Seasonal differences in concentrations of particulate lipids,proteins and chitin in the North Sea

The concentrations of particulate lipids, proteins and chitin were determined in the North Sea in January 1992, October 1992 and March 1993, with additional measurements of total suspended matter concentrations and organic matter contents in the suspended matter (POC) by ashing and wet-oxidation. During each of the three cruises, the proteins were by far the most important of the three components measured, followed by the lipids. The concentrations of chitin were always very low. The concentrations of these three components were highest in March and lowest in January; there was also a variation in the distribution over the North Sea between the three cruises. In January 1992, the suspended matter contained more organic matter in the northern North Sea than in the southern North Sea, but the higher concentrations of total suspended matter in the southern North Sea resulted in an inverse distribution for the concentrations of organic matter per volume of water. In March 1993, highest concentrations of the three organic compounds were observed in the Skagerrak and along the eastern side of the North Sea, decreasing towards the west. The suspended matter was richest in organic compounds in the Skagerrak and in the Norwegian Channel. In October 1992, the situation was very similar to that observed in January 1992, but the concentrations of organic compounds in the suspended matter and per volume of water were higher. The ratio of proteins to lipids was similar to this ratio in phytoplankton. The composition of the particulate organic matter became very close to that of phytoplankton if we assume that we missed a large amount of carbohydrates; the small differences persisting were probably due to the contributions of zooplankton, bacteria and terrestrial sources. The total contents of particulate lipids + proteins + chitin were low, but when estimated amounts of carbohydrates were added, the total particulate organic-matter concentrations found were very similar to the total particulate organic carbon concentrations found by wet-oxidation. During the period of sampling, no large concentrations of phytoplankton occured.     

Distribution,organic content and particle size of suspended matter in the north sea

Data on suspended matter concentrations and the organic content of the suspended matter for January 1980 showed a division in the North Sea between the southern North Sea (high suspended matter concentrations, but relatively low organic content) and the central and northern North Sea (low suspended matter concentrations, but relatively high organic content). The Skagerrak, which receives suspended matter from the southern as well as from the central and northern North Sea, took up an intermediate position.In summer suspended matter concentrations were lower than in winter but more variable, in concentration as well as in organic content, because of admixtures of particulate matter from primary production. On deposition of the suspended matter, a considerable part of the organic matter was apparently lost (in the order of 75% or more), resulting in low organic-matter concentrations of fine-grained bottom deposits.Particle-size distributions followed two main types: one (A) with a sharp peak at 30 to 100 μm, and one (B) bell-shaped with a peak at 5 to 15 μm. Type A occurred in deeper water and consisted of particles with a high organic-matter content, type B occurred in shallow areas and consisted of particles with a low organic-matter content. The suspended particles were mainly microflocs of mineral particles and organic matter. The mineral particles of both types were predominantly of 2 to 5 μm size, which was determined after oxidation of the organic matter. It is concluded that particles of type-B distributions are regularly exchanged with the bottom through deposition and resuspension, which results in low organic-matter contents and prevents the microflocs reaching large sizes. Paricles of type-A distributions, on the contrary, can reach much larger sizes, because mostly they remain in suspension and do not lose organic matter, so that they do not easily fall apart.     

Input of selected chlorinated hydrocarbons into the coastal area of East Java and adjacent waters: Distribution patterns in the dissolved and suspended phase

Selected organochlorines were analysed in water and suspended particulate matter collected at stations in two rivers on East Java, the adjacent coastal zone, the Java Sea and the Indian Ocean. The sampling period covered the dry monsoon and the beginning of the wet monsoon. Concentrations of dissolved polychlorinated biphenyls (PCBs) were in the same range as in Western Europe and North America. In contrast, the concentrations of all measured organochlorines in suspended matter were lower and often not detectable.p,p′-DDT and its metabolites p,p′-DDD and p,p′-DDE showed the highest concentrations of all compounds determined. The rivers Bengawan Solo and Kali Porong can be considered sources of these compounds for the coastal environment, although their impact is restricted to a small area.Significant differences between the dry and wet monsoon were only observed for dissolved PCBs in the river Porong.     

