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1.
The purpose of this study is to investigate historical and current mercury (Hg) contamination in the surface and core sediments of the Ambarl? Port area. Textural parameters, total organic carbon (TOC), 210Pb and total Hg (THg) contents were measured. Mercury contamination of the sediments was assessed on the basis of the enrichment factor (EF), anthropogenic factor (AF), index of geoaccumulation (Igeo) and corresponding sediment quality guidelines. Most surface sediment samples were also non-toxic with mercury concentrations below the effects range-low (ERL) value, but mercury levels at five stations were between ERL and effects range-median (ERM) values, where occasional adverse effects concerning risk analysis are expected. The EF and Igeo analysis showed that there was no significant mercury enrichment and contamination in the core sediment before the 1650s, but values increased from then onwards to 2009 (being especially accelerated in line with port activities from 1989), disclosing a serious ecotoxicological risk to sediment-inhabited marine organisms.  相似文献   

2.
This paper presents results of a social cost–benefit analysis (CBA) of afforestation and soil moisture treatment of common lands under an integrated watershed development programme in Karnataka State, India. The aim of the study was to find out if soil moisture conservation and afforestation measures were justified in terms of economic efficiency. The assessment was undertaken by calculating the economic internal rate of return (EIRR) for five village common lands in two watersheds, Uparhalla and Chinnahagari, in central Karnataka. Focused group discussions were organised, using a semi-structured questionnaire and various stakeholders, including project implementing agencies, self help groups and other community-based organisations. The attractiveness of the programme in both watersheds for landless and land owners was high in three out of five sampled villages, with an EIRR ranging from 19% to 91%, while two villages in Chinnahagari watershed had extremely low EIRR, reflecting poor management of soil moisture and afforestation interventions and lack of institutional cohesion to sustain investments made to develop common lands. Therefore, the CBA conducted in the KAWAD project, except for two villages, shows that the investment made to develop common lands should yield substantial economic returns in the long term under a business as usual scenario.  相似文献   

3.
Harmful bugs affect food production,directly by the qualitativeor quantitative reduction of the harvests,or indirectly while servinglike vectors of several illnesses of the plants and human[1].Many chemical products are used by human for a long time inthe…  相似文献   

4.
The distribution of lignin in sediment is a useful tool for tracing the transport of land-derived organic matter in an aquatic environment. Tetramethylammonium hydroxide (TMAH) flash chemopyrolysis, or chemolysis followed by GC–MS analysis can be used for evaluating the origin of organic carbon in sediments. TMAH chemopyrolysis or chemolysis of organic matter produces a myriad of semi-volatile products. Among these products are methylated phenols which are an indirect measure of lignin in sediment. In this study, total organic carbon, elemental carbon, and lignin were measured in Lake Mead sediments. This study indicates that terrestrial runoff makes a contribution to Lake Mead sediments, and that this contribution is most apparent in sediment that is close to the Las Vegas Wash. Two chemolysis methods (on-line and off-line) were examined and compared for detection of lignin phenols. The results from these sediment cores indicate that comparable results can be obtained from the two approaches, although detection levels are significantly lower for the off-line approach.  相似文献   

5.
Diuron samples at 40mg/L concentration were photolyzed with ultraviolet lamps and with natural sunlight to determine if data from ultraviolet lamp photolysis could be used to predict results from sunlight photolysis. Seven photoproducts were identified from the photolysis experiments. The identified photoproducts and the photoproduct yields were essentially the same for the two light sources.  相似文献   

