多通道化学传感器及其在热液喷口探测中的应用

热液喷口附近的羽状流中存在明显的化学及浊度异常,通过探测这些异常可判断是否存在热液喷口及确定喷口的具体位置。本文研制了一款可用于探测热液喷口的多通道化学传感器,该传感器具有体积小、精度高的特点,且可在4000米深海中进行工作。该化学传感器共配备五个全固态电极,一个为参比电极,其余四个为离子选择性电极,并且可根据所测量的化学离子进行更换。本文基于该化学传感器共进行了两组实验。在第一组浅海试验中,化学传感器集成了pH,Eh,CO₃^2-和SO₄^2-电极,在浅海海域中测量对应化学量,结果表明该化学传感器可在实际应用中获得高精度、稳定的测量数据。第二组实验为深海热液探测,装配了pH,Eh,CO₃^2-和H₂S电极的化学传感器在西南印度洋中脊区域的29次测线中投入使用,共获得有效数据27组。通过对测量所得到的化学量进行分析,本文提出了一种确定热液喷口的化学异常探测方法,若某时间段内Eh和H₂S的电势降低,而pH和CO₃^2-的电势上升则可判定存在化学异常。利用该方法对27组有效数据进行分析,共发现5个潜在的热液喷口。实验结果表明,该化学传感器可有效地探测由热液引起的化学异常,适用于实际热液探测中。     

海洋化学传感器研制的动态评述

化学海洋学研究数据的获得要方便、经济、高效的分析测试手段,化学传感器则是海洋调查和监测ＤＯ、ｐＨ、ＣＯ２、ＮＨ３－Ｎ和Ｓ（－ＩＩ）等的理想手段和工具。本文评述了６０年代末以来用于天然水体中ＣＯ２、ＮＨ３－Ｎ和Ｓ（－ＩＩ）检测的化学传感器的研制情况,进一步讨论了海洋化学传感器研制所需解决的问题和发展方面,并分析了海洋化学传感器研制进展缓慢的原因。     

Electric potential due to a ring electrode

Electrical sensors utilizing ring electrodes mounted on cylindrical rods have been used by several workers to measure the resistivity of marine sediments. As the resistivity of sediment is dependent upon the water content of the sediment, such measurements are extremely valuable for determining the density of sediments. Recently, ring electrodes have also been used in instrumentation to determine fluctuations in the marine sediment-seawater interface due to erosion or deposition. In the past, approximate formulas have been used to evaluate the response of the sensors. In this work, an exact formula is derived, and it is shown that the previous formulas are in error by up to 5%. Although this is not serious for most borehole logging applications, it is essential to use the exact formulas to interpret data from electromagnetic sediment level sensors     

基于多参数化学传感器的海底热液探测方法研究

基于热液及其羽状流的化学异常提出了一种海底热液的化学式探测方法。根据自行开发的Eh.Ag/Ag₂S和pH三种化学电极,设计了多参数化学传感器系统。通过海试证明多参数化学传感器可灵敏地检测出由热液异常引起的化学量变化,并在长达半年的多次使用中表现出其稳定性好、寿命长的特点。在东太平洋中脊(EPR)赤道区域和西南印度洋中脊(SWIR)的60条测线中,获得有效测线55条,其中在29条测线上发现明显或可能的热液异常。研究表明,应用多参数化学传感器探测进行海底热液化学异常,是一种有效的方法。     

New generation CTD system [conductivity-temperature-depth sensor]

A microprocessor-based CTD (conductivity-temperature-depth) sensor unit is described in which the microprocessor is used to vary the analog-to-digital conversion process to achieve 16-bit resolution at a measurement rate of 500 measurements per second, or 18-bit resolution at 30 measurements per second. Software control of resolution, sampling rate, and sampling sequence permit the sensor unit to be software-configured for a wide variety of missions. Pressure and conductivity sensors are expected to substantially improve the system accuracy. The conductivity cell design has six electrodes which are all relatively remote from the external measurement volume (approximated by a 2-cm diameter sphere). This so called recessed-electrode concept is expected to eliminate calibration drift due to contamination of the electrodes and the insulating surfaces of the cell, thus ensuring excellent long-term stability     

海珍品养殖水质微机自动监测系统

化学传感器用于海洋增养殖业水质环境监测领域，它与传统的物理传感器相比具有许多不便之处，如易漂移、难校准、受环境影响大等问题。因此在现场测量和实现长期连续监测方面受到了限制。文中主要介绍了海珍品养殖水质自动监测系统利用先进的电化学传感器技术（863－818－01－01课题研究成果）与计算机技术相结合，实现了海珍品养殖中必须监测的常规化学要素的现场定点长期连续监测，为水产养殖业提供实时的数据服务。     

Diel nitrate cycles observed with in situ sensors predict monthly and annual new production

We report on a direct and autonomous measure of new production based on time series observations with ISUS nitrate sensors deployed for several years on oceanographic moorings offshore of Monterey Bay, California. The amplitude of diel cycles of surface nitrate is correlated with rates of primary production measured by ¹⁴C uptake. The drawdown of nitrate averaged over a year is about 70% of the fixed nitrogen needed for biomass production. Phytoplankton biomass predicted from the diel nitrate uptake and a fixed rate constant for nitrate loss (grazing and export) matched observations over the annual cycle. New production rates determined with the moored sensors are highly correlated with nitrate concentration and the intensity of upwelling. The implication is that arrays of moorings with chemical sensors can now be used to estimate new production of biomass and ecosystem processes over multiple temporal and spatial scales.     

