Environmental Engineering Reference
In-Depth Information
Table 3.2
World reserves and production of phosphate rock expressed as a thousand tonne.
Country
Production (2008)
Reserves*
Reserve base
†
United States
30,900
1,200,000
3,400,000
Australia
2,300
82,000
1,200,000
Brazil
6,000
260,000
370,000
Canada
800
25,000
200,000
China
50,000
4,100,000
10,000,000
Egypt
3,000
100,000
760,000
Israel
3,100
180,000
800,000
Jordan
5,500
900,000
1,700,000
Morocco and Western Sahara
28,000
5,700,000
21,000,000
Russia
11,000
200,000
1,000,000
Senegal
600
50,000
160,000
South Africa
2,400
1,500,000
2,500,000
Syria
3,700
100,000
800,000
Togo
800
30,000
60,000
Tunisia
7,800
100,000
600,000
Other countries
10,800
890,000
2,200,000
World total (rounded)
167,000
15,000,000
47,000,000
* That part of the reserve base which could be economically extracted or produced at the time of determination.
†
The reserve base includes those resources that are currently economic (reserves), marginally economic (marginal reserves),
and some of those that are currently subeconomic (subeconomic resources).
Adapted from United States Geological Survey (USGS), 2009a.
wastewater treatment plants and then are discharged to rivers that transport them to oceans.
Similarly, waste generated by animal production contains important amounts of phosphorus
that end up, in most cases, carried to freshwater bodies.
The discharge of phosphorus into freshwater systems leads to eutrophication (excess of
nutrients) that promotes the development of algae and other invasive species. The fast devel-
opment of photosynthetic organisms decreases the dissolved oxygen in water (hypoxia)and
kills fish and other freshwater animals.
In contrast with freshwater bodies, coastal marine waters are limited generally in nitrogen
instead of phosphorus. Therefore, the constant discharge of nitrogen from agricultural and
human excretions leads to eutrophication of costal ecosystems with similar consequences of
lakes with excess phosphate.
Potassium is an important nutrient for plants' development and its source is potash, a
salt rich in soluble potassium. Potash is produced from underground mines, from solution
mining operations, and from evaporation of lake and subsurface brines. The advantage of
potassium over phosphorus is that its majority does not end up in the edible parts of fruits
and vegetables (USGS, 1999). Nevertheless, constant fertilization with potash produces the
dispersion of a resource that is concentrated in limited amounts (see Table 3.3 for potash
world reserves).
Besides the depletion of resources to produce phosphate and potassium fertilizers, fossil
fuels are used in the process. Significant amounts of diesel are used to extract the minerals
from the ground and transport them to processing plants where they are transformed into com-
mercial fertilizers. At this step, electricity runs electrical motors and natural gas burned in
boilers generates steam that is used in the process.
