wiz-icon
MyQuestionIcon
MyQuestionIcon
12
You visited us 12 times! Enjoying our articles? Unlock Full Access!
Question

A large quantity of urban sewage is drained to a nearby river. Which among the given conditions would happen after mixing of sewage into the river?
(i) BOD of receiving water body increases.
(ii) DO of receiving water body decreases.
(iii) It will not cause mortality among fishes and other aquatic creatures.
(iv) It will lead to nutrient enrichment of receiving water body.

A
i, ii and iii
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
i, ii and iv
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
ii and iii
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
iii and iv
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is B i, ii and iv
A large quantity of urban sewage will have a large amount of organic and inorganic material. Due to this, the decomposition of the organic mass will initiate the use of dissolved oxygen and so, the DO of receiving water body decreases. This will cause increase in the biological oxygen demand (BOD) by the decomposing bacteria. As the DO decreases, the aquatic animals will suffocate and die. Also, the inorganic nutrients, as well as the decomposed nutrients, will cause lush growth of algae, causing algal bloom over the surface of the water, which will further decrease the DO by not allowing the mixing of atmospheric oxygen.
Hence, the correct answer is 'i, ii, iv'

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Volume of a Sphere
BIOLOGY
Watch in App
Join BYJU'S Learning Program
CrossIcon