Vertical Distribution Characteristics Research Articles

Distribution of lead in urban soil and its potential risk in Shenyang City, China

The horizontal and vertical distribution characteristics of Pb in urban soil of Shenyang City, China were investigated in this study. The range of Pb concentration in the soil was 22.02–2910.60mg/kg. The standard deviation was 443.07mg/kg, and coefficient of variation was 1.64. Tiexi District was seriously contaminated by lead. In general, Pb concentration in the soil decreased with distance from pollution source. Lead concentration varied in different functional areas with the order of industrial area>commercial area>residential area>suburb>reference area. Pb concentration decreased with the depth of soil profile. Both geo-accumulation index and ecological risk index were used to estimate the potential risk of soil Pb pollution in Shenyang City. The results showed that the high potential risk area included Tiexi District and traffic roads.

Soil animal communities at five succession stages in the litter of the evergreen broad-leaved forest in Tiantong, China

Soil animals are abundant in forest litter layer, but little attention has been paid to the vertical distribution of community structure of soil animals in the layers at different plant community succession stages. The forest litter layer can be divided into fresh litter layer (L), fermentation layer (F) and humus layer (H), which may represent different litter decomposition stages. The aim of the study is to ascertain the vertical distribution features of soil animal communities among the three litter layers and the change in the succession process of the Evergreen Broad-Leaved Forest (EBLF) in Tiantong, Zhejiang Province, China. Soil animal communities in the five plant communities at different succession stages were investigated during the 2003 winter. Soil animals, which were collected by using Tullgren funnels, amounted to a total of 13 381 individuals falling into 2 phyla, 8 classes and 20 orders. The dominant groups were Acarina and Collembola, accounting for 94.24% of the total individuals, with the number of Acarina individuals 7.66 times than that of Collembola. The common group was Diptera. The results indicated that there was a distinctive vertical distribution of the soil animal communities in the forest litter layer, but it differed from that in soil below the litter layer. In contrast to those in the soil, the soil animals in the litter layer generally tended to increase in both group abundance and density from the top fresh litter layer to the bottom humus layer. Altogether 19 groups and 59.03% of total individuals were found in the bottom layer, while only 8 groups and 5.35% of the total individuals in the top. Moreover, there were some variations in the distribution of the soil animals at different plant succession stages. 85.19% of Homoptera and 100% of Symphyla were found in the litter layer at the climax succession stage, while 75.61% of Thysanoptera at the intermediate succession stage. Therefore, these groups might be seen as indicative groups. The total numbers of soil animal groups and individuals in the litter layers greatly changed in the succession process of the EBLF. They both were greatest at the climax, moderate at the intermediate and smallest at the primary succession stage. However, the main soil animal groups in the litter at the different succession stages were essentially the same. They were Acarina, Collembola, Diptera and Lepidoptera. Although similarity analysis revealed that the soil animal communities in the litter at the intermediate succession stage were most similar to those at the climax succession stage, they differed greatly from each other in the Shannon-Wiener diversity index. The Shannon-Wiener index was highest at the climax succession stage and lowest at the intermediate succession stage. Finally, the paper discusses the following three questions: the role of soil animals as indicators for plant community succession; the role of different soil animal groups in the litter decomposition at different stages; and the major factors affecting the composition and distribution of soil animals in the litter. This paper provides a new perspective for the research on the succession mechanism of plant communities and the decomposition functions of soil animals.

Characteristics of vertical ozone distribution in the lower troposphere in the Yangtze River Delta at Lin’an in the spring of 2001

We analyzed vertical distributions of ozone (O3) in the lower troposphere (< 5 km above ground) at Lin’an (119.75°E, 30.30°N), Zhejiang Province using electrochemical concentration cell (ECC) ozonesonde data obtained from February 21 to April 13, 2001. The results showed that the vertical O3 distributions are controlled by metrological conditions and the characteristics of O3 profiles are related to those of wet bulb potential temperature and wind field. O3 below 2 km showed that the strongest variability and enhanced O3 mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the Yangtze River Delta (YRD) region. Vertical O3 profiles below 5 km can be grouped into 5 categories: (1) peak mixing ratio type, (2) well-mixed type, (3) layered-structure type, (4) episodic pollution type and (5) altitudinal increasing type. Vertical distributions of O3 affected by regional transport of polluted air masses were investigated. Transport of polluted air from high latitudes of northern China, accompanying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3 at Lin’an. The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the YRD and central-eastern China also lead to regional accumulation of O3 and high O3 mixing ratio at Lin’an. Long-range transport of O3 and pollutants from the Pearl River Delta in South China and insitu O3 formation also resulted in elevated O3 mixing ratios at around 1 km altitudes and layered O3 distribution in the lower troposphere.