6.
The nettle caterpillar, Darna pallivitta (Moore) (Lepidoptera: Limacodidae), is an invasive pest with established populations on three Hawai’ian islands. Indigenous to Southeast Asia, D. pallivitta caterpillars cause defoliation of ornamental nursery stock and pose a human health hazard due to their urticating hairs that can cause painful skin reactions. Identification of the pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOnBu) from D. pallivitta has made it possible to investigate the phenology and population dynamics using baited traps. Male captures in Jackson traps baited with E7,9-10:COOnBu showed a vegetation preference for tall-grass fields and forest/grass interfaces over forest areas. Microlocation preferences were also found for trap height, with over 65% of males being caught in traps suspended at 1 m, compared with the traps at 3 and 5 m. Captures of male moths in traps baited with live females, and direct observations of female calling behavior, showed peak activities 6–7 h after the onset of scotophase. This is a much later communication period than for D. bradleyi and D. trima and may provide a mechanism by which D. pallivitta maintains reproductive isolation in areas where all three species are present. Coastal and inland transects established in eastern Hawai’i measured aspects of population fluctuations and radiation into new areas with relation to elevation and microclimate. Population expansion was measured by comparing moth population means and 80% population boundaries over time. Both population measures showed a higher expansion for the coastal transect. Differences in population expansion may be attributed in part to temperature and elevation, while precipitation does not seem to have a strong effect. Both the behavioral and ecological data collected can be used to optimize deployment of detection/control strategies and to predict population expansion/risk assessment for establishing quarantine protocols for the nettle caterpillar.  相似文献   

7.
The influence of four synthetic chemicals (nonylphenol, ethynyl-estradiol, ivermectin, monesin) on the biomass and on the microbial activity was studied in a laboratory experiment using a typical luvisol derived from loess. The polyether antibiotic monensin, the antiparasitic agent ivermectin and the two environmental chemicals with endocrine effects nonylphenol and ethynylestradiol were chosen because of their toxicity to different organisms and known biological activity. These agents may enter the soil together with sewage sludge or manure. To date, however, the effects on soil have hardly been studied. Selected microbial methods revealed in part very significant effects on the microbial biomass and microbial activity during constant physical (15°C, 50% water holding capicity) and chemical conditions (pH, Corg) 1, 14 and 42 days after contamination.  相似文献   

8.
The De?irmendere and Galyan (De?irmendere tributary) Rivers that discharge their water into the Black Sea are important watersheds in the northeastern part of Turkey. Water quality parameters were sampled from 1997 through 2001 for each year at five sites (three for Galyan, two for Degirmendere) along 29 and 42 km gradients, respectively covering all seasons. Surface water was collected from the sites and analyzed for temperature, total alkaline (MAAL), total dissolved solids (TDS), dissolved oxygen (DO), pH, conductivity (EC), nitrate (NO3), nitrite (NO2), total hardness (TH), phenolphthalein alkalinities (PAL) and organic matter (PV). Seasonal changes of water quality were analyzed statistically for both Rivers and evaluated according to the TS 266, EU and WHO standards. The analysis of variance results showed that Ca, Mg, MAL, NO3, pH, TDS and TH parameters of the De?irmendere River and Ca, DO, EC, MAL, NO3, pH and TH parameters of the Galyan River showed seasonal differences (p<0.05). The maximum values of the water pollution parameters for the two Rivers were below the threshold values throughout the study period. When both Rivers were compared, the mean values of the pollution parameters of the Degirmendere River were higher than those of the Galyan River and very close the limits. The results indicate that both Rivers can be used for the production of potable water during all seasons but only with an advanced treatment in the De?irmendere and a moderate treatment in the Galyan River, and for indirect and non-contact recreational activities.  相似文献   

9.
Blood level of calcium fractions (ionized and bound), phosphates, magnesium and albumin were measured in non‐insulin dependent diabetic patients (NIDD). Results were compared with healthy controls to elucidate the pathogenesis of probable changes of these elements. Total ionized calcium and magnesium showed significant decrease (p<0.001, p<0.05 and p<0.05) respectively. Phosphates showed non‐significant decrease while albumin reported nearly similar results. Positive correlation between inorganic phosphates and ionized calcium (r = 0.48, p<0.05) was observed only in healthy control group, not in diabetics. This may be attributed to alteration of ions excretions under diabetic condition through unknown mechanism. Additive increase of heparin sodium units in vitro to normal blood resulted in progressive fall in ionized calcium. Significant decrease was only observed upon addition of higher unit (5IU/ml). This must be taken into consideration biochemically for plasma determination of ionized calcium.  相似文献   

