Translocation of Heavy Metals to Tomato ( Solanum lycopersicom L.) Fruit irrigated with

Treated Wastewater

Omar B. AllahhamMinistry of Agriculture

Studies and Policies DepartmentAmman-Jordan

2010

Introduction• A field experiment was conducted to investigate the extent of

translocation of heavy metals to tomato (Solanum lycopersicom L. cvs. ‘GS12 ‘ and ‘RS589956’ ) fruit produced in an open field near to Abu-Nusair Wastewater Treatment Plant , Amman-Jordan . Seedlings were planted during the seasons of 1999 and 2000 and furrow irrigated with different mixtures of potable water to treated wastewater { 100%:0% (1:0, control); 25%:75% (1:3); 50%:50% (1:1); 0%:100% (0:1)}. Tomato fruit , soil and water were examine for heavy metals concentrations, and changes in the pH and electrical conductivity (EC) of the soil were tested .

• Treated wastewater can be used for irrigation under controlled conditions that minimize health risks from pathogenic and toxic pollution to the agricultural products , soil , surface and ground water.

• Treated wastewater is a good source of water to control problems such as wastewater disposition, lack of water availability in arid zones , in addition , it can improve soil quality for crop production.

• Wastewater and sewage effluents contain significant quantities of heavy metals and other substances that may be toxic to people but beneficial to horticultural crops . Metals such as Zn, Cd, Pb, Fe, Cu, Mn, and Mo may be phytotoxic and /or if accumulated in the fruit will impose a health risk to humans.

Introduction

Material and Methods 1. Field experiment

• Tomato seedlings of two cultivars , ‘GS12 ‘ and ‘RS589956’ , were transplanted , with no fertilizers added, in an open field near Abu-Nusair Wastewater Treatment Plant , Amman-Jordan.

• Four treatments were applied in a three replicates , randomized complete block design (RCBD) with split plot arrangements

• Experimental treatments were two cultivars grown with four mixtures , applied by furrow irrigation , of potable water to treated wastewater ratios at the following proportions: 100%:0% (1:0, control); 25%:75% (1:3); 50%:50% (1:1); 0%:100% (0:1) .

2. Sample collection and preparation

• Tomato fruit samples were hand harvested at an advanced full red stage of maturity (vine-ripe) by the end of July till the end of September at weekly intervals between harvests.

• 960 fruits were tested in this experiment.

• Soil samples ( four samples from each depth ) were taken randomly at three depths ( 0-20, 20-40 and 40-60 cm) in each block, Samples were tested for their pH, Electrical Conductivity EC, and Heavy Metals

• Water samples were collected in polypropylene bottles .

Material and Methods

3. Measurements

• The Heavy Metals [ Cadmium (Cd), Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni), Lead (Pb) and Zinc (Zn) ] in the Soil, Water and in Fruit were determined by Graphite Furnace Atomic Absorption Spectrophotometry.

• The electrical conductivity EC of the soil was determined directly by using a Conductivity Meter

• The pH of the soil and water was determined using a pH meter.

Material and Methods

Testa

Prior to planting After harvest Sig LSD

0-20 0-40 40-60

0-20 0-40 40-60

pH 7.46 7.18 7.32 7.60 7.60 8.20 * 0.2182

EC 1418 1604 1431 1710 1064 1676 * 57.57

Cd 0.003 0.015 0.000 0.003 0.018 0.002 * 0.003

Cu 0.595 0.979 0.670 0.82 1.440 0.725 * 0.090

Fe 3.731 5.076 5.426 3.903 5.393 5.942 * 0.437

Mn 3.801 3.665 4.398 3.920 3.904 4.431 * 0.171

Zn 8.112 10.370 11.270 8.920 10.770 11.650 * 0.744

Ni 0.280 0.350 0.270 0.287 0.231 0.297 * 0.024

Pb 0.034 0.051 0.015 0.041 0.030 0.000 * 0.173

Table1:Values of the soil pH, electrical conductivity (µs cm) and heavy metals concentrations (mg/kg) at three depths (0-20, 20-40 and 40-60 cm) in the soil measured prior to planting and after the last harvest following irrigation with treated wastewater.

a Means are the average of 12 samples.* Significant at P ≤ 0.05 .

