**1. Introduction**

Plastic litter transport in the oceans is a complex phenomenon. In particular, the accumulation of floating debris is a serious problem in the Mediterranean whose hydrodynamics comprise an inflow of surface water from the Atlantic. Several researchers argue that plastic litter is owed in large quantities to traveling vessels [1, 2]. It was argued that about 90% of consumer goods worldwide are moved through an international fleet of cargo ships and most of these goods are contained or wrapped in plastic. Hundreds of containers tip over in rough seas every year and eventually sink and break open, releasing their contents in the ocean. There are several cases of tipped containers that were abandoned on the seafloor. Off the coast of Monterrey Bay, California, over twenty-four containers were lost in a February 2004 storm, one of which is still resting on the seafloor at a depth of about 1500 meters [3].

#### **Figure 1.**

*Drifter starting and ending points in total; starting and ending points in summer and winter. Source: Zambianchi et al. [5].*

Significant plastic loads originate from the shore from various sources such as solid waste dumps, trash conveyed from dry land to shore through rivers, and ocean currents carrying plastic debris from shore to shore. There have been several documentaries by environmental activists showing that rivers are a significant source of solid waste, in particular plastic, that make it into the marine environment [4]. There is no evidence yet that the Mediterranean contains a permanent trash island, but there are signs of litter accumulation. Possible retention areas can be identified by analyzing historical data to compute the probability of debris particles circulating into subbasins. The prediction of the location of floating trash islands becomes feasible once accumulation rates are quantified. Climatological reconstructions were performed using empirical data to study the evolution of litter concentration. Floating litter has a general tendency to concentrate in the southern portion of the Mediterranean [5]. A long-term accumulation of litter seems to be forming in the southern and southeastern Levantine basin.

Based on data collected and processed by Zambianchi et al., note how the near-surface drifters were used to track currents starting from a dispersed status (red dots) and ending along coasts on the East Mediterranean including Lebanon and North African countries [5]. Besides the Adriatic Sea portion, and focusing on the Mediterranean, a large percentage of the ending-points concentrate on the East Mediterranean coast, including Lebanon for both summer and winter seasons (**Figure 1**). As such, the author recommends that special attention be placed on the Levantine area to estimate existing, and forecast potential, plastic debris accumulation.

#### **2. Rivers and challenges related to Land-To-Ocean data**

Several sources of secondary data in the literature provide quantitative estimates about plastic pollution at large. In Europe and the United States, significant progress was made in data collection and availability in relation to weight, volume, and movement of plastics from their original points on dry land to the oceans. However, such data is not as available or reliable in Lebanon and several countries around the Mediterranean. In subsequent parts of this chapter, it is recommended that

#### *Plastic Pollution in the Mediterranean and Public-Private Partnerships to Manage It - A Case… DOI: http://dx.doi.org/10.5772/intechopen.102354*

fieldwork, surveys, and quantification techniques be developed over the next few years to build a database in support of decision-making and policy design.

It is estimated from various studies that about 8 million metric tons of plastic waste per year travels to oceans worldwide and this figure is expected to increase. Studies in the U.S. and Australia present computational models that analyze data from 192 countries with coastlines. Starting from a total amount of solid waste generated as household refuse per capita, an assumption is made about its percentage of plastics. Another assumption is made about the proportion that will reach the oceans to estimate these amounts over the next decade on the basis of census data and population growth [6].

Results from different sources show corroboration that marine plastic debris, which originates inland and travel the most through rivers. A simplified infographic in **Figure 2** shows residential, commercial, and industrial conglomerates mismanaging plastic waste and discarding it in rivers, which in turn carry it to the oceans, terming the process as "plastic load." A study of 57 rivers investigated the concentration of plastic bags, bottles, fibers, and beads, and used the river flow to compute the total weight of plastic transported by the river to the ocean. Plastic litter per day per person was computed for each river and compared with littering onshore. Rivers were proven to be substantial conveyors of plastic debris into the marine environment. Schmidt et al., compiled global data on plastics in the water in rivers of a wide range of flows, including macroplastics (particles >5 mm) and microplastics (particles <5 mm). They identified mismanaged plastic waste (MMPW) discharged over river catchments basins, transported along the main river artery and into the sea [7]. They concluded that the mathematical relationship is not linear. Major rivers surrounded by densely populated areas generate a higher fraction of MMPW. Further, they concluded that 88–95% of the global plastic river load is conveyed through the ten top-ranked rivers, with an estimated range between 410 tons and 4 million tons per year [7]. This large disparity is owed to uncertainty in data. In fact, such a model requires additional parameters related to seasonality, climate change, hydrological factors, and local or regional precipitation [8]. There has been a misconception related to river loads in the articles attributed to ten rivers that these

#### **Figure 2.**

*Rivers exert "plastic loads" from common use and mismanaged plastic waste that make their way to the oceans Schmidt et al. [7].*

ten rivers take 90% of total plastic pollution in the oceans. It should be clarified that the 90% estimate of the top ten river load is a percentage of total river load and not total ocean pollution.
