Airborne Fungi Survey of Some Residences in Durham,North Carolina,USA

Gravity settling culture (GSC) plate collections of endogenous fungi were made at four homes in Durham, North Carolina. During frost-free periods (May-August), the most frequently isolated genera included Mucor, Cladosporium (Hormodendrum), Aspergillus, Penicillium, Rhizopus, Alternaria, Cunninghamella, Aureobasidium, Fusarium, Heterosporium, Amblyosporium, and other (unidentified) fungi. Higher numbers of mold isolates were associated with high shade and high levels of organic debris near the home and poor landscaping and landscape maintenance. Lower concentrations of mold isolates were associated with the presence of a central electrostatic filtration system and good compliance with dust controls. The viable mold spore levels were lower in homes where the electrostatic filtration unit was operated continuously rather than intermittently. These findings reflect the ease with which outdoor spore clouds may penetrate structures and obscure evidence of internal fungus source. The data also imply that because of size-related undersampling, open plates can exclude abundant types of recovery. No statistically significant correlations could be made between indoor mold isolates and any of the following: number and age of the occupants, age and size of home, month of survey or the presence of plants. Attempts have been made to facilitate the diagnosis of fungal allergy by gathering together examples of places and materials which are most likely to be a risk for mold sensitive patients.     

Vertical distribution and release characteristics of phosphorus forms in the sediments from the river inflow area of Dianchi Lake,China

Columnar sediment samples were collected from five representative river inflow areas of Dianchi Lake, China. The vertical distribution of each form of P were tested. Results showed that the concentration of TP in the sediments from areas A, B, C, D and E in the order of D > B > A > C > E, and the average concentration of D, B, A, C and E were 2991, 2064, 1308, 879, and 759 mg?kg^?1, respectively. The concentration of Ex-P, Fe/Al-P, Ca-P and Org-P all decreased with increasing depth. The release of Ex-P was significantly related to TP whereas the Fe/Al-P was not significantly related to TP in the samples from areas polluted by domestic sewage. However, the release of Ex-P and Fe/Al-P were both significantly related to TP in the samples from areas polluted by phosphate mining and phosphate fertilizer application. The results of equilibrium P concentration (EPC0) analysis showed that P in the sediments of areas A, D and E were the source of P in Dianchi Lake, and the P in the sediments of areas B and C were in relative equilibrium with the overlying water.     

肇庆市七星岩里湖水化学因子相关性研究

广东省肇庆七星岩是我国著名的风景游览胜地 ,里湖是其中的重要组成部分。面积约 2 .6× 1 0 5 ｍ2 ,近年来 ,里湖水质有劣化趋势 ,表观上出现不同颜色 ,有藻类突发现象。对景区产生不良影响。既往研究表明 ,影响里湖水质的关键组分除浮游藻类叶绿素ａ与氮、磷含量之外 ,水中的ＤＯ和ＣＯＤ、ＢＯＤ也是极其重要的指标。研究它们的相互关系 ,旨在探讨其内在联系及变化规律 ,对于湖泊生态环境的保护和水污染的治理具有重要意义。1　研究材料与方法1 .1　主要仪器日立Ｆ -30 0 0型荧光分光光度计 (日本) ;ＷＺ -80 0Ｄ2 型紫外分光光度计(北京…     

A filmy fern from the Upper Triassic of North Carolina (USA)

Modern cladistic analyses support earlier suggestions that the Hymenophyllaceae (the "filmy ferns") are basal filicaleans. However, the fossil record of the family is ambiguous. A new fossil fern, Hopetedia praetermissa gen. et sp. nov., from the Upper Triassic Pekin Formation of North Carolina (USA), is described and interpreted as the oldest unequivocal representative of the Hymenophyllaceae based primarily on general frond morphology, indirect evidence for a filmy (membranaceous) habit, and soral position and morphology. Particularly compelling as evidence for the hymenophyllaceous affinity of H. praetermissa is the funneliform structure of the indusium (involucre), which is similar to that found primarilly in the extant Trichomanes (sensu lato) clade. However, the receptacle in H. praetermissa is relatively short and, thus, more like most representatives of the Hymenophyllum (sensu lato) clade. The Triassic age of this fossil is consistent with the basal or near basal position of the Hymenophyllaceae in all recent phylogenetic analyses of the filicalean ferns. Hopetedia preatermissa is evaluated in relationship to several previous reports of fossil Hymenophyllaceae.     

