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21.
Theodore J. Abatzopoulos Luc Brendonck Patrick Sorgeloos 《International Journal of Salt Lake Research》1999,8(4):351-360
As the result of a first screening of temporary inland water habitats,Branchinella spinosa is here recorded for the first time in Greece. This finding extends the circum-Mediterranean part of its vast distribution.
The species was collected from a shallow astatic coastal salt-marsh that is mainly fed by rainwater, where it coexists but
rarely co-occurs withArtemia parthenogenetica. Branchinella spinosa is only the fourth anostracan species currently known from Greece. The poor knowledge of anostracan richness and abundance
is mainly due to limited sampling efforts in this area. As temporary aquatic habitats are threatened by several anthropogenic
activities, especially agriculture and land clearing for urbanisation and tourism, there is an urgent necessity for further
monitoring and protection of these precious habitats. 相似文献
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24.
Theodore D. Kanellopoulos Michael O. Angelidis Dimitrios Georgopoulos Aristomenis P. Karageorgis 《Environmental Geology》2009,57(8):1729-1738
Evros River is the most important river flowing into the North Aegean Sea (eastern Mediterranean) in terms of freshwater discharge,
and the second largest one of Eastern Europe after the Danube River. Salinity and temperature measurements, together with
suspended particulate matter concentrations were obtained in various depths at 14 stations in the adjacent Alexandroupolis
Gulf during four seasons (June 1998, September 1998, February 1999 and March 2000) in order to investigate the particle dynamics
and distributions in the northern Aegean Sea. Analysis of the collected data, together with particle observations under the
scanning electron microscope and study of satellite images showed that, under certain circumstances driven by the hydrological
and wind regime of the area, the Evros River particulate matter, with the associated pollutants, can be transferred far away
from the estuary and implicitly comprise a hazardous factor for the environmental status of the northern Aegean Sea. This
fact, combined with the future construction of the Burgas-Alexandroupolis pipeline, may cause a negative impact on the studied
natural ecosystem. 相似文献
25.
Aristomenis P. Karageorgis Theodore D. Kanellopoulos Vasileios Mavromatis Christos L. Anagnostou Eleni Koutsopoulou Mark Schmidt Kosmas Pavlopoulos Efthymios K. Tripsanas Rolf O. Hallberg 《Geo-Marine Letters》2013,33(1):13-29
The Pagassitikos Gulf in Greece is a semi-enclosed bay with a maximum depth of 102 m. According to the present-day bathymetric configuration and the sea level during the latest Pleistocene, the gulf would have been isolated from the open sea, forming a palaeolake since ~32 cal. ka b.p. Sediment core B-4 was recovered from the deepest sector of the gulf and revealed evidence of a totally different depositional environment in the lowest part of the core: this contained light grey-coloured sediments, contrasting strongly with overlying olive grey muds. Multi-proxy analyses showed the predominance of carbonate minerals (aragonite, dolomite and calcite) and gypsum in the lowest part of the core. Carbonate mineral deposition can be attributed to autochthonous precipitation that took place in a saline palaeolake with high evaporation rates during the last glacial–early deglacial period; the lowest core sample to be AMS 14C dated provided an age of 19.53 cal. ka b.p. The palaeolake was presumably reconnected to the open sea at ~13.2 cal. ka b.p. during the last sea-level rise, marking the commencement of marine sedimentation characterised by the predominance of terrigenous aluminosilicates and fairly constant depositional conditions lasting up to the present day. 相似文献
26.
