Status and Impacts of Industrial Pollution on the Karnafully River in Bangladesh: A Review

Rapid growth of urbanization and industrialization in Bangladesh has been coupled with increasing environmental pollution. The coastal and estuarine ecosystems of the country are now facing increasing pollution pressures because of the elevated level of waste discharges from various sources. Major sources of pollution include domestic sewage, industrial waste, commercial waste, agricultural waste, institutional waste, street sweepings, construction debris, mining activities and sanitation residues etc. In this review, status and effect of solid waste pollution, heavy metal pollution, organochlorine pesticides pollution and oil pollution along with the Karnafully River Estuary is assessed by a comprehensive review, recorded by researchers especially on water, sediment and aquatic biota. Different study show that metal concentrations in estuarine water relatively higher due to rapid acceleration of industrial sector. Metal concentrations is higher in fish than water and sediment. Elevated level of trace metals is highly detrimental for fish and human mechanism shown by different studies. Oil pollution is responsible for environmental deterioration due to its adverse effects on estuarine biota, fish and shellfishes, phytoplankton and zooplankton. Industrialization is needed for the development of the country. But it should be eco-friendly for the effective and sustainable development and for the protection of the environment (aquatic).


Sediment
The overlying deposits of the Karnafully river is consist of successive layers of mud and sand (Rizvi, 1971). During rainy season, a large amount of sand and mud particles run down into the river water increasing turbidity and decreasing navigability of the river by siltation (Hossain, 1992). Chowdhury (2005) conductd a comprehensive study on the soil of the Karnafully river (Table 6).

Macro benthos
Macro benthos distribution vary spatially and temporally . According to Chowdhury (2005) maximum population density 148583 indiv/m 2 was recorded during pre-monsoon at Amanat Shah Bridge and minimum population density 1333.33 indiv/m 2 was recorded at Jetty no.15 during monsoon. Sharif et al. (2017) recorded 25 major taxa of zooplankton from the Karnafully River of which 23 taxa during monsoon, 20 taxa during post monsoon and 20 taxa during pre-monsoon. Species richness, diversity and evenness were very low in the mouth of the Chaktai canal where majority of sewage materials of Chittagong city falls into the Karnafully estuary in comparison with the Goverment Fish landing station and Eastern side of the third Karnafully Bridge (Molla et al., 2014). Oligochaetes, the most common that constitute the largest assembles of benthic form during pre-monsoon and lowest during monsoon (Kamruzzaman, 2003) (Table 7).

Bacteria
Health hazard bacteria are Escherichia coli, Fecal Streptococci sp. and Staphylococcus. Occurrence of Salmonella sp. and Vibrio cholerae were also found (Alam, 2005). In compare with bacterial load between water and sediment, sediment sample carry higher bacteria than water sample in the Karnafully River (Alam, 2005). The available DO consumed by bacterial activity and thus the presence of such materials quickly leads to a depletion of DO (Islam, 1998).  recorded as many as 18000 coliforms/100 mL in the Karnafully River Estuary near sewage disposal areas which is higher than safer level (0/100 mL) for drinking water and greater than 200 cells/100 mL for bathing recommended by WHO (1984) ( Table 8).  Bacteriological study showed that coliform bacteria and faecal streptococci occurred in greater frequency in the polluted area of the Karnafully River rather than pristine area. Polluted stations (Sadarghat and Majhirghat) were dominant in respect of quantitative distribution of Oligochaetes and Polychaetes and occasionally Molluscs (Hossain, 1983) (Table 9).

Fish diversity
Total 30806 numbers of species were found and the range of species number was from 397 to 1296 with a mean of 855.72±202.58 (Habib, 2011). According to Khan (2005) there are about 51 species under 23 families were found in the Karnafully River Estuary. Among seventy four (74) fish species have been reported by Bhuiyan and Gafur (1977). Twenty eight (28) have neither obtained in sample nor interviewing to fishermen revealed to exit which showed in Kamal (1992) observation. This is probably due to huge pollutant discharges from various sources into the estuary. Pollution status and its hazardous effects in the Karnafully River Estuary have been reported by Khan and Talukder (1993) and Mahmood et al. (1992). Diversity of ichthyofauna is closely related with physico-chemical parameters. Species distribution also vary temporal and spatial basis. In the monsoon, species diversity was found than that of the any other seasons (Khan, 2005). The combination of diverse fluctuating parameters are responsible for distribution and occurrence of ichthyofauna in the estuarine waters (Zafar, 1986).

