Water Quality Trends - The applicability of a Water Quality Index (WQI) as an assessment tool f

CHAPTER 4 RESULTS

4.1 Water Quality Trends

Analysis of figure 4-1, showed that the concentration of Mg²⁺ in site 90194 ranged from 15 mg/l Mg²⁺to 10 mg/l Mg²⁺from 1979 to 2018 but there was a steady increase in Mg²⁺ concentration from 1976 (23 mg/l Mg²⁺) to 1984 (38 mg/l Mg²⁺) per year. Figure 4-1 indicated a temporal change in Mg²⁺ concentration in site 90194 where it decreased over time from concentration of 15.7 mg/l Mg²⁺in 1976 to 9.7 mg/l Mg²⁺ in 2018. Figure 4-1 showed a temporal change in Mg²⁺ concentration in site 90167 from 1976 to 2018. There was a steady decrease in Mg²⁺ concentration from 45 mg/l Mg²⁺ to 25 mg/l Mg²⁺ from 1984 to 2018 (Figure 4-1). The Mg²⁺ concentration in site 90203 showed temporal changes over time. Magnesium concentration is high in mid-1980s and mid- 1990s (40 mg/l of Mg²⁺). The concentration of Mg²⁺ on site 90203 was low between 2008 and 2018 where the concentration of Mg²⁺ was 25 mg/l (Figure 4-1). Similarly, the average Mg²⁺

concentration on site 90204 from 1984 to 2018 was 20 mg/l. Site 90233 also recorded low Mg²⁺

concentration of 25 mg/l Mg²⁺ from 1990 to 2018 (Figure 4-1).

The figure 4-1 represents the water quality trend of Ca²⁺ of the Crocodile-West River from 1976 to 2018. There was no temporal change in Ca²⁺ concentration in site 90194 from 1976 to 2018.

The Ca²⁺ concentration for forty-two years ranged between 20 mg/l Ca²⁺ and 40 mg/l Ca²⁺ (Figure 4-1). The concentration of Ca²⁺ on site 90167 showed a temporal change in from 1976 to 2018.

There was a gradual increase in Ca²⁺ concentration from 29 mg/l Ca²⁺ in 1976 to 65 mg/l in 1984 (Figure 4-1). The Ca²⁺ concentration decreased to 30 mg/l Ca²⁺ from 1985 to 2000. The concentration of Ca²⁺ increased from 2001(33mg/l Ca²⁺) to 2018 (51 mg/l Ca²⁺).

The water quality trend in figure 4-1 showed a temporal change in the concentration of Ca²⁺ in site 90203 from 1976 to 2018. The Ca²⁺ concentration on site 90203 was high in 1980s and 1990s (60 mg/l Ca²⁺). The concentration of Ca²⁺ decreased to 45 mg/l Ca²⁺ from 1997 and remained constant in the mid-2000s until 2018 (Figure 4-1). The concentration of Ca²⁺ in site 90204 changed slightly from 1976 to 2018.The average Ca²⁺ concentration in site 90204 was 40 mg/l Ca²⁺ from 1984 to 2018 (Figure 4-1). The Ca²⁺ concentration in site 90233 showed temporal changes from 1990 to 2018. The Ca²⁺ concentration on site 90233 increased gradually from 46 mg/l Ca²⁺ in 1990 to 55 mg/l Ca²⁺ in 2018 (Figure 4-1).

Figure 4-1: Water quality trend of magnesium (Mg²⁺) and calcium (Ca²⁺) for Crocodile-West River from 1976 to 2018. The green line represents the target water quality ranges as presented in Table 3-2. The following colours represent the sites surveyed: Light Blue=Site 90194, Red=90167, Grey=90203, Orange=90204 and dark Blue=Site 90233

The figure 4-2 of the water quality trend represents the seasonal concentration of K⁺ and Cl^- from 1976 to 2018 in site 90194 of the Crocodile-West River. There were temporal changes in Cl^- concentration on site 90194 from 1979 to 1985. The concentration of Cl^- on site 90194 increased from 32 mg/l Cl^- in 1979 to 89 mg/l Cl^- 1985 (Figure 4-1). The concentration of Cl^- on site 90194 decreased to 50 mg/l Cl^- from 1985 to 1988 and remained constant at 50 mg/l Cl^- from 1988 to 2018 (Figure 4-2). Site 90167 had the highest concentration of Cl^- in 1970 and mid-1980s. The Cl^- concentration on site 90167 increased from 37 mg/l Cl^- (1976) to 136 mg/l Cl^- (1985). There was a significant temporal change in Cl^- concentration on site 90167 during that period (Figure 4- 1). Site 90203 recorded high Cl^- concentration of 130 mg/l Cl^- in the mid-1980s and mid-1990s and in the mid-2000s (140 mg/l Cl^-). The concentration of chloride on site 90204 was 60 mg/l Cl^- from 1976 to 2018 while site 90233 recorded a concentration of 100mg/l Cl^- from 1976 to 2018 (Figure 4-2). There was a temporal change in K⁺ concentration in site 90194 between the 1970s

