthalate concentrations in salt lake waters.

A simple and green synthesis of gold nanoparticles (AuNPs) was achieved in tea solution and fruit juices with auric tetrachloride (HAuCl₄) without the addition of any other chemicals. Natural antioxidants present in tea leaves and fruit juices were able to reduce Au³⁺ ions to form AuNPs spheres with an average diameter of 22.9 ± 2.7 nm in the tea solution and 12.8 ± 2.4 nm in the orange juice. A colorimetric determination of antioxidant activities based on the formation of citrate-capped AuNPs has been developed. It was found that the colorimetric response of AuNPs was dependent on the concentration of antioxidants tested. As compared with the standard reference assay, i.e., the Folin–Ciocalteu method, the colorimetric method reported in this study showed a very good correlation (R² = 0.9996). The results indicate that the AuNPs-based colorimetric method provides a simple, effective and reliable measurement of the antioxidant capacity in the tested fruit juices.

Aquifer storage and recovery (ASR) wells along northern Lake Okeechobee, Florida, have been proposed as part of the Comprehensive Everglades Restoration Plan. However, researchers have linked elevated concentrations of As, Hg and transition metals in groundwater because of ASR in carbonate rocks. This study presents portable X-ray fluorescence (pXRF) analyses of four continuous cores (C38S, C59, L63N, and L63S) recovered from the Floridan Aquifer System north of Lake Okeechobee, Florida. A total of 5078 pXRF measurements were collected at approximately 30.5 cm along the four cores. Measurements along the cores included the Intermediate Confining Unit, Upper Floridan Aquifer (UFA), Avon Park Permeable Zones (APPZ), and portions of the Lower Floridan Aquifer (LFA). Emphasis was placed on the concentrations of mercury (Hg), arsenic (As), molybdenum (Mo), chromium (Cr), and nickel (Ni), which have been identified as elements of concern during ASR operations. Major-element trends in the cores often reflect lithologic changes in the Floridan Aquifer System. This includes decreases in Ca and Sr and increases in Mg associated with dolomitization in the Avon Park Formation. Trace-metal concentrations vary systematically within hydrostratigraphic units. Mercury commonly exhibits elevated concentrations near the base of the UFA, whereas Mo is often enriched near the top of the UFA. Elevated concentrations of Hg, As, Mo, Ni, and other trace metals frequently occur at hydrostratigraphic boundaries, formation contacts, clay-rich intervals, and especially within organic-rich layers. Organic layers contained metal concentrations several times greater than surrounding carbonate rocks and hosted the highest measured concentrations of Hg, As, and Mo in the cores. The paucity of organic layers and generally lower metal concentrations in the UFA suggest it may represent a favorable zone for ASR storage. In contrast, the APPZ and LFA contain numerous metal-enriched organic layers which may increase the potential for trace metal mobilization during ASR operations. These results suggest pXRF characterization provides an effective tool for geochemical characterization of storage zones and evaluating water-quality risks potentially associated with ASR development.

Copper (Cu) is both an essential micronutrient and a pollutant, with its effects depending on its concentration, environmental context, and the species and life history stages of the organisms exposed. To advance the understanding of copper effects in the context of variation in other environmental conditions, eastern oyster (Crassostrea virginica) spat recruitment and adult tissue copper concentration [Cu] were monitored in conjunction with water column [Cu], salinity, pH, dissolved oxygen, and temperature for a year at five sites in or near Naples Bay, Florida, an urbanized estuary with some of the highest copper pollution levels in the US. Relationships among the environmental variables were explored using principal component analysis, then the effects of key variables on oyster responses were assessed using regression models and multi-model comparison. There were significant differences among sites and dates in terms of salinity, water column and tissue [Cu], and spat recruitment. Tissue [Cu] was high, up to 2868 ppm, and was correlated with high water column [Cu] in parts of the estuary (up to 7.55 mg/L). Oyster tissue [Cu] was best predicted by a linear model incorporating both salinity and water column [Cu], and oyster spat recruitment was best modeled using a polynomial fit to salinity and a negative linear relationship with water column [Cu]. This is consistent with the hypothesis that high [Cu] in conjunction with low salinities reduces spat recruitment in this system, but alternative hypotheses cannot be excluded without further assessment. Given these findings, hydrologic restoration to stabilize salinity regimes and management actions to eliminate copper pollution sources are recommended to protect oysters and improve ecological integrity in the system.