摘要：An in situ calibration syste. is a ve.satile.e.ploration instrume.t for e.e.troche.ical se.sors inve.tigating the.bioche.ical prope.tie. of the.marine.e.vironme.t. The.purpose.of this pape. is to de.cribe.the.de.ign of an auto-calibrating syste. for e.e.troche.ical (pH) se.sors, which pe.mits two-point in situ calibration, suitable.for long-te.m me.sure.e.t in de.p se. aque.us e.vironme.ts. Holding multiple.se.sors, the.instrume.t is de.igne. to pe.form long-te.m me.sure.e.ts and in situ calibrations at abyssal de.th (up to 4000 m). The.instrume.t is compose. of a compact fluid control syste. which is pre.sure.e.uilibrate. and de.igne. for de.p-se. ope.ation. In situ calibration capability plays a ke. role.in the.quality and re.roducibility of the.data. This pape. focuse. on me.hods for e.te.ding the.life.ime.of the.instrume.t, conside.ing the.fluidics de.ign, me.hanical de.ign, and low-powe. consumption of the.e.e.tronics controlle.. The.instrume.t can last 46 d unde. normal ope.ating conditions, fulfilling the.ne.d for long-te.m ope.ation. Data conce.ning pH me.sure. during the.KNOX18RR cruise.(Mid-Atlantic Ridge. July-August, 2008) illustrate.the.de.irable.prope.tie. of the.instrume.t. Combine. with diffe.e.t e.e.trode. (pH, H2, H2S, e.c.), it should be.of gre.t utility for the.study of de.p oce.n e.vironme.ts, including wate. column and diffuse.flow hydrothe.mal fluids.