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1.
Located at southern coast of China, the Pearl River Delta (PRD) is facing serious water problems in both quantity and quality after its rapid urbanization in the last decade. Most remarkably, the local groundwater, that was used to be the source of drinking water before the urbanization was polluted due to poor management of the septic tanks. In order to study the effects of suburban development on local groundwater flow and water quality in the PRD region, Fengcun of Guangzhou has been chosen as the study area. In Fengcun, drinking water was groundwater before the 1990s, but now piped reservoir water is used by each family because the groundwater has been polluted. This study clarifies the source and process of the groundwater pollution from septic tanks using isotopic and geochemical characteristics, especially nitrate (NO3?) concentrations. Water samples were collected from the wells and ponds in Fengcun in March and July 2005 and in July 2006. Based on the pe–pH diagram, NO3? and ammonium of groundwater are from the effect of human activities, rather than from nitrification and ammonification of N2. NO3? pollution of groundwater is from point sources, and NO3? concentrations decrease from northeast to southwest. Groundwater is polluted rapidly by the leakage of septic tanks. NO3? concentrations of pollution sources were lower than 20 mg l?1 in March 2005, but had increased to about 120 mg l?1 in July 2006. This implies that groundwater protection should be strengthened in rural areas of the PRD. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

2.
Small quantities of drilling cuttings (100 g/250 cm2) were found to affect both the survival and general behaviour of Nephrops norvegicus held in experimental aquaria. In one experiment volatile hydrocarbons released from the cuttings caused a significant decrease (p < 0.05) in the beat of the exopodite on the third maxilliped. Flicking rates of the antennule and the time taken to identify and capture food introduced into the tanks were unaffected by exposure to cuttings. When the water flow through the tanks was interrupted for 12 h, 58% of animals died after exposure to the highest concentration of cuttings but those at the lower concentrations survived. After the water flow was restored the remaining survivors showed disorientated behaviour and uncoordinated movements which lasted for about 36 h. In this condition animals will be more vulnerable to predators. This unnatural behaviour may have serious implications for natural populations exposed to cuttings discharge in the close vicinity of offshore drilling platforms.  相似文献   

3.
Curved surface sliding bearings, which are usually called as friction pendulum system (FPS) are commonly used for base isolation of liquid storage tanks since the period of the isolation system is independent of the storage level. However the restoring force and the damping at the isolation system are functions of axial load which changes during an earthquake excitation. This change might be in appreciable amounts especially for the tanks with high aspect ratios. The present paper focuses on earthquake performances of both broad and slender tanks base isolated by FPS bearings. The effects of overturning moment and vertical acceleration on axial load variation at the bearings are considered. The efficiency of the isolation system is investigated by analyzing the effects of various parameters such as; (i) isolation period, (ii) tank aspect ratio and (iii) coefficient of friction. The Haroun and Housner's three-degrees-of-freedom lumped mass model was used to solve the governing equations of motion in which convective, impulsive and rigid masses were included. A number of selected ground motions were considered and the results were compared to those of non-isolated cases.As a result, base isolation was found to be effective in reducing the base shear values for both broad and slender tanks without significantly affecting the sloshing displacements of the broad ones. The efficiency was even more pronounced for slender tanks subjected to near fault ground motions for isolation periods above 3 s. This specific value of isolation period also eliminated possible design problems arising from under-estimation of base shear values (up to 40%) due to ignoring the effects of axial load variation in lower isolation periods. Overturning effects should not be ignored especially for tanks with high aspect ratios (S) and being subjected to near fault ground motion.  相似文献   

4.
In a sewage pollution experiment in the lagoon system at Strunjan, Yugoslavia, an artificially polluted lagoon showed significantly lower chlorophyll a biomass and cell density, and the relationship between these two variables was altered.  相似文献   

