Microvariability in the early stages of cobble weathering by microenvironment on a glacier foreland,Storbreen, Jotunheimen,Norway

The initial stages of cobble weathering, measured as increasing percentage porosity, were calculated for sets of cobbles taken from the foreland of Storbreen, a cirque glacier in the Jotunheimen, Norway. Cobbles were taken from in front of the 1998 glacier snout, from the 1928, 1870, 1810 and 1750 moraine crests and from the ～10 000‐year‐old land surface beyond the Neoglacial foreland limit. Three microenvironments were examined within each site: (1) lichen‐free surfaces from exposed cobbles, (2) lichen‐covered surfaces from exposed cobbles and (3) buried cobbles taken from a soil depth of ～40 cm. Percentage porosity within plagioclase minerals was calculated using backscatter electron images of prepared thin sections. Porosity was calculated from five depth profiles into each cobble. Depth profiles were subdivided into a sequence of 50 µm × 50 µm rectangles running to at least a nominal depth of 500 µm within each cobble. Three cobbles from each dated land surface were sampled, except for the 1750 surface, which had five cobbles. Statistical analysis was by analysis of variance of rank‐order transformed data. Findings indicate that cobbles close to the glacier snout are largely unweathered; also, weathering is generally weak in the 1928, 1870 and 1810 positions, but statistically significantly higher in the 1750‐ and 10 000‐year‐old positions. Weathering of buried cobbles always exceeded weathering of exposed cobbles and may possibly reach a value beyond which it cannot progress while retaining surface cohesion. The degree of weathering on lichen‐free and lichen‐covered cobble surfaces is not initially distinguishable, but diverges sharply after ～250 years, when lichen‐covered surfaces experience significantly higher totals. Overall, the weathering trend in cobbles matches that found in soils at the same sites. Copyright © 2007 John Wiley & Sons, Ltd.     

Competitive Adsorption of Nickel and Copper Ions from Aqueous Solution Using Nonliving Biomass of the Marine Brown Alga Laminaria japonica

The adsorption of nickel and copper in a bicomponent system using the nonliving biomass of the marine brown alga Laminaria japonica was investigated in batch systems as a function of initial solution pH, contact time and temperature. The adsorption of nickel and copper was strongly pH dependent. Kinetic studies pointed to a rapid uptake with an equilibrium time of about 30 min. The kinetic curves were successfully fitted by linear regression to pseudo first and pseudo‐second‐order equations. The equilibrium data was analyzed using several models, including the extended Langmuir equation, modified extended Langmuir model and combined extended Langmuir‐Freundlich model. The results suggested that the competitive adsorption of nickel and copper at all temperatures was best represented by the combined extended Langmuir‐Freundlich isotherm. The isotherms indicated competitive uptake, with copper being preferentially adsorbed followed by nickel with an increase in the amount of solute in solution. Thermodynamic analysis revealed that the simultaneous adsorption of nickel and copper ions could be considered to be a spontaneous, endothermic process, with increased randomness.     

Effects of the herbicide diuron on the early life history stages of coral

The effects of the herbicide diuron on the early life history stages of broadcast spawning and brooding corals were examined in laboratory experiments. Fertilisation of Acropora millepora and Montipora aequituberculata oocytes were not inhibited at diuron concentrations of up to 1000 microg l(-1). Metamorphosis of symbiont-free A. millepora larvae was only significantly inhibited at 300 microg l(-1) diuron. Pocillopora damicornis larvae, which contain symbiotic dinoflagellates, were able to undergo metamorphosis after 24 h exposure to diuron at 1000 microg l(-1). Two-week old P. damicornis recruits on the other hand were as susceptible to diuron as adult colonies, with expulsion of symbiotic dinoflagellates (bleaching) evident at 10 microg l(-1) diuron after 96 h exposure. Reversible metamorphosis was observed at high diuron concentrations, with fully bleached polyps escaping from their skeletons. Pulse amplitude modulation (PAM) chlorophyll fluorescence techniques demonstrated a reduction in photosynthetic efficiency (Delta F/F(m)') in illuminated P. damicornis recruits after a 2 h exposure to 1 microg l(-1) diuron. The dark-adapted quantum yields (F(v)/F(m)) also declined, indicating chronic photoinhibition and damage to photosystem II.     

