Environmental Engineering Reference
In-Depth Information
• Maintaining a lexible and competitive industry which contributes to an economi-
cally viable rural society
• Ensuring effective protection of the environment and prudent use of natural resources
• Conserving and enhancing the landscape, wildlife, cultural and archaeological
value of agricultural land
• Respecting a high level of animal welfare
The U.S. Sustainable Agriculture Network deines sustainable agriculture as “agricul-
tural production and distribution system” that
• Achieves the integration of natural biological cycles and controls
• Protects and renews soil fertility and the natural resource base
• Optimises the management and use of on-farm resources
• Reduces the use of non-renewable resources and purchased production inputs
• Provides an adequate and dependable farm income
• Promotes opportunity in family farming and farm communities
• Minimizes adverse impacts on health, safety, wildlife, water quality, and the
environment
6.6.2 Development of Analytical Tools
A pertinent question that can be posed is:
What methods can we use to determine the impact of the practices on the geoenviron-
ment, and how can we measure and optimize the improvements of these practices so as
not to adversely impact the geoenvironment?
The development of predictive models and sustainability indicators to measure sustainability
progress is an ongoing process to accomplish the task needed to answer the question posed.
We have seen in Chapter 2 that soil can provide means to retain contaminants by nat-
ural attenuation of both organic and inorganic contaminants. This subject is discussed
in greater detail in Chapter 10. For example, in Germany, levels of nitrate as high as
250 mg/L, aluminum as high as 0.64 mg/L and potassium up to 60 mg/L have been found
in the groundwater in agricultural areas (Houben, 2002). Acid rain has decreased the pH
of the soil to 2.75 and that of the groundwater to 3.4, and soil buffering capacity had also
been diminished. Cation exchange, autotrophic denitriication (reaction of nitrate with
FeS
2
) and other natural attenuation mechanisms have restricted the movement of the con-
taminants. Modeling, in Houben's (2002) study, together with determination of the age of
the groundwater, mass balances, and reactive transport were undertaken using hydro-
chemical and geochemical data. The PHREEQC-2 geochemical model was used for the
hydrochemical equilibrium modeling. Sorption and desorption column experiments with
undisturbed samples of sandy sediments for magnesium, sodium, potassium, and alu-
minum ions were performed. Modeling was accurate for most ions with the exception of
potassium. Competition cannot be accounted for in the mass balance approach. Due to
the high velocity of luid low in the columns, there was insuficient time for the nitrate to
react with the pyrite. The models indicated that the contaminants move a few centimeters
per year. A newer version PHREEQC-3 is now available (USGA, 2014). New features were
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