5.
《Marine pollution bulletin》2009,58(6-12):672-680
In order to test its ability as a bioaccumulator, the deposit feeding clam Asaphis deflorata, collected from a clean coastal area in Hong Kong (Ding Chau, Ma On Shan), was exposed to field-collected sediments representing a gradient of contamination. Sediments were collected from four sites, namely Shek O in the southeast of Hong Kong Island, Ap Lei Chau in Aberdeen district, Tai Kok Tsui in the Mong Kok waterfront, and To Kwa Wan near Kowloon City pier. Shek O was the cleanest and To Kwa Wan was the most polluted site. Replicate 30 L fiberglass tanks containing equal numbers of organisms were maintained for 28 days, with equal quantities of sediment and filtered seawater. Prior to this the animals were depurated for 10 days in clean sediment. During the 28-day holding period, sampling of both sediment and clams was performed on days 0, 10 and 28, along with condition index measurements. Concentrations of organochlorine pesticides and PCBs in sediments showed that Shek O was the cleanest of the sites, followed by Ap Lei Chau, Tai Kok Tsui and To Kwa Wan. There were marked differences among the sites, especially in PAH concentrations, with To Kwa Wan showing extremely high sediment concentrations.Following exposure, the biota concentrations of various organochlorine pesticides and PCBs suggested that there was sediment concentration-dependent accumulation by A. deflorata on day 10 of the experiment. However, there was no significant increase on day 28 for any of the compounds tested. Contaminant concentrations in clams feeding on Shek O sediments were minimal and almost the same on all sampling days, indicating the presence of only baseline contaminant concentrations. The condition indices (CI) of the clams on various sampling days showed that the animals were relatively more stable in sediment from Shek O. There were some deaths in all the test tanks (including those containing Shek O sediments). In addition, clams appeared to bury faster in the cleaner Shek O sediment and remained buried, unlike those in the sediment from the other locations, where some remained predominantly on the surface. Nevertheless, despite not completely burying, the clams in other test sediments still exhibited sediment concentration-dependent tissue accumulation. The results of the investigation indicate the possibility of developing a standard test protocol for bioaccumulation by sediment dwelling invertebrates, for practical use in Hong Kong, using A. deflorata.  相似文献   

6.
Heavy metal pollution is common in rivers in the vicinity of mining areas. In these polluted environments, the survival of alien species with a high tolerance to metals may be favored. The Tinto River (Southwest Iberian Peninsula) is an excellent natural laboratory for the study of plants’ responses to acidic and metal polluted sediments. This work analyzes the tolerance of the alien species Spartina densiflora to low pH and high metal loads in the Tinto River. The main aim of this study was to determine if this alien species can invade landward along the banks of the Tinto River. S. densiflora seeds were able to germinate in heavy metal polluted aerobic sediments even at pH 2. However, these conditions decreased S. densiflora final germination, altered germination dynamics, decreased aerial and subterranean growth rates, and prevented its establishment.  相似文献   

7.
One year after an accidental spill of approx. 2000 t of Iranian crude oil on the west coast of Norway, specimens of the gastropod Littorina littorea were collected from the oil polluted shore and allowed to spawn in the laboratory. Snails were also collected from an unpolluted reference site. The oil contamination seemed to have no detectable effects on fertilization. However, the hatching success of the veliger larvae was significally less in the ‘oil polluted’ population. Some highly abnormal eggs were also observed in this egg population.  相似文献   

8.
The oil content in the sediment and the marine life along the arctic shores of Van Mijenfjord, Spitzbergen, were investigated about two years after a spill from diesel storage tanks. High values of oil were recorded in the sediment along the shore near the tanks. The shore fauna is generally poor in these areas and the only biological effect detected was the disappearance of the amphipod Gammarus setosus from the surface layers.  相似文献   

9.
The uptake and loss of zinc and lead from the whole soft parts of the mussel Mytilus edulis were investigated under natural conditions in north-east England. Mussels in which high concentrations of these metals were found were transferred to an area where low concentrations were found, and vice versa. Mussels from both areas were also kept in tanks and periodic measurements of metal contents were made. Indications of uptake and loss were greatly affected by changing body weights and the work suggests that phase of reproductive cycle (for animals in the environment) and condition (for animals in tanks) have to be closely considered when reporting on levels of metals in mussels, especially in terms of concentration.  相似文献   