Compositional fractionation of polyaromatic hydrocarbons in the karst soils, South China 总被引:1,自引:0,他引:1
Yinghui Wang Rui Xue Jie Li Hongxiang Zhu Yiyin Xu Baoming Xue Shihua Qi Daoxian Yuan Oramah I. Theodore 《Environmental Earth Sciences》2012,66(7):2013-2019
This study aims to explore the condensation and fractionation trends of persistent organic pollutants (POPs) in the karst soils. The tiankeng is a karst surface expression that can act as a focal point for introduction of contaminants to a karst aquifer, which may serve both as condenser for vapor phase POPs and as barrier/sink for particulate associated less volatile POPs. The fractionation of POPs in soils from the upper rim and floor of tiankeng is of interest in understanding the role of tiankeng in the long-distance transport of POPs. In the present study, polycyclic aromatic hydrocarbons (PAHs) in the surface soils from the upper rim and floor of Dashiwei tiankeng in Southern China were analyzed. The total PAH concentrations in soils were 23.40–190 ng g−1, with phenanthrene being the most abundant. The distribution patterns of PAH compounds in the soil samples matched well with their properties. It indicated the heavy PAHs were susceptible to retention by the floor soils of tiankeng than light PAHs. A plot of Cfloor/Crim against PAH molecular weight gave a good positive relationship in the molecular weight range of 152–276. It is suggested that the floor soils can be focal points of more concentrated PAH and deserve attention. The concentrations of total PAHs in the floor soils (43.40–190 ng g−1, mean 87.76 ng g−1) were higher than those in the upper rim (23.40–88.94 ng g−1, mean 57.74 ng g−1). In addition, there was a shift in compound pattern with an increase in the proportion of light PAHs (2–3 rings), a decrease in heavy PAHs (5–6 rings) and a relatively stable content of 4-ring PAHs. A combination of particulate scavenging and cold condensation is proposed as the major mechanism for the compositional fractionation of PAHs in the soils from the upper rim and floor of tiankeng. 相似文献
27.
David Folkes William Wertz Jeffrey Kurtz Theodore Kuehster 《Ground Water Monitoring & Remediation》2009,29(1):70-80
The vapor intrusion impacts associated with the presence of chlorinated volatile organic contaminant plumes in the ground water beneath residential areas in Colorado and New York have been the subject of extensive site investigations and structure sampling efforts. Large data sets of ground water and indoor air monitoring data collected over a decade-long monitoring program at the Redfield, Colorado, site and monthly ground water and structure monitoring data collected over a 19-month period from structures in New York State are analyzed to illustrate the temporal and spatial distributions in the concentration of volatile organic compounds that one may encounter when evaluating the potential for exposures due to vapor intrusion. The analysis of these data demonstrates that although the areal extent of structures impacted by vapor intrusion mirrors the areal extent of chlorinated volatile organic compounds in the ground water, not all structures above the plume will be impacted. It also highlights the fact that measured concentrations of volatile organic compounds in the indoor air and subslab vapor can vary considerably from month to month and season to season. Sampling results from any one location at any given point in time cannot be expected to represent the range of conditions that may exist at neighboring locations or at other times. Recognition of this variability is important when designing sampling plans and risk management programs to address the vapor intrusion pathway. 相似文献
28.
M. Anne Visser Nik Theodore Edwin J. Melendez Abel Valenzuela Jr. 《Urban geography》2017,38(2):243-265
Day labor worker centers have emerged as an important mode of regulatory action in the informal economy of major US cities. Research suggests that these organizations are beneficial in improving employment outcomes experienced by migrant workers engaged in this labor market sector. Yet, the extent to which these organizations impact the social integration of this working population remains relatively undeveloped in the literature. Using data from the National Day Labor Survey, we examine the impact of day labor worker centers on the level of social inclusion experienced by migrant day laborers. We find that worker centers have a modest, but statistically significant, impact on the levels of social integration experienced by this working population and that this varies from city to city. Ultimately we argue that the social intermediary role of these organizations may offer a type of counter mobilization necessary to promote the socioeconomic integration of this working population, but that issues of capacity remain. 相似文献
29.