Major sources of pollution
Water is the most vital element among the natural resources and is crucial for the survival of all living organisms including humans, for food production and economic development (Shiklomanov, 1993). Surface water of the country is vulnerable to pollution from untreated industrial effluents, municipal wastewater, runoff from chemical fertilizers and pesticides, and oil and lube spillage in the coastal area from the operation of sea and river ports (Hossain, 2001). Water quality depends on effluent types and discharge quantity from different types of industries, types of agrochemicals used in agriculture and seasonal water flow and dilution capability by the river system (DHV, 1998). Industries along the side of the River Karnafully damp 50 to 60 ton of wastes per day directly into the river (Table 10). Moreover, 05 major canals carry domestic and municipal wastes and effluents to the River Karnafully. Urea Fertilizer Factory discharges untreated effluents directly into the River Karnafully. Hg, Pb, Cr, Cd and As from 144 industries, degradable and persistent organic and inorganic compounds from 297 industries and oil, lubricants from (40-50) tankers polluting Karnafully river (MoFL, 2013). From the survey of effluents from different industries, it has been found that the discharge is generally composed of organic and inorganic wastes. The organic wastes are the effluents from the tanneries, fish processing units, degradable wood chips, pulps and untreated municipal and sewage (about 40,000 kg BOD daily) etc. The inorganic waster are chemicals used by the industries such as various acids, bleaching powder, lissapol, hydrogen peroxide, alkali, salts, lime, dyes, pigments, aluminium-sulphate and heavy metals etc. The DDT factory and fertilizer factory disposing of DDT, toxic chemicals and heavy metals to the Karnafully River and ultimately to the Bay of Bengal. Some survey showed about 220 ppm of chromium, 0.3-2.9 of cadmium, 0.05-0.27 ppm of mercury, 0.5-21.8 ppm of lead entering into river and sea water much higher than allowable limits and extremely alarmingly to aquatic flora and fauna and through food chains to human beings (Table 11). Note: Maximum deterioration of the water quality was observed during summer and rainy season due to excessive disposal of wastes and outfall of land washing  It may be mentioned that Bangladesh obtain table salt from solar drying of sea water and consequently increase pollution of sea water shell create a serious national health hazard situation (IEDS, 2003). The concentration of Pb, Cu, Fe, Ni and Cr were observed higher and concentration of Mn and Cd were found lower than that of the recommended values. It was assumed that from the analytical findings that the estuary has been polluted from domestic sewages, land washout, river runoff and shipping activities . There are some study on the contamination level of heavy metals in water and in sediments along the Karnafully estuary and its adjacent coastal area (Sarker, 1998;Sanjoy, 2007;Tamanna and Hossain, 2010;Hossain, 2010). An ADB study reported According to a government report, in the 1994-1995 fiscal year alone, 2528 metric tonnes of wastes were dumped from shrimp processing units into the Bay of Bengal via the Karnafully River (Hassan, 2006). Human excreta from the city's 50,000 sanitary and 24,000 service latrines are thrown into the river (Khan et al., 1996). Technical workshops, automobile factories, motor garage, vehicle repairing units, asphalt road constructions, etc. discharge lube oil, grease, diesel, bitumen, and tar, which ultimately contaminate the sediment. The industrial zones, EPZs and city dwellers activities are also responsible for oil contamination in the Karnafully River (Hossain, 2006). Rajakhali Canal, a tributary of the Karnafully River estuary, flowing through Chittagong City (the commercial capital of Bangladesh) receives a huge amount of domestic and industrial wastes and sewages (Islam et al., 2015). In Chittagong region, wastewater from Nasirabad industrial area (mainly chemical, leather, textile and steel re-rolling industries) is discharged into surface drains that ultimately carry it to the Karnafully river (Dey et al., 2015). There are rather few studies published in recent years on pollution sources in the Karnafully River (Hossain et al., 1992;2001). Annually about 1216 ships and 45-60 oil tankers are handled at the Chittagong port (Ashraful, 2003). As a result, various refuse and disposable materials are discharged and spills from ships, oil tankers and fishing boats get mixed with water and sediments. The high level of Cu in sediments of the Karnafully coast indicates a higher input of deposited organic matter which comes from the industrial and domestic sewages (Siddique, 2012). Nutrient pollution occurred at the Karnafully River to St Martin Island, BoB when concentrations of nitrate, phosphate and silicate vary from 0.16 to 8.98 μg-at/1, 0.08 to 2.33 μg at/1 and 0.67 to 6331 μg-at/1 which indicate high productivity (Holmgren, 1994). Running water of the Rivers Karnafully and Padma is heavily contaminated by industrial influents of factories from the river banks (Sarker, 2009) (Table 12).

