CAJ | 학술논문

碳酸盐风化能否形成稳定持久碳汇很大程度上取决于风化产生的溶解无机碳(DIC)能否被水生光合生物利用及其利用程度,后者可通过地表水水化学和d13CDIC 的昼夜变化进行探讨。本研究对冬季茂兰拉桥表层岩溶泉及其中游和下游池水的温度、pH、电导率(EC)和溶解氧(DO)进行了为期30 h(1月27日10：00至1月28日16：00)高分辨率(15 min/次)的昼夜动态监测和d13CDIC定期取样(白天每隔2 h,夜间每隔4 h)测定,以了解水生光合生物对水化学和d13CDIC昼夜动态变化的影响。同时,结合水面静态箱CO2测定获得的岩溶水与空气 CO2交换通量,对生物碳泵效应进行了估算。结果表明,在少有沉水植物生长的泉口及其下游水池,水化学和d13CDIC的昼夜变化明显偏小,而在沉水植物(轮藻为主)大量生长的中游水池,水的DO、pH、SIC (方解石饱和指数)和d13CDIC在白天呈逐渐增加趋势,而在夜间逐渐降低,与水生生物的新陈代谢进程(白天以光合作用为主,晚上以呼吸作用占优势)相一致；另一方面,水的EC、3HCO-、Ca2+和p(CO2)(二氧化碳分压)呈现相反的变化趋势,即白天下降,晚上上升。计算得到中游水池因类似海洋“生物碳泵”效应固定下来的有机碳通量达到336 t C/(a·km2),是海洋的51倍,表明陆地水生生态系统应该作为“遗失碳汇”的一个重要方面继续进行研究。
탄산염풍화능부형성은정지구탄회흔대정도상취결우풍화산생적용해무궤탄(DIC)능부피수생광합생물이용급기이용정도,후자가통과지표수수화학화d13CDIC 적주야변화진행탐토。본연구대동계무란랍교표층암용천급기중유화하유지수적온도、pH、전도솔(EC)화용해양(DO)진행료위기30 h(1월27일10：00지1월28일16：00)고분변솔(15 min/차)적주야동태감측화d13CDIC정기취양(백천매격2 h,야간매격4 h)측정,이료해수생광합생물대수화학화d13CDIC주야동태변화적영향。동시,결합수면정태상CO2측정획득적암용수여공기 CO2교환통량,대생물탄빙효응진행료고산。결과표명,재소유침수식물생장적천구급기하유수지,수화학화d13CDIC적주야변화명현편소,이재침수식물(륜조위주)대량생장적중유수지,수적DO、pH、SIC (방해석포화지수)화d13CDIC재백천정축점증가추세,이재야간축점강저,여수생생물적신진대사진정(백천이광합작용위주,만상이호흡작용점우세)상일치；령일방면,수적EC、3HCO-、Ca2+화p(CO2)(이양화탄분압)정현상반적변화추세,즉백천하강,만상상승。계산득도중유수지인유사해양“생물탄빙”효응고정하래적유궤탄통량체도336 t C/(a·km2),시해양적51배,표명륙지수생생태계통응해작위“유실탄회”적일개중요방면계속진행연구。
Whether carbonate weathering could form stable and durable carbon sink or not depends mainly on the efficiency of the utilization of dissolved inorganic carbon (DIC) by aquatic phototrophs. The latter can be investigated by determing the diurnal variations in hydrochemistry and stable carbon isotope composition of DIC (δ13CDIC) in surface waters. In this research, four parameters, including water temperature, pH value, electrical conductivity (EC) and dissolved oxygen (DO), were synchronously monitored with high resolution (an interval of 15 min.) from 10: 00, 27th Jan. to 16: 00, 28th Jan. (30-hour period) at the spring, midstream pond, and downstream pond at Laqiao, Maolan, SW China. In addition, δ13CDIC values were sampled and analyzed at an interval of 2 hours in daytime and 4 hours in nighttime. Moreover, a static floating chamber was placed on the water surface to obtain CO2 exchange flux between atmosphere and water to evaluate the biological carbon pump effect with the hydrochemical change. The results show that diurnal changes in hydrochemical characteristics andδ13CDIC values at the spring and downstream pond where few submerged plants developed were much smaller than those at the midstream pond where submerged plants (dominated by Chara Fragilis) flourished. DO, pH, SIC (saturation index of calcite) andδ13CDIC values in the midstream pond show the largest increase in daytime while the largest decrease happened during the nighttime, which had synchronous change with the process of aquatic metabolism (photosynthesis dominated in daytime while respiration dominated in nighttime). On the other hand, EC, [ 3HCO-], [Ca2+] and p(CO2) (CO2 partial pressure) showed the inverse variations. The calculated biological carbon pump flux in the middle pond was 336 t C/(a·km2) which was about 50 times higher than that in the ocean, indicating that the carbon fixation in terrestrial freshwater ecosystems may need to be considered as an important part of the missing carbon sink. Further research is needed.