Effect of ammonium jarosite on early life stages of a saltwater fish,Cyprinodon variegatus

Embryos and juveniles of the sheepshead minnow (Cyprinodon variegatus), a saltwater fish, were exposed to ammonium jarosite, a waste product of the processing of zinc ore, during a 28-day posthatch, flow-through toxicity test. Exposure to measured ammonium jarosite concentrations ≤ 290 ppm had no significant effect on the hatching success of embryos. However, slight delays in hatching were observed in test concentrations ≥ 140 ppm. Although exposure to test concentrations ≥ 140 ppm significantly decreased the ability of juvenile fish to uncurl after hatching, juvenile mortality was significantly increased only in test concentrations ≥ 230 ppm. There was no effect on growth of juvenile fish in jarosite concentrations ≤ 230 ppm. The estimated maximum acceptable toxicant concentration (MATC), based on measured concentrations, was > 140< 230 ppm.     

Structural analysis of the early stages of catastrophic stratovolcano flank-collapse using analogue models

Many major volcanic flank collapses involve the failure of low-angle strata in or under the edifice. Such failures produce voluminous, destructive debris avalanches that are a major volcanic hazard. At Socompa, Las Isletas-Mombacho and Parinacota volcanoes, field studies have shown that during catastrophic flank collapse a significant segment of their substrata was detached and expelled from beneath the volcanic edifice and formed a mobile basal layer on which the sliding flanks were transported. Previous studies have proposed that gravitational flank spreading was likely involved in the onset of sudden substrata failure. The early stages of this particular type of flank collapse can be modelled under laboratory conditions using analogue models. This allows us to study the development of structures accommodating early deformation of the sliding flank during catastrophic collapse. In the experiments, the detached substratum segment (low-viscosity basal layer) was modelled with a silicone layer, and the overlying stratovolcano with a layered sand cone. The first structure developed in the models is a graben rooted in the low-viscosity basal layer. This graben forms the limits of the future avalanche-amphitheatre and divides the sliding flank into a ‘toreva’ domain (upper sliding flank) and a ‘hummock’ domain (lower sliding flank). These domains display distinctive structural patterns and kinetic behaviour. Normal faults develop in the toreva domain and inside the graben, while the hummock domain is characterised by transtensional structures. The hummock domain also over-thrusts the lower amphitheatre sides, which allows subsequent sideways avalanche spreading. Measurements show that horizontal speeds of the hummock domain are always higher than that of the toreva domain during model collapse. The main role played by the low-viscosity basal layer during this type of collapse is to control the size, shape and structural complexity of the sliding flank; it also transmits mass and momentum from the toreva to the hummock domain.     

Embryotoxic and genotoxic effects of heavy metals and pesticides on early life stages of Pacific oyster (Crassostrea gigas)

This study evaluated embryotoxicity and genotoxicity of two dissolved metals copper and cadmium (Cu and Cd) and two pesticides (metolachlor and irgarol) occurring in Arcachon Bay (SW France) in Pacific oyster (Crassostrea gigas) larvae and investigated the relationship between those two endpoints. Embryotoxicity was measured by calculating the percentage of abnormal D-shaped larvae and genotoxicity was evaluated with DNA strand breaks using the comet assay. After 24 h exposure, significant increases of the percentage of abnormal D-larvae and the DNA strand breaks were observed from 0.1 μg L⁻¹ for Cu, 10 μg L⁻¹ for Cd and 0.01 μg L⁻¹ for both irgarol and metolachlor in comparison with the controls. A strong positive relationship between embryotoxicity and genotoxicity was recorded for Cu, Cd and metolachlor. The current study suggests that copper, irgarol and metolachlor can induce larval abnormalities and DNA damage in a population of exposed oysters at environmentally relevant concentrations.     

Effects of anionic detergent on the growth of Laminaria

Anionic detergents affect the growth of sporophytes of the alga Laminaria saccharina. The effect of these detergents on all phases of the life history of the alga has now been examined. The motility and settling of the zoospores and growth of sporophytes are affected by the detergent. The development of individuals of the gametophyte generation is least affected.     

