ScientistsinIsraelhavediscoveredanewwaytotestforwaterpollutionby"listening"towhattheplantsgrowinginwaterhavetosay．Byshiningalaserbeam(激光束)onthetinypiecesofalgae(海藻)floatinginthew
ScientistsinIsraelhavediscoveredanewwaytotestforwaterpollutionby"listening"towhattheplantsgrowinginwaterhavetosay．Byshiningalaserbeam(激光束)onthetinypiecesofalgae(海藻)floatinginthewatertheresearcherssaidtheyhearsoundwavesthattellthemthetypeandamountofpollutioninthewater．
"Itisaredlighttellingusthatsomethingisbeginningtogowrongwiththequalityofwater"saidZvyDubinskyanaquaticbiologistatIsrael'sBarIlanUniversity．"Algaeisthefirstthingtobeaffectedbyachangeinwaterquality．"
AswatersourcesdeteriorateworldwidethetestingofalgaecouldbeusedtomonitorwaterqualityfastermorecheaplyandmoreaccuratelythantechniquesnowinuseDubinskysaid．Thesecretistomeasuretherateofphotosynthesis(光合作用)inthealgaemeaningtheplant'sabilitytotransformlightintoenergy．Duringphotosynthesisplantsalsoreleaseoxygenintotheair．
Dubinsky'stechniqueiseasytoperformbecauseoftheover-abundanceofalgaeintheplanet'swater．Mostoftheoxygenintheatmospherecomesfromalgae．Aprototypetestershootsalaserbeamatwatersamplestostimulatephotosynthesisinthealgae．Butnotallofthelaser'sheatisused．
DependingontheconditionofthealgaeandtherateofphotosynthesissomeoftheheatisshotbackintothewatercreatingsoundwavesDubinskysaid．Withaspecialunderwatermicrophoneresearchersareabletoanalyzethestrengthofthesoundwavesanddeterminethehealthofthealgaeandtheconditionofthesurroundingwater．
"Algaesufferingfromleadpoisoninglikewastedischargedfrombatteryandpaintmanufacturingplantswillproduceadifferentsoundthanthosesufferingfromlackofironorexposuretoothertoxins"saidresearcherYuliaPinchasov．
72．Tostudywaterqualityscientistschoosealgaemainlybecause ．
A．algaeismosteasilyaffectedbypollution
B．mostoxygenisproducedbyalgae
C．theamountofalgaeisdecreasing
D．algaeisakindofplantfloatinginthewater
73．WhenDubinskystudiedwaterqualityhemainlyfocusedon ．
A．theamountoflaserusedbyalgae
B．therateofphotosynthesisinthealg