Phytodiversity for Metals in Plants Grown in Urban Agricultural Lands Irrigated with Untreated City Effluent

Abstract

In developing countries, farmers use effluent as a source of irrigation and nutrients and the government takes this practice as a viable option for disposal. Sewage samples have hazardous electrical conductivities (EC), sodium adsorption ratios (SARs), and residual sodium carbonate (RSC) for irrigation, but metals were close to upper permissible limits. The EC of saturated soil paste extract (EC_e) ranged from 2.18 to 4.02 dS m^–1 and soil SAR 7.72 to 16.00 in soils 0.2 m deep. Average cadmium (Cd), nickel (Ni), lead (Pb), zinc (Zn), and copper (Cu) in soils ranged from 0.02 to 0.13, 0.00 to 4.45, 2.27 to 4.57, 0.71 to 13.76, and 3.17 to 10.37 mg kg^–1, respectively. Plants acquired metal contents greater than in raw sewage or soils. The wide biodiversity regarding metals in shoots of natural and planted vegetation that receives raw sewage is of practical significance. It seems imperative to study under controlled conditions various plants' metal tolerance and mechanisms of metal partitioning among plant parts.

Keywords:

• Cereals
• city effluent
• fodders
• grasses
• metals
• phytodiversity
• shrubs

Acknowledgment

The authors are thankful to the Agricultural Linkages Program (ALP) of the Pakistan Agricultural Research Council (PARC), Islamabad, Pakistan, for funding these studies under the project “Management Strategies for Metal-Contaminated Soils Receiving City Waste Effluent for Sustainable Crop Production and Food Security.”