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191.
Use of crops for green manure as a substitute for chemical fertilizers and pesticides is an important approach towards more sustainable agricultural practices. Green manure from white clover is rich in nitrogen but white clover also produces the cyanogenic glucosides (CGs) linamarin and lotaustralin; CGs release toxic hydrogen cyanide (HCN) upon hydrolysis which may be utilized for pest control. We demonstrate that applying CGs in the form of a liquid extract of white clover to large columns of intact agricultural soils can result in leaching of toxic cyanide species to a depth of at least 1m. Although degradation of the CGs during leaching proceeded with half lives in the interval 1.5-35 h depending on soil characteristics, a fraction of the applied CGs (0.9-3.2%) was recovered in the leachate as either CGs or toxic cyanide species. Detoxification of the HCN formed was rapid in soil and leachate from both sandy and loamy soil. However, 30% of the leachate samples exceeded the EU threshold value of 50 micrgl(-1) total cyanide for drinking water and 85% exceeded the US threshold of 5 micrgl(-1) for cyanide chronic ecotoxicity in fresh water. This study demonstrates that even easily degradable natural products present in crop plants as defense compounds pose a threat to the quality of groundwater and surface waters. This aspect needs consideration in assessment of the risk associated with use of crops as green manure to replace chemical fertilizers and pesticides as well as in genetic engineering approaches to design crops with improved pest resistance. 相似文献
192.
Yasundo?KurataEmail author Yusaku?Ono Yoshiro?Ono 《Journal of Material Cycles and Waste Management》2008,10(2):144-152
The concentrations of 41 phenols in leachates from 38 municipal solid waste (MSW) landfill sites in Japan were measured. The
main phenols detected in leachates were phenol, three cresols, 4-tert-butylphenol, 4-tertoctylphenol, 4-nonylphenol, bisphenol
A, and some chlorophenols. The concentration levels of phenols were affected by the pH values of the leachates and the different
types of landfill waste. The origins of phenol and p-cresol were considered to be incineration residues, and the major origin of 4-tert-butylphenol, bisphenol A, and 2,4,6-trichlorophenol
was considered to be solidified fly ash. In contrast, the major origins of 4-tert-octylphenol and 4-nonylphenol were considered
to be incombustibles. The discharge of leachates to the environment around MSW landfill sites without water treatment facilities
can cause environmental pollution by phenols. In particular, the disposal of incineration residues including solidified fly
ash and the codisposal of solidified fly ash and incombustibles might raise the possibility of environmental pollution. Moreover,
the discharge of leachates at pH values of 9.8 or more could pollute the water environment with phenol. However, phenol, 4-nonylphenol,
and bisphenol A can be removed to below the con centration levels that impact the environment around landfill sites by a series
of conventional water treatment processes. 相似文献
193.
Various developmental stages (early larvae to adults) of Euphausia superba have been collected in different seasons in the Weddell Sea, the Lazarev Sea and off the Antarctic Peninsula to investigate
the role of lipids and fatty acids in the life cycle of the Antarctic krill. The total-lipid data for E. superba exhibited seasonal variations, with low lipid levels in late winter/early spring and the highest levels in autumn. Seasonal
changes were most pronounced in the immature and adult specimens, increasing from about 10% lipid of dry mass to more than
40%. The fatty-acid compositions of the younger stages were dominated by 20:5(n-3), 22:6(n-3) and 16:0. These are typical
phospholipid fatty acids, which are major biomembrane constituents. The phospholipid composition was similar in the older
stages. With increasing storage of triacylglycerols in the lipid-rich immature and adult stages, the fatty acids 14:0, 16:0
and 18:1(n-9) prevailed, comprising about 70% of total triacylglycerol fatty acids. The trophic-marker fatty acids 16:1(n-7)
and 18:4(n-3), indicating phytoplankton ingestion, were less abundant. They reflected, however, the dependence of the larvae
on phytoplankton as well as the seasonal changes in algal composition. The generally close linear relationships between fatty
acids and lipid suggest that the fatty-acid compositions of the collected specimens were largely independent of the respective
developmental stage, season and region. The linear fit indicates that triacylglycerol accumulation started at a level of about
5% of total lipid. Considering the various overwintering scenarios under discussion, the life cycle and reproductive strategies
of krill are discussed in the context of the lipid metabolism and fatty-acid composition of E. superba. Lipid production is effective enough to accumulate large energy reserves for the dark season, but E. superba does not exhibit the sophisticated biosynthetic pathways known from other Antarctic euphausiids and copepods. Although important,
lipid utilisation appears to be just one of several strategies of E. superba to thrive under the extreme Antarctic conditions, and this pronounced versatility may explain the success of this species
in the Southern Ocean.