Geochemical behavior of trace elements in Lake Biwa

A monthly survey of dissolved concentrations of various trace elements was performed in Lake Biwa. Particulate concentrations of the elements were also measured in early autumn and winter. Based on these results, the geochemical behaviors of trace elements are discussed. The redox-sensitive elements Mn and Fe showed characteristic vertical distribution profiles. Profiles of Mn changed drastically with the progression of the stagnation period. The dynamics of Ba were affected by the redox cycle of Mn. Dissolved V concentration showed a clear seasonal variation. In contrast, dissolved concentrations of Sr, Mo, Cu, Zn, and Ni were almost uniform, i.e., not dependent on the season or the depth. The distribution ratios of these elements between lake water and Mn nodules formed in the lake were calculated to assess their geochemical behaviors.

Investigations of urban surface conditions for urban canopy model

The authors carried out several investigations to clarify the features of urban surface conditions in the urban canopy Model (UCM). The authors first conducted field investigations regarding the solar reflectance of urban surfaces. First, the wall reflectance and the proportion of the glazing area were measured in several urban areas. The relationship between the solar reflectance of road and traffic density is clarified based on the outdoor measurement and the field survey. It is also presented that the reflectance of the building rooftop varies significantly depending on building use and the influence of machinery in the area of the HVAC. The authors secondly investigated the height of released anthropogenic heat from the HVAC system based on a field survey and a database of HVAC systems provided by certain journals. From these investigations, it is presented that the type of HVAC system and the height of released anthropogenic heat vary with the building scale. Finally, an investigation of urban geometric figures was conducted using GIS data from Tokyo and Fukuoka in Japan. The vertical distribution features of both the roughness volume density and the building wall area density were classified according to the gross ratio of building volume.

都市気候モデルの境界条件生成のための建物空調排熱位置及び都市形状の実態に関する調査

First, the authors performed the investigations on the released height of anthropogenic heat from HVAC system. The subjects of investigation are 203 buildings in the central city of Fukuoka and 111 buildings recorded in the database of HVAC system of a certain journals. From these investigations, following features are summarized. 1. The ninety percent of buildings with less than 5000 square meters of building area adopt the air-cooling type of heat disposal equipment, so-called cooling tower, which are mainly sited at the each floor level. 2. The fifty percent of buildings with more than 5000 square meters of building area adopt the water-cooling type of heat disposal equipment of HVAC system, which are mainly sited at the roof. Secondly, the investigation on the urban geometric figure was conducted using the GIS data of Tokyo and Fukuoka. The features of vertical distribution of both roughness volume density and building wall area density were classified with the gross ratio of building volume. And the histograms of building area, floor area, story, distortion factor and aspect factor are presented, which are grouped into 6 classed according to both the gross ratio of building volume and building plan area fraction.

Characteristics and Genetic Analysis of the Deep‐buried Weathered‐crust Karst Hydrocarbon Reservoirs of the Lower Paleozoic Group in the Tarim Basin

Abstract The genetic analysis of the deep‐buried reservoirs of the Lower Paleozoic carbonate rocks in the Tarim basin is a difficult task involving many factors. Firstly, the object of study is carbonate rocks, which have undergone a long term of modification. Secondly, the rocks are deeply buried with depths of 3800–7000 m in the Tarim basin. The primary reservoir properties formed in the deposition have been strongly modified during the deep burial process. Concurrently, the different burial depths in different areas result in diversities of burial temperature, pressure, underground water, hydrochemistry and various physicochemical changes, which further lead to differences in the diagenetic type, diagenetic property, diagenetic degree and their impacts on the reservoir properties. The Lower Paleozoic Cambrian and Ordovician carbonate reservoirs in the Tarim basin can be grouped into four types, i.e., paleo‐weathered‐crust reservoirs, reef reservoirs, buried karst reservoirs and dolomite reservoirs. This paper presents a detailed discussion on the vertical and horizontal distribution characteristics, morphological division, reservoir properties and the efficiency in accumulating hydrocarbons of the paleo‐weathered‐crust type. Furthermore, its genesis is also analyzed. We proposed that the composition of the carbonate rocks, the tectonic movement with associated fractures and fissures, the paleomorphology and paleoclimate, the sea level fluctuation, and the protection of the pores and fissures by the deep burial diagenesis and burial dissolution are the main factors controlling the formation of the paleo‐weathered‐crust reservoirs. We also consider that the petroleum exploration of the Lower Paleozoic carbonate rocks should be focused on the paleo‐weathered‐crust reservoirs.