0 20 40 60 80 100 120 140

25/2/76 30/8/77 30/11/78 25/2/80 30/5/81 30/8/82 30/11/83 25/2/85 30/5/86 30/8/87 30/11/88 25/2/90 30/5/91 30/8/92 30/11/93 25/2/95 30/5/96 30/8/97 30/11/98 25/2/00 30/5/01 30/8/02 30/11/03 25/2/05 30/5/06 30/8/07 30/11/08 25/2/10 30/5/11 30/8/12 30/11/13 25/2/15 30/5/16 30/8/17 30/11/18

Year

Mgcocentration (mg/l)

0 20 40 60 80 100 120

Calcium cocnentration on Crocodile-West River from 1976 to 2018

Ca concentration(mg/l)

Year

and 1990s. The K⁺ concentration on site 90194 increased from 46 mg/ K⁺ to 62.5 mg/l K⁺ between 1979 and 1992 and declined to an approximately 45 mg/l K⁺ from 1992 to 2018 (Figure 4-2). The K⁺ concentration in site 90167 was low at 4 mg/l of K⁺ in the 1970s and mid-1980s but increased to approximately 9 mg/l K⁺ in the late 1980s and 1990s and the concentration of K⁺ in site 90167 remained constant until 2018 (Figure 4-2). Similarly, the time series of K⁺ concentration of site 90203, 90204 and 90233 followed the same temporal changes as site 90167 and 90194 from 1980 to 2018. The K⁺ concentration in site 90204,90203 and 90233 was approximately 10 mg/l K⁺ between 1980 to 2018 (Figure 4-2).

Figure 4-2: Water quality trend of potassium (K⁺) and chloride (Cl^-) for Crocodile-West River from 1976 to 2018. The green line represents the target water quality ranges as presented in Table 3- 2. The following colours represent the sites surveyed: Blue=Site 90194, Red=90167, Grey=90203, Orange=90204 and Black=Site 9023

0 20 40 60 80 100 120

Potassium concentration on Crocodile-West River from 1976 to 2018

Year

K concentration (mg/l)

0 50 100 150 200 250 300

30/5/76 30/11/77 25/2/78 30/5/80 30/8/81 30/11/82 25/2/84 30/5/85 30/8/86 30/11/87 25/2/89 30/5/90 30/8/91 30/11/92 25/2/94 30/5/95 30/8/96 30/11/97 25/2/99 30/5/00 30/8/01 30/11/02 25/2/04 30/5/05 30/8/06 30/11/07 25/2/09 30/5/10 30/8/11 30/11/12 25/2/14 30/5/15 30/8/16 30/11/17

Chloride concentration in the Crocodile-West River from 1976 to 2018

Year

Cl concentration (mg/l)

Figure 4-3: Water quality trend of ammonia (NH3) and nitrate/nitrite (NO3-/NO2-) for Crocodile- West River from 1976 to 2018. The green line represents the target water quality ranges as presented in Table 3-2. The following colours represent the sites surveyed: Blue=Site 90194, Red=90167, Grey=90203, Orange=90204 and Black=Site 90233

The figure 4-3 represents the water quality trend of NH3 and NO3-/NO2- for Crocodile-West River from 1976 to 2018. The NH3 concentration in site 90194 was constant from 1976 to 2018 with a few spikes NH3 concentration visible in 1992 and 2005 (Figure 4-3). There were peaks of NH3

concentrations in 1992 (0.24 mg/l NH3), 2005 (0.18 mg/l NH3) and an increasing trend of ammonia from 2011 to 2018 (0.001mg/l NH3 to 0.0564 mg/l NH3) on site 90194 (Figure 4-3). The NH3

concentration on site 90167 showed an increasing temporal change from 0.0010 mg/l NH3 to 0.063 mg/l NH3 from 1976 to 2018. There were spikes in concentration of site 90167 that exceeded the target water quality guideline of 0,007 mg/l NH3.There were spikes of NH3

concentrations in 1997 (0.025mg/l NH3), 2000 (0.044 mg/l NH3), between 2004 to 2005 (0.018 mg/l NH3 and between 2009 to 2018 (0.063mg/l NH3).