Major pollutants
SO 2 , CO 2 , NO 3 , H 2 S and lignin vapor from tanning industries; Na 2 SO 4 , NaOH, CaCO 3 , Ca(OH), Hg, Na 2 CO 3 , Na 2 SO 3 , H 2 SO 4 , HCl etc. from pulp and paper industries; Cr, Ni, Cd textile industries; NH 3 , NO 2 , SO 2 , H 2 SO 4 , Sulphur dust, rock dust and COD from fertilizer industries; Lime components, silica, alumina iron from cement industries; DDT, Caustic soda, HCl, H 2 SO 4, bleaching powder, acids, alkalis, ammonia, chlorine and suspended solid from chemical industries; waste water containing high level of BOD, COD, Phenol, Cyanides and very low value of DO from iron, steel and metal industries; crude oil from oil refinery; baling, jute fibre and dust from jute industries; minerals, organic acids, alkalis, ammonia, suspended solids and various chemicals from pharmaceutical industries; acids, solvents, cyanides, chlorophenolic components, lead, copper, arsenic, suspended solids etc. from pesticides and herbicide manufacturing industries; Zn, Cd and grease from rubber and plastic industries; pigments, resins, solvent, Pb, Sal, Cr, Cd, and Zn from paint manufacturing industries are major pollutants of the Karnafully water pollution (Ahmed et al., 2002). According to Chowdhury (1994) caustic soda, lime stone, lime, salt cake, resin size, china clay, alum, sodium sulphate, sodium sulphide, chlorine gas, calcium hydrochloride, hydrochloride, sulphuric acid and sodium hexameta phosphate are major chemicals used in KPM and KPRC industries.

Domestic sewage
The mixture of water and waste products popularly called sewage (EQS, 1991). Human excreta is only one component of domestic sewage with the wastes of personal washing, household cleaning and home food preparation adding to the dissolved and suspended, organic and inorganic materials in the carrier water (Uddin, 1993) consist of nitrogenous materials, carbohydrates, fats and soaps (EQS, 1991). The Chittagong city has about 50000 sanitary latrines, 24000 service latrines and 3 public toilets whose excreta collected by the municipality are stored in 5 large tanks for 2 months and then discharged into the rivers (Mozumder, 2003). In case of sewage, Chaktai canal contributes 30%, Monoharkhali canal 15%, Majhirghat canal 25% and Firingi-Bazar canal 18% into the Karnafully River (Source: Ahammod, 1995).

Oil pollution
Oil pollution is only one of man's untreated wastes which contributing to the deterioration of the environment (Ahmed, 2006). In the coastal area, it is about 0-2.3 to 0-3.4 ug/kg on the surface of the water. In the tanker routes, it is about 21.7 to 11.2 ug/kg on the surface and the value of the same varies from 23.2 to 13.6 ug/kg at 10 m deep water (Alam, 2004) (Table 14). Not known Oil emulsion from workshop Not known Crude oil residue process oil and wash water from refinery 50000 metric ton/year Refuse oil from ship breaking activities from Fauzderhat 400 kg/year Note: Assuming 0.5% transportation loss during crude oil transfer at Chittagong port; Source: ESCAP (1988) According to Ahmed (2006) about 102-230 mg/L residual oil from surface area, 33.6 mg/L-180 mg/L from 5 m depth and 35.5-230.5 mg/L from 10 m depth were found (Table 15).

Heavy metal pollution
Heavy metal concentrations in the water of the river varied temporally and spatially . Heavy metal concentration varied according to seasons in water, sediment and fish (Table 16; Table 17).  Note: Source: Sarkar (1998) Most of the dissolved heavy metals were found to be in slightly higher concentrations during winter than that of the rainy season. This trend indicates that during low flow condition of river, the accumulation of the metal concentration increases (Dey et al., 2015) (Table 18).  (Ahamed et al., 2003;Datta et al., 2008) and some study on the seasonal contamination level of heavy metals in water and in sediments along the Karnafully estuary and its adjacent coastal area (Sarker, 1998;Sanjoy, 2007;Tamanna and Hossain, 2010;Hossain, 2010) (Table 19; Table 20).  Water is presently contaminated by heavy metals from dyeing industries and oil spills from ship braking industries and ongoing vessels (Sarker, 1991;Sarker and Sarker, 1986;1988).

