The volume-weighted mean concentrations (VWMs) of components in the rainwater were calculated based on the rainfall amount and rainwater quality data of 25 rainfall events during 2011–2012. TOC has a VWM of 3.98 mg/L, which is the highest among all the measured components; Ca
2+ and NH
4+ have VWMs of 0.86 mg/L and 0.47 mg/L, respectively, which are much higher than the other cations; NO
3– and SO
42– have VWMs of 1.74 mg/L and 1.71 mg/L, respectively, which are much higher than the other inorganic anions; and formic acid and acetic acid have VWMs of 0.26 mg/L and 0.12 mg/L, respectively, which are higher than the other organic acids. Furthermore, the VWMs of PO
43–, glutaric acid, succinic acid, malonic acid, methanesulfonic acid in the samples are lower than 0.1 mg/L, and some of them are lower than detective limits. In addition, the VWM pH in the rainwater is 4.99, showing the acidity of rainfall in the study area. The concentrations of components in rainwater in the study area are lower than those in Guangzhou, Beijing, Shanghai, Nanjing, Ankara and Galicia; while they are similar to those in other cities listed in Table 3. Water quality of rainwater in rainfall events is shown in a box-whisker plot, which indicates that the concentrations of components in the rainwater are highly variable, dependent upon different rainfall events (
Figure 2(a)).
Table 3The volume-weighted mean pH and component concentrations in rainwater in Shenzhen and other cities (mg/L)
Area
. | Time
. | pH
. | Na+
. | NH4+
. | K+
. | Mg2+
. | Ca2+
. | Cl–
. | NO3–
. | SO42–
. | Reference
. |
---|
This study | 2011 | 4.99 | 0.235 | 0.473 | 0.180 | 0.042 | 0.857 | 0.554 | 1.743 | 1.712 | |
Guangzhou | 2006 | 4.56 | 1.265 | 1.271 | 1.283 | 0.204 | 2.072 | 3.077 | 3.311 | 7.838 | Cao et al. (2009) |
Shanghai | 2005 | 4.49 | 1.152 | 1.453 | 0.581 | 0.355 | 4.08 | 2.067 | 3.088 | 9.581 | Huang et al. (2008) |
Beijing | 2003 | 6.18 | 1.346 | 6.768 | 1.564 | 1.92 | 7.94 | 2.935 | 10.788 | 25.008 | Hu et al. (2005) |
Jinhua | 2004 | 4.54 | 0.173 | 1.746 | 0.207 | 0.053 | 1.122 | 0.365 | 2.294 | 5.611 | Zhang et al. (2007) |
Nanjing | 1992–2003 | 5.15 | 0.529 | 3.478 | 0.472 | 0.38 | 5.908 | 5.055 | 2.455 | 11.606 | Tu et al. (2005) |
Mexico | 2001–2002 | 5.08 | 0.161 | 1.663 | 0.086 | 0.03 | 0.528 | 0.34 | 2.641 | 2.971 | Báez et al. (2007) |
Ankara | 1994–1996 | 6.3 | 0.359 | 1.555 | 0.382 | 0.112 | 1.428 | 0.723 | 1.81 | 2.304 | Topçu et al. (2002) |
Singapore | 1999–2000 | 4.2 | 0.754 | 0.344 | 0.281 | 0.078 | 0.322 | 1.212 | 1.383 | 4.008 | Hu et al. (2003) |
Tokyo | 1990–2002 | 4.52 | 0.851 | 0.727 | 0.113 | 0.138 | 0.498 | 1.957 | 1.891 | 2.41 | Okuda et al. (2005) |
Seoul | 1996–1998 | 4.7 | 0.242 | 1.195 | 0.137 | 0.083 | 0.698 | 0.645 | 1.854 | 3.403 | Lee et al. (2000) |
Galicia | 1999 | 6.55 | 3.358 | 4.536 | 1.599 | 0.528 | 1.7 | 6.097 | 1.55 | 4.752 | Vázquez et al. (2003) |
Newark | 2006–2007 | 4.6 | 0.251 | 0.439 | 0.051 | 0.04 | 0.12 | 0.379 | 0.893 | 1.829 | Song & Gao (2009) |
Area
. | Time
. | pH
. | Na+
. | NH4+
. | K+
. | Mg2+
. | Ca2+
. | Cl–
. | NO3–
. | SO42–
. | Reference
. |
---|
This study | 2011 | 4.99 | 0.235 | 0.473 | 0.180 | 0.042 | 0.857 | 0.554 | 1.743 | 1.712 | |
Guangzhou | 2006 | 4.56 | 1.265 | 1.271 | 1.283 | 0.204 | 2.072 | 3.077 | 3.311 | 7.838 | Cao et al. (2009) |
Shanghai | 2005 | 4.49 | 1.152 | 1.453 | 0.581 | 0.355 | 4.08 | 2.067 | 3.088 | 9.581 | Huang et al. (2008) |
Beijing | 2003 | 6.18 | 1.346 | 6.768 | 1.564 | 1.92 | 7.94 | 2.935 | 10.788 | 25.008 | Hu et al. (2005) |
Jinhua | 2004 | 4.54 | 0.173 | 1.746 | 0.207 | 0.053 | 1.122 | 0.365 | 2.294 | 5.611 | Zhang et al. (2007) |
Nanjing | 1992–2003 | 5.15 | 0.529 | 3.478 | 0.472 | 0.38 | 5.908 | 5.055 | 2.455 | 11.606 | Tu et al. (2005) |
Mexico | 2001–2002 | 5.08 | 0.161 | 1.663 | 0.086 | 0.03 | 0.528 | 0.34 | 2.641 | 2.971 | Báez et al. (2007) |
Ankara | 1994–1996 | 6.3 | 0.359 | 1.555 | 0.382 | 0.112 | 1.428 | 0.723 | 1.81 | 2.304 | Topçu et al. (2002) |
Singapore | 1999–2000 | 4.2 | 0.754 | 0.344 | 0.281 | 0.078 | 0.322 | 1.212 | 1.383 | 4.008 | Hu et al. (2003) |
Tokyo | 1990–2002 | 4.52 | 0.851 | 0.727 | 0.113 | 0.138 | 0.498 | 1.957 | 1.891 | 2.41 | Okuda et al. (2005) |
Seoul | 1996–1998 | 4.7 | 0.242 | 1.195 | 0.137 | 0.083 | 0.698 | 0.645 | 1.854 | 3.403 | Lee et al. (2000) |
Galicia | 1999 | 6.55 | 3.358 | 4.536 | 1.599 | 0.528 | 1.7 | 6.097 | 1.55 | 4.752 | Vázquez et al. (2003) |
Newark | 2006–2007 | 4.6 | 0.251 | 0.439 | 0.051 | 0.04 | 0.12 | 0.379 | 0.893 | 1.829 | Song & Gao (2009) |
Figure 2
Water quality of rainwater and roof runoff in rainfall events.
Figure 2
Water quality of rainwater and roof runoff in rainfall events.
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