Continuous input of plastic litter in ocean and coastal environments achieved alarming levels that are exposing new settings in natural systems. While novel plastic debris pollution, with rock-like appearance, has been reported worldwide, fundamentally geological analyses are still lacking. We surveyed the first occurrence of multiple associated plastic debris on a single outcrop located in a remote site (Trindade Island, SE Atlantic Ocean). Even though all plastic debris forms consisted of polypropylene and polyethylene, through a sedimentary approach (cross section, macro, and micro analyses) distinct types were identified. We detected plastiglomerates, geogenic analogous to conglomerates, divided into in situ and clastic types, and formed over beach sediment. We identified plastistones as a new type with homogeneous composition (lacking incorporated materials), geogenic-looking igneous rocks, divided into in situ and clastic types, and formed over rock surfaces. We linked pyroplastics, geogenic analogous to clasts, to clastic plastiglomerates/plastistones, therefore representing clastic types of plastic debris forms. This association was correlated in a depositional system model, which suggests that plastic debris forms are rock synthetic equivalents in which humans act as depositional and post-depositional agents.

In this chapter, we consider the linear radiative transfer model for a passive medium with no intrinsic thermal contributions. The domain is a one-dimensional slab for which reflectivity and transmissivity are determined from the total in- and outgoing radiative fluxes across the boundaries. Further, we assume isotropic scattering in the medium and no emissivity and reflectivity on the boundaries but thermal radiation from the latter and an isotropic incoming radiation from an external source. Our developments are based on the discrete ordinate method in the angular variable and a modified version of the finite volume method in the spatial variable. The solution is obtained by an iterative method, and we present a necessary condition for its convergence based on norm operations.