159
specifically with the detergent concentration rather than pH.
The significant uptake of phosphorus in Spirodela polyrrhiza
was recorded in 30, 40, and 50 ppm detergent solution at
almost all pH levels ranging from 6.0 to 8.0 (Table 12.19).
12.3.6.4 Water Quality
Table 12.20 comprises the data on the physico–chemical
characteristics of water with varying concentrations of Surf
Excel analyzed after the growth of Spirodela polyrrhiza. A
glance on the data shows that the turbidity was higher in the
solutions of acidic pH 6.0 than in the solution of alkaline pH
8.0. The turbidity was also found to be higher in the detergent solution of 40 and 50 ppm concentration. The turbidity
of the detergent solutions at all pH levels was higher. The
dissolved oxygen consistently decreased with the increase
in the concentration of Surf Excel at all pH levels. The dissolved oxygen at lower pH showed a significant reduction
even at lower concentration of the detergent. The nitrate content was highest in control at neutral pH. The nitrates at pH
8.0 did not show much variation at 10 ppm concentration.
But at higher concentration (50 ppm), the nitrate contents
were lower at pH 6.5–7.5 than in control (probably owing
to greater uptake). The phosphates were more significantly
related with the concentration of Surf Excel and not with
the pH. The potassium contents were slightly lower in Surf
Excel solutions as compared to control probably owing to
higher uptake of potassium (Table 12.20).
12.4 Discussion
In the screening experiments with 36 selected detergents it
was recorded that the dry weight of both the selected duckweeds increased in response to varying detergent concentrations. The growth, (in the form of dry weight) varied with
the detergent types and its concentrations. There were three
general types of growth pattern. The variation in the type
of growth response may be owing to the variations in the
relative proportion of constituents of the detergents. There
might have been some variation in the relative proportion of
the phosphorus content as well. It is evident from the experiments with varying concentrations of Surf Excel (conducted
in the polyvinyl and earthen pots) that enough phosphorus
was available in the water even after the adequate uptake.
Thus, the variation in phosphorus content alone may have
not caused variation in responses of the duckweeds to the
selected detergents. The detergents used in the present study
might have caused varying degree of changes in the water
quality parameters.
Some of the factors which affects the growth and development of the aquatic plants include turbidity, temperature,
nutrients, dissolved oxygen, CO 2, light, and pH. Shen Dong
Sheng and Shen (2002) noted that light intensity, temperature,
and nutrients (mainly phosphorus and nitrogen) influenced
the algal population in the river network of Zhejiang, China.
The phosphorus was considered to be the major determinant
in regulating the algal biomass (Shen Dong Sheng and Shen
2002, Kwang-Guk et al. 2003). All the 36 detergents studied
might have resulted into the three major sets of aquatic environments with their specific growth responses (Tables 12.5,
12.6, 12.7 and 12.8).
The Surf Excel (a commonly used detergent in India) was
selected for the detailed studies on the responses of two selected weeds. Both the duckweeds (in screening experiment)
showed type-B growth pattern in response to Surf Excel.
The optimum growth of both the duckweeds was observed
at 30 ppm of Surf Excel. The duckweeds were studied for
their growth responses in large 15 L earthen pots and 150 mL
polyvinyl pots to work out the impact of space and volume
of the medium. The aquatic microcosm systems have been
evaluated as a tool for the quantitative description of phytoplankton, bacteria their nutrient relationship and nutrient
cycling in the eutrophication studies (Tsirtsis and Karydis
1997).
In the screening experiments with 36 detergents, three
concentrations of the selected detergents (viz., 10, 30, and
50 ppm) were used to study the growth responses of the selected duckweeds. However, in the earthen pot experiment,
five concentration levels (10, 20, 30, 40, and 50 ppm) of Surf
Excel were used. In the later experiment, the peak of growth
of Lemna minor was observed at 40 ppm level of Surf Excel.
The Surf Excel concentration level up to 50 ppm increased
the dry weight accumulation and uptake of phosphorus and
nitrogen in Lemna minor. The chlorophyll content in Lemna
minor increased only at lower concentrations (Table 12.9).
The varying concentration of Surf Excel changed the
water quality in proportion to their concentration as evident
from the data summarized in Table 12.10. The pH, turbidity, and dissolved oxygen varied noticeably with the detergent concentration. The higher pH in the present study retarded the growth of Lemna minor and Spirodela polyrrhiza
(Tables 12.10 and 12.12). It is evident that in addition to
phosphate availability, the water quality played more effective role in enhancing the growth of the plants. As evident
from the data (Table 12.10), 50 ppm of Surf Excel detergent
at lower pH were significantly more effective in promoting
the growth of Lemna minor as compared to higher pH. The
water quality analysis of earthen pots showed 8.8 ± 0.2 pH at
50 ppm of Surf Excel (Table 12.10).
The availability of ions to plant roots has been found to
be profoundly affected by hydrogen ion concentration. The
monovalent phosphate ion (H 2 PO 4
− ) formed at acidic pH
becomes more readily available to the plants. When the medium approaches towards a more alkaline environment, first
the production of bivalent phosphate (HPO 4
2− ) and thereafter the trivalent phosphate (PO 4
3− ) ions is favored. The biva12 Household Detergents Causing Eutrophication in Freshwater Ecosystems
specifically with the detergent concentration rather than pH.
