The tide turns: Episodic and localized cross-contamination of a California coastline with cyanotoxins.

The contamination of coastal ecosystems from a variety of toxins of marine algal origin is a common and well-documented situation along the coasts of the United States and globally. The occurrence of toxins originating from cyanobacteria along marine coastlines is much less studied, and little information exists on whether toxins from marine and freshwater sources co-occur regularly. The current study focused on the discharge of cyanotoxins from a coastal lagoon (Santa Clara River Estuary) as a consequence of an extreme tide event (King Tides; December 3-5, 2017) resulting in a breach of the berm separating the lagoon from the ocean. Monthly monitoring in the lagoon throughout 2017 documented more than a dozen co-occurring cyanobacterial genera, as well as multiple algal and cyanobacterial toxins. Biotoxin monitoring before and following the King Tide event using Solid Phase Adsorption Toxin Tracking (SPATT) in the lagoon and along the coast revealed the co-occurrence of microcystins, anatoxin, domoic acid, and other toxins on multiple dates and locations. Domoic acid was ubiquitously present in SPATT deployed in the lagoon and along the coast. Microcystins were also commonly detected in both locations, although the beach berm retained the lagoonal water for much of the year. Mussels collected along the coast contained microcystins in approximately half the samples, particularly following the King Tide event. Anatoxin was observed in SPATT only in late December, following the breach of the berm. Our findings indicate both episodic and persistent occurrence of both cyanotoxins and marine toxins may commonly contaminate coastlines in proximity to cyanobacteria-laden creeks and lagoons.

Mixed organic and inorganic tapwater exposures and potential effects in greater Chicago area, USA.

Safe drinking water at the point of use (tapwater, TW) is a public-health priority. TW exposures and potential human-health concerns of 540 organics and 35 inorganics were assessed in 45 Chicago-area United States (US) homes in 2017. No US Environmental Protection Agency (EPA) enforceable Maximum Contaminant Level(s) (MCL) were exceeded in any residential or water treatment plant (WTP) pre-distribution TW sample. Ninety percent (90%) of organic analytes were not detected in treated TW, emphasizing the high quality of the Lake Michigan drinking-water source and the efficacy of the drinking-water treatment and monitoring. Sixteen (16) organics were detected in >25% of TW samples, with about 50 detected at least once. Low-level TW exposures to unregulated disinfection byproducts (DBP) of emerging concern, per/polyfluoroalkyl substances (PFAS), and three pesticides were ubiquitous. Common exceedances of non-enforceable EPA MCL Goal(s) (MCLG) of zero for arsenic [As], lead [Pb], uranium [U], bromodichloromethane, and tribromomethane suggest potential human-health concerns and emphasize the continuing need for improved understanding of cumulative effects of low-concentration mixtures on vulnerable sub-populations. Because DBP dominated TW organics, residential-TW concentrations are potentially predictable with expanded pre-distribution DBP monitoring. However, several TW chemicals, notably Pb and several infrequently detected organic compounds, were not readily explained by pre-distribution samples, illustrating the need for continued broad inorganic/organic TW characterization to support consumer assessment of acceptable risk and point-of-use treatment options.

Effects of environmentally relevant concentrations of mixtures of TiO2, ZnO and Ag ENPs on a river bacterial community.

Effluent from wastewater treatment plants contains a wide variety of engineered nanoparticles (ENPs) released from different sources. Although single type ENPs have been studied extensively with respect to their environmental impact, ENPs in mixed forms have not been investigated much at environmentally relevant concentrations. This study was designed to test the effect of mixed ENPs at three combinations and concentrations on an aquatic bacterial community. After mixing artificial treated wastewater with river water and exposing the microbial community to ENPs for three days, the ENPs were characterized by SP-ICP-MS. Results from this study showed that: 1) the size distribution of Ti and Zn at the beginning and end of the experiment did not vary much among all tested conditions. For Ag, the most frequent size increased more than 2-fold when the highest Ag ENPs were added; 2) particle concentrations of ENPs generally correlated positively with added concentrations; 3) dissolved Zn and Ag increased significantly as a result of spike; and 4) the bacterial community structure was shifted significantly as a consequence of ENPs' addition. With the dominant population being suppressed, the community exposed to ENPs became more diverse and even. Surprisingly, further increase of the doses of the three ENPs did not bring significant change to the microbial community. These results revealed that ENPs could bring significant impacts to prokaryotes even at low concentrations. But these impacts do not necessarily correlate positively with doses.

Fate of nanoparticles during alum and ferric coagulation monitored using single particle ICP-MS.

