PAKISTAN: AT A GLANCE

Area 877406 sq.km

Population 169 millions Female:Male 100:108

ProvinceFour

ClimateDiverse

Cropscotton, wheat, riceSugar cane, citrus and many more

Silk Route

Dravidian Civilization(2800 BC)

Hindus and Nature Worshipers

Harappa City

Mohenjo-Daro City

Sewer drain

Civilization destroyed

by

Aryan Invasion

Drought

Salinity

Present-day Hindu God : Shiva

Alphabets

Kushan-Gandhara Civilization

(200 BC)

Buddhist

TexlaCity

Vihara (temple) and University

Buddha

Persian/Greek

Muslim culture (900 BC

Decedents of the Alexander

the great

Nitrate pollution in vegetable-soil-water ecosystems

Muhammad M. Qureshi

Institute of Pure and Applied BiologyBahauddin Zakariya University

Multan, Pakistan

INTRODUCTION

Excessive N fertilization of crops is considered by producers as an insurance against yield losses in Pakistan.

High nitrate content sewer water for irrigating crops is common in Pakistan.

Increasing nitrate concentration in vegetables, soil and drinking is a public health concern.

Nitrate by itself is non-toxic, however, its metabolites are related to Gastric cancer, Methaemoglobinaemia (blue babies syndrome in infants and elderly people), and blocking of iodide uptake (neuro-transmitter).

The USEPA has set a standard for 10 ppm nitrate in drinking water.

Thus, a reduction of nitrate pollution in plant-soil-water ecosystems is highly desirable.

The present study was conducted to evaluate the extent of nitrate pollution in vegetable-soil-water ecosystems of Punjab, Pakistan

MATERIALS AND METHODS

Data collection

Collection of vegetables

Summer and winter vegetables were collected from all 35 districts in Punjab, Pakistan. In each district, 9 markets and agricultural fields were selected to collect:

Carrot, Eggplant, Okra, Onion, Potato, Radish, Spinach, Squash, Tomato, and Turnip.

Total number of vegetables = 35 x 9 x 2 = 630

Sample collection points from differentlocalities in Punjab, Pakistan

Data collection…...

Collection of soil samples

Soil samples were randomly collected from all 35 districts. In each district, 4 soil samples were collected at 0 - 15, 15 - 30, 30 - 60, 60 - 90, and 90 - 120 cm depth.

Total number of soil samples = 35 x 4 x 5 => 700

Data collection....

Collection of water

Water samples were randomly collected from all 35 districts in summer and winter. In each district, 20 samples of 5 different types of water samples were collected.

Data collection.....

The water samples collected from

Water & Sanitation Authority = Deep well water (~ 400 ft)

Medium Depth Pump = Medium well water (~ 200 ft)

Shallow Depth Pump = Shallow well water (~ 100 ft)

Tube-well = Water collected from rural areas (~ 300 ft)

Bottled water = As standard

Total number of samples = 35 x 2 x 20 => 1400

Sample analysis

Vegetables were analyzed for

Nitrate, phosphorus, potassium, iron, manganese, zinc, copper and boron content

Soils were analyzed for

Nitrate, pH, organic matter, Ec, phosphorus, potassium, iron, manganese, zinc, copper and boron content

Sample analysis……….

Water samples were analyzed for

Nitrate, pH, Ec, bi-carbonate, carbonate, residual

sodium carbonates, sodium absorption ratio, chloride,

sulfate, calcium/magnesium, sodium, phosphorus,

potassium, iron, manganese, zinc, copper and boron

content

Data organization and statistical analyses

Vegetable, soil and water data were organized and a number of suitable predictor variables were created for multi-variate statistics. The variables were:

Division - Different locations

Population density - High, medium and low

Season - Summer and winter

Types of water

Types of vegetables

Agricultural intensity - High, moderate, and low

Sewer water use - High, moderate, and low

Types of soil, and soil depth

Data organization and statistical analyses….

Multi-variate statistics were performed as follows:

Mean and standard error of meanAnalysis of varianceRepeated analysisDuncan multiple range test (DMRT)

To evaluate predictor variables

Simple and interactive effects on nitrate pollution of vegetables, soil and water samples

RESULTS AND DISCUSSION

Winter vegetablesCarrot H-spinachL-spinach Radish Turnip Potato

Nit

rate

co

nc.

(p

pm

)

0

1000

2000

3000

4000

5000

6000

Nitrate concentration in winter vegetables

Summer vegetablesEggplant Okra Squash Onion Tomato

Nit

rate

co

nc.

