LEESU

Plastic transport from land to sea may be non-linear with a great influence of tides and wind, in particular downstream. We thus performed tracking of plastic waste using GPS-trackers sealed into floating plastic bottles. Those data are discussed in the following paper: "Transfer dynamic of macroplastics in estuaries – New insights from the Seine estuary: Part 2. Short term dynamic based on GPS-trackers" in Marine Pollution Bulletin. This dataset gathers .csv files each coresponding to a trajectory recorded in the Seine river. Each file name is set as follows: dd_mm_yy_Macroplast_ENPC_GPS IMEI-City. The date and the city are the time and the location of release. ENPC for Ecole National des Ponts et Chaussées (one of the partner institution, with UPEC). Half-submerged and floating bottles were used in pairs to identify changes in trajectories related to windage. To rely each bottle, i.e. each .csv file, to its respective buoyancy, please refer to the research paper. Data show that 100% plastic debris strand somewhere along their way to the Sea. But, they are frequently remobilized, espacially by tides in the estuary. They can be transported upstream and deposited again. Those processes may greatly delay the transfer of plastics from land to Sea. Increasing the residence time of plastics in rivers may also increase the probability of fragementation into microplastics. Since the probability of stranding is 100% and the time spent stranded up to three times higher than the time spent in water, cleaning riverbanks constitutes the best curative solution to tackle the marine pollution accordingly. Because cleaning rivers from macroplastics with prevention policies and curative actions is far easier than cleaning the open ocean from the resulting microplastics. Data might also be used to constrain modelisation on plastic transport to take into account the stranding/remobilization processes and then better constrain global estimation of plastic input into the Ocean.

Inventory of Microlax packaging collected in the Seine estuary showing date-prints. Rivers are a major transport pathways for plastics from land into the ocean. At the land-ocean interface, estuaries are very specific hydrodynamic systems. However, very little is known about the transport dynamic of plastics in estuaries. Tidal regimes, winds and the mixing of fresh and salt water make the transfer dynamic of plastics complex and nonlinear. Microlax packagings were systematically investigated in different riverbanks of the Seine estuary to identify the share of “old” and “fresh” litter transiting through the estuary toward the ocean. Results show that up to 70% of Microlax were “old” plastic items probably related to the meandering dynamic of the river at large time and space scales, and hydrodynamic conditions at smaller scales. This contributes together to increase the residence time of plastics into the estuary up to decades with numerous transport, deposit and remobilization cycles. It finally may results in the fragmentation of macroplastics into microplastics well before they reach the ocean.

The reported data have been acquired within a research project investigating the ability of infiltration-based Sustainable Drainage Systems to mitigate pollutant fluxes in stormwater runoff. Sorption experiments have been carried out in batch systems, in order to characterize the sorption behavior of three soils towards copper and zinc, and one soil towards four organic micropollutants: Bisphenol A (BPA), 4-tert-Octylphenol (OP), 4-Nonylphenol (4NP), and Nonylphenol Ethoxylate (NP10). The soil samples originate from three source-control infiltration facilities. • Soil 1 is a sandy loam from a roadside swale; • Soil 2 is a silt loam from a roadside filter strip; • Soil 3 is a sandy clay loam from an infiltration basin. All experiments were carried out in non-competitive systems (i.e., individual contaminants in each batch system). The “reference conditions” corresponded to an electrolyte solution which mimicked the composition of runoff water (Evian and ultrapure water, volumetric ratio of 1:10). The sorption behavior of metals onto soils 1 and 3 was also investigated in different conditions: • 1.0 g/L of sodium chloride, to investigate the effects of deicing salt in runoff water; • 10 mg/L of humic acids, to represent the natural generation of dissolved organic matter in the soil solution. The methodology used to select the experimental conditions is thoroughly described in a research article entitled: “Evaluation of contaminant retention in the soil of Sustainable Drainage Systems: methodological reflections on the determination of sorption isotherms” (Blue-Green Systems 1(1), doi: 10.2166/bgs.2019.196). The appended files present the experimental points of the sorption isotherms for each characterized soil. • Soil 1: metals in the reference conditions (Metals_ref), metals with sodium chloride (Metals_NaCl), metals with humic acids (Metals_HA), organic micropollutants; • Soil 2: metals in the reference conditions; • Soil 3: metals in the reference conditions, metals with sodium chloride, metals with humic acids. The concentrations in the dissolved phase are referred to as “X_diss”, where X is the studied species (Cu, Zn, etc.), and are expressed in mg/L. BPA stands for Bisphenol A, OP stands for 4-tert-Octylphenol, 4NP stands for 4-Nonylphenol, and NP10 stands for Nonylphenol Ethoxylate. The contents in the solid phase are referred to as “X_sorb” and are expressed in mg/kg. In case the tests were carried out in duplicates, the columns “X_diss” and “X_sorb” correspond to the mean values of the experiments; two additional columns, referred to as “sdX_diss” and “sdX_sorb”, provide the standard deviations (also expressed in mg/L and mg/kg, respectively).

