Physico-Chemical Characteristics of river water
The values of physico-chemical parameters measured in the Balu river water at different sites are given in Tables 1 and 2. The study revealed that water properties of Balu River were significantly varied between wet season and dry season. The mean water temperature of three sampling stations was recorded as 27.6ºC and 26.1ºC in wet and dry season, respectively. There was no significant difference in temperature between three stations with below standard limit of WHO. Three colors of water were observed at the sampling sites (Slightly black, black and slightly grey). It seems that the water was unsuitable for domestic usage and aquatic life. The mean value of dissolved oxygen was the lowest at sampling station 1 and significantly different between two seasons (from 2.10–3.20 mg/l in the wet season and 1.24–1.60 mg/l in dry season). The optimum level of the DO for aquatic organism is 4–6 mg/l and the most of organism cannot survive in low DO in aquatic environment (Dara, 2006). The observed DO values were lethal for aquatic life and created severe negative impact on aquatic life in the river. The DO condition of this river was also found same in the finding of Hasan et.al. (2014). The DO condition of the sampling area was also found unsuitable for drinking, domestic, irrigation and industrial purposes. The mean pH was 7.45 and 6.51 in wet and dry season, respectively.
Table 1
Physical parameters of water of different locations of the Balu River in wet and dry season
Parameter | Wet Season | Dry Season | Standard value |
Station 1 | Station 2 | Station 3 | Mean ± SD | Station 1 | Station 2 | Station 3 | Mean ± SD | DoE [47] |
Color | Slightly Black | Transparent | Transparent | - | Black | Light grey | Slightly Black | - | - |
Odor | Slightly pungent | Odorless | Odorless | - | Highly pungent | Pungent | Pungent | - | Odorless |
Temperature (ºC) | 27.5 | 27.2 | 28 | 27.57± 0.40 | 26.2 | 26 | 26 | 26.07± 0.12 | 20–30 |
TS (mg/l) | 163.2 | 115.2 | 94.9 | 124.43 ± 35.07 | 400.3 | 349.1 | 305.6 | 351.67 ± 47.40 | - |
TDS (mg/l) | 71 | 59.2 | 54.4 | 61.53 ± 8.54 | 267 | 243 | 237 | 249± 15.87 | 1000 |
Table 2
Chemical parameters of water from different locations of the Balu River in wet and dry season
Parameters | Wet season | Dry season |
Station 1 | Station 2 | Station 3 | Station 1 | Station 2 | Station 3 |
DO (Dissolved Oxygen) | 2.1 | 3 | 3.2 | 1.24 | 1.33 | 1.60 |
pH | 7.31 | 7.36 | 7.45 | 6.45 | 6.41 | 6.51 |
EC ( Electrical Conductivity) | 126.7 | 116.52 | 107.4 | 487 | 454.1 | 443.7 |
Salinity | 0.01 | 0.01 | 0.01 | 0.2 | 0.2 | 0.2 |
The TDS value of water was near four to five times lower during the wet season (54.4–71 mg/l) compared to the dry season (237–267 mg/l). The high TDS value of water is not desirable due to high content of dissolved solids elevates of water, influences osmoregulation of aquatic organisms, and reduces solubility of gases (like oxygen). The mean TS value was higher during dry season (400.3) than wet season (305.6) but it was within the standard limit. The EC value of water was recorded as 107.4-126.7 µS/cm and 443.7–487 µS/cm in the wet and dry season, respectively. The high EC value during dry season might impose unpleasant impact on the existence, sustainability, growth and development of aquatic life.
Heavy metals in fish samples
Discharge of heavy metals into river or any aquatic environment can change both aquatic species diversity and ecosystems, due to their toxicity and accumulative behavior (Heath, 1987). Fish can accumulate heavy metals in their tissue either in their diet or through their gills (Dallinger et al., 1987) and the metal accumulation in fish organs provided evidence of exposure to contaminated aquatic environment (Qadir and Malik, 2011). Fish are often at the top of the aquatic food chain and may contain concentrated, large amounts of heavy metals, such as Pb, Zn, Fe, Cu, Cd, Cr and Hg. Many fishes show respiratory distress with heavy metal toxicity (Samad et al., 2015). In the present study, fish muscles, which is edible parts for Bangladeshi consumers, were evaluated for the trace metal concentration. The ranking order of mean concentrations (Fig. 3) of trace metals in fish were, Zn (1.38) > Cu (0.47) and Pb (0.47) > Cr (0.46) > Cd (0.10) (mg/kg ww), respectively. The concentrations of trace elements were varied considerably in fish species A. mola (1.03) > G. giuris (0.78) > C. punctatus (0.76) > M. vittatus (0.65) > P. ticto (0.64) and seasons.