(p

pm

)

0

500

1000

1500

2000

2500

Nitrate concentration in summer vegetables

Agricultural activityHigh Moderate Low

Veg

etab

le n

itra

te c

on

c. (

pp

m)

0

1000

2000

3000

4000Winter: High in radish/spinach

Summer: High in Eggplant

Nitrate concentration in seasonal vegetables as influenced by agricultural activities

Sewer water-use

High Moderate Low

Ve

ge

tab

le n

itra

te c

on

c.

(pp

m)

0

1000

2000

3000

Winter: High in radish/spinach

Summer: High in Eggplant

Nitrate concentration in seasonal vegetables as influenced by sewer water-use irrigation

Soil texture

Loam S Loam C Loam SC Loam

Ve

ge

tab

le n

itra

te c

on

c.

(pp

m)

0

1000

2000

3000

Winter: High in radish/spinach

Summer: High in Eggplant

Nitrate concentration in seasonal vegetables as influenced by soil texture

Soil nitrate concentration

Different divisions (city)

Bawal DGKhan Faisal Gujan Lahor Multan Rawal Sargo

So

il n

itra

te c

on

c.

(pp

m)

5

10

15

20

25

Summer Winter Average

Seasonal variation in soil nitrate concentrationin different divisions (cities)

Agricultural activity

High Moderate Low

So

il n

itra

te c

on

c. (

pp

m)

6

8

10

12

14

16

18

20Summer Winter Averg

Seasonal variation in soil nitrate concentration as influenced by agricultural activities

Sewer water-useHigh Moderate

So

il n

itra

te c

on

c. (

pp

m)

6

8

10

12

14

16

18

20

Summer Winter Averg

Seasonal variation in soil nitrate concentration in response to sewer water irrigation

Soil textureC Loam Loam SC Loam S Loam

So

il n

itra

te c

on

c. (

pp

m)

5

10

15

20

25

Summer Winter Averg

Seasonal variation in soil nitrate concentration as influenced by soil texture

Soil textureClay loam Loam SC loam S loam Aveg

So

il n

itra

te c

on

c. (

pp

m)

5

10

15

20

25

High Moderate

Nitrate concentration in different textured soil as influenced by agricultural activities

Seasonal variation in soil nitrate concentration as influenced by soil texture

Water nitrate concentration

Different divisions (City)

Bawal DGKhan Faisal Gujan Lahor Multan Rawal Sargo

Wa

ter

nit

rate

co

nc

. (p

pm

)

6

8

10

12

14

Deep well () Med. well Sahllow well TW BW

EPA limit: 10 ppmin drinking water

Nitrate concentration of drinking water sourcesin different divisions (cities)

SeasonSummer Winter

Wat

er n

itra

te c

on

c. (

pp

m)

6

8

10

12

WASA IPMD IPSD TW Averg

Seasonal variation in nitrate concentrationof drinking water sources

Agricultural activityHigh Moderate Low

Wa

ter

nit

rate

co

nc.

(p

pm

)

6

7

8

9

10

11

12WASA IPMD IPSD TW Averg

Nitrate pollution of drinking water sources as influenced by agricultural activities

Sewer water-use

High Moderate

Wa

ter

nit

rate

co

nc

. (p

pm

)

6

8

10

12WASA IPMD IPSD TW Averg

Nitrate pollution of drinking water sources as influenced by sewer water-use

Soil textureC Loam Loam SC Loam S Loam

Wat

er n

itra

te c

on

c. (

pp

m)

6

8

10

12

WASA IPMD IPSD TW Averg

Nitrate pollution of drinking water sources as influenced by soil texture

Conclusions

Greater Ag-intensity and sewer water use for irrigation significantly increased nitrate pollution.

Among the winter vegetables, nitrate accumulation was highest (> 5000 ppm) in radish/spinach and lowest (<1000 ppm) in potatoes.

Among the summer vegetables, nitrate accumulation was highest (~ 2000 ppm) in eggplant and lowest (<1000 ppm) in tomatoes.

Conclusions…..

Averaged across soils, wide-spread nitrate accumulation was found at 2 - 3 feet deep

The nitrate pollution was more pronounced in Sandy Clay Loam than other soils

Conclusions…..

Except deep well, nitrate pollution was more abundant in medium, shallow and tube-well water

The medium, shallow and tube-well drinking water sources were easily affected by agricultural intensity, and sewer water use for irrigating crops