Received: 16 June 2000 / Accepted: 18 December 2000 相似文献
194.
Juvenile and adult marine organisms differ in their morphology, chemistry, physiology, behavior, and ecology. Because juvenile
algae are thinner, smaller, and have more delicate tissues than adults, they are often assumed to be more susceptible to grazers.
We examined within-species food preferences of four common generalist herbivores for juvenile and adult tissues of eight common
brown algae in two-choice laboratory food-preference experiments. Our results showed that juvenile algae did not tend to be
a preferred food of herbivores. Juvenile tissues were significantly preferred over adult tissues in only four of the 32 combinations
of algae and herbivores tested. In 12 experiments, adult tissues were preferred over juvenile tissues, and no choice occurred
in the remaining 16 experiments. When sea urchins exhibited a preference, it was always for adult tissues. The other three
herbivores, an isopod and two snails, were more variable in their choices, sometimes preferring juveniles, sometimes adults,
and sometimes having no preference. We measured nitrogen and phlorotannin concentrations in adult and juvenile seaweeds to
see whether these parameters were correlated with herbivore food preferences. Nitrogen levels were similar in juveniles and
adults of three algal species and were higher in juveniles of two. Phlorotannin levels were higher in juveniles of four species
and lower in juveniles of one. The other three species showed no differences in phlorotannin levels. Phlorotannin concentrations
decreased with increasing juvenile size in three species and increased with increasing size in one species. Neither nitrogen
nor phlorotannin concentrations explained overall herbivore food preferences for algae of different stages. Our results suggest
that preferences of certain grazers for juvenile algae are not as strong as previously assumed and are dependent on herbivore
species. Preferences between juveniles and adults are likely to be determined by a combination of morphological and chemical
features of the tissues and the unique responses of herbivore species to those features.
Received: 10 April 2000 / Accepted: 19 November 2000 相似文献
195.
A distinct smell of dimethylsulfide (DMS) was noted at the edge of the intertidal mudflat of Marennes-Oléron Bay, at the
French Atlantic coast, where dense populations of the marine flatworm Convoluta roscoffensis Graff (Platyhelminthes: Turbellaria) were present. DMS is the cleavage product of dimethylsulfoniopropionate (DMSP). DMSP
was shown to be present in high amounts in sediment containing the flatworm as well as in axenic cultures of the symbiotic
alga Tetraselmis sp. that was isolated from the flatworm. In untreated sediment samples containing C. roscoffensis the concentration of DMS was as high as ∼55 μmol l−1 sediment, and in samples that were fixed with glutaraldehyde the concentration of DMS was even three orders of magnitude
higher (∼66 mmol l−1 sediment). This rapid cleavage of DMSP to DMS in fixed samples was unexpected. Pure DMSP was stable in glutaraldehyde, and
it was therefore concluded that a DMSP-lyase was responsible for cleavage in the field samples. The isolated symbiotic alga,
Tetraselmis sp., did not show DMSP-lyase activity, indicating that DMSP-lyase may have been present in the flatworm, although the role
of bacteria could not be excluded. The Chl a-specific DMSP content of C. roscoffensis (∼200 mmol g−1) was much higher than that of Tetraselmis sp. (∼30 mmol g−1). Possibly, DMSP was not only present in the symbiotic alga, but was also incorporated in the body tissue of the flatworm.
It remains unclear what the function of DMSP is in C. roscoffensis. In Tetraselmis sp., but not in C. roscoffensis, DMSP increased with increasing salinity. It was concluded that salinity probably does not play an important role in the
dynamics of DMSP and DMS in sediment containing C. roscoffensis.
Received: 21 January 2000 / Accepted: 29 August 2000 相似文献
196.
197.
