Jitendra Pandey

Accumulation of heavy metals in dietary vegetables and cultivated soil horizon in organic farming system in relation to atmospheric deposition in a seasonally dry tropical region of India

Increasing consciousness about future sustainable agriculture and hazard free food production has lead organic farming to be a globally emerging alternative farm practice. We investigated the accumulation of air-borne heavy metals in edible parts of vegetables and in cultivated soil horizon in organic farming system in a low rain fall tropical region of India. The factorial design of whole experiment consisted of six vegetable crops (tomato, egg plant, spinach, amaranthus, carrot and radish) × two treatments (organic farming in open field and organic farming in glasshouse (OFG)) × seven independent harvest of each crop. The results indicated that except for Pb, atmospheric deposition of heavy metals increased consistently on time scale. Concentrations of heavy metals in cultivated soil horizon and in edible parts of open field grown vegetables increased over time and were significantly higher than those recorded in OFG plots. Increased contents of heavy metals in open field altered soil porosity, bulk density, water holding capacity, microbial biomass carbon, substrate-induced respiration, alkaline phosphatase and fluorescein diacetate hydrolytic activities. Vegetable concentrations of heavy metal appeared in the order Zn > Pb > Cu > Ni > Cd and were maximum in leaves (spinach and amaranths) followed by fruits (tomato and egg plant) and minimum in roots (carrot and radish). Multiple regression analysis indicated that the major contribution of most heavy metals to vegetable leaves was from atmosphere. For roots however, soil appeared to be equally important. The study suggests that if the present trend of atmospheric deposition is continued, it will lead to a destabilizing effect on this sustainable agricultural practice and will increase the dietary intake of toxic metals.

Air pollution tolerance index of plants

In order to evaluate the susceptibility level of plants to air pollutants, four parameters, namely ascorbic acid, chlorophyll, relative water content, and leaf-extract pH, were determined and computed together in a formulation signifying the air pollution tolerance index (APTI) of plants. APTI values of 69 plant species, including herbs shrubs and trees, growing in the urban-industrial Lahartara region of Varanasi were estimated. Plants with a high index value were tolerant to air pollutants and vice-versa. On the basis of their indices, different plant groups were categorized into sensitive, intermediate, moderately tolerant plant groups were categorized into sensitive, intermediate, moderately gigantea, C. roseus, etc. were tolerant and D. sissoo, L. chinensis, C. carandus, C. rottleri, etc. were sensitive to air pollutant. The susceptibility level of plants to air pollution, as indicated through their index values, compared well with the responses of plants observed under laboratory and field experiments. The APTI determination provides a reliable method for screening sensitive/tolerant plants under field conditions where the air-shed is contamined by a variety of pollutants

Air pollutant concentrations in Varanasi, India

This study reports the diurnal patterns in the concentrations of ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and total suspended particulate matter (TSP) in the urban atmosphere of Varanasi city in India during 1989. The city was divided into five zones and three monitoring stations were selected in each zone. Ambient concentrations of NO2 and SO2 were maximum during winter but ozone and TSP concentrations were highest during summer. The measured maximum concentrations (2-h average) were 150 and 231 μg m−3 (0.078 and 0.086 ppm) for NO2 and SO2, respectively, for the winter season. Ozone and TSP concentrations reached a maximum of 160 (0.08 ppm) and 733 μg m−3, respectively, in the summer. NO2 and SO2 concentrations peaked in the morning and evening. Peak concentrations of O3 occurred in the afternoon, generally between noon and 4 p.m. Maximum concentrations of O3, NO2, SO2 and TSP were measured in zones I and II, and minimum in zone V.

Dietary intake of pollutant aerosols via vegetables influenced by atmospheric deposition and wastewater irrigation.

Pot culture experiments were conducted to study dietary intake of heavy metals via vegetables, spinach (Spinacia oleracea L.), radish (Raphanus sativus L.) and tomato (Lycopersicon esculentum Mill) grown under the influence of atmospheric deposition and wastewater irrigation. The results indicated substantial accumulation of heavy metals in vegetables, which contribute significantly to dietary intake of total heavy metals ranging from 1.34 to 110.40 μg g⁻¹ through leaves (spinach), 1.04 to 105.86 μg g⁻¹ through root (radish) and 0.608 to 82.19 μg g⁻¹ through fruits (tomato). Concentration of Cd, Ni and Pb in vegetables exceeded the safe limits of Prevention of Food Adulteration Act 1954. Health risk index for Cd and Pb exceeded the safe limits set by the United States Environmental Protection Agency. The study indicated that the atmospheric depositions as well as wastewater irrigation have significantly elevated the levels of heavy metals in dietary vegetables presenting a significant threat for the health of users.

Ozone : concentration variabilities in a seasonally dry tropical climate

Abstract This paper reports seasonal and diurnal variations in the ambient air concentrations of ozone in Varanasi city, India for the years 1989 and 1990. Different monitoring zones were established in the city on the basis of pollution sources, traffic densities, and structure of built-up areas. At most of the monitoring stations, two-hourly ozone concentrations frequently exceeded 60 μg m −3 (0.03 ppm) during summer months. However, the zone dominated by residential colonies, offices, and cultivated land showed maximum O 3 concentrations less than 60 μg m −3 (0.03 ppm). Higher concentrations of ozone were mainly recorded in warmer months between 11 am to 4 pm. The highest concentration (2-h mean) of 160 μg m −3 (0.08 ppm) O 3 was recorded in the month of April at Zone I which was mainly due to emissions from heavy-duty automobiles. Monthly average ozone concentrations were significantly correlated with temperature (r = 0.69), relative humidity (r = 0.81), wind speed (r = 0.76), and atmospheric pressure (r = −0.46). The frequency distribution of 2-h mean ozone concentrations was close to the logarithmic normal. Maximum 2-h mean O 3 concentrations in some areas of Varanasi city were above the limit that has been shown to cause significant vegetation damage. The temporal variation in ozone concentrations was mainly due to the variations in meteorological conditions.