-0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9

Year NH3cocnentration(mg/l)

0 2 4 6 8 10 12 14 16

1976/02/25 1977/11/30 30/05 1979 1980/11/30 1982/05/30 1983/11/30 1985/05/30 1986/11/30 1988/05/30 1989/11/30 1991/05/30 1992/11/30 1994/05/30 1995/11/30 1997/05/30 1998/11/30 2000/05/30 2001/11/30 2003/05/30 2004/11/30 2006/05/30 2007/11/30 2009/05/30 2010/11/30 2012/05/30 2013/11/30 2015/05/30 2016/11/30 2018/05/30

Nitrate/nitrite concentration on Crocodile-West River from 1976 to 2018

Year NO3/NO2concentration (mg/l)

The concentration of NH3 on site 90203 increased gradually from 0.008 mg/l NH3 in 1985 to 0.0118 mg/l NH3 in 2018 (Figure 4-3). High concentrations of NH3 in 1990 to 1993 (0.015 mg/l NH3), 1994 (0.07 mg/l NH3), 2006 (0.023 mg/l NH3) and 2012 to 2016 (0.025 mg/l NH3) were visible on site 90204. The NH3 concentrations in site 90233 increased from 1990 to 2018 (0.007 mg/l NH3) with spikes in NH3 concentration observed in 1993 (0.023 mg/l NH3,1995 (0.020 mg/l NH3), 2001 (0.007 mg/l NH3), 2007 (0.025 mg/l NH3),2010 (0.884 mg/l of NH3). The concentration of NH3 also exceeded the target water quality guideline in 2012-2017 where the concentration of NH3 was between 0.007 mg/l NH3 and 0.032 mg/l NH3.

The water quality trend in figure 4-3 showed that the range of NO3-/NO2-concentration in site 90194 increased from 3.0 mg/l NO3-/NO2- to 14 mg/l NO3-/NO2- from 1979 to 1993 and decreased to 3.0 mg/l NO3-/NO2- from 1994 to 1995 and remained constant from 1995 to 2018. The NO3-

/NO2- in site 90194 exceeded the target water quality guideline of 10 mg/l NO3-/NO2- in 1992, 1993 and 1986. Site 90194 had the highest NO3-/NO2- concentration than the other sites from 1976 to 2018 (Figure 4-3). High concentrations of NO3-/NO2- on site 90167 was in the 1970s and 1980s (3.5 mg/l NO3-/NO2-) and from 2010 to 2018 (2.87 mg/l NO3-/NO2-) while the concentration of NO3-

/NO2- on the Crocodile-West River on site 90203 increased gradually from 0.10 mg/l NO3-/NO2- to 1.9 mg/l NO3-/NO2- from 1990 to 2018 (Figure 4-3). The concentration of NO3-/NO2- on the Crocodile-West River on site 90204 increased gradually to 1.5 mg/l NO3-/NO2- from 1980s to 2018.

The concentration of NO3-/NO2- on the Crocodile-West River on site 90233 increased gradually to 1.7 mg/l NO3-/NO2- (Figure 4-3).

The water quality trend figure 4-4 showed temporal changes in the concentration of PO43- on site 90194 where it increased from 2.8 mg/l PO43- in 1979 to 11 mg/l PO43- between 1979 and 1984 and declined to 0.16 mg/l PO43- from 1984 to 2018. The concentration of PO43-during this period exceeded the target water quality guideline set at 0.15 mg/l PO43-

. There were two periods on site 90167 where the concentration of PO43- on site 90167 exceeded the water quality guidelines (Figure 4-4). The first period was from 1976 to 1983 where the concentration of PO43- was 0.35 mg/l PO43- and the second period was from 2006 to 2018 where the concentration of PO43-was high was in 2018 (0.34 mg/l PO43-).

The water quality trend in figure 4-4 presented the water quality trend of SO42- concentration in site 90194 from 1976 to 2018. The concentration of SO42- showed temporal changes in all sites between 1976 to 2018. The SO42- concentration increased from 50 mg/l SO42- in 1979 to 137 mg/l SO42- in 1985 and declined to 30 mg/l SO42- and remained constant until 2018 (Figure 4-4). The SO42- concentration on site 90167 increased from 59 mg/l SO42- to 160 mg/l SO42- between 1976

concentration of 70 mg/l of SO42- between 1998 and 2018 (Figure 4-4). The SO42- concentration on site 90203 increased from 44 mg/l SO42- to 108 mg/l SO42- between 1985 and 1993 and declined gradually between 1993 and 2001 (77 mg/l SO42-) and concentration of 75 mg/l of SO42-

remained constant between 2001 and 2018 (Figure 4-4). The average concentration of SO42- from 1984 to 2018 on site 90204 was 60 mg/l SO42- and the average concentration of SO42- from 1990 to 2018 was 66 mg/l SO42- on site 90233 (Figure 4-4).

