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11.
Theoretical advances and short-term experimental studies have furthered our understanding of how ecosystems respond to perturbation. However, there are few well-replicated experimental studies that allow an assessment of long-term responses. Results from a controlled, large-scale field experiment in a subalpine grassland near Interlaken, Switzerland, show that 2-4 years of liming (Ca: 40 g x m(-2) x yr(-1)) still significantly affected the composition of the vegetation and the soil microbial community nearly 70 years after the treatments were imposed, whereas NPK fertilization (8 g x m(-2) x yr(-1)) only marginally affected vegetation composition. The exchangeable content of Ca ions and soil pH were higher in limed plots but were unaffected in fertilized plots. Plant species and PLFAs (phospholipid fatty acids) indicating low pH values were found in higher abundance in the unlimed plots, suggesting that the long-lasting effects of liming on the above- and belowground communities were mediated through changes in soil pH. The results of this long-term study indicate that the resilience of mountain ecosystems may be particularly low in response to perturbations that substantially alter soil pH or other key determinants of belowground processes. 相似文献
12.
Benzotriazoles, Alkylphenols and Bisphenol A in Municipal Wastewaters and in the Glatt River, Switzerland 总被引:3,自引:2,他引:1
Voutsa D Hartmann P Schaffner C Giger W 《Environmental science and pollution research international》2006,13(5):333-341
- DOI: http://dx.doi.org/10.1065/espr2006.01.295
Background Many organic micropollutants occur at trace concentrations in municipal wastewater effluents and in the aquatic environment.
Some of these xenobiotic chemicals can be considered as 'emerging' contaminants and some are suspect to have endocrine disrupting
effects. Among the latter are nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA), which deserve special attention due
to their ubiquitous occurrence in the aquatic environment. The complexing agents benzotriazole (BT) and tolyltriazole (TT)
are applied as anticorrosive agents (e.g. in cooling and hydraulic fluids, in antifreezing fluids, in aircraft deicing fluids,
in dish washing liquids for silver protection), as antifogging agents and as intermediates for the synthesis of various chemicals.
The environmental occurrence of NP and OP is caused by the fact that they are intermediate products (metabolites) in the biodegradation
of alkylphenol polyethoxylate surfactants. BPA is globally used for the production of polycarbonate and epoxy resins.
Methods BT, TT, NP, OP and BPA were quantitatively determined in municipal wastewater effluents in Switzerland and in the Glatt River.
The analytes were enriched by solid-phase enrichment. BT and TT were determined underivatized by electrospray LC/tandem MS.
Reversed-phase LC was performed on octylsilica columns with isocratic water/methanol elution. Multiple reaction monitoring
of the positive ions provided selective and sensitive detection for reliable quantifications. NP, OP and BPA were determined
by GC/MS after derivatization with N-methyl-N-(trimethylsilyl)-trifluoroacetamide.
Results and Discussion BT and TT concentrations in primary and secondary effluents of municipal wastewater treatment plants varied from below 10
to 100 μg/L. The ranges of the concentrations in the Glatt River in ng/L were 636–3,690 for BT, 122–628 for TT, 68–326 for
NP, 6–22 for OP and 9–76 for BPA. The corresponding mass flows in g/d were 93–1,870 for BT, 18–360 for TT, 24–183 for NP,
1–16 for OP and 2–72 for BPA. The concentrations and mass flows of NP in the River Glatt were drastically lower than the analogous
values found 15 years ago. Thus, a substantially decreased environmental exposure can be observed due to the reduction of
the use of alkyphenol polyethoxylate surfactants in Switzerland. The current concentrations of NP, OP and BPA are within the
ranges reported for weakly impacted surface waters.
Conclusion The investigated contaminants occur at quantitatively measurable but varying concentrations in municipal wastewaters and
in the Glatt River reflecting their ubiquitous input into wastewaters and their different behaviour during biological wastewater
treatment. 相似文献
13.
In soft-sediment marine and estuarine habitats, population dynamics of resident species are an important aspect of commnity structure and function, yet the population dynamics of many members of these communities remain poorly studied. The population dynamics and secondary production of the infaunal terebellid polychaete Loimia medusa (Savigny) were investigated in a shallow sand habitat of the York River, Chesapeake Bay, Virginia, between June 1989 and December 1990. Monthly sampling throughout 1 yr revealed that individuals were present year-round with maximum densities of 60 ind m-2 and a life span of 1 yr. Abundances were highest from August through September when two cohorts recruited to the population. Mean individual growth was highest in summer, and appeared to be a function of temperature rather than food limitation. Adults were reproductive from May through October and exhibited high fecundity; the number of oocytes segment-1 ranged from 201 to 15840 among worms. Larvae initially appeared approximately 1 mo after gametes were first observed in adult L. medusa, and these larvae appeared to spend less than 1 mo in the plankton. Abundances of larvae in the water column were significantly higher around new moon, suggesting lunar spawning periodicity. New recruits attained sexual maturity within 2 mo of settlement. Secondary production was 3.3 g ash-free dry wt m-2 yr-1 and the P/B (production/biomass) ratio was 3.0. Despite equilibrium species characteristics such as large size, high fecundity, and planktonic larvae, L. medusa exhibits some characteristics typically ascribed to opportunistic species, namely, the capacity for rapid growth and maturation, a short life span and a relatively high P/B ratio. This mixture of life history characteristics emphasizes that there is no simple dichotomy between opportunistic and equilibrium species. We caution that the dominance of large infaunal polychaetes in soft-bottom estuarine and marine environments may not be a useful indicator of undisturbed habitats. 相似文献
14.
