海原断裂带东南段土壤气体地球化学特征

在海原断裂带东南段4个地点跨断层测量了土壤气中He、H2、N2、O2、CH4、C2 H6、Rn和Hg 的浓度及He、H2、CH4、Rn和Hg的通量.测量结果表明,N2/O2、Hg和Rn的背景值分别是4.2、50.4ng/m3和5.8k Bq/m3;土壤气中He和CH4在海原断裂带东南段端部有强烈异常,并且脱气强烈,通量...     

Stable isotope and trace element status of subsistence-hunted bowhead and beluga whales in Alaska and gray whales in Chukotka

Tissues of bowhead, beluga, and gray whales were analyzed for Ag, Cd, Cu, Se, Zn, THg and MeHg (belugas only). Delta15N and delta13C in muscle were used to estimate trophic position and feeding habitat, respectively. Trace element concentrations in tissues were significantly different among whale species. Hepatic Ag was higher in belugas than bowheads and gray whales. Gray whales had lower Cd concentrations in liver and kidney than bowhead and belugas and a sigmoid correlation of Cd with length was noted for all whales. Renal and hepatic Se and THg were higher in belugas than in baleen whales. The hepatic molar ratio of Se:THg exceeded 1:1 in all species and was negatively correlated to body length. Hepatic and renal Zn in subsistence-harvested gray whales was lower than concentrations for stranded whales. Se:THg molar ratios and tissue concentrations of Zn may show promise as potential indicators of immune status and animal health.     

Seasonal distribution of trace metals in suspended particulate and bottom sediments of four microtidal river estuaries,west coast of India

ABSTRACT

The seasonal distribution of metals (V, Cr, Co, Cu, Ni, Zn, Pb, Mn, Fe, Al and Ti) in suspended and bottom sediments of four minor estuaries (Terekhol, Chapora, Sal and Talpona rivers) of Goa, India was investigated to understand the metal distribution process in the estuarine region. The highest particulate-metal concentrations were found in low-salinity regions of all the estuaries, in the wet season (e.g. in the Terekhol River, the averages in ppm were Co: 53, Ni: 197, Cu: 208, Zn: 212 and Pb: 65) compared to the dry season averages (Co: 27, Ni: 76, Cu: 105, Zn: 164 and Pb: 13 ppm). The estuarine-mixing diagrams showed non-conservative behaviour in both seasons. The Sal River had the highest particulate-metal concentration (Co: 106, Ni: 300 and Zn: 323 ppm), suggesting an anthropogenic input. The enrichment factor for suspended matter was higher than bottom sediments with extremely high enrichment for Mn (>10). The Geo-accumulation index displayed unpolluted to polluted class for all metals. The study highlights the important role played by small estuaries in seasonal metal release and accumulation along the coastal region.     

Effect of Copper on Activity and Feeding in the Subtidal Prosobranch Babylonia lutosa (Lamarck) (Gastropoda: Buccinidae)

Individuals of the subtidal gastropod Babylonia lutosa were exposed to three sublethal concentrations of copper (0.02, 0.06 and 0.20 ppm) for four weeks. The percentage of normally active individuals (body extended and moving with the foot attached) decreased and the percentage of snails retracted (body extended, foot not attached, unable to move) and in a distressed stage (body retracted within the shell) increased with increase in copper concentration. Exposure to copper also decreased significantly the ability of an individual to move, and to burrow, but the effect was only observed in week 1, individuals were fully recovered in week 2. Feeding, however, was not affected, both in terms of the percentage number of individuals which fed, and the time spent feeding. Results were discussed with respect to the potential of using this animal as a bioassay tool in monitoring the effect of environmental perturbations on the subtidal community in Hong Kong.     

Effects of heavy metals on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus (Powys)

The effects of Cu, Cd, Zn and Cr on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus were compared. The 96-h LC₅₀ for Cu, Cd, Zn and Cr were 0.36, 1.52, 1.76 and 36.9 mg l⁻¹, respectively. Four sublethal concentrations of each metal plus a control were prepared and the snails were exposed to experimental solutions for 96 h. Feeding behaviour was studied after the snails were starved for five days. As compared with the control, the number of individuals feeding was significantly reduced by exposure to 0.05 mg l⁻¹ Cu, 0.2 mg l⁻¹ Zn, 0.5 mg l⁻¹ Cd and 5 mg l⁻¹ Cr. The time spent feeding was greater for individuals exposed to greater concentrations of Zn and Cd but no effect was found for Cu and Cr. Chemoreception of food was studied by placing the snails at a fixed distance of 15 cm from the bait. The success rate of reaching the bait was less for individuals exposed to Cr but no effect was found for Zn, Cu or Cd. The time required for an individual to reach the bait decreased as the concentration of Zn increased. In contrast, a longer time was required for individuals exposed to Cr whereas the effect of Cd and Cu was insignificant. The potential of using feeding behaviour and chemoreception in contaminant evaluations is discussed.     

