檢測土(tu)壤氡濃度的注意事項

地質特征與(yu)地理位置的影響

檢(jian)測(ce)(ce)機構證實，土(tu)(tu)(tu)(tu)壤(rang)里的(de)(de)氡(dong)(dong)主要(yao)(yao)來(lai)自于(yu)地(di)(di)層(ceng)(ceng)深處的(de)(de)放射元素通過地(di)(di)質(zhi)活動進入(ru)地(di)(di)表(biao)土(tu)(tu)(tu)(tu)壤(rang)。因(yin)此土(tu)(tu)(tu)(tu)壤(rang)中(zhong)氡(dong)(dong)的(de)(de)濃(nong)(nong)度(du)(du)主要(yao)(yao)取決于(yu)地(di)(di)下土(tu)(tu)(tu)(tu)壤(rang)的(de)(de)鈾、鐳、滲透率(lv)、孔隙率(lv)和滲透率(lv)以及(ji)水蒸氣(qi)含量。在調查(cha)中(zhong)，我們發現同(tong)一(yi)臺(tai)機器在同(tong)一(yi)地(di)(di)區(qu)的(de)(de)非地(di)(di)質(zhi)斷裂(lie)(lie)帶測(ce)(ce)量砂土(tu)(tu)(tu)(tu)和亞粘土(tu)(tu)(tu)(tu)時，結(jie)果要(yao)(yao)差得多。沙地(di)(di)氡(dong)(dong)平均濃(nong)(nong)度(du)(du)[2]大(da)于(yu)1000bq/m3。然(ran)而(er)，亞粘土(tu)(tu)(tu)(tu)很(hen)少(shao)超過100bq/m3。可見土(tu)(tu)(tu)(tu)壤(rang)附著力低(di)(di)、濕度(du)(du)低(di)(di)、孔隙率(lv)高(gao)、氡(dong)(dong)濃(nong)(nong)度(du)(du)高(gao)；而(er)粘附強度(du)(du)高(gao)，氡(dong)(dong)濃(nong)(nong)度(du)(du)檢(jian)測(ce)(ce)方(fang)法有(you)哪些，濕度(du)(du)大(da)，孔隙率(lv)低(di)(di)，氡(dong)(dong)濃(nong)(nong)度(du)(du)檢(jian)測(ce)(ce)，氡(dong)(dong)濃(nong)(nong)度(du)(du)低(di)(di)。地(di)(di)理位置處在地(di)(di)質(zhi)斷層(ceng)(ceng)地(di)(di)區(qu)，氡(dong)(dong)濃(nong)(nong)度(du)(du)也相(xiang)對較(jiao)高(gao)。由于(yu)裂(lie)(lie)縫的(de)(de)存(cun)在，土(tu)(tu)(tu)(tu)壤(rang)氡(dong)(dong)濃(nong)(nong)度(du)(du)檢(jian)測(ce)(ce)的(de)(de)資質(zhi)要(yao)(yao)求，地(di)(di)層(ceng)(ceng)深處的(de)(de)氡(dong)(dong)有(you)上升和沉淀的(de)(de)趨勢，氡(dong)(dong)濃(nong)(nong)度(du)(du)較(jiao)高(gao)。據一(yi)些地(di)(di)區(qu)的(de)(de)調查(cha)報告，地(di)(di)質(zhi)斷層(ceng)(ceng)地(di)(di)區(qu)表(biao)層(ceng)(ceng)土(tu)(tu)(tu)(tu)壤(rang)的(de)(de)氡(dong)(dong)濃(nong)(nong)度(du)(du)比其(qi)他地(di)(di)區(qu)要(yao)(yao)高(gao)出好幾倍。

土(tu)壤氡濃度檢測方法  

土壤中氡濃(nong)度的測量可以采(cai)用電離室法(fa)、靜電收集(ji)法(fa)、閃(shan)爍瓶法(fa)、金硅面壘型探測器等方法(fa)進行檢測。

土壤氡(dong)濃度檢測儀器性(xing)能(neng)指標要求

工作條件：溫度：-10～40℃

相對濕度：≤90％

儀器(qi)性能：不確定度：≤20％

探測下(xia)限(xian)：≤400 Bq/m3

氡(dong)(dong)氣(qi)是危害(hai)人們身體健康的輻射源之一。在民(min)用建筑工(gong)程施工(gong)前(qian)，需要(yao)進(jin)行(xing)場地(di)土(tu)壤(rang)氡(dong)(dong)濃(nong)度(du)的測(ce)(ce)量(liang)，當(dang)(dang)地(di)土(tu)壤(rang)氡(dong)(dong)濃(nong)度(du)實(shi)測(ce)(ce)平均值(zhi)較低(不大(da)(da)于(yu)10000Bq／m3)、且工(gong)程地(di)點(dian)無(wu)地(di)質斷(duan)裂構造時，土(tu)壤(rang)氡(dong)(dong)濃(nong)度(du)檢測(ce)(ce)怎么做，土(tu)壤(rang)氡(dong)(dong)對工(gong)程的影(ying)響不大(da)(da)，工(gong)程可不進(jin)行(xing)土(tu)壤(rang)氡(dong)(dong)濃(nong)度(du)測(ce)(ce)定(ding)。當(dang)(dang)已知當(dang)(dang)地(di)土(tu)壤(rang)氡(dong)(dong)濃(nong)度(du)實(shi)測(ce)(ce)平均值(zhi)較高(gao)(大(da)(da)于(yu)10000Bq／m3)或(huo)工(gong)程地(di)點(dian)有地(di)質斷(duan)裂構造時，工(gong)程仍需要(yao)進(jin)行(xing)土(tu)壤(rang)氡(dong)(dong)濃(nong)度(du)測(ce)(ce)定(ding)。

國外降低氡(dong)氣的措(cuo)施：

 1、英國：針對(dui)氡氣濃度的(de)不同采取以下五種(zhong)方法(fa)：

安(an)裝氡坑抽氣(qi)系統(tong) 、密封(feng)地面和墻(qiang)、增設地板下通風(feng)(feng)系統(tong)、整個屋(wu)(wu)子安(an)裝主動加壓或強制通風(feng)(feng)系統(tong)、改善房屋(wu)(wu)通風(feng)(feng)。

 2、美國： 在(zai)降(jiang)氡(dong)措施方(fang)面美國有標準： RMS是美國環保署在(zai) 1993 年發布的并于 1994 年進行了修(xiu)訂，在(zai)不久要施行 ASTMI E2121 ，在(zai) RMS 中有清楚的描述。