硬水

出自維基百科,自由嘅百科全書
跳去導覽 跳去搵嘢
硬水令水喉頭污糟邋遢
礦物沉積水管裏面

硬水礦物成份高嘅。硬水係因為水捐過流過石灰岩白埴土石膏呢啲岩層而形成[1],佢哋有好重嘅礦物質。

硬水裏頭嘅礦物質沉積喺金屬,其他用具表面,特別係發熱嘅表面,好似茶煲,熱水喉噉[2]。其他問題包括番梘牙膏難起泡。不過飲硬水就對身體有益,飲起嚟會有少少澀味[3]

硬度[編輯]

水嘅硬度由 pH、溫度同埋礦物成份嚟決定,美國地質勘探對水嘅軟硬度分類[4]

分類 硬度 (mg-CaCO3/L) 硬度(mmol/L) 硬度(dGH/°dH) 硬度 (gpg) 硬度 (ppm)
0–60 0–0.60 0–3.37 0–3.50 0–60
普通硬 61–120 0.61–1.20 3.38–6.74 3.56–7.01 61–120
121–180 1.21–1.80 6.75–10.11 7.06–10.51 121–180
好硬 ≥ 181 ≥ 1.81 ≥ 10.12 ≥ 10.57 ≥ 181

海水就係好勁硬,一般硬度去到 6,630 ppm (每公升 6.63 克)。新鮮水硬度係 15 to 375 ppm[5]

另外,根據離子嘅含量,硬水可分為暫時硬水永久硬水兩種。前者係流過石灰岩地層嘅河水同地下水,裏頭有好多嘅碳酸氫鈣 CaCO3,煲滾之後軟化。後者含鈣同鎂嘅硫酸鹽同氯化物,煲滾唔會軟化。以前,硬水係用蒸餾方法軟化,而家可以用離子交換樹脂拎走離子,令水軟化。

化學[編輯]

硬水煲滾之後,令碳酸鈣(灰石)沉澱。

另外,用軟化劑可以將鈣沉澱。

水軟化[編輯]

因為硬水影響機器操作、水輸送系統、清潔劑難起泡呢啲問題。軟化啲水有佢嘅實際需要,方法有離子交換樹脂,用離子代替硬水裏頭嘅鎂同鈣離子(4 Na+ 換 2 Ca2+)。

蘇打水(碳酸鈉,Na2CO3)加入番梘、洗衣粉呢啲清潔劑一齊用,可以軟化硬水。

硬水經過處理之後叫「軟化水」,軟化咗嘅水會有比較多嘅碳酸氫鹽(bicarbonate)、鈉、鉀同離子。

健康考慮[編輯]

世界衛生組織表示似乎冇信得過嘅證據,去講「硬水影響人嘅健康」[2]。美國國家研究委員會發現硬水嘅鈣同鎂可以當做食嘢嘅補充劑[6]

有研究指出,水硬度同男人心血管病有少少嘅反比關係。不過,世界衛生組織話數據唔足夠去建議提高硬度嘅水平[7]。其他研究指出心血管健康同水硬度有少少相關[8][9][10]

一啲研究話用硬水嘅屋企同細路濕疹個案有關連[11][12][13][14]。軟化水濕疹試驗(Softened-Water Eczema Trial SWET),有關用離子交換軟化水機同細路濕疹治療,係個多中心隨機對照試驗,喺二〇〇八年做,搵唔到用唔用軟水機對濕疹有分別[15]

地區[編輯]

澳洲主要城市,跟澳洲水協會(Australian Water Association)嘅數據,由好軟到硬(ppm):

澳洲水質硬度(ppm)
Canberra 墨爾本 雪梨 珀斯 布里斯本 阿地利
水質數據 40[16] 10–26[17] 39.4–60.1[18] 29–226[19] 100[20] 134–148[21]

加拿大中部平原省份沙斯卡寸旺曼尼托巴省,有好多鈣同鎂,即白雲石地質,地下水有好多二氧化碳,總硬度成日超過 200 ppm。西面省份大部份水係由雨水、湖水同埋冰川融雪嚟。一般係:

加拿大水質硬度(ppm)
滿地可 卡加利地區 利載拿 沙斯加通 溫尼辟 多倫多 溫哥華 查洛城 PEI 滑鐵盧地區 聖約翰 渥太華
水質數據 116[22] 165 496[23] 160–180[24] 77[25] 121[26] < 3[27] 140–150[28] 400 160–200[29] 30[30]

香港水喉水平均值係 21 ppm[31]

廣州住宅供水 1999 年嘅數據水硬度係 300 mg/L[32]

臺北地區「自來水」總硬度狀況:取決於水源區,唔同水源,硬度亦唔同。新店溪水源係長興公館直潭場,硬度介乎於 25.2 - 49.6 mg/L,平均 33.9 mg/L[33]

[編輯]

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