Organochlorines in benthic polychaetes (Nephtys Spp.) and sediments from the southern North Sea. identification of individual PCB components

ΣPCB concentrations (as the sum of concentrations of 35 individual components) on a lipid basis varied more than an order of magnitude between samples of polychaete worms (Nephtys spp.) from different stations in the southern North Sea. PCB patterns, i.e. the relative contribution of each component to ΣPCB, were highly similar for the larger part of the area.The geographical differences between concentrations of PCB's reflected the general routes of residual water and suspended particulate matter transport throughout the North Sea. The Rhine is likely to be the main source for PCB's in Dutch coastal waters, including the entire coastline formed by the Dutch Wadden Sea islands. Theoretical patterns of PCB's in solution were calculated from the PCB patterns in Nepthys and values of bioconcentration factors reported.Concentrations of HCB, α- and γ-HCH, dieldrin, p,p′-DDD and p,p′-DDT were at least an order of magnitude lower and close to, or even below, detection limit in most samples. Although concentrations of α-and γ-HCH in solution were the highest of the compounds investigated, their concentrations in Nephtys were among the lowest, which might have been due to their relatively high solubility in water, or metabolism to more polar derivatives.Based on total sediment analyses, organochlorine concentrations in Nephtys spp. were not correlated with the concentrations in the (type of) sediment which they inhabited. In sediments the fraction of grains <63 μm appeared to be very important.A sewer outlet near Grimsby (U.K.) was found to be a source for HCB and Σ-DDT.     

Distribution of dissolved and particulate minor and major elements in the river and coastal environment of East Java during the Snellius-II expedition

The concentration and distribution of dissolved Cu, Zn, Cd, Ni, Pb and Fe, and Cu, Zn, Cd, Ni, Pb, Cr, Fe, Si, Ca, Mg, Mn and K in suspended matter have been determined in the rivers Porong and Solo and in Strait Madura (East Java), during the dry- and wet-monsoon periods. Based on element/Al ratios, the suspended matter supplied by each of the two rivers can be traced offshore. The main source of material supplied to the coastal area is the Solo river. The distribution of the trace-metal content in suspended matter collected in the rivers can be described as a mixture of metal-rich, organic-rich particles and a metal-poor, detrital fraction. Due to the presence of mud barriers at the river mouths, particles with high trace-element contents are trapped in the estuaries. Compared to European rivers the dissolved trace-metal concentrations in these rivers are relatively low. The dissolved concentrations of the different trace elements in Strait Madura show no uniform distribution pattern during the two sampling periods.     

Cyclic organochlorines in the hermit crabs Pagurus bernhardus and P. pubescens from the North Sea. A comparison between winter and early summer situation

The body burdens of 5 cyclic organochlorine compounds were determined in abdomens of Pagurus bernhardus and P. pubescens from the North Sea during two seasons. The seasonal bioaccumulation of ΣPCB (as the sum of concentrations of 24 individual components) is influenced by the substances associated with food originated from the spring plankton bloom and the resuspended sediments during the winter.The patterns of individual PCB congeners depended on the weight of the abdomens, and the geographical position of sampling. In offshore samples, the findings indicated a relationship between the weight of the abdomen (roughly the age) and the bioconcentration of higher chlorinated biphenyls. The results from the coastal areas demonstrated that the uptake by food determines the steady state concentration of the higher chlorinated congeners in the hermit crab. Pagurus pubescens probably possesses a mixed-function oxygenase (MFO)-system different from that of Pagurus bernhardus because the congeners 2,2′, 3,3′, 4,5,6′-heptachlorobiphenyl (174) and 2,2′, 3,3′, 4′, 5,6-heptachlorobiphenyl (177) were absent in all samples of the former species but were always present in the latter.The geographical differences between concentrations of ΣPCB reflect the general mean-routes of water and suspended particular matter transport through the North Sea: the Southern Bight and the continental coasts were more polluted with PCBs than the central North Sea. Maximum concentrations of p-p′-DDE were found in the southern parts and parts of the central North Sea. Samples from the German Bight showed the highest concentrations of Lindane. The results indicate that the atmospheric transport of lower chlorinated biphenyls, HCB, α-HCH and Lindane may be important in the distribution of these components, because they only showed slight gradients or even none at all in the area investigated.     

