Hydrochemical Atlas of the Arctic Ocean

Introduction: Chemical composition of water determines its physical properties and character of processes proceeding in it: freezing temperature, volume of evaporation, density, color, transparency, filtration capacity, etc. Presence of chemical elements in water solution confers waters special physical properties exerting significant influence on their circulation, creates necessary conditions for development and inhabitance of flora and fauna, and imparts to the ocean waters some chemical features that radically differ them from the land waters (Alekin & Liakhin, 1984).
Hydrochemical information helps to determine elements of water circulation, convection depth, makes it easier to distinguish water masses and gives additional knowledge of climatic variability of ocean conditions. Hydrochemical information is a necessary part of biological research. Water chemical composition can be the governing characteristics determining possibility and limits of use of marine objects, both stationary and moving in sea water.
Subject of investigation of hydrochemistry is study of dynamics of chemical composition, i.e. processes of its formation and hydrochemical conditions of water bodies (Alekin & Liakhin 1984). The hydrochemical processes in the Arctic Ocean are the least known. Some information on these processes can be obtained in odd publications. A generalizing study of hydrochemical conditions in the Arctic Ocean based on expeditions conducted in the years 1948-1975 has been carried out by Rusanov et al. (1979).
The "Atlas of the World Ocean: the Arctic Ocean" contains a special section "Hydrochemistry" (Gorshkov, 1980). Typical vertical profiles, transects and maps for different depths - 0, 100, 300, 500, 1000, 2000, 3000 m are given in this section for the following parameters: dissolved oxygen, phosphate, silicate, pH and alkaline-chlorine coefficient. The maps were constructed using the data of expeditions conducted in the years 1948-1975. The illustrations reflect main features of distribution of the hydrochemical elements for multi-year period and represent a static image of hydrochemical conditions. Distribution of the hydrochemical elements on the ocean surface is given for two seasons - winter and summer, for the other depths are given mean annual fields.
Aim of the present Atlas is description of hydrochemical conditions in the Arctic Ocean on the basis of a greater body of hydrochemical information for the years 1948-2000 and using the up-to-date methods of analysis and electronic forms of presentation of hydrochemical information. The most wide-spread characteristics determined in water samples were used as hydrochemical indices. They are: dissolved oxygen, phosphate, silicate, pH, total alkalinity, nitrite and nitrate. An important characteristics of water salt composition - "salinity" has been considered in the Oceanographic Atlas of the Arctic Ocean (1997, 1998).
Presentation of the hydrochemical characteristics in this Hydrochemical Atlas is wider if compared with that of the former Atlas (Gorshkov, 1980). Maps of climatic distribution of the hydrochemical elements were constructed for all the standard depths, and seasonal variability of the hydrochemical parameters is given not only for the surface, but also for the underlying standard depths up to 400 m and including. Statistical characteristics of the hydrochemical elements are given for the first time. Detailed accuracy estimates of initial data and map construction are also given in the Atlas. Calculated values of mean-root deviations, maximum and minimum values of the parameters demonstrate limits of their variability for the analyzed period of observations. Therefore, not only investigations of chemical statics are summarized in the Atlas, but also some elements of chemical dynamics are demonstrated.
Digital arrays of the hydrochemical elements obtained in nodes of a regular grid are the new form of characteristics presentation in the Atlas. It should be mentioned that the same grid and the same boxes were used in the Atlas, as those that had been used by creation of the US-Russian climatic Oceanographic Atlas. It allows to combine hydrochemical and oceanographic information of these Atlases.
The first block of the digital arrays contains climatic characteristics calculated using direct observational data. These climatic characteristics were not calculated in the regions without observations, and the information arrays for these regions have gaps. The other block of climatic information in a gridded form was obtained with the help of objective analysis of observational data. Procedure of the objective analysis allowed us to obtain climatic estimates of the hydrochemical characteristics for the whole water area of the Arctic Ocean including the regions not covered by observations. Data of the objective analysis can be widely used, in particular, in hydrobiological investigations and in modeling of hydrochemical conditions of the Arctic Ocean. Array of initial measurements is a separate block. It includes all the available materials of hydrochemical observations in the form, as they were presented in different sources. While keeping in mind that this array contains some amount of perverted information, the authors of the Atlas assumed it necessary to store this information in its primary form. Methods of data quality control can be developed in future in the process of hydrochemical information accumulation. It can be supposed that attitude can vary in future to the data that were rejected according to the procedure accepted in the Atlas.
The hydrochemical Atlas of the Arctic Ocean is the first specialized and electronic generalization of hydrochemical observations in the Arctic Ocean and finishes the program of joint efforts of Russian and US specialists in preparation of a number of atlases for the Arctic. The published Oceanographic Atlas (1997, 1998), Atlas of Arctic Meteorology and Climate (2000), Ice Atlas of the Arctic Ocean prepared for publication and Hydrochemical Atlas of the Arctic Ocean represent a united series of fundamental generalizations of empirical knowledge of Arctic Ocean nature at climatic level.