Results and Discussion

TreatmentHeavy Metals a

Cd Cu Fe Mn Zn Ni Pb

1:0 (control) 0.000 0.330 4.130 0.180 2.460 0.300 0.000

1:1 0.000 0.670 11.980 0.160 3.970 0.550 0.000

1:3 0.000 0.970 12.220 0.260 10.150 0.760 0.000

0:1 0.000 1.360 12.220 0.370 11.790 0.210 0.000

Significance ns * * ns * * ns

LSD - 0.199 2.778 - 2.828 0.509 - a Means are the average of six samples.

*Significant at P ≤ 0.05 .

Table 2 : Heavy metal concentrations in four treatments (control 1:0; 1:1; 1:3 and 0:1 potable water to treated wastewater)

Results and Discussion

Month Heavy Metals a

Cd Cu Fe Mn Zn Ni Pb

July 0.000 1.137 11.700 0.240 7.230 0.680 0.000

August 0.000 0.440 8.190 0.270 5.420 0.100 0.000

September 0.000 0.910 10.530 0.220 8.620 1.340 0.000

Significance ns * * ns * * ns

LSD - 0.730 2.406 - 2.449 0.441 -

a Means are the average of six samples.*Significant at P ≤ 0.05 .

Table 3 : Heavy Metal concentration in the treated wastewater for3 months.

Results and Discussion

TreatmentHeavy Metals a

Cd Cu Fe Mn Zn Ni Pb

GS12

1:0 (control) 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1:1 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1:3 0.000 0.000 0.000 0.013 0.000 0.000 0.000

0:1 0.000 0.000 0.000 0.025 0.025 0.000 0.000

RS589956

1:0 (control) 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1:1 0.000 0.025 0.007 0.000 0.000 0.100 0.000

1:3 0.000 0.050 0.020 0.000 0.050 0.100 0.000

0:1 0.000 0.075 0.035 0.013 0.100 0.300 0.000a Means are the average of 60 fruits.

Table 4: Heavy metal accumulation in the fruit following four irrigation treatments (control 1:0; 1:1; 1:3 and 0:1 potable water to treated wastewater ).

Results and Discussion

These results indicate that,

• The accumulation of heavy metals varied according to cultivar, but was more pronounced with increasing the proportions treated wastewater used in irrigation of plants (the pattern of accumulation follows the order of 1:0 < 1:1 < 1:3 < 0:1).

•In the two cultivars irrigated with potable water (control), no accumulation of heavy metals in the fruit was noticed.

• The two tomato cultivars and the different fruit parts actually differ in their ability to accumulate heavy metals.

Results and Discussion

Conclusions

• Irrigation with treated effluent increased the concentration of Cu, Fe and Mn accumulation at different soil depths, with an increase in the soil pH and salinity.

• The increased levels of Cu, Fe and Mn in the soil was analogous to the increased concentration of these metals in the treated wastewater, indicating repositioning into soil, and then a strong possibility of, at least, partial translocation into the fruit.

• The accumulation of heavy metals in tomato irrigated with treated wastewater was affected according to cultivar, plant part and the use of treated wastewater.

• Tomato fruit from the ‘GS12’ cultivar accumulated Mn and Zn, whereas, fruit from ‘RS589956’ cultivar accumulated Fe, Cu, Mn, Ni and Zn.

• Partial translocation of heavy metals from the soil to the fruit

occurred, due to the presence of these metals in treated effluent, however, the concentration of these heavy metals in the fruit were below the standard limits.

• The use of wastewater in irrigation of tomato fruit might be feasible because of it’s high nutritive value that may improve plant growth, reduce fertilizer application rates and increase productivity of poor soils.

Conclusions

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