Mechanisms and climatic-ecological effects of the Great Oxidation Event in the early Proterozoic

Science China Earth Sciences - This paper briefly introduces the conception and research history of the Great Oxidation Event (GOE) in the early Paleoproterozoic and summarizes the primary...     

Copper,zinc, cadmium,nickel, iron and manganese in the Southern Bight of the North Sea

Ni, Cd, Cu, Zn, and Fe were determined in water and suspended matter samples and Mn in suspended matter samples from the Southern Bight region of the North Sea. Four distinct areas, comprising the Rhine estuary, the Dutch coastal waters, the centre of the Bight, and the English coastal water can be distinguished on the basis of the distribution of the trace metals. The total concentrations of all metals were high in the Rhine estuary, decreased in a seaward direction to reach very low values, comparable to continental shelf water, in the centre of the Bight, and increased again towards the English coast. Elevated concentrations of dissolved Cu, Ni, Cd and Zn near the English coast are not only due to river inputs. Over the entire region, the fraction of Cd, Ni and Zn in solution was consistently more important than the fraction in the suspended particulate phase. In contast, the fraction of Fe and Mn in the solid phase was consistently greater than the fraction in solution. Total concentrations of Fe, Mn and Cu are more dictated by the suspended particulate matter concentration than Cd, Ni and Zn.     

A model study of the Copper River plume and its effects on the northern Gulf of Alaska

A three-level nested Regional Ocean Modeling System was used to examine the seasonal evolution of the Copper River (CR) plume and how it influences the along- and across-shore transport in the northern Gulf of Alaska (NGoA). A passive tracer was introduced in the model to delineate the growth and decay of the plume and to diagnose the spread of the CR discharge in the shelf, into Prince William Sound (PWS) and offshore. Furthermore, a model experiment with doubled discharge was conducted to investigate potential impacts of accelerated glacier melt in future climate scenarios. The 2010 and 2011 simulation revealed that the upstream (eastward) transport in the NGoA is negligible. About 60 % of the passive tracer released in the CR discharge is transported southwestward on the shelf, while another one third goes into PWS with close to 60 % of which exiting PWS to the shelf from Montague Strait. The rest few percent is transported across the shelf break and exported to the GoA basin. The downstream transport and the transport into PWS are strongly regulated by the downwelling-favorable wind, while the offshore transport is related to the accumulation of plume water in the shelf, frontal instability, and the Alaskan Stream. It takes weeks in spring for the buoyancy to accumulate so that a bulge forms outside of the CR estuary. The absence of strong storms as in the summer of 2010 allows the bulge continue growing to trigger frontal instability. These frontal features can interact with the Alaskan Stream to induce transport pulses across the shelf break. Alternatively as in 2011, a downwelling-favorable wind event in early August (near the peak discharge) accelerates the southwestward coastal current and produces an intense downstream transport event. Both processes result in fast drains of the buoyancy and the plume content, thereby rapid disintegration of the plume in the shelf. The plume in the doubled discharge case can be two to three times in size, which affects not only the magnitude but also the timing of certain transport events. In particular, the offshore transport increases by several folds because the plume appears to be more easily entrained by the seaward flow along the side of Hinchinbrook Canyon.     

Artificial light at night: implications for early life stages development in four temperate freshwater fish species

