Trace metal uptake by garden herbs and vegetables.

Area of Science:

• Environmental Science
• Agricultural Science
• Toxicology

Background:

• Agricultural irrigation in Iran frequently utilizes municipal and industrial wastewater.
• This wastewater often contains a diverse range of potentially toxic metals.
• Contamination of crops through irrigation poses risks to plant health and potentially human consumption.

Purpose of the Study:

• To simulate and assess the impact of metal contamination from wastewater on crop plants under controlled laboratory conditions.
• To quantify metal uptake and evaluate the effects on yield across various common crop species.
• To identify plant species with differential accumulation of specific metals.

Main Methods:

• Seven plant species (garden cress, leek, basil, mint, onion, radish, tarragon) were subjected to simulated wastewater irrigation.
• Metals including cadmium, lead, arsenic, chromium, mercury, nickel, copper, zinc, and selenium were applied at a high rate (200 g metal/ha/wk).
• Metal accumulation in plant tissues and effects on plant growth and yield were measured and compared to control groups.

Main Results:

• All tested plant species demonstrated significant uptake of all applied metals compared to controls (p=0.05).
• Plant growth and yield were significantly reduced across all species due to metal exposure (p=0.05).
• Tarragon exhibited the highest accumulation of selenium (16.5±5.8 μg/g), while cadmium and chromium levels were notably high in unspecified species (85±7.4 and 47.6±8.9 μg/g, respectively). Zinc, mercury, and lead levels were similar across species, whereas nickel and copper uptake varied significantly by plant type.

Conclusions:

• Wastewater irrigation with metal contaminants poses a significant threat to crop production, causing reduced yield and growth.
• Plant species differ in their capacity to accumulate specific metals, indicating potential for differential risk assessment.
• Further research is needed to understand the long-term ecological and health implications of metal accumulation in crops irrigated with wastewater.