Seasonal occurrence of Lernaea cyprinacea on fishes in Belews Lake, North Carolina

Prevalence, abundance, and mean intensity of Lernaea cyprinacea were monitored on 3 species of fishes from June 1984 through August 1986 in Belews Lake, North Carolina. Copepods were observed parasitizing fishes only during summer, when water temperatures exceeded 25 C. Infection levels in mosquitofish (Gambusia affinis) and red shiners (Notropis lutrensis) were very low, but they were much higher in fathead minnows (Pimephales promelas). Infection levels do not appear to be related to the size of the host. Host differences in parasite prevalence may be due to the host habitats.     

Mathematical modelling of primary production in Green Bay (Lake Michigan,USA), a phosphorus-and light-limited system

Application of mathematical models in the design and evaluation of lake restoration programmes must include due consideration of three basic concepts of model development; 1) that the model framework is appropriately matched to the intended management use, 2) that selection of the proper degree of model complexity is fundamental to the achievement of model credibility and 3) that field and laboratory studies must be designed and interpreted with the aid of the model to insure development of a comprehensive, integrated tool.These concepts are demonstrated for the case of lake restoration efforts in Green Bay (Lake Michigan, USA). Striking gradients in water quality (transparency, algal standing crop, hypolimnetic oxygen depletion) and trophic state occur along the major axis of the bay in response to phosphorus loaded from the Fox River. A simple model for gross primary production is developed to permit calculation of the relative importance of internal carbon production to the total organic carbon budget of the bay. Primary production varies from high rates over a limited photic depth in the turbid, phosphorus-rich waters of the eutrophic portions of the bay to low rates over an extensive photic depth in the transparent, phosphoruspoor reaches of the oligotrophic regions. Internal production accounts for approximately 90% of the total organic carbon loaded to the system over the summer growing season. Water quality management strategies must address the stimulation of primary production by phosphorus loaded from the Fox River in any attempt to lower the standing crop of nuisance algae, improve water clarity, and reduce rates of hypolimnetic oxygen depletion in Green Bay.     

Paleolimnological evaluation of historical trophic state conditions in hypereutrophic Lake Thonotosassa, Florida, USA

We used paleolimnological methods to evaluate historical water quality in Lake Thonotosassa, Hillsborough County, Florida, USA. Sediment mapping shows that organic deposits are unevenly distributed in the lake. Two short (<130 cm) sediment cores from the depositional zone were analyzed for radioisotopes (²¹⁰Pb, ²²⁶Ra, and ¹³⁷Cs), bulk density, organic matter concentration, nutrients (C,N,P), and diatoms. ²¹⁰Pb results indicate that the profiles represent > 100 years of sediment accumulation. There is an abrupt change in sediment composition at about the turn of the century (80 cm depth), above which bulk density decreases and concentrations of organic matter, total C, total N, total P, and ²²⁶Ra activity increase. Diatom-based reconstructions of historical water-column trophic conditions indicate progressive nutrient enrichment in the lake during the past 100 years. Stratigraphic changes in diatom assemblages suggest that anthropogenic nutrient loading converted Lake Thonotosassa from a naturally eutrophic system to a hypereutrophic waterbody after 1900. Given the edaphic setting of Lake Thonotosassa, efforts to mitigate recent anthropogenic impacts will, at best, yield the eutrophic conditions that characterized the lake prior to human disturbance. This study illustrates the importance of paleolimnological data for targeting realistic water quality conditions when lake restoration is contemplated.Journal Series No. R-05019 of the Florida Agricultural Experiment Station     

Nitrogen and phosphor compounds in bottom sediments: mechanisms of accumulation,transformation and release