Lidar observations of Asian dust over Hefei, China, in spring 2000

A Mie lidar was used to make observations of Asian dust over Hefei (31.90°N, 117.16°E) in spring 2000. This paper presents main features of vertical distribution and temporal variation of Asian dust extinction coefficient at 532‐nm wavelength. It was found that the Asian dust events contributed significantly to very large aerosol extinction coefficients in the boundary layer or middle troposphere. Extinction coefficient value as large as 0.7 km−1 at 3 km above ground level (AGL) has been observed. The Asian dust extinction coefficient profiles showed very big changes from early morning to evening and also appeared substantial amount of temporal variation during the nighttime. For the severe Asian dust days the depth of boundary layer rose up to around 4 km AGL, but only 1∼2 km AGL for normal days. The seasonal average aerosol extinction coefficient profiles also showed that larger aerosol extinction coefficients from 1‐ to 10‐km altitude range were observed in the springtime rather than in any other season. Meanwhile, solar extinction and radiation measurements indicated that the Asian dust particles were composed of larger size particles and they produced significantly perturbation in solar radiation on the Earth surface.

Vertical ozone distribution characteristics deduced from ∼ 44,000 re-evaluated Umkehr profiles (1957-2000)

Umkehr observations taken during the 1957–2000 period at 15 stations located between 19 and 52° N have been reanalyzed using a significantly improved algorithm-99, developed by DeLuisi and Petropavlovskikh et al. (2000a,b). The alg-99 utilizes new latitudinal and seasonally dependent first guess ozone and temperature profiles, new vector radiative transfer code, complete aerosol corrections, gravimetric corrections, and others. Before reprocessing, all total ozone values as well as the N-values (radiance) readings were thoroughly re-evaluated. For the first time, shifts in the N-values were detected and provisionally corrected. The re-evaluated Umkehr data set was validated against satellite and ground based measurements. The retrievals with alg-99 show much closer agreement with the lidar and SAGE than with the alg-92. Although the latitudinal coverage is limited, this Umkehr data set contains ∼ 44,000 profiles and represent the longest (∼ 40 years) coherent information on the ozone behavior in the stratosphere of the Northern Hemisphere. The 14-months periods following the El-Chichon and the Mt. Pinatubo eruptions were excluded from the analysis. Then the basic climatological characteristics of the vertical ozone distribution in the 44–52° N and more southern locations are described. Some of these characteristics are not well known or impossible to be determined from satellites or single stations. The absolute and relative variability reach their maximum during winter–spring at altitudes below 24 km; the lower stratospheric layers in the middle latitudes contain ∼ 62% of the total ozone and contribute ∼ 57% to its total variability. The layer-5 (between ∼ 24 and 29 km) although containing 20% of the total ozone shows the least fluctuations, no trend and contributes only ∼ 11% to the total ozone variability. Meridional cross-sections from 19 to 52° N of the vertical ozone distribution and its variability illustrate the changes, and show poleward-decreasing altitude of the ozone maximum. The deduced trends above 33 km confirm a strong ozone decline since the mid-1970s of over 5% per decade without significant seasonal differences. In the mid-latitude stations, the decline in the 15–24 km layer is nearly twice as strong in the winter-spring season but much smaller in the summer and fall. The effect of including 1998 and 1999 years with relatively high total ozone data reduces the overall-declining trend. The trends estimated from alg-99 retrievals are statistically not significantly different from those in WMO 1998a; however, they are stronger by about 1% per decade in the lower stratosphere and thus closer to the estimates by sondes. Comparisons of the integrated ozone loss from the Umkehr measurements with the total ozone changes for the same periods at stations with good records show complete concurrence. The altitude and latitude appearances of the long-term geophysical signals like solar (1–2%) and QBO (2–7%) are investigated.