Evaluation of air pollution phytotoxicity in a seasonally dry tropical urban environment

This study was conducted in the urban environment of Varanasi, India, to evaluate the plant responses to urban air pollution. Twenty sites were selected in four different zones of the city. At each site, seven woody perennials of same age classes were selected. Out of the four zones (I, II, III and IV), zone IV was used as a reference (control) zone as it received the minimum pollution input. Plant species growing in polluted and control areas were compared with respect to foliar dust load, per cent leaf area injury, leaf area, specific leaf weight and chlorophyll, ascorbic acid, SO42−S and total N concentration in the leaves. Results indicated that the air pollution level in Varanasi causes leaf damage, reduces leaf area, specific leaf weight and chlorophyll, ascorbic acid and total N concentrations in the leaves. Sulphur concentration in leaves increased with increasing level of SO2 in the ambient air. The magnitude of such changes was maximum at the zone receiving maximum pollution load. Carissa carandas was found to be the most sensitive species and Bougainvillea spectabilis, the least. The study shows that the urban air pollution level in Varanasi is detrimental for the growth of plants involved in this study.

Heavy metals in sediments of Ganga River: up- and downstream urban influences

Bottom sediment in a river often acts as a sink and indicator of changes in water column and magnitude of anthropogenic influences through air and watersheds. Heavy metal concentration in sediments of Ganga River was studied along a 37-km stretch to assess whether there is a significant difference between sites situated upstream and downstream of Varanasi urban core. Metal concentration increased consistently along the study gradient, indicating the influence of urban sources. Concentration in the river sediment was found highest for Fe followed by Mn, Zn, Cr, Cu, Ni, Pb, and Cd. Mann–Kendall trend analysis showed marked seasonality in the concentration with values being highest in summer and lowest in rainy season. Enrichment factor revealed severe enrichment of Cd and Pb at downstream sites, and principal component analysis segregated sites into four distinct groups indicating source relationships. Concentrations of Cd, Pb, Ni, Cu, and Cr did exceed WHO standards. The study has relevance designing control measures and action plans for reducing sediment contamination in anthropogenic impacted rivers.

Growth responses of tomato plants to low concentrations of sulphur dioxide and nitrogen dioxide

Abstract Forty-five-day-old plants of Lycopersicon esculentum were exposed to 0.1 ppm SO2, 0.2 ppm NO2 and 0.1 ppm SO2 + 0.2 ppm NO2 for 4 h daily for 50 days. Plant height, number of leaves, total leaf area, total leaf biomass, total shoot biomass and total plant biomass were increased by these low dosages. When exposed to either NO2 or SO2 alone, relative growth rate, net assimilation rate, leaf production rate and specific leaf area increased initially but declined after exposure for longer times. Both SO2 and NO2 reduced root growth and resulted in a low root:shoot ratio. Number of leaves, total leaf area, total leaf biomass and leaf area duration increased up to 30 days of both SO2 and NO2 exposure, indicating that the tomato plants in response to SO2 and NO2 allocated a greater proportion of its photoassimilates for growth and development of photosynthetic organs. Chlorophyll concentration increased initially but declined after exposure for longer periods. Foliar N and SO2−4-S content increased in plants exposed to NO2 and SO2, respectively. P content was reduced following exposure to SO2 and NO2 alone or in combination. The study suggests that low dosages of pollutants are fertilizing the plants, promoting vegetative growth at the expense of reproductive growth.

Adaptational strategy of a tropical shrub Carissa Carandas L. to urban air pollution

This paper reports the adaptational response of a tropical shrub Carissa Carandas L. to urban air pollution stress in Varanasi, India. Saplings of C. carandas were grown at a density of one per pot and kept for two years at 25 selected sites in the urban environment. Different sites received different levels of air pollution input. Changes in vegetative growth pattern (leafing and branching), in morphological features and in the distribution of biomass to above and below ground structures were considered in relation to the ambient air quality.Different levels of air pollution input produced different sets of harmful effects. Although the air pollution level at Varanasi reduced the plant height, basal diameter, canopy area, leaf area and total plant biomass of C. carandas, this species retained a major fraction of its photosynthate to above-ground plant parts where foliage assumes predominance. Since carbon gain is dependent not only on the rate of carbon acquisition per unit leaf tissue but also on the amount of photosynthetic tissue present, a shift in relative contribution of photosynthate to leaf production and shoot growth appears to be a pollution-induced adaptive response in C. carandas.

Water Quality Interaction with Alkaline Phosphatase in the Ganga River: Implications for River Health

Carbon, nitrogen and phosphorus inputs through atmospheric deposition, surface runoff and point sources were measured in the Ganga River along a gradient of increasing human pressure. Productivity variables (chlorophyll a, gross primary productivity, biogenic silica and autotrophic index) and heterotrophy (respiration, substrate induced respiration, biological oxygen demand and fluorescein diacetate hydrolysis) showed positive relationships with these inputs. Alkaline phosphatase (AP), however, showed an opposite trend. Because AP is negatively influenced by available P, and eutrophy generates a feedback on P fertilization, the study implies that the alkaline phosphatase can be used as a high quality criterion for assessing river health.