Asia bottles civilisation contamination damage danger death decay Dirt dirty disaster disposal dump ecological ecology ecosystem Eichhornia environment environmental fish garbage grunge hyacinth invasive nature patterns of decay plastic poison pollute polluted pollution poor problem problems recycle river rubbish scrap sewage toxic trash unhygienic urban urban decay warning waste water acuática agua bloom camalote estanque floating flor flores flotante flower invasora jacinto de agua lila lilac morada ornamental pest plaga plant planta pond purple violeta