This paper is an overview of Russian literature dealing with the accumulation, the transformations and the release of phosphate and nitrogen compounds in a great number of Russian lakes and reservoirs. A considerable data bank has been analysed. Special attention is given to the relations of N- and P-accumulation with the input and transformation of organic carbon, as well as to the release mechanisms, often in relation to eutrophication of the lakes and reservoirs. It is shown that the major input of organic matter into the sediments comes from autochthonous material, and is usually > 70 %. The relative importance of phytoplankton and macrophytes as sources of organic matter is discussed; it appears that trophic state, depth and other factors may have a large influence on this ratio. In shallow eutrophic lakes macrophytes may be the source of organic matter, which source can amount to 1.5–2.5 times that of phytoplankton. It is also shown that the C/N ratio is not a good indicator of the source of the organic matter, because their C/N ratios often are not very different. The decomposition rate of organic matter was analysed; it depends on trophic state and other factors. Sediment N accumulation is mostly (> 90%) in organic form, and depends on nitrogen and organic matter inputs coming from phytoplankton or macrophytes. A correlation coefficient of 0.9–0.95 was found in 176 lakes. In 113 lakes the N accumulation was 0.11 x C accumulation, with C/N ratios between 7.4 and 12.9. Ammonification was rather constant in different groups of lakes; values were often about 20–25 mg m⁻² d⁻¹. The presence of the different forms of nitrogen in interstitial water and in adsorbed forms is discussed. The N in interstitial water is usually in the form of NH₃. Sediment P-accumulation is usually in inorganic form and is related to primary production. Three different groups of sediments could be distinguished with C/P ratios of 31–100, of 101–350 and > 350. In hard water lakes P sedimentation was found to be 0.3–0.5 times that in soft water lakes with comparable primary production. The relative occurrence of apatite, non-apatite and residual P in sediments was calculated. In the interstitial water the P concentration appeared to be controlled by the input and decomposition of organic matter. The concentration of phosphate dissolved in the interstitial water of the top 2 cm layer is often 10–100 times lower than that of the dissolved N. The concentrations of interstitial phosphate are from a few μgl⁻¹ up to 15 mgl⁻¹, but the higher concentrations occur only rarely. Different types of vertical profiles of P compounds in the sediments were shown to be related with the presence of an oxidised zone, the presence of clay etc. Autochthonous apatite and non-apatite phosphates are more mobile than the allochthonous ones and are in equilibrium with interstitial phosphate. Accumulation of autochthonous apatite in sediments is controlled by decomposition of organic matter and accumulation of carbonates.     

Stratigraphy and geologic history of a southeastern salt marsh basin,North Inlet,South Carolina,USA

Forty seven vibracores and fifteen radiocarbon dates have beenobtained to outline the Holocene history of the North Inlet saltmarsh basin. Marsh deposits date from about 3500 years BP and havetransgressed over a Late Pleistocene beach-ridge terrain that waspartly eroded by Late Holocene tidal channel meandering. Marsh mudalso has prograded southward over shallow subtidal estuarine Macomamuds which date from about 4500 years BP and which are stillaccumulating in adjacent Winyah Bay. The southward migration of themarsh environment probably is due to the southward migration ofboth North Inlet and the mouth of Winyah Bay. The stratigraphy ofthe North Inlet basin offers no evidence for Late Holocene sea-level oscillations.Application of this model of marsh history to the study long-term ecosystem succession driven by slowly rising sea level isdiscussed.     

Sediments and sedimentary history of Lake Attersee (Salzkammergut,Austria)

Attersee represents a good example of a lake situated in the Northern forelands of the Northern Calcareous Alps and influenced by different sediment-supplying processes during the postglacial. Several compounds, of different origin, form the sediments of the basin. Clastics which are mainly composed of dolomites derive from the Northern Calcareous Alps. Clastic input of organic and inorganic particles is accomplished by rivers and landslides. They are responsible for the main input of siliciclasts like quartz, feldspar and mica. A high proportion of the sediment results from autochthonous biogenic carbonate precipitation. In the shallow sublittoral areas of the northern part of the lake benthic decalcification caused by encrusting macro- and micro-phytes is dominant, while in the southern and central parts of the lake epilimnetic decalcification caused by the blooming of phytoplancton is more important during summer. The total biogenic calcium carbonate production reaches about 11 000 to 12 000 metric tons a year.Nutrients and residues of cyanophytes (Oscillatoria rubescens) deriving from the eutrophic lake Mondsee were washed into lake Attersee by the Mondseeache. High amount of phosphorus in the sediments of the southern basin depicts local eutrophication in the mouth area of the Mondseeache. The average sedimentation rate in lake Attersee can be determined by different dating methods. Sedimentation rates increased during the last 110 years from 1 mm a year to 1.8–2 mm a year as a result of human activities. Five main phases in the postglacial sedimentary history can be recognized: Würm moraines and finely banded varves (before 13 000 B.P.), the early Attersee stage (from 13 000 B.P. up to 1200 B.P.), and the later Attersee stage after the Bavarian colonization (from 1200 B.P. on). Using heavy metal and isotope analyses the sedimentary history can be reconstructed in more detail for the last 100 years.     