Characteristics of Vertical Density Distribution and Internal Tidal Waves of Uranouchi Bay

Characteristics of Vertical Density Distribution and Internal Tidal Waves of Uranouchi Bay

An intercomparison exercise for trace metal monitoring in oxygen-rich and anoxic Baltic waters

Seawater samples for a laboratory intercomparison of trace metal concentrations (Mn, Fe, Ni, Cu, Cd, Pb) in the dissolved (<0.4 µm filtered) and particle-bound phases as well as total and reactive Hg were collected in the Gotland Basin, a region in the Baltic Sea with trace metal gradients in the halocline and the redox boundary. Two laboratories took part in this exercise, each laboratory analysing samples from two vertical profiles collected using ”clean” sampling techniques. The hydrographic and hydrochemical situation was determined to characterise the water column and help interpret the results. An estimation of the conformity of the two laboratories was performed by comparing the results with international intercalibration exercises and certified reference materials. For all metals the characteristic vertical distribution and the concentration range of the data were comparable to other results published for the region. The concentration differences in the amount contents of Mn, Fe, Ni, Cu, Cd, Pb and Hg determined between both laboratories were better than the confidence intervals given by an ICES (International Council for the Exploration of the Sea) international comparison exercise for Baltic waters. Differences for Ni in the anoxic water body are attributed to the sulphidic matrix and their influence on the different methods used by the laboratories. For Pb and Hg the concentrations were near the detection limit of our methods, low level contamination was possibly responsible for the concentration differences. Small differences for dissolved Mn were attributed to different sampling techniques. We conclude that sampling and sample handling are still weak links in the trace metal analysis of anoxic seawater and that the analytical methods we used for this exercise are satisfactory for the accurate determination of Cd, Cu, Pb, Mn, Fe, and also for studying biogeochemical cycling of these trace metals in oxygen-rich and anoxic water bodies.

EXPERIMENTAL STUDY ON ABRASION OF SAND PARTICLES AND VERTICAL DISTRIBUTION OF GRAIN SIZE DUE TO DRIFT SAND

Abrasion of sand particles due to littoral drift was studied experimentally by large scale oscillatory flow apparatus. Abrasion of sand of 1.5mm in median diameter generates fine-grained sand with a wide range (2μm-1000μm) diameter. Fine-grained sand accumulates below the layer of sheet-flow sediment motion. The characteristics of vertical distribution of grain size are studied.

Vertical distribution, life cycle, and developmental characteristics of the mesopelagic calanoid copepod Gaidius variabilis (Aetideidae) in the Oyashio region, western North Pacific Ocean

Vertical distribution, life cycle, and developmental characteristics of the mesopelagic copepod Gaidius variabilis Brodsky in the Oyashio region were investigated by combining analyses of field copepodite populations with laboratory-rearing data of egg hatching and naupliar development. Field samplings from five discrete depths between the surface and ≤2000 m were made approximately every month for 1 year. Most populations of G. variabilis occurred between 600 and 1000 m depth. A modest degree of reversed diel vertical migration behavior and some stage-specific depth-distribution patterns were noted. All copepodite stages were observed throughout the year, suggesting a year-round spawning of G. variabilis. From a prominent abundance peak of Copepodite Stage 1 (C1) seen in June to August, together with development times of eggs and nauplii obtained in laboratory-rearing experiments, the major spawning season was extrapolated to be April to June, the phytoplankton bloom season. Tracing the peak abundance of each copepodite stage (distinguishing males and females for C4 to C6), the generation times of males and females were deduced as 2 and 1 year, respectively. All between-stage increments in terms of wet-, dry-, and ash-free dry weights were greatest in C3/C4, and least in C5/C6 for both males and females. The increments in C3/C4 and C4/C5 were greater for males than for females, reflecting a longer stage duration of the males. These weights did not increase in C5/C6 males, possibly because feeding ceased in C6 males. These results for G. variabilis are compared with those for some mesopelagic copepods previously reported from other regions.

Evaluation and Field Load Testing of Timber Railroad Bridge

Several spans of a 60-year-old open-deck timber railroad bridge on the Southern Pacific Railroad Line (now the Union Pacific) in Southwest Texas were field tested. The tests were conducted with the sponsorship and cooperation of the Association of American Railroads to determine the vertical live load distribution characteristics of the superstructure. The bridge was originally constructed with Douglas-fir larch solid sawn stringers but was rehabilitated on several occasions to allow comparisons to be made with respect to different rehabilitation options, including the use of a helper stringer and the use of glued laminated timber (glulam) stringers. The test spans measured approximately 4.1 m (13.5 ft) center-to-center of supports and included two closely “packed” chords, each consisting of four timber stringers (one test span included an additional helper stringer added to one chord). One chord was made up of glulam timber and the other was made up of solid sawn timber. The bridge superstructure was generally in satisfactory condition, with some stringer horizontal splitting noted over the bents. The bents were in reasonably good condition, but chord bearing was uneven on bent caps. Static and dynamic deflection load test data were obtained using a special test train. The test results indicate that the glulam chord performed better than the older sawn stringer chord, even when a helper stringer was added. Individual stringers within a chord did not always share the load equally.