Trace Element Levels in the Groundwater of Mediterranean Coastal Plains – The Case of Silifke,Turkey

The Silifke plain is located near the coast of the Mediterranean Sea in Turkey. The delta in the plain is a highly fertile land that supports the agriculture of more than twenty types of crop. Some trace element content of the groundwater samples taken from the existing wells in this area are analyzed using inductively coupled plasma optical emission spectrometry (ICP‐OES). The mean levels (ppm) of boron (B), barium (Ba), iron (Fe), manganese (Mn), lead (Pb), zinc (Zn), total chromium (TCr), cadmium (Cd), copper (Cu), aluminum (Al), and nickel (Ni) were obtained for the sampling points in the area for four seasons. Groundwater samples taken in the study area don't exhibit significantly elevated levels of these elements during a period of twelve months between December 2007 and November 2008. Furthermore, all of the elements exhibit values lower than 0.005 ppm, with the exception of B, Ba, and Fe. The results demonstrate that although these three elements produce the highest values, most are found to be appropriate for activities such as irrigation and human consumption in terms of trace elements.     

Toxicity of 17alpha-ethynylestradiol and norethindrone,constituents of an oral contraceptive pill to the swimming and reproduction of cladoceran Daphnia magna,with special reference to their synergetic effect

Toxicity of 17alpha-ethynylestradiol (EE2) and norethindrone (NOR), constituents of low dosage oral contraceptives, was assessed for the freshwater cladoceran Daphnia magna. Acute toxicity tests showed that 5 ppm of EE2, the highest concentration in this study, never inhibited swimming, whereas NOR inhibited swimming at >3 ppm: 48 h EC(50) for NOR was 6.41 ppm. Chronic toxicity tests were carried out for 25 days by measuring the number of offspring, moltings and sex ratios of neonates at 20, 100 and 500 ppb. EE2>100 ppb significantly decreased the number of offspring to 75% of the control; however, no effect was observed in molting and sex ratios at <500 ppb. NOR did not affect reproduction and sex ratios at <500 ppb. Mixture of EE2 (5.88 ppb) and NOR (94.12 ppb) also significantly decreased the number of offspring to 57% of the control. This result indicates the importance of examining synergetic effects of chemicals in the context of natural environments which face exposure to myriad chemicals.     

1988-2018年滇池氮磷比的时空演变特征与原因解析

氮、磷浓度是制约湖泊营养状态和生产力水平的重要环境因子,而氮磷化学计量比是湖泊生态系统的主要指标,因此,判识氮磷比变化趋势及其驱动力对湖泊生态恢复具有重要意义.研究基于19882018年连续观测数据,分析了滇池氮磷浓度和氮磷摩尔比(简称氮磷比)的时空分布演变特征;采用多元线性回归模型分别对滇池草海和外海氮磷比驱动效应进行定量解析,筛选出影响湖体氮磷比变化的潜在驱动因子.结果表明:①19882018年滇池氮磷比呈现显著的线性上升趋势,其中草海和外海氮磷比分别上升1.3和0.7 a^-1.②草海和外海分别在2008年和2004年发生了氮磷比上升突变,突变前上升归因于总氮浓度快速增加,突变后则是由于总磷浓度下降较快.③滇池的氮磷浓度变化主要是受流域氮磷输入负荷、跨流域调水、流域氮磷削减、风速和水位的综合影响,但受控因子在不同区域可能存在差异.④气温是滇池氮磷比变化的主要驱动因子,流域人为氮磷输入差异是滇池氮磷比变化的次要驱动因子.     

Effects of heavy metals on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus (Powys)

The effects of Cu, Cd, Zn and Cr on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus were compared. The 96-h LC₅₀ for Cu, Cd, Zn and Cr were 0.36, 1.52, 1.76 and 36.9 mg l⁻¹, respectively. Four sublethal concentrations of each metal plus a control were prepared and the snails were exposed to experimental solutions for 96 h. Feeding behaviour was studied after the snails were starved for five days. As compared with the control, the number of individuals feeding was significantly reduced by exposure to 0.05 mg l⁻¹ Cu, 0.2 mg l⁻¹ Zn, 0.5 mg l⁻¹ Cd and 5 mg l⁻¹ Cr. The time spent feeding was greater for individuals exposed to greater concentrations of Zn and Cd but no effect was found for Cu and Cr. Chemoreception of food was studied by placing the snails at a fixed distance of 15 cm from the bait. The success rate of reaching the bait was less for individuals exposed to Cr but no effect was found for Zn, Cu or Cd. The time required for an individual to reach the bait decreased as the concentration of Zn increased. In contrast, a longer time was required for individuals exposed to Cr whereas the effect of Cd and Cu was insignificant. The potential of using feeding behaviour and chemoreception in contaminant evaluations is discussed.     