Figure 4-4: Water quality trend of phosphate (PO43-) and sulphate (SO42-) for Crocodile-West River from 1976 to 2018. The green line represents the target water quality ranges as presented in Table 3-2. The following colours represent the sites surveyed: Blue=Site 90194, Red=90167, Grey=90203, Orange=90204 and Black=Site 90233

0 2 4 6 8 10 12

25/2/76 30/11/77 30/05 1979 30/11/80 30/5/82 30/11/83 30/5/85 30/11/86 30/5/88 30/11/89 30/5/91 30/11/92 30/5/94 30/11/95 30/5/97 30/11/98 30/5/00 30/11/01 30/5/03 30/11/04 30/5/06 30/11/07 30/5/09 30/11/10 30/5/12 30/11/13 30/5/15 30/11/16 30/5/18

Phosphate concentration in Crocodile-West River from 1976 to 2018

Year PO4concentration (mg/l)

0 50 100 150 200 250 300 350 400 450

1976/02/25 1977/08/30 1978/11/30 1980/02/25 1981/05/30 1982/08/30 1983/11/30 1985/02/25 1986/05/30 1987/08/30 1988/11/30 1990/02/25 1991/05/30 1992/08/30 1993/11/30 1995/02/25 1996/05/30 1997/08/30 1998/11/30 2000/02/25 2001/05/30 2002/08/30 2003/11/30 2005/02/25 2006/05/30 2007/08/30 2008/11/30 2010/02/25 2011/05/30 2012/08/30 2013/11/30 2015/02/25 2016/05/30 2017/08/30 2018/11/30 Sulphate concentration in Crocodile-West River from 1976 to 2018

Year SO4concentration(mg/l)

Figure 4-5: Water quality trend of pH for Crocodile-West River from 1976 to 2018. The green and dark blue line represents the target water quality ranges as presented in Table 3-2. The following colours represent the sites surveyed: Blue=Site 90194, Red=90167, Grey=90203, Orange=90204 and Black=Site 90233

The water quality trend in figure 4-5 represents the water quality trend of pH in all sites of the Crocodile-West River from 1976 to 2018. There was a temporal change of pH levels in site 90194 where the pH levels increased between 1976 to 2018. The pH levels on site 90194 increased from 7.3 units to 8.3 units between 1979 and 2018. The pH levels on site 90167 also increased from 7.3 units to 8.41 units between 1976 and 1985 and remained basic (8.1 units) between 1985 and 2018 (Figure 4-5). The pH levels on site 90203 have been basic (pH = 8.3 units) since 1984

5 5,5 6 6,5 7 7,5 8 8,5 9

Year

10 60 110 160 210 260 310 360

EC in the Crocodile-West River from 1976 to 2018

Year

EC(µS/cm)

and continued to be basic until 2018 (Figure 4-5). Site 90204 had an average pH value of 8.5 units from 1985 to 2018 and the pH levels on site 90233 remained basic (pH = 8.3 units) from 1990 to 2018 (Figure 4-5). Generally, the pH levels in all sites experienced a temporal change between 1976 and 1980s where there was an exponential increase of pH levels in all sites. The pH levels stabilised above 8 units in all sites between 1990s to 2018 (Figure 4-5).

The water quality trend in figure 4-5 represented the EC levels in all sites. The average EC on site 90194 remained constant at 10 µS/cm between 1979 to 2018. The EC on site 90167 experience temporal changes during 1976 and 2018 (Figure 4-5). The EC levels increased from 1976 (55.6 µS/cm) to 1984 (114 µS/cm). The concentration of electrical conductivity declined from 1984 to 2018 (71 µS/cm). Site 90203 exhibited high concentration of EC in the mid-1980s, mid- 1990s and mid-2000s with EC values ranging between 80 µS/cm and 140 µS/cm (Figure 4-5).

The EC value on site 90204 did not change significantly between 1076 to 2018 and remained constant (70 µS/cm) between 1984 and 2018. The EC levels on site 90233 did not change significantly between 1990 to 2018. The EC Levels remained constant at an average of 85 µS/cm (Figure 4-5).

4.2. Water Quality Index Calculations

Dalam dokumen The applicability of a Water Quality Index (WQI) as an assessment tool for urban rivers : a case study in the Crocodile River (Halaman 54-62)