The Hydrochemical Atlas of the Arctic Ocean was elaborated in the result of joint efforts of the SRC of the RF AARI and IARC. Dr. Ye. Nikiforov was scientific supervisor of the Atlas, Dr. R. Colony was manager on behalf of the USA and Dr. L. Timokhov - on behalf of Russia.

引言：水的化学组成决定其物理性质与内部进行的过程特征，包括冰点、蒸发量、密度、色度、透明度、过滤能力等。水溶液中的化学元素赋予水体独特的物理性质，不仅对水体环流产生显著影响，还为动植物群落的繁衍与栖息提供必要条件，同时赋予海洋水体区别于陆地水体的独特化学特征（Alekin与Liakhin，1984）。
水文化学（Hydrochemistry）信息可用于解析水体环流要素、对流深度，辅助识别水团（water masses），并为认识海洋环境的气候变率提供补充依据。水文化学信息亦是生物研究的必要组成部分。水体化学组成可作为核心特征参数，决定海洋中各类固定与移动物体的利用可能性与使用边界。
水文化学的研究对象为水体化学组成的动态变化，即其形成过程与水体的水文化学环境（Alekin与Liakhin，1984）。北冰洋的水文化学过程是目前认知程度最低的领域之一，相关过程的信息仅零散见于部分出版物中。Rusanov等人（1979）基于1948-1975年的科考航次数据，完成了首份北冰洋水文化学环境的综合性研究。
《世界大洋图集：北冰洋》（Gorshkov，1980）设有专门的“水文化学”章节，该章节针对溶解氧、磷酸盐、硅酸盐、pH值与碱氯系数（alkaline-chlorine coefficient）等参数，提供了0、100、300、500、1000、2000、3000米共7个深度层的典型垂直剖面（vertical profiles）、断面图（transects）与分布图。所有图集均基于1948-1975年的科考航次数据绘制。
该章节的插图展示了多年尺度下水文化学要素的分布特征，呈现了北冰洋水文化学环境的静态图景。其中，海洋表层的水文化学要素分布按冬、夏两季分别呈现，其余深度层则提供了年均场数据。
本水文化学图集的编制目标，是基于1948-2000年积累的海量水文化学数据，结合最新的分析方法与电子化的信息呈现形式，系统阐述北冰洋的水文化学环境。本次图集选取了水样检测中最常用的参数作为水文化学指标，包括：溶解氧、磷酸盐、硅酸盐、pH值、总碱度、亚硝酸盐与硝酸盐。水体盐组成的重要参数——“盐度”的相关内容已在《北冰洋海洋图集》（1997、1998）中单独收录。
本北冰洋水文化学图集的水文化学参数呈现范围较1980年版图集（Gorshkov，1980）更为广泛：本次图集为所有标准深度层绘制了水文化学要素的气候分布地图，且不仅针对表层，还涵盖了直至400米（含）的所有下层标准深度层的水文化学参数季节变率。本图集首次提供了水文化学要素的统计特征数据，并详细给出了原始数据与成图过程的精度评估。通过计算均方根偏差（mean-root deviations）、参数的最大值与最小值，本图集展示了观测分析时段内各参数的变化范围。因此，本图集不仅总结了化学静态学的相关研究成果，还呈现了部分化学动态学的研究内容。
本图集采用了一种全新的参数呈现形式：基于规则网格（regular grid）节点获取的水文化学要素数字阵列。需要说明的是，本图集所使用的网格与分区方案，与美俄联合气候海洋图集保持一致，这使得本图集的水文化学信息与海洋学信息可与该图集实现融合。
数字阵列数据分为三个模块：第一模块包含基于直接观测数据计算得到的气候特征参数。对于无观测数据的区域，该模块未生成对应的气候特征参数，因此这些区域的信息阵列存在数据空缺。第二模块的网格化气候信息则通过对观测数据进行客观分析（objective analysis）得到，该分析方法可覆盖北冰洋全部海域，包括无观测数据的区域，从而生成完整的水文化学气候特征估算值。
客观分析得到的数据可广泛应用于水文生物学研究以及北冰洋水文化学环境的数值模拟。第三模块为原始测量数据阵列，该模块完整收录了所有来源的水文化学观测原始数据。尽管该阵列中存在部分失真信息，但图集编委会认为保留原始数据形式具有重要价值，因此未对其进行修改。未来可在水文化学信息积累的过程中逐步完善数据质量控制方法。可以预见，未来学界对本图集依据既定流程剔除的数据的评价可能会发生变化。
本北冰洋水文化学图集是首部针对北冰洋水文化学观测的专业化电子化综合图集，标志着美俄专家联合编制北极系列图集的项目圆满完成。已出版的《北冰洋海洋图集》（1997、1998）、《北极气象与气候图集》（2000）、即将出版的《北冰洋海冰图集》以及本水文化学图集，共同构成了一套系统性的北冰洋自然环境气候尺度经验知识综合研究成果。
本北冰洋水文化学图集由俄罗斯联邦北极与南极研究所（AARI）科学研究中心（SRC）与国际北极研究中心（IARC）联合编制。图集的科学负责人为Ye. Nikiforov博士，美方负责人为R. Colony博士，俄方负责人为L. Timokhov博士。