Abundance of nanoplankton-size chlorophyll-containing particles caused by diatom disruption in surface waters of the Southern Ocean (Antarctic Pensinsula region)

In samples taken during a cruise to the western Atlantic sector of the Southern Ocean (Antarctic Peninsula region), between 10 and 80% of chlorophyll a containing particles were smaller than 8 μm. At stations in the northern part of the survey area the percentage was highest; in the south (southern Bransfield Straits and northern Weddell Sea) most chlorophyll a was found in larger diatoms. Microscopic observations revealed that in many samples more than 50% of the nanoplankton-size chlorophyll-containing particles were free-floating chloroplasts; the relative abundance of 19′-hexanoyloxyfucoxanthin in acetone extracts of suspended matter indicates that the nanophytoplankton itself consisted mostly of Prymnesiophyceae (Haptophyceae). Experiments showed that diatom chloroplasts remain fluorescent for several days after cell disruption at the low temperature prevailing in the Southern Ocean. Evidence is presented that causes of algal cell disruption in the field include mechanical effects on cells during storms and during grazing by krill. Spatial variability in the proportion of chlorophyll a not associated with viable phytoplankton cells may impede the use of chlorophyll a as a measure of biomass and of primary productivity during large-scale surveys.     

North Sea Scyphomedusae; summer distribution,estimated biomass and significance particularly for 0-group Gadoid fish

Data on the by-catch of Scyphomedusae from pelagic trawls was collected during the routine ICES International 0-group Gadoid Surveys of the North Sea, in June and July of the years 1971–1986 (except 1984). These data are used to describe the distributions, abundances and biomasses of three common North Sea Scyphomedusae: Aurelia aurita (L.), Cyanea capillata (L.) and C. lamarckii (Péron & Lesuer). Information is also presented on inter-annual variability, size (umbrella diameter) frequencies and, for the Cyanea species, umbrella diameter: wet weight relationships. The general role and ecological significance of Scyphomedusae is discussed and, given the well known ‘shelter’ relationships between Scyphomedusae and certain 0-group fish, whiting (Merlangius merlangus) and haddock (Melanogrammus aeglefinus), in particular. The data were examined for evidence of such relationships.Aurelia aurita, although fairly widespread in the northern North Sea was virtually absent from the central North Sea but very abundant in coastal waters. This species was particularly abundant off the Scottish east coast and especially in the Moray Firth.Cyanea lamerckii was most abundant in the southern and eastern North Sea. More widespread than Aurelia, this species was also most abundant in coastal regions, particularly off the Danish west coast.Cyanea capillata, with a more northern distribution was also more widely distributed and abundant offshore. This species was most abundant in the area between the Orkney/Shetland Isles and the Norwegian Deep and in shelf waters of the north west approaches to the North Sea. As with C. lamarckii it was also, in some years, abundant off the Scottish east coast and west of Denmark.The abundance and the size frequency of the jellyfish show considerable inter-annual variability, and variability between regions of the North Sea. It is considered that hydrographic variability and differences in food supply to both medusae and to their sessile benthic polyps, are the major causes of the observed differences between years and areas.The impact of Scyphomedusae on fishing and recreational activities is discussed.     

近54a新疆地区水资源的气候特征分布

为了探究气候变化背景下新疆地区水资源的气候特征,利用新疆地区50 个站点1961—2014 年的气象数据,通过陆面蒸发经验公式估算蒸发量及相应的降蒸差,并结合Mann-Kendall 非参数检验方法分析探讨近54 年新疆地区水资源的气候变化特征及时空分布。结果显示：（1）近54 年来新疆地区降水量、平均气温、蒸发量自发生突变以来呈显著上升趋势;（2）北疆的降水量最高,东疆降水量最低并且未通过显著性检验;（3）新疆各区域年平均气温变化趋势均以0.03℃/a 持续增加;（4）北疆降蒸差量接近全疆水平,南疆大部分地区与东疆区域降蒸差均小于0,表明该地区水资源严重不足,常年处于干旱;（5）降水量、蒸发量和降蒸差空间分布主要表现在由北至南,由西至东呈减少的趋势,平均气温呈增加的趋势。     