10.
Growth dynamics of Saccharina latissima in a Danish embayment (56°03.793N, 10°16.148E) were investigated through an annual cycle (March 1999–March 2000) and related to patterns found in previous studies covering the distribution range of the species. The kelps exhibited meristematic growth as well as distal tissue loss all year around. Elongation rate peaked in spring (March–May, 0.75 cm day?1), whereas maximum biomass growth occurred in May–July at higher insolation. S. latissima accumulated nitrogen (N) in November–March, when ambient N levels were high and the fast growth in March–July was followed by a depletion of these reserves. Light regimes and seasonal fluctuations of nutrients were, thus, major factors explaining the seasonal growth pattern of S. latissima in this temperate bay. Differences in light and exposure along depth gradients affected the growth, loss and storage product dynamics. High losses of N and carbon (C) through summer abscission of distal tissue question the efficiency of translocation, especially at shallower depths, where losses are accelerated by, e.g., high temperature. A large-scale comparison further highlighted that warming advanced the timing, increased the level of peak growth and also seemed to expand the growth period. Growth rates of the studied Danish population fell in the low end of the range for similar latitudes and temperatures, probably due to sub-optimal salinities (avg. 23.3 psu) in combination with periodically high summer temperatures (max. 21.1 °C).  相似文献   

11.
The high consumption of crabs (Ucides cordatus) stimulated interest in the present study on the northern coast of Brazil, which encompasses a preserved area of mangrove forest. The objective was to describe and quantify the transfer of metals from the muddy sediments to the leaves of the Rhizophora mangle, and thence the crabs and humans. The samples were collected along two transects, while samples of hair were obtained from local habitants. The pH, interstitial salinity, Eh (mV) were measured, the granulometry and mineralogical and multi-element chemical analyses were run, and the organic material determined. The sediments are silty-clayey, composed of quartz, kaolinite, iron oxides, and illite, as well as smaller portions of smectite, pyrite, halite, and high levels of SiO2 (56.5 %), Al2O3 (18.5 %), and Fe2O3 (7 %). The elements Zn, Sr, As, and Zr are concentrated in the leaves, while the bioaccumulation of Zn, Se, Sr, and As was recorded in the crabs, of which, Se is the most concentrated in the tissue of the muscles and the hepatopancreas. The concentrations of nutrient and toxic elements were similar in all age groups (hair samples), with only Hg presenting an increasing concentration between infants and adults. The highest rates of transfer were recorded for the elements Zn and Se in the crabs and Hg in leaves and hair. The accumulation of metals in the leaves and crabs reflects the chemical composition of the sediments and low rates of sediment-vegetation-crab transfer, with the exception of Hg, which accumulated in the hair.  相似文献   

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14.
Hooghly–Matla estuarine ecosystem of India is very rich in natural resources and receives large amount of nutrients through litterfall from adjacent mangrove forest. Nitrogen as an important nutrient occurs in various forms and plays a crucial role in the regulation of productivity in this estuarine system. Modelling of nitrogen dynamics from mangrove litterfall and particularly the release of dissolved inorganic nitrogen in this estuarine system is important because of its role in augmenting growth of phytoplankton and other higher plants and all other biological components of grazing food chain.  相似文献   

15.
The reproduction and growth of Isostichopus fuscus (Ludwig, 1875) at Isla Espíritu Santo, Baja California Sur, México from July 1992 to September 1993 and from August 1996 to July 1997 were analyzed. The reproductive cycle was monitored by using histological analysis. Five gonadal stages were described according to cell types present in the gonad; undetermined, gametogenesis, maturity, spawning and post-spawning. This holothurian reproduces annually during summer (July to September), when sea surface temperature reaches 27 °C. The gonad index is related to the gonadal stages. The first sexual maturity for I. fuscus was calculated at 367 g (4 to 5 years old) according to the von Bertalanffy equation, and nearly all the specimens at Isla Espíritu Santo were 5 to 7 years old (including some individuals over 35 years old). Data of the length–weight relationship showed that I. fuscus grows allometrically at the studied site (b = 1.83). The mortality rate was relatively high (M = 0.51), indicating that in a typical cohort, 40% of the recruits does not survive the first year, and less than 20% reaches maturity. Received: 15 July 1998 / Accepted: 19 August 1999  相似文献   