The significant uptake of phosphorus in Spirodela polyrrhiza
was recorded in 30, 40, and 50 ppm detergent solution at
almost all pH levels ranging from 6.0 to 8.0 (Table 12.19).
12.3.6.4 Water Quality
Table 12.20 comprises the data on the physico–chemical
characteristics of water with varying concentrations of Surf
Excel analyzed after the growth of Spirodela polyrrhiza. A
glance on the data shows that the turbidity was higher in the
solutions of acidic pH 6.0 than in the solution of alkaline pH
8.0. The turbidity was also found to be higher in the detergent solution of 40 and 50 ppm concentration. The turbidity
of the detergent solutions at all pH levels was higher. The
dissolved oxygen consistently decreased with the increase
in the concentration of Surf Excel at all pH levels. The dissolved oxygen at lower pH showed a significant reduction
even at lower concentration of the detergent. The nitrate content was highest in control at neutral pH. The nitrates at pH
8.0 did not show much variation at 10 ppm concentration.
But at higher concentration (50 ppm), the nitrate contents
were lower at pH 6.5–7.5 than in control (probably owing
to greater uptake). The phosphates were more significantly
related with the concentration of Surf Excel and not with
the pH. The potassium contents were slightly lower in Surf
Excel solutions as compared to control probably owing to
higher uptake of potassium (Table 12.20).
12.4 Discussion
In the screening experiments with 36 selected detergents it
was recorded that the dry weight of both the selected duckweeds increased in response to varying detergent concentrations. The growth, (in the form of dry weight) varied with
the detergent types and its concentrations. There were three
general types of growth pattern. The variation in the type
of growth response may be owing to the variations in the
relative proportion of constituents of the detergents. There
might have been some variation in the relative proportion of
the phosphorus content as well. It is evident from the experiments with varying concentrations of Surf Excel (conducted
in the polyvinyl and earthen pots) that enough phosphorus
was available in the water even after the adequate uptake.
Thus, the variation in phosphorus content alone may have
not caused variation in responses of the duckweeds to the
selected detergents. The detergents used in the present study
might have caused varying degree of changes in the water
quality parameters.
Some of the factors which affects the growth and development of the aquatic plants include turbidity, temperature,
nutrients, dissolved oxygen, CO 2, light, and pH. Shen Dong
Sheng and Shen (2002) noted that light intensity, temperature,
and nutrients (mainly phosphorus and nitrogen) influenced
the algal population in the river network of Zhejiang, China.
The phosphorus was considered to be the major determinant
in regulating the algal biomass (Shen Dong Sheng and Shen
2002, Kwang-Guk et al. 2003). All the 36 detergents studied
might have resulted into the three major sets of aquatic environments with their specific growth responses (Tables 12.5,
12.6, 12.7 and 12.8).
The Surf Excel (a commonly used detergent in India) was
selected for the detailed studies on the responses of two selected weeds. Both the duckweeds (in screening experiment)
showed type-B growth pattern in response to Surf Excel.
The optimum growth of both the duckweeds was observed
at 30 ppm of Surf Excel. The duckweeds were studied for
their growth responses in large 15 L earthen pots and 150 mL
polyvinyl pots to work out the impact of space and volume
of the medium. The aquatic microcosm systems have been
evaluated as a tool for the quantitative description of phytoplankton, bacteria their nutrient relationship and nutrient
cycling in the eutrophication studies (Tsirtsis and Karydis
1997).
In the screening experiments with 36 detergents, three
concentrations of the selected detergents (viz., 10, 30, and
50 ppm) were used to study the growth responses of the selected duckweeds. However, in the earthen pot experiment,
five concentration levels (10, 20, 30, 40, and 50 ppm) of Surf
Excel were used. In the later experiment, the peak of growth
of Lemna minor was observed at 40 ppm level of Surf Excel.
The Surf Excel concentration level up to 50 ppm increased
the dry weight accumulation and uptake of phosphorus and
nitrogen in Lemna minor. The chlorophyll content in Lemna
minor increased only at lower concentrations (Table 12.9).
The varying concentration of Surf Excel changed the
water quality in proportion to their concentration as evident
from the data summarized in Table 12.10. The pH, turbidity, and dissolved oxygen varied noticeably with the detergent concentration. The higher pH in the present study retarded the growth of Lemna minor and Spirodela polyrrhiza
(Tables 12.10 and 12.12). It is evident that in addition to
phosphate availability, the water quality played more effective role in enhancing the growth of the plants. As evident
from the data (Table 12.10), 50 ppm of Surf Excel detergent
at lower pH were significantly more effective in promoting
the growth of Lemna minor as compared to higher pH. The
water quality analysis of earthen pots showed 8.8 ± 0.2 pH at
50 ppm of Surf Excel (Table 12.10).
The availability of ions to plant roots has been found to
be profoundly affected by hydrogen ion concentration. The
monovalent phosphate ion (H 2 PO 4
− ) formed at acidic pH
becomes more readily available to the plants. When the medium approaches towards a more alkaline environment, first
the production of bivalent phosphate (HPO 4
2− ) and thereafter the trivalent phosphate (PO 4
3− ) ions is favored. The biva12 Household Detergents Causing Eutrophication in Freshwater Ecosystems