Flora and fauna have both evolved under a natural cycle of light and dark. But especially in urban areas, the night is now increasingly disturbed by artificial light. Many traits and behaviours in fish are triggered by a circadian clock, for example hatching and swim bladder inflation, which predominantly take place at dusk or night. As lighting becomes brighter and extends farther into rural areas, the distinction between day and night becomes increasingly blurred. Therefore, the loss of diurnal trigger by artificial light at night was hypothesized having deleterious effects on these traits and impact fish reproduction. To assess these effects, eggs of four native freshwater fishes, Eurasian perch Perca fluviatilis, roach Rutilus rutilus, bleak Alburnus alburnus and chub Leuciscus cephalus, were incubated under two different light conditions: a photoperiod of 14 h light:10 h darkness (LD) and continuous illumination (LL). The time to hatch and swim bladder inflation was recorded. The species showed inconsistent reactions to the light treatments. In roach and bleak, the time to 50% hatch was longer in LL, whereas continuous lighting had an accelerating effect in chub. Incubation in LL elongated the hatching period in perch and roach and, in perch, the onset of darkness seemed to trigger hatching. The swim bladder inflation was significantly promoted by continuous light in chub and bleak but was not affected in roach. In conclusion, nocturnal artificial illumination could have an effect on hatching and initial swim bladder filling by masking the day–night-change and thereby diminish the trigger effect. However, the reactions were species specific and the increase in variation indicated a lack of diurnal triggering, whilst a general deleterious effect of artificial light at night has not been identified on early life stages.     

三峡库区涪陵江段产漂流性卵鱼类的早期资源及其对水文和水温特征的响应

三峡水库调度运行改变了库区江段的水文情势,影响漂流性卵苗在库区江段内的时空分布特征。在水库低水位运行时,具有流水生境特征的库中和库尾江段是产漂流性卵鱼类在整个三峡库区内重要的产卵江段。了解三峡库中和库尾江段产漂流性卵鱼类的早期资源状况及其对水文和水温特征的响应关系,对于采取适宜的保护措施促进鱼类早期资源的恢复具有重要的意义。本文通过2017—2020年5—7月在库中涪陵断面进行的逐日早期资源监测,了解三峡库中和库尾江段产漂流性卵鱼类早期资源的种类组成、产卵规模、产卵场分布及其年际变动特征,并采用随机森林(RF)模型,分析鱼类逐日产卵规模变动与水文、水温格局及其过程的关系,辨识影响不同种类产卵规模变动的关键水文及水温要素。结果表明:2017—2020年共采集到漂流性鱼卵21种,包括长江上游特有鱼类鱼卵3种;以圆筒吻鮈Rhinagobio cylindricus、蒙古鲌Chanodichthys mongolicus、贝氏(?)Hemiculter bleekeri等6种鱼类的鱼卵为主,占总采集鱼卵数的88.76%;各年的鱼卵规模分别为83.04×10⁸、14.29×...     

Copper,cadmium and zinc in seaweeds from the south coast of Ireland

Copper, cadmium and zinc levels were determined by atomic absorption spectrophotometry in five seaweed species from the south coast of Ireland. The levels from eight sites on the south coast were compared with those from five sites in Cork harbour. Whereas the levels of copper and cadmium from Cork harbour compared favourably with those of the other sites, the levels of zinc at some of the Cork harbour sites were appreciably higher than those of the other sites.     

Detrimental effects of reduced seawater pH on the early development of the Pacific abalone

The hatching process of the Pacific abalone Haliotis discus hannai was prolonged at a pH of 7.6 and pH 7.3, and the embryonic developmental success was reduced. The hatching rate at pH 7.3 was significantly (10.8%) lower than that of the control (pH 8.2). The malformation rates at pH 7.9 and pH 8.2 were less than 20% but were 53.8% and 77.3% at pH 7.6 and pH 7.3, respectively. When newly hatched larvae were incubated for 48 h at pH 7.3, only 2.7% of the larvae settled, while more than 70% of the larvae completed settlement in the other three pH treatments. However, most 24 h old larvae could complete metamorphosis in all four pH treatments. Overall, a 0.3-unit reduction in water pH will produce no negative effect on the early development of the Pacific abalone, but further reduction in pH to the values predicted for seawater by the end of this century will have strong detrimental effects.     