10.
A common effective method to reduce the seismic response of liquid storage tanks is to isolate them at base using base-isolation systems. It has been observed that in many earthquakes, the foregoing systems significantly affect on the whole system response reduction. However, in exceptional cases of excitation by long-period shaking, the base-isolation systems could have adverse effects. Such earthquakes could cause tank damage due to excessive liquid sloshing. Therefore, the numerical seismic response of liquid storage tanks isolated by bilinear hysteretic bearing elements is investigated under long-period ground motions in this research. For this purpose, finite shell elements for the tank structure and boundary elements for the liquid region are employed. Subsequently, fluid–structure equations of motion are coupled with governing equation of base-isolation system, to represent the whole system behavior. The governing equations of motion of the whole system are solved by an iterative and step-by-step algorithm to evaluate the response of the whole system to the horizontal component of three ground motions. The variations of seismic shear forces, liquid sloshing heights, and tank wall radial displacements are plotted under various system parameters such as the tank geometry aspect ratio (height to radius), and the flexibility of the isolation system, to critically examine the effects of various system parameters on the effectiveness of the base-isolation systems against long-period ground motions. From these analyses, it may be concluded that with the installation of this type of base-isolation system in liquid tanks, the dynamic response of tanks during seismic ground motions can be considerably reduced. Moreover, in the special case of long-period ground motions, the seismic response of base-isolated tanks may be controlled by the isolation system only at particular conditions of slender and broad tanks. For the case of medium tanks, remarkable attentions would be required to be devoted to the design of base-isolation systems expected to experience long-period ground motions.  相似文献   

11.
The distribution of Polychaetous Annelids (Serpulidae excluded) from infralittoral rocky shores of the French Mediterranean coast has been studied for 18 yr. Several hundred rock scrapings, each measuring 400 cm2, have been made and the results analysed for species composition, Shannon-Weaver index of diversity and Sanders' similarity coefficient. These mathematical measures are well correlated with the degree of pollution. In the levels considered, the annelid settlements are structurally identical. No unique group of species was associated with the degree of pollution as is typical in the sediments. An index of biological detectors is proposed which is based on the premise of the sensitive modification of the polychaete population as a whole and is defined as the ratio of the amount of dominances of ‘polluted waters biological detectors’ (Platynereis dumerili, Theostoma oerstedi, Dorvillea rudolphi, …) to ‘pure water’ ones (Syllis spp., Amphiglena mediterranea). This ratio increases with the intensity of pollution and is always higher than 1 in a polluted environment.  相似文献   

12.
A field study was conducted to examine the fate and potential effects of olestra, a non-caloric fat replacer, in septic tanks. The study compared the performance of parallel septic tanks, which were led domestic waste water with liquid and solid forms of olestra, against a control tank receiving waste water without olestra. Results showed that 36 g/d of olestra dosed to the tanks (a three-fold exaggeration of expected loadings) had no adverse effect on system operation (based on visual observations and sludge accumulation) or performance (based on removal of organic content and solids) over a six-month period. Removal efficiencies for total suspended solids (TSS), carbonaceous biochemical oxygen demand (CBOD), and chemical oxygen demand (COD) were not significantly different (p<0.05) in the olestra tanks when compared to the control tank. In addition, a relatively small amount of the total olestra added (3 to 6%) was recovered in the septic tank effluents over the course of the study. Accumulation of tank solids was not affected as measured sludge levels in the tank at the middle and end of the study showed no difference between the olestra dosed tanks and the control tank.  相似文献   

13.
Theoretical and experimental investigations of the dynamic behaviour of ground-supported, deformable, cylindrical liquid storage tanks were conducted. The study was carried out in three phases: (I) a detailed theoretical treatment of the coupled liquid-shell system for tanks rigidly anchored to their foundations; (II) an experimental investigation of the dynamic characteristics of full-scale tanks; and (III) a development of an improved seismic design procedure.  相似文献   

14.
Ballast water is a potential source of invasive species, including viruses that target a variety of hosts. We sampled ballast during two trans-Pacific voyages and analyzed the efficacy of mid-oceanic exchange in reducing virus-like particle (VLP) abundance. Exchange did not significantly reduce virus abundance during the first voyage (P = 0.874), whereas it reduced viral abundance 3.9-fold from 1.8 × 107 to 0.47 × 107 VLP mL−1 during the second voyage (P < 0.0001). Despite the impact of exchange during the second voyage, virus abundances were not significantly different between exchanged and unexchanged tanks upon arrival in Canada (P = 0.363) and Canadian port water samples (P = 0.502). Regressions between environmental parameters and VLP abundance uncovered negative correlations between salinity and viral abundance during one, and dissolved oxygen and viral abundance during the second voyage. In summary, ballast tanks are highly variable with respect to total virus abundance, and the efficacy of exchange requires investigation into the dynamics of specific viruses.  相似文献   