This data includes micropollutant concentrations evaluated in untreated road runoff, water drained from a biofiltration swale, water drained from a vegetative filter strip and the filter media from the biofiltration swale produced on the Compans study site as a part of the Roulépur research project. Sampling and analytical methods are detailed in Field performance of two biofiltration systems treating micropollutants from road runoff and Retention and transport processes of particulate and dissolved micropollutants in stormwater biofilters treating road runoff. Basic characteristics of sampled rain events are provided in "Rain event characteristics," while locations of soil sample collection within the biofiltration swale are provided in the "Location of BFS soil samples."

Inventory of plastic items collected in a quadrat of 1m2 in a historical polluted shore in the Seine river (downstream of the estuary; Lat. 49.4339; Long. 0.6160). Data are representative of the historical plastic pollution occurring in this river with few items dated from 1965, 1974, 1983, 1992 or 2010. Plastic items were classified according to OSPAR and MSFD classifications, which give insights about the origin of the items and their chemical composition. A total of 20 259 plastic debris were individually counted, classified and weighted by category. Those plastic debris are more than 150% heavier in mass (> 4kg) than organic debris, i.e. dead vegetation and gastropod shells, found in this kind of dry march surrounded by reedbeds. The Top 3 categories of items collected are plastic preproduction pellets, unidentified plastic fragments and plastic sticks (cotton bud and lollipop sticks). Plastic preproduction pellets are 15 times more numerous than gastropod shells. High concentration of pellets could be linked to the vicinity of plastic manufacturers near the sampled site. They represent 50% of the items collected during this campaign but only 5.6% of the mass. In contrast, around 30% of the mass is carried by the unidentified fragments of macroplastics >2.5cm, which only represent 7% of the total items. Hundreds of caps, lids, and rings were also found without their associated bottles, which are often prompt to sink. Furthermore, the dataset refers to specific activities in the estuary with for example 100 g/m2 of polyethylene from shotgun plastic wads related to intense hunting activities. Those items have to be mentioned because they are very common in the estuary and their origin is clearly identified, while alternatives such as biodegradable wads do exist. Reporting number of items, associated mass and volumes will improve conversions of unit for other studies related to river pollution when only one of the units are available. To facilitate conversions, mass per item were also reported for the Top 10 items. In addition, specific items such as plastic tag ties (e.g. textile), or plastic fibers from toilet brushes were unusually reported and should be considered as additional categories in OSPAR/MSFD classifications for rivers.

The dataset gives the concentrations of benzalkonium chloride (C12 and C14), a biocide used for tile roof maintenance, to fight against moss, lichens and algae, in the runoff of 10 pilote scale roof frames. Concentrations were measured over a one year period following biocidal tratment of the roof frames. Results show a major contamination of roof runoff immediately after treatment (from 5 to 30 mg/L), followed by an exponential decrease. 175 to 375 mm of cumulated rainfall is needed before the runoff concentrations become less than EC50 values forfish (280mg/l). The residual concentration in the runoff water remains above 4mg/L even after 640 mm of rainfall. The level of benzalkonium ions leaching depends on the roofing material, with lower concentrations and total mass leached from ceramic tiles than from concrete tiles, and on the state of the tile (new or worn out).