Use of physicochemical parameters and macroinvertebrates to assess impacts of anthropogenic activities on water quality in Pnyinyi river, Arusha, Tanzania
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Date
2024
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Publisher
Sokoine University of Agriculture
Abstract
River are one of the most important fresh water resources for the
sustainability of living organisms. However, various anthropogenic
activities such as agriculture, livestock keeping, industrial and domestic
activities have been reported to degrade the quality of rivers in
supporting the aquatic life and human need in large. To address this
situation, this study assesses the impacts of anthropogenic activities in
Pinyinyi River water quality using physicochemical parameters,
macroinvertebrates and social economic activities during the dry season
(11/2021) and wet season (02/2022). Nine water quality parameters were
analyzed, namely; Biological Oxygen Demand (BOD), Chemical Oxygen
Demand (COD), phosphate, potential of Hydrogen (pH), Electrical
Conductivity (EC), Total Dissolved Solid (TDS), turbidity, Dissolved
Oxygen (DO) and nitrate. Multi-parameter analyzer (model HANNA HI
9829) used for onsite measurement of pH, EC, TDS, DO and turbidity,
HACH spectrophotometer (HACH DR/2700) used for laboratory analysis
of phosphate and nitrate, BOD incubator and COD digester was used for
analysis of BOD and COD respectively. A macroinvertebrates hand net
with 250 μm mesh size was used to collect the macroinvertebrates per
sampling point. Structured questionnaire were used to collect data about
social economic activities. The DO, BOD, COD and turbidity were above
the permissible limit during dry and wet seasons. Phosphate, pH, EC,
TDS and nitrate were within the permissible limit during dry and wet
seasons. During dry season, aquatic caterpillar, pouch snail, dragon flies
and mosquitoes were collected whereas, creeping water bugs,
predacious dividing beetles, pigmy back swimmer, water mites, back
flies, mosquitoes larva, midges, aquatic earth worm, snail and moth flies
were collected during the wet season. Identification of these
macroinvertebrates was done using the Aquatic invertebrates of South
African Rivers field guidebook. Average score per taxon (ASPT)
indicated that, the Pinyinyi River was moderately polluted (ASPT = 5.25)
during the dry season and seriously polluted during the wet season
(ASPT = 3.6). The social economic activities were agriculture, livestock
keeping, soda ash harvesting, fishing, bathing and washing along the
river, deforestation, water diversion, sand mining and tourist guidance.The study revealed that, agricultural activities, sand mining, fishing, water
diversion, deforestation, livestock keeping, bathing and washing affect
the river water quality of the river. The study recommends riparian buffer
creation, strict laws, and best management of agriculture practices,
education provision and livestock exclusion to be the best ways of
Pinyinyi River restoration.
Description
Dissertation
Keywords
Anthropogenic activities, Biodiversity, Macroinvertebrates, Physicochemical parameters, Shannon Weiner diversity index, Water quality, Water pollution.