Copper (Cu) is a biogenic element, necessary for supporting the metabolic processes of all organisms and essential for the haemoglobin synthesis (Sivaperumal et al., 2007). However high intake of Cu can cause adverse health problems (Gorell et al. 1997). In the present study, Cu was detected in all fish samples and its concentration ranged from 0.31–0.67 mg/kg with the highest Cu concentration was found in G. giuris during dry season and the lowest in P. ticto during wet season (Fig. 4). In a heavily polluted river in Bangladesh, Buriganga River, Ahmed et al. (2010) found the highest Cu concentration in C. punctatus (5.27 mg/kg) and the lowest in Gudusia chapra (4.25 mg/kg) in premonsoon fish samples. The present findings in Balu River fish were lower than the standard value and in agreement with other previous studies in Bangladesh (Table 4).
Table 4
Comparison of heavy metals in fish (mg/kg wet weight) with different international guidelines and other studies in the world.
Study area | Cu | Pb | Cd | Zn | Cr | Reference |
Fish | | | | | | |
Wet season | 0.350 (0.31–0.38) | 0.290 (0.21-.43) | 0.055 (0.018–0.095) | 0.844 (0.71–1.01) | 0.312 (0.29–0.36) | This study |
Dry season | 0.576 (0.51–0.67) | 0.652 (0.52–0.75)* | 0.130 (0.073–0.21)* | 1.902 (1.29–2.9) | 0.603 (0.45–0.912) | This study |
Bangshi river a,b (Bangladesh) | 8.33– 43.18, 1.7-9.0 | 1.76– 10.27, 0.37–2.1 | 0.09– 0.87, 0.019–0.18 | 42.83– 418.05, | 0.47– 2.07, 0.098–0.43 | [14] |
Dhanmondi lake µg/g (Bangladesh)a | 5.07 | 2.08 | - | 60.1 | - | [50] |
Gumti river (Bangladesh)a | 1.48– 21.30 | 0.5–4.05 | - | 3.14– 186.9 | - | [51] |
Turag river (Bangladesh) b,c | 2.9 (1.1–5.7), 0.30–0.74 | 0.84 (0.052-1.6), 0.01–0.13 | 0.018 (0.008–0.03), 0.001–0.02 | - | 2.2 (0.97–3.6), 0.17–0.48 | [3,52] |
Buriganga River b (Bangladesh) | 4.5 (2.3–7.2) | 1.4 (0.78–2.7) | 0.05 (0.022–0.13) | | 2.8 (1.0-4.8) | [3] |
Shitalakha River b (Bangladesh) | 3.8 (2.3-6.0) | 0.83 (0.13–1.7) | 0.036 (0.011–0.086) | | 2.1 (0.75-4.0) | [3] |
Hooghly River (India) a | 16.22– 47.97 | 12.40– 19.96 | 0.62– 1.20 | 12.13– 44.74 | 3.89 | [53] |
Okumeshi River a (Nigeria) | - | < 0.01, 0.45 | 0.62, 1.32 | - | 0.06, 0.87 | [54, 44] |
Pearl River (China)a | 1.17–6.72 | 0.05–1.94 | Nd-33.2 | 2.62–20.2 | Nd-5.36 | [55] |
WHO | 1.0 | 0.3 | 0.05 | 5.0 | 1.0 | [48] |
*indicates values exceeding permissible limits of WHO (World Health Organization) in fish. |
a Values present the ranges or mean expressed as mg/kg dry wt. |
b Values present the ranges or mean expressed as mg/kg wet wt (mg/kg dry wt) |
c not mansion weather dry r wet wt |
Lead (Pb) is a toxic element which shows carcinogenic effect on aquatic biota and human (Qadir and Malik, 2011). It has critical effect in the developing nervous system of children who are particularly sensitive to the Pb (Castro-Gonzalez and Mendez-Armenta, 2008). From this study, the highest Pb concentration was in A. mola (0.75 mg/kg) during dry season and the lowest value in G. giuris during wet season (Fig. 4). In this study, the Pb value of all fish samples was from 1.6 to 2.5 times higher than the standard limit (0.3 mg/kg) in the dry season. This indicated high concentration of lead in water and accumulated in fish through bioaccumulation. However, the high Pb concentrations (1.4 mg/kg) were detected in the fishes of Buriganga River, Bangladesh (Islam et al. 2015) (Table 4), as much as 12.32 mg/kg in pre-monsoon samples of Mystus vittatus; fishes of Upper lake, Bhopal, India (Malik et al., 2010); River Chenab, Pakistan (Qadir and Malik, 2011).