16.
Marine coast modification and human pressure affects many species, including sea turtles. In order to study nine anthropogenic impacts that might affect nesting selection of females, incubation and hatching survival of loggerhead (Caretta caretta) and green turtle (Chelonia mydas), building structures were identified along a 5.2 km beach in Kanzul (Mexico). A high number of hotels and houses (88; 818 rooms), with an average density of 16.6 buildings per kilometer were found. These buildings form a barrier which prevents reaching the beach from inland, resulting in habitat fragmentation. Main pressures were detected during nesting selection (14.19% of turtle nesting attempts interrupted), and low impact were found during incubation (0.77%) and hatching (4.7%). There were three impacts defined as high: beach furniture that blocks out the movement of hatchlings or females, direct pressure by tourists, and artificial beachfront lighting that can potentially mislead hatchlings or females. High impacted areas showed lowest values in nesting selection and hatching success. Based on our results, we suggest management strategies to need to be implemented to reduce human pressure and to avoid nesting habitat loss of loggerhead and green turtle in Kanzul, Mexico.  相似文献   

17.
A potentiometric titration technique has been used to determine the stability constants for the various complexes of Co(II) and Cu(II) with L‐asparagine and from DNA base, e.g. adenine. Stability constants of ternary systems have been evaluated by the method suggested by Irwing‐Rossotti. In addition, the conditional constants were calculated as a function of pH. The maximum values of the conditional formation constants were found to be in accordance with the mixed‐ligand complex formation constants in a determined pH region. Furthermore, the molar fractions of different species from mixed complexes were calculated by means of formation constants. The values of stability constants of mixed‐ligand complexes at 25°C are as follows: log K= 5.25 for Co(II)‐L‐asparagine‐adenine; log K= 9.30 for Cu(II)‐L‐asparagine‐adenine. The ionic strength was kept constant at I = 0.20 with NaClO4.  相似文献   

18.
The acute toxicity of manganese (Mn) in Caspian roach Rutilus caspicus was determined. The 96 h-LC50 was calculated to be 300 (240–360) mg L?1. Then, fish were exposed for 96 h to 300 (96 h-LC50), 150 (50% of 96 h-LC50), 60 (20% of 96 h-LC50), and 0 (control group) mg L?1 Mn. Exposure to all Mn concentrations led to fish gill damages, including epithelial lifting, hyperplasia, lamellar fusion, aneurism, and lamellar curling. Also, the fish exposed to all Mn concentrations showed decreased plasma alternative complement and lysozyme activity. Whole body superoxide dismutase, catalase, and malondialdehyde showed significant increases in the Mn-exposed fish which also exhibited lower tolerance to saltwater than the control group.  相似文献   

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阿维菌素作为一种生物农药被广泛使用,是我国取代高毒有机磷农药的主要品种之一.为探讨阿维菌素对家蚕的生理影响,采用阿维菌素亚致死剂量LC0.(10.001mg·L-1)和LC(50.0045mg·L-1)处理的桑叶饲喂5龄家蚕,通过取血、染片和显微镜观察以及琼脂糖凝胶电泳,对血细胞数量、形态和DNA损伤进行了研究.结果表明,低剂量LC0.1处理的家蚕血球细胞数量明显高于对照,而LC5处理的家蚕其血细胞数量整体低于对照.试验所用的亚致死剂量阿维菌素未对家蚕血细胞DNA产生损伤,但血细胞出现了空泡、肿胀等病态变化,且随着用药浓度增高细胞异型数量和程度有加大趋势.  相似文献   

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