EFFECTS OF WAVE-ENVIRONMENTS ON VERTICUL DISTRIBUTION OF Laminaria religiosa IN COASTAL AREA OF SHIMAMAKI, HOKKAIDO

Communities of Algae have disappeared from the shallow waters along the Japan Sea coastline in southwest Hokkaido. There are many studies of relationships between wave-environments and feeding behavior of the Sea Urchin Strongylocentrotus nudus.We made a study on the effects of wave-environments on characteristics of vertical distribution of kelp Laminaria religiosa using field survey and numerical calculation. Laminaria religiosa was seen in the limited shallow area in the depth of approximately 2-7m. Our estimation explains that wave velocity on the bottom in spring at this area limits the vertical distribution of Laminaria religiosa, and the calculation was fairly coincident with the result of field survey.

State of knowledge of the Corallinales (Rhodophyta) of Tierra del Fuego and the Antarctic Peninsula

Corallinales (Rhodophyta) in Tierra del Fuego are abundant, with 9 genera, 17 species and 1 subspecies. Pseudolithophyllum with 1 species ( P. fueguianum ), which represents 35.8% of the coralline algae, is dominant. The genera Parahydrolithon with 4 species ( P. consociatum, P. discoideum, P. falklandicum, P. subantarcticum ) and 20%, Lithothamnion with 3 species ( Lt. heterocladum, Lt. rugosum, Lt. granuliferum ) and 17.5%, and Synarthrophyton with 3 species ( S. neglectum, S. patena, S. schmitzii ) and 12% share are abundant. Clathromorphum with 4 species ( Cl. annulatum, Cl. lemoineanum, Cl. obtectulum, Cl. Variabile ) and a share of 5.8%, and Mesophyllum with 1 species (M. fueguianum) and a share of 4.9% are frequent. The remaining three genera, Bossiella with 1 subspecies ( B. orbigniana ssp. orbigniana), Corallina with 2 species ( C. elongata, C. officinalis ) (1.1%), and Titanoderna with 1 species ( T. conspectum ) (1%) are scarce. C. officinalis is a cosmopolitan, and the other geniculate corallines are found in both hemispheres, whereas the crustose coralline occur only in the southern hemisphere. The characteristic vertical distribution of the species in the intertidal and subtidal zone of Tierra del Fuego is given. The Corallinales in the Antarctic Region are poorly known and need further investigation.

Vertical Distribution of &lt;sup&gt;210&lt;/sup&gt;Pb and &lt;sup&gt;137&lt;/sup&gt;Cs and Their Dating in Recent Sediments of Lugu Lake and Erhai Lake, Yunnan Province

云南省沪沽湖、洱海²¹⁰Pb_ex的垂直分布受 Fe、Mn循环下²¹⁰Po和²¹⁰Pb沉积后再迁移的影响,分别表现为三种不同的剖面分布特征.²¹⁰Pb_ex计年的沉积物堆积速率分别为0.050-0.051g·cm^-2a^-1和0.044-0.045g·cm^-2a^-1,反映百年时间尺度上的堆积结果.沪沽湖、洱海¹³⁷_Cs的垂直剖面分布虽然受分子扩散作用的影响,但并没有改变其峰值位置.沪沽湖深水湖区¹³⁷Cs计年的沉积物堆积速率为0.045 ± 0 004g·cm^-2a^-1(1964年时标).按不同时标,洱海¹³⁷_Cs计年的沉积物堆积速率为对.048±0.0039·cm^-2a^-1(1964年时标),0.047 ± 0.0029·cm^-2a^-1(1975年时标),0.046±0 005g·cm^-2a^-1(1986年时标).三种时标给出的沉积物堆积速率一致,其平均值为0.047±0.0029·cm^-2a^-1,与²¹⁰Pb_ex计年方法获得的数值吻合.;Two plateau lakes (Lugu Lake and Erhai Lake) with different conditions are selected to show 210Pb geochemical behavior. ²¹⁰Pb and ¹³⁷Cs vertical profiles in sediments are measured by the Multichannel Analysis System (Caberra 100) in order to attain creditable sediment accumulation rates. By the Fe-Mn circulation, ²¹⁰Pb_ex vertical distribution in the sediments of Lugu Lake and Erhai Lake shows three types of distribution characteristics. But this has no influence on the ²¹⁰Pb_ex dating result. Sediment accumulation rates of Lugu Lake and Erhai Lake are 0. 050 -0.051 g·cm a and 0.044 -0.045 g· cm^-2a^-1 respectively by ²¹⁰Pb_ex method which repsents the average sediment accumulation result on 100-year scale. The discrepancy between the ¹³⁷Cs vertical distribution characteristics and the depositional fluxes is probably caused by the Cs diffusion in early-diagenesis process. However, the Cs diffusion does not change the location of Cs peaks. Sediment accumulation rate of Lugu Lake is 0. 045 土 0. 004g · cm^-2a^-1 by ¹³⁷Cs time marker (1964), and that of Erhai Lake is 0. 048 ± 0. 003g·cm^-2a^-1 (1964), 0. 047 ± 0. 002g-cm^-2a^-1(1975), and 0. 046 ± 0. 005g· cm^-2a^-1(1986) respectively which reflects the average sediment accumulation result.