贵州草海湿地不同水位梯度土壤碳、氮、磷含量及其生态化学计量比分布特征

对贵州草海湿地4种水位梯度下(农田区、过渡区、浅水区和深水区)表层土壤(0~10 cm)碳、氮、磷含量及其生态化学计量比进行研究,以期揭示草海湿地不同水位梯度下土壤碳、氮、磷生态化学计量比的分布特征及其影响因素.结果表明:土壤总有机碳(TOC)、总氮(TN)及总磷(TP)含量在不同水位梯度之间均差异显著,由过渡区至深水区,土壤TOC及TN含量均呈递增趋势,而TP含量呈先降低后增加的趋势;农田区土壤TN含量显著高于浅水区,但深水区土壤TP含量显著低于农田区.不同水位梯度土壤碳氮比(C/N)、碳磷比(C/P)和氮磷比(N/P)也存在显著差异,由过渡区至深水区,土壤C/P和N/P均呈递增趋势,而C/N呈先增加后降低的趋势;与过渡区相比,农田区土壤C/N、C/P和N/P总体偏低.相关性分析表明:土壤C/N、C/P和N/P的空间分布与土壤TOC、TN、含水量等理化性质有关.可见,草海湿地水位变化对土壤TOC、TN和TP含量以及C/N、C/P及N/P的空间分布具有显著影响,且水位升高有利于增强土壤碳、氮、磷的固存潜力.     

Rare-earth and trace elements and hydrogen and oxygen isotopic compositions of Cretaceous kaolinitic sediments from the Lower Benue Trough,Nigeria: provenance and paleoclimatic significance

This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma–mass spectrometry and isotope ratio mass spectrometry was used to investigate trace and rareearth element geochemistry and hydrogen and oxygen isotopic compositions. These data were then used to infer the sediments' provenance and paleoclimatic conditions during their deposition. The sediments contained low concentrations of most trace elements, with the exceptions of Zr(651–1352 ppm), Ba(56–157 ppm), V(38–90 ppm),and Sr(15.1–59.6 ppm). Average values of Co and Ni were1.5 and 0.7 ppm, respectively. Trace and rare earth element values were lower than corresponding values for upper continental crust and Post-Archean Australian Shale, with the exception of Zr. The samples showed only slight light rare-earth enrichment and nearly flat heavy rare-earth depletion patterns, with negative Eu and Tm anomalies,typical of felsic sources. Geochemical parameters such as La/Sc, Th/Sc, and Th/Co ratios support that the kaolinitic sediments were derived from a felsic rock source, likely deposited in an oxic environment.^(18 )O values ranged from+ 15.4 to + 21.2% for the investigated samples, consistent with a residual material derived from chemicalweathering of felsic rock and redeposited in a sedimentary basin(typical values of + 19 to + 21.2%). While in the basin, the sediments experienced extended interactions with meteoric water enriched in d D and d16 O. However,the variation in d D and d16 O values for the investigated samples is attributed to the high temperature of formation(54–91 °C). The d D and d^(18 )O values suggest that the sediments, although obtained from different localities within the Lower Benue Trough, formed under similar hot,tropical climatic conditions.     

Simulating estuarine nitrous oxide production by means of a dynamic model

We describe a dynamic model developed from a commercially available modeling package (ECoS-III) to simulate estuarine dissolved inorganic nitrogen (DIN) dynamics, and consequent N(2)O production and atmospheric flux on the timescale of tidal cycles. Simulated model state variables were NH(4)(+), NO(3)(-) and N(2)O concentrations, and salinity. Model outputs were evaluated through comparison with summer field data for the Tyne estuary, UK. The model adequately reproduced the observed axial profiles of NH(4)(+), NO(3)(-) and N(2)O concentrations. Nitrification was shown to be the dominant N(2)O source and estimates of the ratios nitrification to DIN load and N(2)O emission to DIN load are considerably lower than the corresponding values adopted in global scale models of estuarine N(2)O emissions based on DIN transformations. Hence our results are consistent with the requirement imposed by atmospheric N(2)O growth rate constraints that the amount of atmospheric N(2)O arising from agriculturally related sources, including estuarine transformations of N, be revised downward.     