Organic carbon in the upper 100 m and downward flux in the banda sea; monsoonal differences

Organic carbon was measured in the upper 100 m and its downward flux from the euphotic zone recorded, as part of a multidisciplinary study in the Banda Sea on monsoonal differences in the upper water layers.All 35 stations occupied showed on average 1.5 times higher POC values in August 1984 (4.9 g·m⁻², SE monsoon, upwelling period) than in February/March 1985 (3.3 g·m⁻², NW monsoon, downwelling period) for the 0 to 100 m water column. Monsoonal variation in POC was confined to the surface layer and related to a variation in phytoplankton content; it can be explained by — local— upwelling during the SE monsoon. At 100 m no seasonal variation occurred.Contrary to POC, average figures for DOC in February/March were almost twice the average observed in August (66.5 against 37.5 g·m⁻² for the 0 to 100 m water column). In February/March spatial variation was more pronounced than in August with highest values occurring in the NE part (>100 g·m⁻², 0 to 100 m), with a subsurface maximum. In this period the NW monsoon causes a surface current to the east. This might cause a westward subsurface countercurrent of Arafura Sea water rich in riverine or benthic layer DOC, influencing the eastern Banda Sea.At 100 m depth daily sedimentation amounted to ∼50 mg C·m⁻². The limited number of data do not indicate a difference between the 2 periods. On average the daily downward flux at 100 m depth amounted to 1.2% of POC and 0.8% of chlorophyll present in the 0 to 100 m water column, and equalled 5% of the daily primary production.     

Ecology of the fishes of the Norwegian Deep: Distribution and species assemblages

An account based on hydroacoustic data and trawl surveys of the distributional patterns and species assemblages of the fishes inhabiting the Norwegian Deep and adjacent slopes is presented. The Norwegian Deep is the moderately deep (275 to 700 m) shelf channel extending from the Norwegian Sea into the North Sea and Skagerrak.The Norwegian Deep has a pelagic and demersal fish fauna which is rather different from the fauna in adjacent shallow areas. Blue whiting (Micromesistius poutassou) and Maurolicu muelleri form a widely distributed and normally two-layered pelagic association. There appears to exist a rather sharp boundary at about the 200 m isobath between species assemblages of the Norwegian Deep and those of the shallow plateaus of the North Sea and Skagerrak. The fish fauna of deeper zones of the Skagerrak differs from the areas off western and southwestern Norway. The more conspicuous feature in the Skagerrak is the rather high abundance of greater argentine (Argentina silus) and roundnose grenadier (Coryphaenoides rupestris) at depths greater than 300 m. The species assemblages of the Norwegian Deep resemble those found in the areas along the outer shelf of the Northeast Atlantic and the deep fjords of Norway. The western and southern slopes appear to be feeding and overwintering areas for some fish species from adjacent shallow areas, particularly populations of saithe (Pollachius virens) and Norway pout (Trisopterus esmarki).It is suggested that the Norwegian Deep, due to its characteristic bathymetry and the strong influence of Atlantic inflow, is colonized by mesopelagic and benthic species from the other shelf areas of the Northeast Atlantic. The shelf channel appears to be deep enough to allow outer shelf species temporary or permanent access to the inner shelf environment.     

Percentage contribution of inputs from the Atlantic,Irish Sea,English Channel and Baltic into the North Sea during 1988: A tracer-based evaluation using artificial radionuclides

A sampling cruise carried out in the North Sea in July 1988 has enabled the construction of general maps showing the distribution of salinity and temperature as well as the activities of the radionuclides ¹²⁵Sb, ¹³⁷Cs and ¹³⁴Cs. An inspection of the raw data and the distribution patterns so obtained shows the important role of meteorological fluctuations in the movement of near-surface waters throughout the North Sea.A simple mixing model is used to interpret the North Sea dataset in terms of four contributory water-masses (the Atlantic, Irish Sea, English Channel and Baltic), each of which can be identified by its specific characteristics. Maps are drawn up which indicate the contribution factor in percentage of each of these water masses at all points in the North Sea to a precision better than 15%. It is also possible to extract the contribution of direct fallout resulting from the Chernobyl accident; comparison with previously obtained results allows an evaluation of the rate of renewal of surface waters in the North Sea over a period of two years. In all areas, this value appears to be better than 75%.     