A Pan African age for the HP-HT granulite gneisses of Zabargad island: implications for the early stages of the Red Sea rifting

Up to now the age of granulite gneisses intruded by the Zabargad mantle diapir has been an unsolved problem. These gneisses may represent either a part of the adjacent continental crust primarily differentiated during the Pan African orogeny, or new crust composed of Miocene clastic sediments deposited in a developing rift, crosscut by a diabase dike swarm and gabbroic intrusions, and finally metamorphosed and deformed by the mantle diapir. Previous geochronological results obtained on Zabargad island and Al Lith and Tihama-Asir complexes (Saudi Arabia) suggest an Early Miocene age of emplacement for the Zabargad mantle diapir during the early opening of the Red Sea rift. In contrast, SmNd and RbSr internal isochrons yield Pan African dates for felsic and basic granulites collected 500–600 m from the contact zone with the peridotites. Devoid of evidence for retrograde metamorphic, minerals from a felsic granulite provide well-defined RbSr and SmNd dates of 655 ± 8 and 699 ± 34 Ma for the HP-HT metamorphic event (10 kbar, 850°C). The thermal event related to the diapir emplacement is not recorded in the SmNd and RbSr systems of the studied gneisses; in contrast, the development of a retrograde amphibolite metamorphic paragenesis strongly disturbed the RbSr isotopic system of the mafic granulite. The initial¹⁴³Nd/¹⁴⁴Nd ratio of the felsic granulite is higher than the contemporaneous value for CHUR and is in agreement with other Nd isotopic data for samples of upper crust from the Arabian shield. This result suggests that source rocks of the felsic granulite were derived at 1.0 to 1.2 Ga from either an average MORB-type mantle or a local 2.2 Ga LREE-depleted mantle. Zabargad gneisses represent a part of the disrupted lower continental crust of the Pan African Afro-Arabian shield. During early stages of the Red Sea rifting in the Miocene, these Precambrian granulites were intruded and dragged upwards by a rising peridotite diapir.     

The toxic effects of hydrocarbons upon the naupliar and adult stages of Balanus (Crustacea: Cirripedia)

The effect of kerosene and BP 1002 upon the naupliar and adult stages of Balanus amphitrite amphitrite and Balanus variegatus variegatus has been studied. The percentage non-motility and actual mortality of the naupliar larvae and the adults of both species has been generally shown to be a function of the dosage and treatment time of these two hydrocarbons. Both barnacles (nauplii and adults) have a similar susceptibility to the hydrocarbons tested, the nauplii being killed at lower concentrations than the adults. Cirral activity of the adults was significantly reduced when the barnacles were treated with 10 and 100 ppm BP 1002.Preliminary experiments have also been performed to compare the toxicity of BP 1002 and kerosene with that of ‘Bukomkleen’ and ‘Chemkleen’. It was found that BP 1002 was the most toxic to these barnacles with a lower and similar toxicity found for Chemkleen and Bukomkleen. The toxicity of kerosene is comparatively low.     

Effect of oils on cell membrane permeability in Fucus serratus and Laminaria digitata

Leakage of electrolytes from discs of treated fronds of Laminaria digitata and Fucus serratus was the criterion used to study the effect of oils over 24 h on cell membrane permeability. Motor fuel oil increased cell membrane permeability in both algae at 1 h, or longer, after treatment. Laminaria changed to a green colour after 3 h, but Fucus was unaffected visibly by the oil. White spirit, diesel oil, or aviation fuel did not alter cell membrane permeability or visibly affect either alga over 24 h.     

Comparison of the lethal effect of CO2 and acidification on red sea bream (Pagrus major) during the early developmental stages

To compare the acute toxicity of CO(2)- and HCl-acidified seawater, eggs and larvae of a marine fish, Pagrus major, were exposed to seawater equilibrated with CO(2)-enriched gas mixtures (CO(2)=5% or 10%, O(2)=20.95% balanced with N(2)) or seawater acidified with 1 N HCl at two pH levels (pH 6.2 (=5% CO(2)) and 5.9 (=10% CO(2))) for 6 h (eggs) or 24 h (larvae). Mortalities of eggs were 85.8% (CO(2)) and 3.6% (HCl) at pH 6.2, and 97.4% (CO(2)) and 0.9% (HCl) at pH 5.9, while those of larvae were 61.2% (CO(2)) and 1.6% (HCl) at pH 6.2, and 100% (CO(2)) and 5.0% (HCl) at pH 5.9. Thus, previous research on the effects of acidified seawater on marine organisms, as a substitute for CO(2), has largely underestimated the toxic effects of CO(2).