•  Nitrate concentration in streams and groundwater.

•  Total nitrogen concentration in streams, lakes, reservoirs, and estuaries.

•  Total phosphorus concentration in streams, lakes, reservoirs, and estuaries.

•  Nitrate loading to streams and groundwater.

•  Total phosphorus loading to streams.

•  Herbicide concentrations in streams.

•  Herbicide loading to streams.

•  Metal concentrations in streams.

•  Metal concentrations in cultures.

•  Salinity of groundwater.

5.1.8 Information and Data Gaps

Good design and engineering would minimize the potential for releases of water and nutrients from open-pond systems to surface water and to ground water. Toxicant concentrations (for example, metals) need to be characterized, particularly if wastewater or produced water is used as culture medium. Information on the nutrient removal efficiencies of commercial-scale facilities would be needed if algal biofuel production is to be combined with wastewater treatment.

5.2 LAND-USE CHANGE

5.2.1 Potential Environmental Effects

Land-use change is a change in anthropogenic activities on land, which often is characterized in part by a change in land cover, including the dominant vegetation. Land-use changes play a role in the sustainability of algal biofuel development because of associated environmental effects, such as net GHG emissions, changes in biodiversity, and changes in ecosystem services such as food production. Moreover, there is growing societal concern about the spatial and temporal scales of some types of conversions, such as deforestation and urbanization. The impacts of algal biofuel development will depend in part on the type of land conversion, the extent (area) of land use that has changed, the intensity of land disturbance and management, and the duration of the change (for example, whether it is reversible).

Commercial-scale production of algal biofuels will require substantial land area for each facility (see Chapter 4), and the large-scale deployment of algal biofuels will lead to conversion of lands from other existing uses. Land conversion for ponds, processing facilities, and refineries for most products will be localized, and potential land conversion for related infrastructure, such as roads and power lines to the facilities, will be more diffuse and will involve linear features. This section focuses on land-use change (LUC) associated with algae cultivation, because change associated with feedstock processing or refining facilities is not different in kind from that of other liquid fuel sources.

High-value lands used by agriculture, by other commodity industries, and for residential purposes are unlikely to be used for algae cultivation because algae cultivation does not require fertile soils and because capital and operating costs would have to be kept low for algal biofuel companies to operate close to the profit margin (Table 5-2). Similarly, the conversion of forestland is unlikely because of the high costs of clearing and site preparation and the high value for residential or recreational use. Land-use change for algal biofuels is



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