The role of small,low density particles on the partition of selected PCB congeners between water and suspended matter (North Sea area)

The dissolved and particulate suspended concentrations of five PCB congeners (with 3–7 chlorine atoms) in the Southern Bight (North Sea) are interpreted in terms of an equilibrium partitioning model. K_d values for riverine/coastal samples generally increase with chlorine number of the congeners (K_d = 10⁴–10⁶). Values are more than an order of magnitude larger at the low suspended matter concentrations offshore (< 1 mg·dm⁻³). This is interpreted in terms of the presence of different SPM fractions with different contents of PCB: a fraction consisting of low size/density particles carrying high contents of PCBs, dominates at low SPM concentrations. The contribution of particulate forms to the total PCB concentration per unit volume may, therefore, be significant even at low SPM concentrations.     

Segregation of herring larvae from inshore and offshore spawning grounds in the north-western North Sea — Implications for stock structure

Herring larvae hatching from spawning sites around the Scottish coast are dispersed by water currents during the weeks following hatching. Hydrographic data, observations on the distribution of caesium-137 and measurements of current velocities by moored meters and drifting buoys, suggest that larvae from offshore spawning sites around the north of Scotland should be more rapidly dispersed than those hatching in inshore areas. This has been confirmed by direct observations on the advection of herring larvae in different regions of the north western North Sea. The conclusion is that larvae hatching in inshore areas, especially in the Moray Firth, are most likely to contribute to nearby juvenile populations, whereas larvae from offshore spawning sites should be widely dispersed over the North Sea.Tagging and parasitology investigations have shown that adult herring spawning in the north-western North Sea have been widely dispersed in the North Sea and adjacent waters as juveniles (six months — one and a half years old). However, a high proportion of adult fish caught at inshore spawning sites and in the Moray Firth were found to have been recruited from more local areas. Taken together with the observations on larval drift, these observations suggest that the stock structure of herring in the northern North Sea may in part be a consequence of the physical oceanography of the area.     

The distribution of suspended matter in the Dutch coastal zone

Results are presented of suspended matter observations taken at bi-weekly intervals during the period 1975–1983, in a strip 70 km wide along the Dutch coast. The average distribution showed a (weak) minimum zone located north of Noordwijk at a distance of about 30 km from and parallel to the Dutch coast, between the salinity maximum and the coast. Variability was large between different years, seasons and individual cruises. A clear seasonal cycle emerged from the observed suspended-matter patterns: in winter a pronounced minimum existed, while in summer generally a monotonically decreasing concentration was measured, to open-sea values much lower than in winter. This seasonal cycle may be explained by a combination of variation in wind, river discharge and the activity of suspended-matter sources. The Flemish Banks and Channel waters are the main sources supplying suspended matter to the Dutch coastal area. Especially the varying transport through the Strait of Dover, large in winter, small in summer, determines the seasonal variation in the total amount of suspended matter. The existence of a localized turbidity minimum is tied to relatively large discharges from the Rhine and associated steep salinity gradients, also occurring mainly in winter and early spring. A simple model of cross-shore density-driven circulation shows the possible influence of the strong salinity gradients on the sedimentation of suspended matter. Particles with a settling rate comparable to the vertical velocity component of the circulation are forced to move offshore until they reach an area they sink out of the surface layer. The strength of this circulation is determined by the cross-shore density gradient due to the inflow of fresh water from the Rhine-Meuse estuary.     

