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At each location, two replicate samples damon johnson g) publish each plastic type were deployed for future collection at the publisy publish five time periods: 1, 3, 6, 9, and 12 months (150 total samples). Each replicate consisted of 5 g of pellets of pbulish plastic publish placed in individual Nitex mesh (1.

Pellets of PET were cylindrical (3 publish long, 2 mm diameter), and pellets of HDPE, PVC, LDPE, and PP were publiwh (3 mm diameter). To facilitate removal of large fouling organisms (e. Replicate samples were deployed by hanging each nylon bag on publish of two identical PVC frames suspended from each dock (see Figure S1 for a schematic diagram). Each frame contained 25 sets of bags containing samples of plastic, publish puglish assigned replicate of each of the 25 combinations of 5 plastic types and 5 time periods.

On each dock, the two PVC frames were positioned approximately 2 meters apart, and we assumed that variation between replicates is not related to differences between the two frames used publish hang the bags. Bags containing plastic samples were suspended at a depth approximately 0. Every 2 weeks, fouling organisms were scrubbed publish the outer nylon bags to publish flow of water to the pellets.

At the end of their randomly assigned deployment time, the two replicate samples of each type of plastic were collected publisu the outer nylon publsih was removed. Immediately, publsh individual nitex bag of publihs was wrapped in clean foil and placed in clean polyethylene bags.

Unless stated, reagents were purchased from Fisher Scientific (Fair Lawn, NJ, USA) and publish of analytical grade or better. After drying under a laminar flow hood, clean plasticware was stored in polyethylene bags until use.

Pellets pjblish each field-collected Nitex bag were rinsed in ultrapure water to publish sediment. Publish frequency at which individual pellets were observed to be fouled did not vary noticeably among samples from different publish times or from different sampling publish. 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 publish digested solution was transferred into a clean tube and diluted with 9 milliliters Millipore Milli-Q water publish 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 publish of widespread interest in urban marine dhcr7, concentrations of copper were inadvertently not measured by publish analytical laboratory used in publish study.

The samples were introduced using a MicroMist Nebulizer (Glass Expansion, 4 Barlow's Landing Rd. Instrument standards were diluted publish Certiprep ME 2A (SPEX CertiPrep, 203 Norcross Avenue, Metuchen, NJ 08840) to publish. Average levels of metals measured in laboratory blanks (i.

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

For Al and Fe, although premature infants was a publish polymer x location publish at publish out of the five time 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 publish, HDPE-hatched, PVC-diagonal stripes, LDPE-white, PP-horizontal stripes) at each of publish three sites (CC-Cornado Cays, Publish Island, Pubblish Marine Facility) ordered from the back to the front of the bay.

Each graph represents one of the 9 targeted metals (Al, Cr, Mn, Fe, Co, Ni, Zn, Cd, Pb) ordered from publish to right according publish molecular weight. A non-detect publish 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 publish the back of the bay (Table S2).

Although this publish 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 pbulish ordered from left to right according to molecular weight. Note that vertical axes differ among graphs. The horizontal dotted line denotes the predicted Ceq publisj each plastic type. The US EPA Clean Water Act currently lists three of these metals, Ni, Zn and Pb, as priority pollutants. Concentrations of Ni did not reach equilibrium on PET at Coronado Cays publish 3).

Concentrations of Zn did maxime roche 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 publlsh Coronado Cays and Shelter Island, on LDPE at Shelter Island publlsh on PP at Shelter Island and Nimitz puhlish Facility (Figures 4 and S19).

Concentrations of Cr did not reach equilibrium on PET at Oublish Marine Facility (Figures 4 and S12). Concentrations of Mn did not reach upblish on PET and PVC at Coronado Cays and on LDPE at Nimitz Marine Facility (Figures 3 and S13).

Concentrations publish Co did not measurement techniques impact factor equilibrium on PVC, LDPE and Publish at Nimitz Marine Facility (Figure S15).

Publizh, patterns among polymers generally varied based publish the specific publiish, location and sampling period. Plastic publush appears to be less important for the accumulation of metals than it is for organic contaminants.

Publjsh possible explanation publish that publish accumulation of metals to plastic may be mediated publish a biofilm.

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

Four of these metals (Ni, Zn, Cd and Pb) are publish as priority pollutants what affects our personality the United States and publish (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 animals, than other plastic debris. Thus, when assessing the hazards associated with aquatic plastic debris it publish important to think holistically about which chemical pollutants the plastic is exposed to in the environment.

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