Irrigation Water.html

Concentrations of Mercury, Lead, Chromium, Cadmium, Arsenic and Aluminum in Irrigation Water Wells and Wastewaters Used for Agriculture in Mashhad, Northeastern Iran

SR Mousavi1, M Balali-Mood1, B Riahi-Zanjani1,
H Yousefzadeh2, M Sadeghi1

1Medical Toxicology Research Center,Department of Clinical toxicology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

2Department of Cellular and Molecular Immunology, Mashhad University of Medical Sciences, Mashhad, Iran

Correspondence to Mahmood Sadeghi, MSc, Medical Toxicology Research Center, Department of Clinical toxicology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

Tel: +98-511-800-2464

Fax: +98-511-800-2467


Received: Nov 5, 2012

Accepted: Jan 20, 2013


Background: Contamination of water by toxic chemicals has become commonly recognized as an environmental concern. Based on our clinical observation in Mashhad, northeastern Iran, many people might be at risk of exposure to high concentrations of toxic heavy metals in water. Because wastewater effluents as well as water wells have been commonly used for irrigation over the past decades, there has been some concern on the toxic metal exposure of crops and vegetables irrigated with the contaminated water.

Objective: To measure the concentrations of mercury, lead, chromium, cadmium, arsenic and aluminium in irrigation water wells and wastewaters used for agriculture in Mashhad, northeastern Iran.

Methods: 36 samples were taken from irrigation water wells and a wastewater refinery in North of Mashhad at four times—May 2008, March 2009, and June and July 2010. Atomic absorption spectrometry was used to measure the concentration of toxic metals. Graphite furnace was used for the measurement of lead, chromium, cadmium and aluminum. Mercury and arsenic concentrations were measured by mercury/hydride system.

Results: Chromium, cadmium, lead and arsenic concentrations in the samples were within the standard range. The mean±SD concentration of mercury in irrigation wells (1.02±0.40 µg/L) exceeded the FAO maximum permissible levels. The aluminum concentration in irrigation water varied significantly from month to month (p=0.03). All wastewater samples contained high mercury concentrations (6.64±2.53 µg/L).

Conclusion: For high mercury and aluminum concentrations, the water sources studied should not be used for agricultural use. Regular monitoring of the level of heavy metals in water and employing the necessary environmental interventions in this area are strongly recommended.

Keywords: Food contamination; Agriculture; Sewage; Spectrophotometry, atomic; Metals, heavy; Water pollution, chemical; Water wells; Waste water; Iran


Agricultural, industrial and anthropogenic wastes may contaminate irrigation water wells and wastewaters with toxic heavy metals.1-3 Mandour and Azab reported aluminum, cadmium, nickel and lead contamination in surface drinking water of Dakahlia Governorate, Egypt.4,5 There is an increasing awareness of the hazards posed by environmental contamination with toxic elements.6 Many studies have so far been published on heavy metal contamination because of their effects on human health and ecosystem.7-9 The use of industrial or municipal wastewater for irrigation in agriculture is common in many parts of the world; this has created opportunities and problems.10-12 The advantages of wastewater irrigation are to disposal of wastes and preparing valuable plant nutrients.13 However, it seems that heavy metal content of soil is increased by wastewater irrigation.12-14 Several studies from developing countries reported toxic metal contamination in wastewaters.14-17

Heavy metals such as lead, mercury, cadmium, chromium, arsenic and aluminum have harmful effects on human health. The health effects of human exposure to these environmental pollutants are well documented. Some of these are nervous system and brain damage, kidney dysfunction and cancer.18

So far, many analytical techniques have been proposed for the measurement of concentrations of heavy metals in water samples; those include spectrophotometry,19 ion chromatography,20 atomic absorption spectrometry,21,22 inductively coupled plasma atomic emission spectrometry (ICP-AES)23,24 and near-infrared spectroscopy25.

Industrial and home wastewater effluents as well as irrigation water wells have been commonly used for irrigation of agricultural lands for decades. For the concerns on the safety of crops and vegetables irrigated with contaminated water and refined wastewater, we therefore, conducted this study in an area near Mashhad, northeastern Iran, to measure the levels of mercury, lead, chromium, cadmium, arsenic and aluminum in irrigation water wells and wastewater stations, which were used for irrigation of the surrounding agricultural lands.

Materials and Methods

This study was carried out in an area near Mashhad city, the so-called Dashte Mashhad, where is close to an industrial town (Toos) and a wastewater refinery (Parkand-Abad). Dashte Mashhad is almost 3351 km2 wide and located in the Northeast of Iran. Figure 1 shows the study area, as well as the positions of the industrial town and wastewater refinery.


Figure 1: Map of the study area. 'I' stands for “irrigation water” and 'W' stands for “wastewater” sampling sites

Wastewaters are one of the sources for irrigation in Dashte Mashhad. There are plants of fluorescent lamps, batteries and similar chemical industries in Toos industrial town which is located closely above the level of agricultural water wells. Their wastes contain mercury, lead and probably other heavy metals. Since there was no appropriate wastewater system for the industrial town, it was very likely that wastewaters of the chemical industries could be the source of the water wells pollution by toxic metals.

Possible sources of contamination were identified as four main irrigation wells, the only wastewater pipe of Toos industrial town and all entering and influent of Parkand-Abad refinery. The entrance of wastewater pipe to Kashaf river was also sampled. Sampling was done in May 2008, March 2009, and June and July 2010. Water samples were collected in 1-L polyethylene bottles. Nitric acid, as preservative, was added to the containers immediately after collecting the samples. The bottles were then labeled and stored in the refrigerator until testing.