洱海苦草(Vallisneria natans)水深分布和叶片C、N、P化学计量学对不同水深的响应

湖泊水深是影响沉水植物生长、繁殖与分布的重要环境因子,水深增加改变了水下光照、风浪和底泥特性等,因而可能导致沉水植物的生理生化指标发生相应变化.本研究通过对云南洱海沉水植物苦草(Vallisneria natans)随水深分布的情况进行调查,并分析了定植于不同水深的苦草叶片碳(C)、氮(N)和磷(P)含量及其比率,以阐明水深变化对苦草叶片生态化学计量学的影响.结果表明洱海苦草定植的水深范围为0.5~5.6 m,在1.5~2.4 m处达到最大频度,在2.5~3.4 m处达到最大相对生物量,这表明苦草在洱海中的最适生长深度在1.5~3.4 m范围内;苦草叶片C、N和P含量平均值分别为356.10、26.13和3.54 mg/g,C:N、C:P和N:P的平均值分别为14.38、113.46和7.85;苦草叶片C含量、C:N和C:P均随水深增加而降低,N和P含量则随水深增加而升高,N:P在0.5~1.4 m较高,其余水深梯度之间则没有显著差异.总体上,苦草叶片C、N、P含量及其化学计量特征显著地受到了湖泊水深的影响.另外,本研究还发现水深的增加使得苦草叶片N、P含量发生聚敛,这导致其N、P之间的耦合性变弱.     

Seacage aquaculture in a World Heritage Area: The environmental footprint of a Barramundi farm in tropical Australia

The fate of aquaculture wastes from a seacage farm within a pristine mangrove environment was studied. Seasonal and tidal differences were most important in determining water quality within receiving waters and obscured any nutrient enrichment effect by the farm. Farm wastes added significantly to the N budget status of the creek system, but overall water quality conformed to Queensland EPA Water Quality standards. Mangrove trees throughout the creek system contained ¹⁵N signatures traceable to aquaculture feeds, but the footprint of the farm itself was best indicated by the ratio of Zn:Li in sediments. The creek became hypoxic (<2 mg l⁻¹) during wet season low tides. Consequently, we recommended monitoring of water-column oxygen concentrations to warn of hypoxic conditions threatening to fish health, as well as Zn:Li ratios in sediment accumulation zones to determine the area of influence of the farm.     

Some Haematological Effects of Crude Oil on Freshwater Catfish,Heteropneustes fossilis (BLOCH)

The exposure of catfish, Heteropneustes fossilis to different concentrations (200, 500, 700, 1000, 1500, 2000 ppm) of crude oil extract for a varying period (for up to 48 h in lethal extract and 360 h in sublethal one) resulted into a number of haematological changes. All the parameters taken here were found to have been increased except the haemoglobin level which fell down to 14.3 % in an acute lethal concentration (2000 ppm) after 48 h of exposure. The haematocrit value increased significantly (12 %) in 2000 ppm. The blood sugar level showed hyperglycemia in all the concentrations. The increase in ascorbic acid (28 %) was pronounced in higher concentrations. Changes occurring in different parameters seemed to be reversible as all the parameters returned to their normal levels after returning the fish to normal media, except the nuclear swelling which did not resume the normal functioning even after a prolonged treatment (1 month or more) in the recovery jar. The haematological effects shown by the crude oil resembled partly those kept in severe hypoxic conditions and partly to the fishes poisoned by heavy metals (Cu and Zn). On the basis of results obtained in this investigation, crude oil may be categorised as a complex toxic agent.     

Field Measurement of Dissolved Oxygen: A Comparison of Methods

The ability to confidently measure the concentration of dissolved oxygen (D.O.) in ground water is a key aspect of remedy selection and assessment. Presented here is a comparison of the commonly practiced methods for determining D.O. concentrations in ground water, including colorimetric, membrane-covered electrode, and modified Winkler techniques. The Winkler titration (azide and permanganate modifications) is the most accurate and precise technique for determining D.O. and is appropriate for applications with stringent data quality objectives. In addition, excellent correlation over a wide range of D.O. concentrations was found between Winkler titrations and colorimetric tests using the rhodazine D (below 1 part per million [ppm]) and indigo carmine reagents (above 1 ppm). Electrode measurements represent the simplest method for determining D.O. concentrations on a continuous basis and electrode determinations positively correlate with Winkler results above 1 ppm. Below 1 ppm, electrodes provide only a qualitative measure of low D.O. level, apparently due to slow electrode response.     