Xiaoqing?DongEmail author Chaolin?Li Binbin?Ding Xiaofeng?He Jia?Zhu Peibing?Shao 《Environmental Modeling and Assessment》2016,21(4):517-529
Frequent monitoring and relatively high fines are usually necessary to bring about improvements in environmental quality, but more challenging for many countries with limited human, material, and financial resources is to put them into practice. This paper developed a three-group model of a state-dependent enforcement in a repeated game to improve the policy implementation under limited inspection capacities. A certain number of firms are grouped (group 1, group 2, group 3) for different supervision intensity (e.g., the order of inspection probability corresponding to each group is p 1?<?p 2?<?p 3) based on their environmental performance. The optimal policy parameters, such as inspection probability of each group and the probability that a firm found in compliance is moved to a better reputation group, were obtained as the basis for regulator’s policy making. Numerical simulations indicated that the three-group inspection regime can significantly increase compliance rate as compared with static enforcement with the same monitoring probability. Among the number of firms in each group under steady state conditions, group 2 had the most, group 1 was the second, and group 3 had the smallest. Analysis and prediction of a three-group reputation example provided a good experiment for the model. The results give a practical reference for the policy makers with inspection capacity constraints to achieve higher compliance rate. 相似文献
198.
Human population growth in coastal areas continues to threaten estuarine ecosystems and resources. Populations of Crassostrea virginica have declined across the USA due to water quality degradation, disease pressure, alteration of habitat, and other changes related to anthropogenic impacts. Metals that may be present in estuarine habitats can bioaccumulate in oysters, with potential consequences to the health of oysters and humans consumers. This study (1) evaluated the occurrence and relationships of metal concentrations in oyster tissue versus estuarine sediments, (2) examined oyster tissue concentrations in relation to state water quality designations, and (3) evaluated the potential risk for humans from oyster consumption related to metal concentrations from harvestable waters. Results indicated metal concentrations in sediments and oysters along coastal South Carolina remain low compared to other areas and that concentrations in oyster tissue and adjacent sediments were not highly correlated with each other. However, high concentrations of some metals occurred in oysters sampled from areas designated as Approved for Harvesting. This is important because most harvest area designation systems rely on regular bacterial monitoring when evaluating the safety of consumption. Others safety measurements may be necessary as part of routine monitoring. 相似文献
199.
Muhammad?Shafiq Tahira?Shaukat Aisha?Nazir Firdaus-e-?BareenEmail author 《Environmental monitoring and assessment》2017,189(8):423
Kasur is one of the hubs of leather industry in the Punjab, Pakistan, where chrome tanning method of leather processing is extensively being used. Chromium (Cr) accumulation levels in the irrigation water, soil, and seasonal vegetables were studied in three villages located in the vicinity of wastewater treatment plant and solid waste dumping site operated by the Kasur Tanneries Waste Management Agency (KTWMA). The data was interpreted using analysis of variance (ANOVA), clustering analysis (CA), and principal component analysis (PCA). Interpolated surface maps for Cr were generated using the actual data obtained for the 30 sampling sites in each of the three villages for irrigation water, soil, and seasonal vegetables. The level of contamination in the three villages was directly proportional to their distance from KTWMA wastewater treatment plant and the direction of water runoff. The highest level of Cr contamination in soil (mg kg?1) was observed at Faqeeria Wala (37.67), intermediate at Dollay Wala (30.33), and the least in Maan (25.16). A gradational variation in Cr accumulation was observed in the three villages from contaminated wastewater having the least contamination level (2.02–4.40 mg L?1), to soil (25.16–37.67 mg kg?1), and ultimately in the seasonal vegetable crops (156.67–248.33 mg kg?1) cultivated in the region, having the highest level of Cr contamination above the permissible limit. The model used not only predicted the current situation of Cr contamination in the three villages but also indicated the trend of magnification of Cr contamination from irrigation water to soil and to the base of the food chain. Among the multiple causes of Cr contamination of vegetables, soil irrigation with contaminated groundwater was observed to be the dominant one. 相似文献
200.
Steven?J.?CookeEmail authorView authors OrcID profile Eduardo?G.?Martins Daniel?P.?Struthers Lee?F.?G.?Gutowsky Michael?Power Susan?E.?Doka John?M.?Dettmers David?A.?Crook Martyn?C.?Lucas Christopher?M.?Holbrook Charles?C.?Krueger 《Environmental monitoring and assessment》2016,188(4):239
Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions. 相似文献