Major causes of fish depletion
In Bangladesh, the fish species from the inland and marine water bodies declined gradually due over the last two decades and the catch of fish declined about 40% compared to the past 20 years (DoF, 2002). A number of studies indicated that the major cause of declining fish catch from the river are the increased fishing pressure and habitat destruction (Tsai and Ali, 1987;Siddique, 1990;Hogarth et al., 1999;Graff et al., 2001). Species diversity also declined due to indiscriminate use of gears, over fishing, destruction of spawning ground and trapping of so called white fish (i.e., carps and butterfish) during their downstream migration from floodplains to river (Ali, 1997;Hogarth et al., 1999;Graff et al., 2001). Pollution, soil erosion, siltation, reclamation of land for settlement, reduction of wetland and biodiversity and proper management problem are the probable causes for the declination of the fishery resources (Khan, 2005).

Impacts of Pollution
The scientists in a recent research on the Karnafully found traces of radioactivity 'very close to risk level' on the soil. If radioactivity of the river soil goes up it will hamper the natural breeding of fish as well as growth of fishes. If the people eat the affected fish it may spread to their body (Amin, 2015). Ahmed and Reazuddin (2000) reported that the availability of the heavy metal in river water directly affects the fish physiology and by the consumption ultimately affects the human health. The presence of heavy metals in the aquatic environment is of major concern because of their heavy toxicity, bio-accumulating tendency in the biota. Pollution by heavy metals is a threat to human life and the entire environment as well as the wetland ecosystem (Islam and Tanaka, 2004;Igwe and Abia, 2006).
Oil pollution responsible for loss of productivity, other resources and exert adverse effects on aquatic environment, sometimes it become carcinogenic to living organisms (Ahmed, 2006). Oil pollution causes severe damage to fishes and crustaceans.
Contaminated water is not suitable for household uses and possibly hazardous to many aquatic animals and human health. Salmonella spp. concentrations found in water and soil samples exceed the standard level both in water and soil that indicates contaminated water is unsuitable for drinking or for even washing without appropriate water treatment for humans (Alam, 2012). Escherichia coli and Staphylococcus causes abdominal cramping, water borne diseases like diarrhea, fever, nausea and vomiting (HACCP, 2000).
Long term consumption of fishes may have a negative impact on human health . Pathogens (Oligochaetes) are causative agents of different types of diseases of human beings found very high abundance near sewage outfalls areas in the Karnafully River estuary, which indicates localized pollution in the estuary (Hossain, 1987). The major channels which carry domestic wastes and spread into the coastal city areas causing pathogenic microbial pollution and serious health hazards during the rainy season and flood periods severity is more in the Bay (Mahmood et al., 1994). 20,000 fishermen in Raujan, Rangunia and Anowara thanas previously dependent on the Karnafully river have given up their fishing profession because they do not have enough catches any more (SEHD, 2002). Lower concentrations of methyl mercury may kill aquatic organisms (Hossain, 2004). Paul (1981) also found the minimum phytoplankton population in the oil polluted Karnafully River Estuary. Most species of fish cannot survive in insecticides in concentrations greater than about 1-10 ppb. A sub lethal dose for fish and birds may bring immediate danger (Ali, 1997).
About 23 species of fishes were found in the Karnafully River during 1975-76, which has come down to 6-7 species during 1987-88. Effluents discharged from the large industries have ruined the Hilsha stock of the Karnafully river (Hossain et al., 2006). Presence of heavy metals in the river water causes perilous impact on the aquatic organisms (Dey et al., 2015). The fish catch is diminishing in the river year after year due to depletion of DO (Ali, 1997). The toxic chemical pollutants like Hg, Pb, Cd, COC and DO were found higher than the EQS value which is dangerous for entire aquatic ecosystem and public health . Excessive discharge of nitrogen, sulphur and phosphorus compounds in the water system can cause eutrophication (Bhouyain, 1981). The presence of NO 3 in natural water associated with ecological and health hazard, excess NO 3 in human food and animal feed has adverse impacts, in human health it causes methmoglobinemia cancer (child cancer), respiratory illness. In animal health, causes loss of livestock. Excess NO 3 pollute water causing eutrophication .
Effects on marine organisms produced by industrial discharged oil studied by Hossain (2011) (Table 21).

Conclusion
From the critical review, it can be concluded that the Karnafully river water is being polluted gradually by haphazard and unplanned industrialization. Polluted water exacerbating the health problems both in human and fish posing different fatal and chronic diseases. This review also proved that, industrial area are severely polluted than non-industrial area. This review suggested that to protect the aquatic ecosystem by eco-friendly and planned industrial growth.

Authors' contributions
Md. Simul Bhuyan designed and conducted the review. Md. Shafiqul Islam provided instructions and performed critical review of the manuscript.