Theodore G. Shepherd Emily Boyd Raphael A. Calel Sandra C. Chapman Suraje Dessai Ioana M. Dima-West Hayley J. Fowler Rachel James Douglas Maraun Olivia Martius Catherine A. Senior Adam H. Sobel David A. Stainforth Simon F. B. Tett Kevin E. Trenberth Bart J. J. M. van den Hurk Nicholas W. Watkins Dimitri A. Zenghelis 《Climatic change》2018,147(3-4):555-569
Investigating the relationships between climate extremes and crop yield can help us understand how unfavourable climatic conditions affect crop production. In this study, two statistical models, multiple linear regression and random forest, were used to identify rainfall extremes indices affecting wheat yield in three different regions of the New South Wales wheat belt. The results show that the random forest model explained 41–67% of the year-to-year yield variation, whereas the multiple linear regression model explained 34–58%. In the two models, 3-month timescale standardized precipitation index of Jun.–Aug. (SPIJJA), Sep.–Nov. (SPISON), and consecutive dry days (CDDs) were identified as the three most important indices which can explain yield variability for most of the wheat belt. Our results indicated that the inter-annual variability of rainfall in winter and spring was largely responsible for wheat yield variation, and pre-growing season rainfall played a secondary role. Frequent shortages of rainfall posed a greater threat to crop growth than excessive rainfall in eastern Australia. We concluded that the comparison between multiple linear regression and machine learning algorithm proposed in the present study would be useful to provide robust prediction of yields and new insights of the effects of various rainfall extremes, when suitable climate and yield datasets are available. 相似文献
30.
Zooplankton in saline lakes of the Southern Interior Plateau of British Columbia were collected on three occasions: mid-May
and early August, 1990, and in late July, 1991. Salinities ranged from 2.6 to 45.8 g L−1. Of the 17 lakes examined, 13 were hyposaline (∼-20g L−1), four, mesosaline (20–50 g L−1) and none, hypersaline (>50 g L−1). pH ranged from 8.7 (Three Mile) to 10.7 (Goodenough), with values <9.6 in 10, and <9.0 in only three lakes. Lakes with
high pHs had high bicarbonate-carbonate alkalinities.
Thirty one species of zooplankton occurred: Protista (1), Rotifera (13), Anostraca (2), Cladocera (7), Ostracoda (1) and Copepoda
(7). Sixteen species were restricted to hyposaline waters, with seven found only in salinities of ≤5 gL−1. Two species (Diaptomus connexus, Artemia franciscana) were restricted to mesosaline waters of salinity >35 g L−1. Eurysaline species includedBrachionus plicatilis, Hexarthra fennica, Limnocythere staplini, Artemia franciscana andDiaptomus connexus. Most species were abundant in 1+ lakes, but six species always had low populations.B. plicatilis, Hexarthra polyodonta, A. franciscana, Limnocythere staplini, Daphnia similis andD. connexus had densest populations in one or more of the three most saline lakes, viz. Long, Goodenough and Three Mile. Cladocerans
other thanD. similis (Alona sp., Ceriodaphnia quadrangula, Daphnia pulex) were usually abundant in lakes of low salinity (<5 g L−1).Diatomus sicilis, present in all except the three most saline lakes, also occurred in abundance in ten of these lakes.Moina hutchinsoni andH. polyodonta were present in both hyposaline and mesosaline lakes, but, more importantly, tended to occur only at higher pH values (>pH
9.4) but not in all such lakes. These can be regarded as alkaline-saline species.
Sorensen’s Coefficient of Community Similarity was used to compare communities in Alberta-Saskatchewan and British Columbia.
It was low (0.37). A comparison restricted to just Cladocera gave a slightly higher value, 0.44, but a comparison of Copepoda
gave a value of 71 per cent similarity between the regions. Multiple regression analyses using pH, TDS and K regressed on
species richness for all samples accounted for only 41 per cent of the variance. However, when the analysis was seasonally
restricted (May), and thus to a limited chemical range, 47 to 77.5 per cent of the variance was accounted for by these three
variables. 相似文献