Cadmium (Cd) is rarely found in natural water (Reash et al., 2006) and 0.50 mg/kg in food is safe for human consumption (Sanstead, 1976). It has negative effects on several organs as kidney, lung, bones placenta, brain and central nervous system (Castro-Gonzalez and Mendez-Armenta, 2008) as well as reproductive toxicity, hepatic, hematological and immunological effects (ATSDR, 2008). In the present study, Cd was the lowest concentration among the metals in the examined fish species. The sequence of bioaccumulation of Cd in the fish samples of this study was C. punctatus > P. ticto > G. giuris > A. mola > M. vittatus in wet season (Fig. 4). Here the lowest Cd value was found in M. vittatus (0.073 mg/kg) and the highest Cd value in C. punctatus (0.21 mg/kg) in the dry season. These variations in concentration are mainly due to feeding habits of fish such as C. punctutus is bottom feeder, chemical form of freshwater environment and season of the year and detoxification process. The average value of Cd was 2.4 times higher in wet season than dry season which might be due to the differences in water capacity of the river where low water flow in dry and industrial activity, atmospheric emission, leaches from defused Ni-Cd batteries and Cd plated items (Islam et al. 2014). In this study the Cd value in all fish samples exceeded the standard level in dry season and slightly higher than Bangshi, Turag, Buriganga River in Bangladesh (Table 4). The high Cd concentration was recorded in fishes of the Buriganga River, Bangladesh by Anonymous (2009), fishes of Lake Qarun, Egypt by Awasthi (2000), Labeo rohita and Ctenopharyngodon idella of Upper Lake, Bhupal, India by Malik et al. (2010), fishes of the River Chenab, Pakistan by Vildana et al. (2007) and salmonid fishes of Una River basin, Bosnia and Herzegovina by Vildana et al. (2007) in their study.
Zinc (Zn) is the essential mineral for both animal and human. It showed a protective effect against the Cd and the Pb toxicity (Sanstead, 1976). The order of accumulation of Zn in the fish samples was A. mola > C. punctutus > G. giuris > M. vittatus > P. ticto in both season (Fig. 4). Here the concentrations of Zn were detected in the fishes of the Balu River was varied from 1.29 to 2.9 mg/kg in dry season which was 3.8 to 1.7 times lower than the standard values given by WHO (Table 4). Present findings in fishes from Balu River was lower than the standard value in both seasons. Similar result was found in the fish samples from Campaign Creek stream, USA (Reash et al., 2006), northern Jordan valley, Jordan (Al-Weher, 2008). Relatively lower Zn accumulation was found in Labeo rohita from Upper Lake, Bhupal, India (Malik et al., 2010).
In this study, the lowest chromium value was observed in C. punctutus (0.28 mg/kg) during wet season and the highest in A. mola (0.912 mg/kg) during dry season (Fig. 4). In the present study, the Cr value in all fish samples was significantly higher during dry season than wet season but it was below the standard level as well as other studies for several rivers in Bangladesh (Table 4). During dry season, the Cr concentration in A. mola was much closed to the standard value. Marked Cr concentration was detected in the tissues of fishes dwelling from the Balu River in dry season, which might be due to the impacts of untreated wastewater discharged from various industries such as dyeing and tanneries (Islam et al 2014).
The concentration of trace metals was observed slightly higher in the examined fish species during dry season than wet season. Especially, Pb and Cd exceeded the standard level which could be due to the effect from point and non-point sources; such as leaded gasoline, petroleum, municipal runoffs, atmospheric deposition (Mohiuddin et al. 2012) etc. In comparison with the concentration of metals in fish and some other studies from Bangladesh and other countries near the industrial area indicated that fishes were contaminated by trace metals (Table 4). The enrichment of metals in fish species could be due to the metal contaminated feed comes from effluents discharged into rivers from several industries and other sources from urban area.
Bio-concentration factor (BCF)
Bio-concentration factor is used to determine the ability of the aquatic organism to accumulate chemicals from the river water. If BCF > 1, it indicates that the fish has a potential to accumulate the metal but is generally not considered to be significant unless the BCF exceeds 100 or more (USEPA,1991). The calculated BCF values of the five metals for different fish species are listed in Table 5.The BCF values of Cd and Cr were higher than 100 for all fish species except Cd in M. vittatus in wet seasons. The BCF value of Cd was greater than other studied metals during dry season and was more than 100 in two fish species P. ticto and C. punctatus; this can be due to the higher capacity to enrich metals from the water environment. Moreover, these two species are increasing metals from the water column through ingestion. The BCF values were not consistent among different fish species and seasons in order to fishes are more widely distributed and may migrate between river areas in response to several environmental conditions of the river (Abal et al. 2005). In addition, the variation of BCF values for different fish species may due to the five fish species have different behavior and response to different trace metals (Tao et al. 2012).
