Botkin Environmental Science Earth as Living Planet 8th txtbk

19.8 Surface-Water Pollution 411
(a)
FIGURE 19.10 The Cuyahoga River (lower left) flows toward
Cleveland, Ohio, and the Erie Canal (lower right) is in the Cuyahoga
National Park. The skyline is that of industrial Cleveland.
Two of the newer techniques are nanotechnology and
urban-runoff naturalization. Nanotechnology uses extremely
small material particles (10 −9 m size, about 100,000 times
thinner than human hair) designed for a number of purposes.
Some nano particles can capture heavy metals such as lead,
mercury, and arsenic from water. The nano particles have a
tremendous surface area to volume. One cubic centimeter of
particles has a surface area exceeding a football field and can
take up over 50% of its weight in heavy metals. 22
(b)
Bioswale
FIGURE 19.12 Bioswales collect runoff from Manzaneta Village
Dormitory Complex at the University of California, Santa Barbara.
(a) Plants in bioswales (b) help filter water and remove nutrients,
reducing cultural eutrophication.
Drain
from roof
X
Drain
from roof
Urban-runoff naturalization is an emerging bio -
engineering technology to treat urban runoff before it reaches
streams, lakes, or the ocean. One method is to create a “closedloop”
local landscape that does not allow runoff to leave a
property. Plants may be located as “rain gardens” below downspouts,
and parking-lot drainage is directed to plants instead
of the street (Figure 19.11). 23 Runoff from five large building
complexes such as Manzaneta Village at the University of
Basin with
water plants
California, Santa Barbara, can be directed to engineered
wetlands (bioswales) where wetland plants remove contaminants
before water is discharged into the campus
lagoon and then the ocean. Removing nutrients has
Water diverted
to other gardens
helped reduce cultural eutrophication of the lagoon
(Figure 19.12).
Rain garden
Overflow to
other gardens
FIGURE 19.11 Water from roof runoff is part of
a closed loop where water remains on the site and is used in rain
gardens. Runoff from parking areas is diverted to other gardens.