Relative optical mass functions for air, water vapour, ozone and nitrogen dioxide in atmospheric models presenting different latitudinal and seasonal conditions

A study of the dependence features of the relative optical mass functions for air, water vapour, ozone and nitrogen dioxide on the apparent solar zenith angle θ was performed by calculating these optical parameters by means of the well-known computer code LOWTRAN 7 at several values of θ and for nine atmospheric models characterized by different latitudes and seasons. Moreover, other investigations were performed on the dependence features of (i) the relative optical air mass on the thermal characteristics of the low troposphere, (ii) the relative optical water vapour mass on the vertical distribution characteristics of absolute humidity in the troposphere, and (iii) the relative optical mass function for ozone and nitrogen dioxide on the shape characteristics of the vertical profiles of the two gaseous concentrations and the concentration peak altitudes. The results are compared with the values given by the two simple formulas proposed by Kasten (1966) for air and water vapour and the formulas defined by Young (1969) and Staehelin et al. (1995) for ozone and nitrogen dioxide. From this comparison, a wide set of correction factors were obtained which can be conveniently used in the analysis of multispectral sun-radiometric measurements for calculating, with a very high precision, the values of the four optical mass functions at all the angles θ in the 0° to 87° range, corresponding to the various latitudinal and seasonal conditions described by the nine atmospheric models.

Ozone vertical profile characteristics over qinghai plateau measured by electrochemical concentration cell ozonesondes

An analysis of 50 ozonesondings in Xining (36.43°N, 101.45°E, 2296 m, ASL), between April 1995 and August 1996 is presented. General vertical distribution characteristics and seasonal changing of ozone profile are reported. The analysis indicates that the stratospheric ozone concentrations of Autumn and Summer are lower than those of Spring and Winter; and the highest value of the tropospheric ozone concentrations is found in Summer; ozone concentration changing is bigger from the troposphere to the lower stratosphere altitude region, while it is stable in the middle and upper stratosphere region; there is a lower ozone concentration region in 10–15 km altitude; the result why higher ozone concentration of the troposphere occurs in Summer is the ozone injecting from the middle and upper stratosphere.

Input and behaviour of linear alkylbenzenesulphonates (LAS) in a stratified estuary

Input and distribution of linear alkylbenzenesulphonates (LAS) in the highly stratified Krka River estuary were studied during 1990–1991. Determinations of individual LAS homologues in wastewater and estuarine waters were performed using reversed-phase high-performance liquid chromatography (HPLC) with spectrofluorimetric detection. The investigated municipal wastewaters contained LAS homologues with alkyl-chain lengths from C 10 to C 13 at total concentrations in the range of 285–1041 μg l −1. Total LAS input via wastewaters into Šibenik Harbour, the most polluted part of the estuary, was estimated at 12.6 kg day −1. A relatively large fraction of total LAS, depending on the wastewater particle load, was found in particulate form (11–59%). Distributions of the individual homologues in dissolved and particulate fractions were rather different, the latter being significantly enriched in higher homologues (C 12, C 13). The LAS concentration in the estuary was quite low (0.2–23.9 μg l −1) which was caused chiefly by a strong and fast dilution process. However, characteristic vertical distribution of LAS in the estuarine water column indicated that the wastewater plume spreads almost exclusively in the upper (brackish) layer. The concentration maxima were observed in the surface microlayer and at the brackish water/seawater boundary.