Table 5
BCF values of different fish species collected from the Balu River in wet and dry season
| Fish species | Cu | Pb | Cd | Zn | Cr |
Wet season | P. ticto | 16.67 | 60.78 | 170.27 | 10.85 | 239.46 |
C. punctatus | 19.89 | 52.94 | 256.76 | 14.05 | 215.38 |
G. giuris | 19.89 | 40.59 | 156.76 | 12.77 | 246.15 |
A.mola | 17.20 | 84.31 | 116.22 | 15.54 | 276.92 |
M. vittatus | 20.43 | 45.29 | 48.65 | 11.69 | 223.08 |
Dry season | P. ticto | 9.46 | 12.04 | 100 | 1.54 | 13.19 |
C. punctatus | 9.82 | 13.15 | 140 | 2.25 | 10.39 |
G. giuris | 11.96 | 11.67 | 88.67 | 2.24 | 13.16 |
A.mola | 9.11 | 13.89 | 55.33 | 3.45 | 21.06 |
M. vittatus | 11.07 | 9.65 | 48.67 | 1.85 | 11.78 |
Pearson’s correlation matrix between each analyzed trace metal, listing the Pearson product moment correlation coefficients was calculated to find if some of the elements interrelated with each other (Table 6). The concentrations of the investigated metals in water were significantly high correlation with each other where Cu and Pb (r = 0.989), Cu and Cd (r = 0.977), Pb and Cd (r = 0.992), Cu and Cr (r = 0.993), Pb and Cr (r = 0.989), Cd and Cr (r = 0.992), at p < 0.01 level except Zn (Table 6). High correlations between specific heavy metals in water may indicate same levels of contamination or release from the same sources of pollution, mutual dependence and identical behavior during their transport in the river system (Ali et al. 2016). Significant positive correlations in fish muscle were found between all trace metals except Cd, where Pb-Cu, Zn –Cu, Zn –Pb, Cr-Cu, Cr- Pb were moderately and Cr-Zn was highly significant correlated at p < 0.01 level. These correlations might indicate that the distributions of these pairs of metals were regulated by common local inputs and similar dispersion processes in the study area.
Table 6
Correlation matrix of different heavy metal in water, fish species collected from the Balu River in wet and dry season
| Cu | Pb | Cd | Zn | Cr | |
Water | | | | | | |
Cu | 1 | | | | | |
Pb | 0.989** | 1 | | | | |
Cd | 0.977** | 0.992** | 1 | | | |
Zn | 0.448 | 0.574 | 0.566 | 1 | | |
Cr | 0.993** | 0.989** | 0.992** | 0.466 | 1 | |
Fish | | | | | | |
Cu | 1 | | | | | |
Pb | 0.783** | 1 | | | | |
Cd | 0.222 | 0.065 | 1 | | | |
Zn | 0.739** | 0.887** | 0.010 | 1 | | |
Cr | 0.698** | 0.869** | -0.019 | 0.937** | 1 | |
*. Correlation is significant at the 0.05 level (2-tailed). |
**. Correlation is significant at the 0.01 level (2-tailed). |
However, the influence of the studied seasons and the different fish species captured from the Balu River, Bangladesh was demonstrated in Table 7. The metal concentrations in the edible fish muscle of each fish species for two seasons were used for two-way variance analysis ANOVA (Table 7). The data obtained from ANOVA clearly demonstrated that there was significant variation (CI = 95%) of the heavy metal concentrations in two seasons in the Balu river. However, the variation was not significant in five species of fish available in Balu River, Bangladesh. The variation in the level of heavy metals between different fish species depands upn its feeding habit, age, size, and length of fish and their habitats (Amundsen et al. 1997; Wantanabe et al. 2003).
Table 7
Two way ANOVA for the effect of inter-season and inter-fish species on the variability of heavy metal concentration in edible fish fillet.
Effect | Cu | Pb | Cd | Zn | Cr |
df | F | P(2-tails) | df | F | P (2-tails) | df | F | P | df | F | P (2-tails) | df | F | P (2-tails) |
Seasona | 1 | 1027.6* | < .001 | 1 | 300.68* | < .001 | 1 | 26.62* | .004 | 1 | 698.05* | < .001 | 1 | 353.56* | < .001 |
Fish speciesb | 4 | 30.99* | .001 | 4 | 8.57* | .018 | 4 | 67.02* | < .001 | 4 | 60.87* | < .001 | 4 | 29.26* | .001 |
Fish*season | 4 | 9.98* | .013 | 4 | 1.7 | .285 | 4 | 143.71* | < .001 | 4 | 27.55* | .001 | 4 | 19.93* | .003 |
Error | 5 | | | | | | 5 | | | | | | 5 | | |
Total | 15 | | | | | | 15 | | | | | | 15 | | |
F critical value for Fishes = 5.19 (α = 0.05). |
F critical value for Seasons = 6.61 (α = 0.05). |
a Seasons: Wet season and Dry season. |
b Fish Species: P. ticto, A. mola, C. punctatus, G. giuris, M. vittatus |
* Significant at 95% confidence level |