Fractal geometry of in situ flocs in the estuarine and coastal environments

One- and two-dimensional fractal dimensions of in situ flocs were determined from the dependence of the are and perimeter of projection of the flocs on their greatest length, using an underwater camera and image-analysis system. Values for the fractal dimensions of flocs in the Elbe estuary and the North Sea varied among the samples: D₁ in the range of 1.03 to 1.14 and D₂ in the range of 1.41 to 1.81. D₂ as obtained here represents the three-dimensional fractal dimension of flocs, which has been obtained in previous studies from the dependence of settling velocity or porosity of flocs on their characteristic length. Comparisons of environmental factors showed no relationships between the fractal dimension and fluid shear. Salinity effects on the fractal dimension were probably also insignificant in our samples. The relationship of D₁ with the concentration of suspended matter was fairly convincing and suggests that the flocs had a rougher edge of projection at high than at low concentrations.     

Particulate and dissolved organic carbon and chlorophyll A in the Zaire river,estuary and plume

Data were collected on POC, DOC and phytoplankton in the Zaire river, estuary and plume. Mean river value for POC was 1.1 mg·l⁻¹, 4.7% of the suspended matter. Average DOC content of the river water was 8.5 mg·l⁻¹. These values are in accordance with the calculations of TOC input from rivers to the world's ocean. Within the estuary POC and chlorophyll decreased regularly up to a salinity of 20. Between salinities of 20 and 32 small phytoplankton bloom occurred resulting also in higher POC values.DOC mixed conservatively up to a salinity of 25; at salinities above 25, values indicate DOC production. This DOC production occurred partly in the bottom water of the canyon where low oxygen values indicated mineralization and conversion of the accumulated POC into DOC. Another area of DOC production observed inside and outside the surface waters of the plume, was partly related to autolysis and degradation of the phytoplankton bloom.This study shows that the influence of rivers on the organic carbon in the ocean will not be confined to the amount introduced directly, but that we have to add the amounts of POC and DOC resulting from enhanced phytoplankton primary production by nutrient input from rivers and by river induced upwelling.     

Contributions of cultivars,management and climate change to winter wheat yield in the North China Plain in the past three decades

The detailed field experiment data from 1980 to 2009 at four stations in the North China Plain (NCP), together with a crop simulation model, were used to disentangle the relative contributions of cultivars renewal, fertilization management and climate change to winter wheat yield, as well as the relative impacts of different climate variables on winter wheat yield, in the past three decades. We found that during 1980–2009 cultivars renewal contributed to yield increase by 12.2–22.6%; fertilization management contributed to yield increase by 2.1–3.6%; and climate change contributed to yield generally by −3.0–3.0%, however by −15.0% for rainfed wheat in southern part of the NCP. Modern cultivars and agronomic management played dominant roles in yield increase in the past three decades, nevertheless the estimated impacts of climate change on yield accounted for as large as −23.8–25.0% of observed yield trends. During the study period, increase in temperature increased winter wheat yield by 3.0–6.0% in northern part of the NCP, however reduced rainfed winter wheat yield by 9.0–12.0% in southern part of the NCP. Decrease in solar radiation reduced wheat yield by 3.0–12.0% across the stations. The impact of precipitation change on winter wheat yield was slight because there were no pronounced trends in precipitation. Our findings highlight that modern cultivars and agronomic management contributed dominantly to yield increase in the past three decades, nevertheless the impacts of climate change were large enough in some areas to affect a significant portion of observed yield trends in the NCP.     

基于GIS和地统计学的黔西北农业园区土壤养分空间变异特征研究

以黔西县水西观光农业示范园区(乌骡坝社区)为研究区域,采用地统计学方法,研究了黔西北山区土壤pH值、有机质、碱解氮、有效磷、速效钾、全氮、全磷、全钾的土壤养分状况及空间变异规律。结果表明：(1)土壤pH值表现为弱变异性,其余各项指标变异均属于中等程度变异;(2)土壤pH、有机质、碱解氮、有效磷、速效钾和全氮均是中部分布较低,全磷是中部分布较高,有机质是北部和南部分布较高;速效钾是东部分布较高,全氮和全钾北部分布最高;(3)土壤有机质C0 /(C0 +C)=31.935%,表现为中等空间相关性,其余各土壤养分指标均表现为强烈的空间相关性。