An electromagnetic current meter-based system for application inunsteady flows

A flexible configuration for an array of sensors has been developed for measurements in energetic regions of the ocean where the flow has high spatial and temporal variability. Central to the system is a two-axis electromagnetic current meter that measures the flow through a ducted volume containing a uniform magnetic field and nonprotruding electrodes flush with the duct surfaces. This geometry minimizes the electrode boundary-layer effect on the output, thus improving calibration and reducing fouling and damage potential. An inexpensive amplifier designed for low signal-to-noise ratios is employed to produce very low zero drift during operation     

光纤化学/生物传感技术在海洋环境监测中的应用

本文通过光纤溶解氧、 p H、湿度等化学传感探头及发光菌水质毒性监测生物传感探头的研制 ,开发出了一类能用于环境监测的新型传感器。本文的创新之处在于传感探头的设计与包装 ,以及数种可逆性、选择性、稳定性、使用寿命、响应时间、灵敏度等响应特性具佳的化学及生物传感膜的配方和制作技术。利用这些技术 ,通过对光纤探头的设计与包装 ,可以实现在现场及实验室模拟条件下对样品的选择性检测。研制的传感器能广泛应用于海洋污染调查、内河水质评价、水产养殖、工矿企业水气排污自检等诸多方面。     

Design of Low-Power Data Logger of Deep Sea for Long-Term Field Observation

This paper describes the implementation of a data logger for the real-time in-situ monitoring of hydrothermal systems.A compact mechanical structure ensures the security and reliability of data logger when used under deep sea.The data logger is a battery powered instrument,which can connect chemical sensors ( pH electrode,H2S electrode,H2 electrode) and temperature sensors.In order to achieve major energy savings,dynamic power management is implemented in hardware design and software design.The working current of the data logger in idle mode and active mode is 15 μA and 1.44 mA respectively,which greatly extends the working time of battery.The data logger has been successfully tested in the first Sino-American Cooperative Deep Submergence Project from August 13 to September 3,2005.     

The future of chemical in situ sensors

Many of the sampling methods used in oceanographic sciences today date back decades, if not centuries. Although there has been a marked change in how sampling for chemical oceanography is carried out it still relies on taking samples of seawater from a research vessel in most cases. Assessing processes on small timescales as well as transient events requires higher temporal and spatial resolution of measurements; long time series stations require high duration deployments of instruments. Both requirements can only be adequately satisfied by in situ sensors; for the physical parameters off the shelf instruments are available, in the field of chemical oceanography only a few parameters, such as oxygen, are covered by off the shelf instruments, for most parameters adequate instrumentation only exists in the form of prototypes, if at all. Chemical in situ sensors are needed to gain new insights in how the oceans and the life in it works.     

用于深海极端环境下的pH电极制备方法改进

pH值是表征深海热液环境以及扩散流区域溶液化学性能的基本参数,因此原位精确获取溶液pH值是很多海洋科学研究者关注的问题。以前试制的电化学原位传感器IrOx电极,在实际海试中虽然对海底异常信号有响应,但由于信号漂移问题,电极只能用于定性地发现异常。基于熔融碳酸锂氧化金属原理,提出了改进传统熔融碳酸锂法,并设计了强制空气对流和碳酸锂添加过氧化钠两种制备方法。通过实验室的性能测试以及相应的表面扫描电镜测试表明,用改进的方法制得的电极,校正曲线均符合能斯特定律。用强制空气对流和混合碳酸锂/过氧化钠法制得的电极,其性能均明显优于传统熔融碳酸锂法。可推断,在熔融碳酸锂氧化贵金属铱的过程中,氧含量的充分与否是影响IrOx电极的性能和表面形态的重要因素,其中性能最优的是混合碳酸锂/过氧化钠法制得的电极。该类电极具有如下优点:重复性好;在大跨度pH溶液之间的响应快速稳定,长时间连续监测的漂移小于5 mV;同一批次所制备电极性能几乎相同;使用寿命长等。因此,该pH电极可用于深海的原位探测。该工作为进一步制备高性能的IrOx电极奠定了坚实的基础。     

Chemical forms of zinc in sea water

Recent experimental evidence concerning the chemical forms of zinc occurring in sea water is reviewed in order to aid in the systematic understanding of zinc geochemistry in the marine environment. The review indicates the necessity of systematizing the results obtained by different methods for the determination of zinc in sea water with respect to the chemical nature of the zinc fractions measured. Analytical procedures for the zinc determinations in sea water by spectrophotometry with dithizone extraction and anodic stripping voltammetry with composite mercury graphite electrodes are described. By using these methods, various pre-treatment tests were carried out to relate the results of different modes of measurements to the chemical forms of zinc involved. The comparisons of the results of these tests lead to an estimation of the occurrence of the following categories of chemical forms of zinc in sea water: (1) ionic plus labile form, (2) inorganic complexes and colloids as well as weak organic complexes and (3) occuled fraction in large organic molecules and/or organic colloids. Capabilities of different analytical procedures for differentiating one category from another are discussed.     

