Use app×
Join Bloom Tuition
One on One Online Tuition
JEE MAIN 2025 Foundation Course
NEET 2025 Foundation Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
950 views
in Biology by (45.1k points)

A large quantity of urban sewage is drained into nearby village river. Which among the given conditions would happen after mixing of sewage into the river?

(i) Biochemical oxygen demand (BOD) of receiving water body increases.

(ii) Dissolved oxygen of receiving water body decreases.

(iii) It will not cause normality among fishes and other aquatic creatures.

(iv) It will lead to nutrient enrichment of receiving water body.

(a) (i), (ii) and (iii) 

(b) (i), (ii) and (iv)

(c) (ii) and (iii) only 

(d) (iii) and (iv) only

1 Answer

+1 vote
by (67.7k points)
 
Best answer

Correct option (b) (i), (ii) and (iv)

Explanation :

When sewage, having biodegradable organic matter is released into the water- body, microorganisms involved in biodegradation of organic matter (in the receiving water body) consume a lot of oxygen to decompose the sewage and as a result there would be a sharp decline in dissolved oxygen downstream from the point of sewage discharge and biological oxygen demand (BOD) would increase. Presence of sewage causes nutrient enrichment (large amount of nutrients) in water which causes excessive growth of planktonic (free-floating) algae. called algal bloom. Algal bloom causes deterioration of water quality and fish mortality.

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...