Concentrations of lead, chromium, cadmium and aluminum were measured by atomic absorption spectrometric method using graphite furnace (Perkin Elmer model 3030, USA); mercury and arsenic were measured by a mercury/hydride system. The reliability of the method was evaluated by spiking heavy metals into five samples, determining recovery, detection limit and accuracy parameters.26 The accuracy for determination of aluminum, arsenic, cadmium, chromium, mercury and lead were 97.5%, 98.2%, 99.2%, 99.0%, 98.4% and 99.4%, respectively.

The heavy metals levels were compared to the maximum permissible levels of heavy metals in agricultural water set by the Food and Agricultural Organization (FAO).27 The FAO guidelines for mercury, lead, chromium, cadmium, aluminum and arsenic in agricultural water are 1, 500, 100, 10, 100 and 500 µg/L, respectively.

Data were analyzed by SPSS® for Windows® ver 11.5 (SPSS Inc, Chicago, Il, USA). Results are presented as mean±SD. A p value <0.05 was considered statistically significant.


A total of 36 samples were collected and examined for the heavy metals. The concentrations of heavy metals in irrigation water wells and wastewater stations are summarized in Table 1. The mean±SD level of mercury in irrigation water wells (1.02±0.40 µg/L) was more than the permissible limit (1 µg/L). Since wastewater was used for irrigation, the permissible concentration standards for irrigation water were used. The wastewater samples had a mean±SD mercury contamination of 6.64±2.53 µg/L.

Table 1: Mean±SD concentrations of the heavy metals (µg/L) in irrigation water and wastewater samples taken from Dashte Mashhad






















The concentrations of heavy metal concentrations in irrigation water and wastewater changed over time (Figs 2 and 3). The change in aluminum concentration in irrigation water was significantly (p=0.03) changed over time. Concentrations of mercury, arsenic, lead and cadmium in wastewaters also changed significantly (p<0.05) over time (Fig 3).


Figure 2: Mean concentration of the heavy metals (µg/L) in the irrigation water wells. Error bars represent SD.


Figure 3: Mean concentration of the heavy metals (µg/L) in wastewaters. Error bars represent SD.


Concentrations of mercury and arsenic in irrigation water and wastewater were compared between each two individual months and showed significant differences in The concentrations of mercury in irrigation water and wastewaters measured in March 2008 were significantly (p=0.038) different from those in July 2010; the values had also significant (p=0.042) variation from May 2008 to March 2009. The arsenic concentration in wastewaters measured in May 2008 was also significantly (p=0.04) different from that in June 2010.


High levels of heavy metals in food result in several acute and chronic health effects. Examples of chronic health problems include cancer, birth defects, disorders of the nervous system, and impairment of the immune system.28 Because of industrial and agricultural operations in the study region, there are toxic heavy metals in the groundwater that lead to the contamination of drinking water, vegetables and crops; this may in turn cause lead and cadmium-induced diseases (e.g., renal failure) or chromium-induced hair loss.29

Six months sampling from a hospital sewage plant and an industrial plant in Abu Dhabi30 revealed a mercury concentration of up to 500 ng/g. Concentrations of cadmium and lead measured in a local river for irrigation in Shahre Rey, Iran31 were 80 and 60 µg/L, respectively. All these measurements were higher than that found in our study. Concentrations of arsenic, cadmium and chromium in effluents used for irrigation in two parts of India2,3 were 584, 321 and 429 µg/L and 592, 431 and 457 µg/L, respectively; these were also higher than those recorded in our study.

Significant variation observed in the concentrations of mercury and arsenic in wastewaters is probably the result of industrial operations and the subsequent accumulation of pollutants. The wastes of many manufacturers in the region contain mercury. High levels of mercury in irrigation water wells are probably originated from the industrial town and the refinery. For the high concentrations of mercury in water wells of this area, it is strongly recommended not to use these wells for agriculture.

Contamination of wastewaters with aluminum is probably due to aluminum blades used in the refinery for stirring and treatment of the wastewater. Because of high mercury and aluminum concentration in the output of the refinery, the treated wastewater should also not be used for agriculture.

Because the water used for irrigation in Dashte Mashhad, either taken from the wells or refinery wastewaters, are significantly contaminated with heavy metals—particularly mercury, arsenic and aluminum, these sources should not be used for agriculture. Furthermore, because of the variance observed in the concentration of heavy metals over months of the year, regular measurements of heavy metals in irrigation water and wastewaters used for agriculture are necessary.

Since the inappropriate waste management in industrial factories operational in this region is probably the main cause of contamination of soil and water with heavy metals, more intense audit and monitoring of waste management as well as establishment of new industrial plants in the region should be considered. These industries should consider removing the toxic elements such as mercury from their effluent.

Our study had some limitations. For example, due to some technical difficulties and lack of co-ordination between the relevant organizations, it was not possible to carry out samplings regularly. However, the findings are conclusive.


The authors are grateful to Mr. Kazem Eshaghian for his cooperation in sampling and Mrs. Mahdizadeh for her assistance. The project was carried out by financial support of the Regional Water Organization.

Conflicts of Interest: None declared.


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  • Contamination of surface drinking water with toxic heavy metals is very important.
  • The use of industrial or municipal wastewater for irrigation in agriculture is common in many parts of the world.
  • For high mercury and aluminum concentrations, the water sources in Dashte Mashhad, Mashhad, northeastern Iran, should not be used for agricultural use.

Cite this article as: Mousavi SR, Balali-Mood M, Riahi-Zanjani B, et al. Concentrations of mercury, lead, chromium, cadmium, arsenic and aluminum in irrigation water wells and wastewaters used for agriculture in Mashhad, northeastern Iran. Int J Occup Environ Med 2013;4:80-86.

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