Nitrogen isotope ratios in estuarine biota collected along a nutrient gradient in Narragansett Bay, Rhode Island, USA

Stable nitrogen isotope ratios were used to study the incorporation of anthropogenically-derived nitrogen into the food webs of salt marsh systems along a contamination gradient in Narragansett Bay. Nitrogen isotope ratios (delta(15)N) were measured in six estuarine species collected from three marshes along this gradient, monthly from June to October between 1997 and 1999. A significant decrease in delta(15)N was found with distance along the estuary for four of the six species. Significant differences were found among monthly isotope ratios for some species. Nitrogen isotope ratios in sea lettuce (Ulva lactuca) increased during the summer season with highest delta(15)N values measured during September and October. This trend was most pronounced at the station receiving the highest nutrient inputs. Elevated delta(15)N values at this station appeared to correlate with seawater ammonia/nitrate concentration ratios. The temporal variations in delta(15)N suggest that care should be taken in species selection and the design of sampling schemes of studies using delta(15)N for monitoring anthropogenic nutrients in aquatic systems. Sampling programs designed to determine long-term trends should consider species that do not show rapid fluctuations in isotope ratios. The mud snail, Nassarius obsoletus, responded this way in the present study. Studies designed to measure short-term changes should include species such as U. lactuca, which rapidly respond to isotope changes. The results from this study also help to establish a baseline for nitrogen isotope values in Narragansett Bay. This information can be used to monitor future trends in nitrogen inputs to this estuary.     

The Contribution of Ecdysis to the Fate of Copper, Zinc and Cadmium in Grass Shrimp, Palaemonetes pugio Holthius

Depuration through ecdysis by grass shrimp, Palaemonetes pugio, was examined by exposure to a sublethal mixture of copper, zinc and cadmium for 72 h, followed by placement in uncontaminated water to molt. Percent eliminated with the exuviae varied for each metal; of the total intermolt body burden, 11% Cu, 18% Zn and 26% Cd was associated with the exuviae. Cu concentrations of intermolt exoskeletons were significantly higher than of the exuviae of post-ecdysis shrimp suggesting that Cu contained in the exoskeleton was reabsorbed before molting. Exuvial Cd concentration was not significantly different than the concentration of the intermolt exoskeleton, suggesting that most Cd in the exoskeleton was depurated with the exuviae. Although Zn whole-body burdens were lower after a molt, Zn losses were most likely due to excretion because exuvial concentrations were significantly lower than in the intermolt exoskeleton. Cu, Cd and Zn concentrations in exuviae shed in metal-enriched water were significantly higher due to adsorption than exuviae produced in uncontaminated water.     

The contribution of ecdysis to the fate of copper, zinc and cadmium in grass shrimp, Palaemonetes pugio Holthius

Depuration through ecdysis by grass shrimp, Palaemonetes pugio, was examined by exposure to a sublethal mixture of copper, zinc and cadmium for 72 h, followed by placement in uncontaminated water to molt. Percent eliminated with the exuviae varied for each metal; of the total intermolt body burden, 11% Cu, 18% Zn and 26% Cd was associated with the exuviae. Cu concentrations of intermolt exoskeletons were significantly higher than of the exuviae of post-ecdysis shrimp suggesting that Cu contained in the exoskeleton was reabsorbed before molting. Exuvial Cd concentration was not significantly different than the concentration of the intermolt exoskeleton, suggesting that most Cd in the exoskeleton was depurated with the exuviae. Although Zn whole-body burdens were lower after a molt, Zn losses were most likely due to excretion because exuvial concentrations were significantly lower than in the intermolt exoskeleton. Cu, Cd and Zn concentrations in exuviae shed in metal-enriched water were significantly higher due to adsorption than exuviae produced in uncontaminated water.     

Effects of Animal Size on Concentrations of Metallothionein and Metals in Periwinkles Littorina littorea Collected from the Firth of Clyde, Scotland

Different sizes of Littorina littorea were collected from four areas in the Firth of Clyde, Scotland. Their metallothionein (MT) and heavy metal concentrations were analysed using the Silver Saturation Method and Atomic Absorption Spectrophotometry, respectively. Concentrations of MT, Cd and Zn (as μg g⁻¹ dry soft-body weight) generally decreased with an increase in size of L. littorea. MT concentrations were better correlated with Cd than with Zn or Cu concentrations. Nevertheless, MT and the metals in periwinkles (as μg individual⁻¹) increased significantly with increasing size. Concentrations of MT and the metals among the sampling areas were compared at a standardised soft-body weight (10 mg). The results from Discriminant Analysis based on all metal concentrations indicate that Largs is different from the other areas and characterised by high Fe concentrations in L. littorea. The problems and differences in using either soft-body weight or shell length as independent variable for size-standardisation are discussed.