A Phosphorus Budget for the Lake Mendota Watershed

A phosphorus (P) budget was calculated for the agriculture-dominated Lake Mendota watershed located in Dane and Columbia Counties, Wisconsin, USA. P inputs included fertilizer for agricultural crops and lawns, dietary supplements for dairy cattle, and natural inputs such as dry and wet deposition. Outputs included agricultural crops, livestock and livestock products, and hydrologic export to Lake Mendota. The total P input to the watershed (1,307,000 kg year^{− 1}) and total output (732,000 kg year^{− 1}) are large relative to the average of 34,000 kg P washing into the lake each year, indicating that the P flux that eutrophies Lake Mendota is a veryminor component of the total watershed P budget. Using the formula inputs − outputs = change in storage, we found that 575,000 kg P accumulated in the watershed in 1995. This estimate was corroborated by long-term soil P concentration data, which showed an average annual increase in soil P of over 450,000 kg year^{− 1}. Future management programs designed to reduce P inputs to Lake Mendota will be compelled to cope with the large amount of P being stored in the watershed. Received 31 August 1998; accepted 21 October 1998.     

A model for the density ofAeromonas hydrophila in Albemarle Sound,North Carolina

The abundance ofAeromonas hydrophila was measured monthly at 29 sites in Albemarle Sound, North Carolina and its tributaries from April 1977 through July 1979. Simultaneous measurements included heterotrophic plate count bacteria, fecal coliform bacteria, and 18 physical and chemical parameters. Using only 6 water quality parameters, multiple correlation and regression analysis of the data produced a best-fit regression which explained 38% of the variation observed inA. hydrophila density. The 6 water quality parameters included dissolved oxygen, temperature, orthophosphate, chlorophyll A trichromatic, total Kjeldahl nitrogen, and ammonia. Heterotrophic plate count bacteria and fecal coliform densities were highly correlated withA. hydrophila density, but made the model very unstable. The model was successfully tested against similar data collected for 2 other North Carolina reservoirs, Lake Norman and Badin Lake. Data from 10 sites in Badin Lake over 18 months and from 7 sites on Lake Norman over 5 months were not significantly different from the Albemarle Sound model. Conditions of water quality that may give rise to “blooms” ofA. hydrophila will simultaneously contribute to the probability of increased epizootics in fish in the southeastern United States.     

Dynamics and predictive modelling of Vibrio spp. in the Neuse River Estuary, North Carolina, USA

Vibrio spp. are naturally occurring bacteria in marine and estuarine environments around the world. The genus includes several human and animal pathogens that can negatively impact human health, seafood and aquaculture. Vibrio spp. populations are capable of rapid adaptation in response to changing environmental conditions, making them dynamic over short-term and seasonal scales. Temperature, vertical mixing, tidal flushing, climate, precipitation and nutrient loading can change the estuarine environment and subsequently alter microbial community structure, including Vibrio spp., affecting estuarine water quality and public health. To describe these dynamics, Vibrio spp. concentrations and a range of microbial, physical and chemical measures were monitored every 2 weeks and after storm events for 19 months in the Neuse River Estuary (NRE). Results showed clear seasonal and geographic trends in Vibrio spp. abundance. Multiple regression analysis revealed a strong relationship to temperature and salinity, with additional minor influences of chlorophyll a and dissolved organic carbon. Similar models based on easily measured environmental parameters should be pursued for individual Vibrio species in the NRE and other estuarine environments. Predictive models provide useful information for managers, researchers and modellers of estuarine ecosystems.     