15.
The physiological and biochemical characteristics of tissue samples of the marine mussel, Donax trunculus, from an oil-polluted site (Qiryat Yam) and from a site adjacent to an industrial factory (Frutarom) producing polyvinyl chloride (PVC) were compared with samples from a clean reference site (Akko). All sites were located along the sandy shores of the Israeli Mediterranean Sea. The mussels from the oil-polluted site showed increased activity of the system of active transport of organic anions (SATOA) in the gills and the renocardial organ and also of the multixenobiotic resistance transporter (MXR) in the gills. In contrast, samples collected near the PVC factory showed a decrease in SATOA activity and no increase in the activity of MXR in the gills. Specimens from the reference site demonstrated a redox state of equilibrium between energy production and utilization, while in Donax from both the oil polluted and the PVC-polluted sites, the mitochondrial redox state reflected intensive consumption of energy. No significant changes were found in the activity of reduced glutathione s-transferase (GST) in the cytosolic fraction of the digestive gland of Donax collected from any of the three sites. The data demonstrate a differential increase in the anti-chemical defense systems and an intensification of energy metabolism in the mussels exposed to pollution.  相似文献   

16.
Sublethal effects of estuarine sediments containing high levels of heavy metals were studied using the marine bivalve, Macoma balthica. Burrowing behaviour was inhibited in all contaminated sediments compared to the control. The time required for 50% of the population to burrow (ET50) ranged from 0.17 h in the control to 4.8 h in the most contaminated substrate. A comparison of linear regressions of the concentrations of individual metals in the sediments vs the burrowing response times showed the regressions for mercury and cadmium to be significant (P < 0.05 and < 0.001 respectively). An active threshold avoidance response by burrowed M. balthica was also demonstrated as clams showed a significant (P < 0.05) avoidance of the sediment containing the highest metal levels. Both behavioural responses were considered useful sublethal tests to assess the impact of polluted sediments.  相似文献   

17.
At the end of the summer a conspicuous feature of some beaches which had been heavily polluted by AMOCO CADIZ oil six months previously was the strong development of grey or black layers close to the surface in sands which would not normally be discoloured at this depth.  相似文献   

18.
Samples of surface sediment and vibrocore were collected in the near-shore area of north Jiangsu Province for grain size, elements, 210Pbexcess and 137Cs analyses. In our study area, the diversity of metal concentration was controlled not by the grain size, but by the source. The element content of the old Yellow River Delta was used as baseline for our study area. Geoaccumulation indexes indicate that no station was polluted by Cu, Pb, Zn and As, but the Igeo values of As were close to zero in some stations. Slight pollution caused by Cd was observed in some stations. Correlation and enrichment factors suggest that Cu, Pb and Zn are lithogenic in origin, while As and Cd are mixed in origin. Especially, in some polluted stations Cd was obviously anthropogenic in origin.  相似文献   

19.
This paper details the damage sustained by a number of wine tanks during the San Juan, Argentina, 1977 earthquake. The available ground motion information is used to compare the actual tank performance with that predicted. Two of the tanks examined were located quite near the two accelerographs that recorded the ground motion in the city of San Juan for the main shock. An empirical attenuation formula which describes the intensity of the shaking was derived for this earthquake and used in a quantitative evaluation of the performance of a number of other tanks. By correlating and comparing the observed performance of the anchors and what was predicted we see the predictions are upheld by the actual damage. When the anchoring system failed during the earthquake the tanks were rendered effectively unanchored. Consequently, the state of stress that results from their base uplift was then examined in conjunction with the tank wall stability approach proposed by the author, and seen to give results consistent with the observed tank wall performance.  相似文献   

20.
Competition between the common toad Bufo bufo (L.) and the green toad Bufo viridisLaurenti was studied in an experimental design. Mixed and single-species groups of 40 larvae were reared in plastic tanks (water volume 411). Growth parameters such as body length, total length, body mass and developmental stage according to Gosner (1960) were measured weekly until metamorphic climax and analyzed by regression analysis. Body condition index was calculated. Tadpoles of B. bufo reached metamorphosis at the same time in mixed and single-species treatments. Larvae and toadlets were insignificantly larger in single-species groups, weighed more and had a higher body condition index than in mixed species designs. In B. viridis the larval period was six days shorter in mixed groups; tadpoles and toadlets were smaller but had a higher body condition index than in the single-species treatment. These results indicate high intraspecific competition in B. viridis and competitive inferiority of B. bufo to B. viridis under the experimental conditions.  相似文献   

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