Biogenic silica content was determined in 25 surface sediment samples from the southern South China Sea to study its distribution and its modern oceanic environmental significance, which may provide further scientific...Biogenic silica content was determined in 25 surface sediment samples from the southern South China Sea to study its distribution and its modern oceanic environmental significance, which may provide further scientific evidence for paleoceanography explaination. This study showed that biogenic silica content in surface sediments and its water depth have evidently positive correlation, and the correlation coefficient was up to 0.782. Biogenic silica content was very low in continental shelf shallows and could not reflect the productivity of siliceous micropaleontology in surface waters, which may be affected by sedimentary types and terrigenous matter dilution. Distribution of biogenic silica content in surface sediments from deep water areas showed that it could not only reflect the paleoproductivity of siliceous micropaleontology in surface waters, but also indicate the strong or feeble upwelling. Thus, it was further confirmed that using biogenic silica content in sediments to trace upwelling and its change was effective and reliable. The analyzed result showed that radiolariia and poriferous specula have more contribution for biogenic opal, comparing with diatom in surface sediments from the northern studied area, probably owing to the diatom dissolved easily away and eaten by other organisms with little effort. In the upwelling areas, radiolarian, diatom and poriferous specula all approximately showed high abundance, which was consistent with high biogenic silica content.展开更多
Artificial upwelling, as a geoengineering tool, has received worldwide attention because it may actualize ocean fertilization in a sustainable way, which could potentially alleviate the pressures on the fish stocks an...Artificial upwelling, as a geoengineering tool, has received worldwide attention because it may actualize ocean fertilization in a sustainable way, which could potentially alleviate the pressures on the fish stocks and human-driven climate change in the ocean. We reviewed the current knowledge on the development of an artificial upwelling system and its potential environmental effects. Special attention was given to the research progress on the air-lift concept artificial upwelling by Zhejiang University. The research on artificial upwelling over the past few decades has generated a range of devices that have been successfully applied in the field for months. Based on field experiments and the associated modeling results, part of them reported positive effects on increasing primary production and enhancing CO2 sequestration. However, as a significant disturbance to the environment, especially for large-scale applications, the uncertainties related to the potential effects on ecosystem remain unsolved. Zhejiang University has overcome the technical challenges in designing and fabricating a robust and high efficiency artificial upwelling device which has been examined in two field experiments in Qiandao Lake and one sea trial in the East China Sea. It was investigated that cold and hypoxic deep ocean water(DOW) could be uplifted to the euphotic layer, which could potentially change the nutrient distribution and adjust the N/P ratio. Both simulation and field experiments results confirmed that utilizing self-powered energy to inject compressed air to uplift DOW was a valid and efficient method. Therefore, further field-based research on artificial upwelling, especially for long-term field research is required to test the scientific hypothesis.展开更多
基金National Natural Science Foundation of China (No. 40476024)National Key Technology R&D Program (No. 2006BAB19B03)+1 种基金supported by Key Laboratory of Marginal Sea Geology, Chinese Academy of Sciences (No. MSGL0613)the Knowledge Innovation Program of the Chinese Academy of Sciences (No. SQ200808)
文摘Biogenic silica content was determined in 25 surface sediment samples from the southern South China Sea to study its distribution and its modern oceanic environmental significance, which may provide further scientific evidence for paleoceanography explaination. This study showed that biogenic silica content in surface sediments and its water depth have evidently positive correlation, and the correlation coefficient was up to 0.782. Biogenic silica content was very low in continental shelf shallows and could not reflect the productivity of siliceous micropaleontology in surface waters, which may be affected by sedimentary types and terrigenous matter dilution. Distribution of biogenic silica content in surface sediments from deep water areas showed that it could not only reflect the paleoproductivity of siliceous micropaleontology in surface waters, but also indicate the strong or feeble upwelling. Thus, it was further confirmed that using biogenic silica content in sediments to trace upwelling and its change was effective and reliable. The analyzed result showed that radiolariia and poriferous specula have more contribution for biogenic opal, comparing with diatom in surface sediments from the northern studied area, probably owing to the diatom dissolved easily away and eaten by other organisms with little effort. In the upwelling areas, radiolarian, diatom and poriferous specula all approximately showed high abundance, which was consistent with high biogenic silica content.
基金financially funded by the National Natural Science Foundation of China(Grant Nos.51120195001&51205346)the Program for Zhejiang Leading Team of S&T Innovation(Grant No.2010R50036)+1 种基金the Public Welfare Project of Science Technology Department of Zhejiang ProvinceChina(Grant No.2015C31096)
文摘Artificial upwelling, as a geoengineering tool, has received worldwide attention because it may actualize ocean fertilization in a sustainable way, which could potentially alleviate the pressures on the fish stocks and human-driven climate change in the ocean. We reviewed the current knowledge on the development of an artificial upwelling system and its potential environmental effects. Special attention was given to the research progress on the air-lift concept artificial upwelling by Zhejiang University. The research on artificial upwelling over the past few decades has generated a range of devices that have been successfully applied in the field for months. Based on field experiments and the associated modeling results, part of them reported positive effects on increasing primary production and enhancing CO2 sequestration. However, as a significant disturbance to the environment, especially for large-scale applications, the uncertainties related to the potential effects on ecosystem remain unsolved. Zhejiang University has overcome the technical challenges in designing and fabricating a robust and high efficiency artificial upwelling device which has been examined in two field experiments in Qiandao Lake and one sea trial in the East China Sea. It was investigated that cold and hypoxic deep ocean water(DOW) could be uplifted to the euphotic layer, which could potentially change the nutrient distribution and adjust the N/P ratio. Both simulation and field experiments results confirmed that utilizing self-powered energy to inject compressed air to uplift DOW was a valid and efficient method. Therefore, further field-based research on artificial upwelling, especially for long-term field research is required to test the scientific hypothesis.