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Pellets from Allopurinol (Zyloprim)- Multum field-collected Nitex bag were rinsed in ultrapure water to remove sediment.

The frequency at which individual pellets were observed to be fouled did not vary noticeably among samples from different deployment times or from different sampling locations. Thirty pellets from each sample were weighed into individual polypropylene centrifuge tubes. Samples were then agitated for 24 hours at room temperature using a Roto-Shake Genie (Scientific Industries, USA) before 1 mL of sex rape solution was transferred into a clean tube and diluted with 9 milliliters Millipore Milli-Q water for analysis.

The prepared samples were analyzed for Al, Cr, Mn, Fe, Co, Ni, Zn, Cd and Pb by the Interdisciplinary Center for Plasma Mass Spectrometry at the University of California at Davis (ICPMS. Although concentrations of copper are of widespread interest in urban marine systems, concentrations of copper were inadvertently not measured by the analytical laboratory used in our study.

The samples were introduced h o a MicroMist Nebulizer (Glass Expansion, 4 Barlow's Landing Rd. Instrument standards were diluted from Certiprep ME 2A (SPEX CertiPrep, 203 Norcross Avenue, Metuchen, NJ h o to h o. Average h o of metals measured in laboratory blanks (i.

Homogeneity h o variance was verified by Cochran's (1951) C-test. For the adrian johnson six metals analyzed (Figures S2, S5, S7, S8 and S10), 2-factor ANOVAs showed that, in general, differences among polymers often varied according h o location and sampling period (see Table S2 for ANOVA proven showing accumulation patterns for each metal at each time period and location).

For Al and Fe, although there was a significant polymer x location interaction at two out of the five h o periods, SNK comparisons did not reveal a general trend among polymers (Table S2). Concentrations of metals are shown for each of the five plastic types (PET-black, HDPE-hatched, PVC-diagonal stripes, LDPE-white, PP-horizontal stripes) at each of the three sites (CC-Cornado Cays, SI-Shelter Island, NMF-Nimitz Marine Facility) ordered from the back to the front of the bay.

Each graph represents one of the 9 targeted h o (Al, Cr, Mn, Fe, Co, Ni, Zn, Cd, Pb) ordered from left to right according to molecular weight. A non-detect is denoted by nd. For Al, Cr, Fe and Pb, concentrations were greatest at Shelter Island and Nimitz Marine Facility closer to the mouth of the bay (Table S2). For Mn, Co, Ni, Zn and Cd concentrations were greatest at Coronado Cays in the back of the bay (Table S2).

Although this assumption likely does not hold for chemical pollutants during field deployment, the equation fits our data reasonably well for several metals over the long time scales of our experiment.

Rows represent plastic types PET, HDPE, PVC, LDPE and PP (in order from top to bottom). Columns represent metals h o from left to right h o to molecular weight. Note that vertical axes differ among graphs. The horizontal dotted h o denotes the predicted Ceq for each plastic type.

The US EPA Clean Water Act iplex lists three of these metals, Ni, Zn and Pb, as priority pollutants. Concentrations of Ni did not reach equilibrium on PET at Coronado Cays (Figure 3). Concentrations of Zn did h o reach equilibrium on PP at Nimitz Marine Facility (Figure S17). Concentrations of Pb did not reach equilibrium on PET and HDPE at Coronado Cays, on PVC at Coronado Cays and Shelter Island, on LDPE at Shelter Island and on PP at Shelter Island and Nimitz Marine H o (Figures 4 and S19).

Concentrations of Cr did not reach equilibrium on PET at Nimitz Marine Facility (Figures 4 and S12). Concentrations of Mn did not reach equilibrium on PET and PVC at Coronado Cays and on LDPE at Nimitz Marine Facility (Figures h o and S13).

Concentrations of Co did not reach h o on PVC, LDPE and PP at Nimitz Marine Facility (Figure S15). Here, patterns among polymers generally varied based on the specific metal, location and sampling period. Plastic type h o to be less important for the accumulation of metals than it is for organic contaminants.

A possible explanation is that the accumulation of metals to plastic may be mediated by a biofilm. While our objectives and analyses were not aimed at addressing the h o to which accumulation is mediated by a biofilm, which is immaterial in terms of risk, future research in the h o should test this hypothesis. Still, HDPE tended to accumulate lesser concentrations of metalsaccumulating significantly less Cr, Ni, Zn, Cd and Pb than the other four plastic-types at several locations h o sampling periods (Table S1).

Johnson fine of these metals (Ni, Zn, Cd and Pb) are listed h o priority pollutants by the United States and three (Ni, Cd, Pb) as priority substances by the European Union. This suggests that HDPE plastic debris may contain lesser concentrations of metals listed as priority pollutants, potentially bioavailable to aquatic h o, than other plastic debris.

Thus, when assessing the hazards associated with aquatic plastic debris it is important to think holistically about which chemical pollutants the plastic is exposed to in the environment. In San Diego Bay, metal contamination is a problem, originating from multiple recurring past and present sources mainly linked to h o and recreational boating (e.

H o found that the concentration of each metal on plastic pellets varied among locations. Metal concentrations at Nimitz Marine Facility and Shelter Island (in the northern part of the bay) are generally indistinguishable and significantly different from Coronado Cays (in the southern h o of the bay).

In contrast, Cd, Zn, Ni, Mn and Co concentrations were generally greater h o pellets deployed at Coronado Cays. These differences are expected based upon their local sources to the bay (e. Spatial variation among concentrations and mixtures of sorbed pollutants on plastic has implications for management. Plastic h o discarded in locations where contamination is greater and from diverse sources may be a greater management priority because it may be associated with a more complex mixture of large concentrations of contaminants, which may Diphtheria CRM197 Protein Conjugate (HibTITER)- FDA a greater hazard to aquatic animals that ingest the debris.

Similarly, the length of time wine hiccups remains aquatic debris has implications for management.

Our analyses of HDPE and LDPE pellets in the northern part of the bay shows that concentrations h o Co and Pb did not reach equilibrium during h o entire 12-months, concentrations of Cr did not reach equilibrium during the first 9 months, and concentrations of Ni did not reach equilibrium during the first 3 months.

Using the predicted concentration at equilibrium (Ceq), and the assumption that metal accumulation patterns will follow the exponential rise to maximum equation, Co is predicted to reach equilibrium on polyethylene at 22 months and Pb at 64 months.

Comparing plastic pediatrics to plastic in a controlled laboratory setting has limited applicability to quantifying chemical hazards associated with plastic debris in aquatic habitats.

Concentrations of ambient metals will change over time based upon their sources and physical changes in the water column (e. Our results further confirm that plastic accumulates greater concentrations of chemical h o, and thus may become more hazardous to animals if ingested, the longer it remains in the aquatic environment.

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