Seasonal dynamics of macrophyte communities from a stream flowing over granite flatrock in North Carolina,USA

The seasonal distribution and abundance of benthic macrophytes were characterized from second- and third-order segments of a stream flowing over granite flatrock in the southeastern United States. Eighteen genera were identified over two annual cycles including macroalgae (60% of the total), angiosperms (30%), and bryophytes (10%). Light availability as affected by riparian shading was a major factor influencing community structure. Based on strong agreement among two-way indicator species analysis, detrended correspondence analysis and cluster analysis, we identified four communities characteristic of distinct light regimes and seasons. In shaded sites the red alga Lemanea australis was dominant during cool seasons, and the aquatic moss Fontinalis sp. was dominant during warm seasons. By contrast, in open sites L. australis and the angiosperm Podostemum ceratophyllum were co-dominant during cool seasons, and P. ceratophyllum was also dominant in warm seasons. The prolific macrophyte communities followed a pattern of broad seasonal maxima for dominant species along with rapid fluctuations in ephemerals. The community dynamics suggest that competitive interactions control space partitioning among macrophytes on the granite flatrock.     

Phosphate adsorption on bottom sediments of the Rio de la Plata

A study of the phosphate adsorption onto the bottom sediments of the Rio de la Plata has been made with the aim to understand the dynamics of this compound in the fluvio-marine system. Previous to the chemical analysis of the phosphate content, an extraction of the different adsorbed phosphate fractions have been made. In addition to phosphate, calcium, iron and aluminium in the sediment samples were determined. The phosphate is associated to the fine fractions of the sediments and good correlations with Al and Fe content in the bottom sediments were found. There is a relative decrease of the adsorbed phosphate on the bottom sediment in the areas where the influence of the marine water is more conspicuous; it is explained by the pH increase of the estuary waters due to the mixture with the marine waters. A hypothesis about the role of the ionic strength and the pH on the phosphate adsorption process is suggested.     

Diatoms of surface sediments of Utah Lake,Utah, U.S.A.

Diatoms in fifty-seven surface sediment samples from Utah Lake were examined. Three hundred and fifteen taxa in forty-three genera were identified and quantified. Statistical analyses of the data showed that distinct geographical subregions of the lake could be delineated according to population patterns of the bottom sediment diatoms. In particular, both Provo Bay and Goshen Bay were distinct from each other and from other areas of the lake.     

Comparison of Soil Organic Matter in Created, Restored and Paired Natural Wetlands in North Carolina

Soil organic matter (SOM) content is a key indicator of soil quality and is correlated to a number of important soil processes that occur in wetlands such as respiration, denitrification, and phosphorus sorption. To better understand the differences in the SOM content of created (CW), restored (RW), and paired natural wetlands (NWs), 11 CW/RW-NW pairs were sampled in North Carolina. The site pairs spanned a range of hydrogeomorphic (HGM) subclasses common in the Coastal Plain. The following null hypotheses were tested: (1) SOM content of paired CW/RWs and NWs are similar; (2) SOM content of wetlands across different HGM subclasses is similar; and (3) interactions between wetland status (CW/RW vs. NW) and hydrogeomorphic subclass are similar. The first null hypothesis was rejected as CW/RWs had significantly lower mean SOM (11.8 ± 3.9%) than their paired NWs (28.98 ± 8.0%) on average and at 10 out of the 11 individual sites. The second and third null hypotheses were also rejected as CW/RWs and NWs in the non-riverine organic soil flat subclass had significantly higher mean SOM content (31.08 ± 14.2%) than the other three subclasses (8.18 ± 2.5, 11.18 ± 8.2, and 10.38 ± 4.2%). Individual sites within this fourth subclass also had significantly different SOM content. This indicated that it would be inappropriate to include the organic soil flat subclass with either the riverine or non-riverine mineral soil flat subclasses when considering restoration guidelines. These results also suggested that if there is a choice in mitigation options between restoration or creation, wetlands should be restored rather than created, especially those in the non-riverine organic soil flat subclass.