In this study, aluminum sulfate, ferric sulfate, ferric chloride, and poly(diallyldimethylammonium chloride) (pDADMAC) coagulation removal of citrate-stabilized silver and gold nanoparticles (NPs) and uncoated titanium dioxide, cerium dioxide, and zinc oxide NPs was investigated using a single particle (SP) ICP-MS direct monitoring technique. Zone 2 (charge neutralization) coagulation was performed in river water and more commonly used Zone 4 (sweep floc) coagulation was performed in both river and lake water with environmentally relevant concentrations of selected NPs added. SP-ICP-MS was used to detect NP and dissolved species, characterize the size distribution, and quantify particle concentration as well as dissolved species before and after treatments. Other parameters including pH, dissolved organic carbon, turbidity, and UV254 absorbance were monitored to characterize treatment efficiency. Charge neutralization (Zone 2) coagulation resulted in 48-85% removal of citrate-stabilized NPs and 90-99% removal of uncoated NPs from river water. Sweep floc (Zone 4) coagulation in river water resulted in 36-94% removal of citrate-stabilized NPs and 91-99% removal of uncoated NPs both with and without polymer addition. Zone 4 coagulation conditions in lake water resulted in 77-98% removal of citrate-stabilized NPs and 59-96% removal of uncoated NPs without polymer. These results indicate that NP removal depends on NP surface and stability, the nature of the source water, and the coagulant type and approach.

Impact of TiO2 and ZnO nanoparticles on an aquatic microbial community: effect at environmentally relevant concentrations.

To investigate effects of engineered nanoparticles (ENPs) at environmentally relevant concentrations to aquatic microbial communities, TiO2 at 700 µg/L and ZnO at 70 µg/L were spiked to river water samples either separately or combined. Compared to controls where no ENPs were added, the addition of TiO2 ENPs alone at the tested concentration had no statistically significant effect on both the bacterial and eukaryotic communities. The presence of added ENPs: ZnO or ZnO + TiO2 led to significant shift of the microbial community structure and genus distribution. This shift was more obvious for the bacteria than the eukaryotes. Based on results from single particle - inductively coupled plasma - mass spectrometry (SP-ICP-MS), all ENPs aggregated rapidly in water and resulted in much larger particles sizes than the original counterparts. "Dissolved" (including particles smaller than the size detection limits and dissolved ions) concentrations of Ti and Zn increased, too in treatment groups vs. the controls.

Detection of zinc oxide and cerium dioxide nanoparticles during drinking water treatment by rapid single particle ICP-MS methods.

Nanoparticles (NPs) entering water systems are an emerging concern as NPs are more frequently manufactured and used. Single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) methods were validated to detect Zn- and Ce-containing NPs in surface and drinking water using a short dwell time of 0.1 ms or lower, ensuring precision in single particle detection while eliminating the need for sample preparation. Using this technique, information regarding NP size, size distribution, particle concentration, and dissolved ion concentrations was obtained simultaneously. The fates of Zn- and Ce-NPs, including those found in river water and added engineered NPs, were evaluated by simulating a typical drinking water treatment process. Lime softening, alum coagulation, powdered activated carbon sorption, and disinfection by free chlorine were simulated sequentially using river water. Lime softening removed 38-53 % of Zn-containing and ZnO NPs and >99 % of Ce-containing and CeO2 NPs. Zn-containing and ZnO NP removal increased to 61-74 % and 77-79 % after alum coagulation and disinfection, respectively. Source and drinking water samples were collected from three large drinking water treatment facilities and analyzed for Zn- and Ce-containing NPs. Each facility had these types of NPs present. In all cases, particle concentrations were reduced by a minimum of 60 % and most were reduced by >95 % from source water to finished drinking water. This study concludes that uncoated ZnO and CeO2 NPs may be effectively removed by conventional drinking water treatments including lime softening and alum coagulation.

Single particle ICP-MS characterization of titanium dioxide, silver, and gold nanoparticles during drinking water treatment.

One of the most direct means for human exposure to nanoparticles (NPs) released into the environment is drinking water. Therefore, it is critical to understand the occurrence and fate of NPs in drinking water systems. The objectives of this study were to develop rapid and reliable analytical methods and apply them to investigate the fate and transportation of NPs during drinking water treatments. Rapid single particle ICP-MS (SP-ICP-MS) methods were developed to characterize and quantify titanium-containing, titanium dioxide, silver, and gold NP concentration, size, size distribution, and dissolved metal element concentration in surface water and treated drinking water. The effectiveness of conventional drinking water treatments (including lime softening, alum coagulation, filtration, and disinfection) to remove NPs from surface water was evaluated using six-gang stirrer jar test simulations. The selected NPs were nearly completely (97 ± 3%) removed after lime softening and alum coagulation/activated carbon adsorption treatments. Additionally, source and drinking waters from three large drinking water treatment facilities utilizing similar treatments with the simulation test were collected and analyzed by the SP-ICP-MS methods. Ti-containing particles and dissolved Ti were present in the river water samples, but Ag and Au were not present. Treatments used at each drinking water treatment facility effectively removed over 93% of the Ti-containing particles and dissolved Ti from the source water.