化学发光动力学法分析海水总有机碳研究与实现

提出了一种基于化学发光动力学方法的海水总有机碳(Total Organic Carbon,TOC)分析手段,利用臭氧与海水中有机污染物进行氧化反应进行化学发光,结合微光光电转换检测技术和对发光动力学曲线进行时间序列积分方法,实现了对海水TOC的快速、实时的现场测量。针对这个方法,进一步讨论了化学传感器、光电检测及动力学算法的设计。实验证明,该设计方法运行可靠、操作简单,为研究海洋环境提供了新的方法和思路。     

Design of chemical sensor arrays for monitoring disposal sites onthe ocean floor

We develop methods for automatic environmental monitoring of disposal sites on the deep ocean floor using chemical sensor arrays and statistical hypothesis testing. Such sites have been proposed to relocate dredge materials from harbors and shipping channels. The transport of pollutants is modeled as a diffusion process, and the measurement and statistical models are derived by exploiting the spatial and temporal evolution of the associated concentration distribution. We derive two detectors, the generalized likelihood ratio (GLR) test and the mean detector and determine their performance in terms of the probabilities of false alarm and detection, The results are applied to the design of chemical sensor arrays satisfying criteria specified in terms of these probabilities, and to optimally select a number of sensors and time samples. Numerical examples are used to demonstrate the applicability of our results     

The chemical potentials of seawater components

An equation for the chemical potential of “seasalt” (R T ln a_s) as a function of salinity is derived from isopiestic and potentiometric data, via the Gibbs-Duhem equation and a simple ion-interaction theory. Estimates of the activity coefficients of seasalts and the major ions are listed for salinities 25‰ and 36‰. The direct measurement of ln a_s is considered, and a related quantity, that could be measured in situ, is suggested as a future oceanographic parameter. The results of laboratory measurements on an average seawater sample, using four ion-selective electrodes, serve to illustrate the concepts involved.     

A novel time-series station in the Wadden Sea (NW Germany): First results on continuous nutrient and methane measurements

In autumn 2002 a time-series station was installed in the tidal inlet between the Islands of Langeoog and Spiekeroog (Southern North Sea, NW Germany) to continuously measure physical, chemical, and meteorological parameters, even during extreme weather conditions (gale-force storms, drifting ice). Inside the pole of the station sensor tubes are installed in direction of the prevailing tidal currents. The tubes are equipped with hydrographic sensors (pressure, temperature, conductivity) and allow retrieval of water for nutrient analysis by automated instruments located inside the pole. Dissolved methane and the nutrients ammonia, nitrite, nitrate, phosphate, and silicate are measured at the station.     

Use of voltammetric solid-state (micro)electrodes for studying biogeochemical processes: Laboratory measurements to real time measurements with an in situ electrochemical analyzer (ISEA)

Solid-state voltammetric (micro)electrodes have been used in a variety of environments to study biogeochemical processes. Here we show the wealth of information that has been obtained in the study of sediments, microbial mats, cultures and the water column including hydrothermal vents. Voltammetric analyzers have been developed to function with operator guidance and in unattended mode for temporal studies with an in situ electrochemical analyzer (ISEA). The electrodes can detect the presence (or absence) of a host of redox species and trace metals simultaneously. The multi-species capacity of the voltammetric electrode can be used to examine complex heterogeneous environments such as the root zone of salt marsh sediments. The data obtained with these systems clearly show that O₂ and Mn²⁺ profiles in marine sedimentary porewaters and in microbial biofilms on metal surfaces rarely overlap indicating that O₂ is not a direct oxidant for Mn²⁺. This lack of overlap was suggested originally by Joris Gieskes' group. In waters emanating from hydrothermal vents, Fe²⁺, H₂S and soluble molecular FeS clusters (FeS_aq) are detected indicating that the reactants for the pyrite formation reaction are H₂S and soluble molecular FeS clusters. Using the ISEA with electrodes at fixed positions, data collected continuously over three days near a Riftia pachyptila tubeworm field generally show that O₂ and H₂S anti-correlate and that H₂S and temperature generally correlate. Unlike sedimentary environments, the data clearly show that Riftia live in areas where both O₂ and H₂S co-exist so that its endosymbiont bacteria can perform chemosynthesis. However, physical mixing of diffuse flow vent waters with oceanic bottom waters above or to the side of the tubeworm field can dampen these correlations or even reverse them. Voltammetry is a powerful technique because it provides chemical speciation data (e.g.; oxidation state and different elemental compounds/ions) as well as quantitative data. Because (micro)organisms occupy environmental niches due to the system's chemistry, it is necessary to know chemical speciation. Voltammetric methods allow us to study how chemistry drives biology and how biology can affect chemistry for its own benefit.