Merz J Nakarmi G Shrestha S Dahal BM Dongol BS Schaffner M Shakya S Sharma S Weingartner R 《Environmental management》2004,34(1):26-37
Inadequacy and poor quality of water supply for domestic purposes is increasingly becoming a concern in rural catchments of the Middle Mountains of Nepal. Water quantity is an issue in pocket areas of these catchments, while water quality is subject to concern in most of the water sources. Microbiological contamination in particular poses a risk to human health. In addition, sediment pollution during the monsoon season is perceived as an issue by the local residents. Elevated phosphate and nitrate levels in many water sources indicate intensive interaction with surface water hailing from agricultural areas and human settlements. These water quantity and quality concerns in two watersheds of Nepal, the Jhikhu Khola and the Yarsha Khola watersheds, are not isolated cases. Similar problems are reported from other watersheds monitored under the People and Resource Dynamics in Mountain Watersheds of the Hindu Kush-Himalayas (PARDYP) project in China, India, and Pakistan and the literature of this region. 相似文献
15.
E(h) measurements by electrodes are commonly used to characterize redox status of sediments in freshwater, marine and estuarine studies, due to the relative ease and rapidity of data collection. In our studies of fine-grained estuarine seabeds, we observed that E(h) values measured in intact sediment cores were influenced by different electrode insertion techniques. Sediment E(h) measurements generated via lateral insertion of platinum electrodes through silicone-filled ports in acrylic cores were systematically more positive (on the order of 10-100 mV) than profiles generated via vertical insertion of platinum electrodes downward through the sediment-water interface of the same cores. A review of the literature indicated that while researchers routinely use both insertion techniques to measure E(h), no discrepancy in output has previously been reported. We discuss the results of three experiments conducted to determine if the discrepancy in output was caused by electrode poisoning by sulfides during the stepwise vertical insertion technique, or was caused by contact of the electrode with the silicone plug during the lateral insertion technique. We conclude that contact between the platinum surface of the electrode and the silicone plug biases the E(h) measurements, resulting in erroneously positive E(h) values. Insertion of electrodes into sediment through silicone plugs produced E(h) values that were an average of 105.6 mV (+/-10.4 SE) more positive than values generated upon electrode insertion directly into sediment. Thus, we recommend against using an insertion technique where the platinum electrode remains in contact with the silicone plug, as this method results in misclassification of sediment redox state and estimated depth of the redoxcline. 相似文献
16.
Summary. The ontogeny of pyrrolizidine alkaloid (PA) synthesis
and constraints on defence level during the seedling stage were examined
in the annual Senecio vulgaris and the monocarpic perennial
Senecio jacobaea. In both species, PAs were actively
synthesized from the onset of seedling growth so that juvenile stages
did not go through an undefended stage. Roots are known to be the
exclusive sites where PAs are produced. Root biomass was the single most
important biomass parameter explaining variation in total PAs per
seedling. All correlation coefficients between—relative growth
rate and PA concentration were negative, but none was significant.
However, a significant negative—correlation was found between
shoot to root ratio and PA concentration in S. jacobaeaseedlings, suggesting a dilution effect of the PAs. Earlier studies have
shown that the shoot to root ratio is positively correlated with
relative growth—rate of established S. jacobaea plants.
It is therefore suggested that young S. jacobaea plants
with a high shoot to root ratio and hence a high growth capacity
necessarily have lower PA defence levels than plants with a low
shoot to root ratio.
Received 10 July 2002; accepted 16 November 2002. 相似文献
17.
Brändli RC Kupper T Bucheli TD Zennegg M Huber S Ortelli D Müller J Schaffner C Iozza S Schmid P Berger U Edder P Oehme M Stadelmann FX Tarradellas J 《Journal of environmental monitoring : JEM》2007,9(5):465-472
Compost and digestate are important recycling fertilizers and have beneficial effects on soil parameters. However, they can contain significant amounts of organic pollutants. Here, the first comprehensive data set on dibenzo-p-dioxins and -furans (PCDD/F), dioxin-like polychlorinated biphenyls (DL-PCB), brominated flame retardants, perfluorinated alkyl substances (PFAS), pesticides, phthalates, nonylphenol and chlorinated paraffins (CP) in source-separated compost and digestate from Switzerland is presented (n = 3-18). The median summation 17PCDD/F and summation 12DL-PCB concentrations were at 3.2 ng I-TEQ kg(-1)dry weight (dw) and 3.0 ng WHO-TEQ kg(-1)dw, respectively. Brominated diphenyl ether 209 (BDE 209) accounted for 72% of the total polyBDE content (10 microg kg(-1)dw). Hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) levels were at 100 and 0.51 microg kg(-1)dw, respectively. PFAS were identified for the first time in compost and digestate (median concentration 6.3 microg kg(-1)dw, summation 21compounds). Out of 269 pesticides analysed, 30 fungicides, 14 herbicides, eight insecticides and one acaricide were detected. Di-(2-ethylhexyl)phthalate (DEHP) median concentration accounted for 280 microg kg(-1)dw and nonylphenol was below the detection limit of 1 mg kg(-1)dw. The sum of short and medium chain CP was between 90 and 390 microg kg(-1)dw. The concentrations observed were at or above the levels found in background soils, which are the main recipient of compost and digestate. Where actually applied, compost can contribute considerably to the total input of organic pollutants to the soil. However, on a total Swiss agricultural area base, inputs seem to be limited. 相似文献
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19.
Alison M. Barker Reitumetse Molotsane Caroline Müller Urs Schaffner Erich Städler 《Chemoecology》2006,16(4):209-218
Summary. The turnip sawfly Athalia rosae sequesters glucosinolates from its cruciferous host plants in the larval stage. Investigation of the chemosensory and behavioural
responses of adult A. rosae to glucosinolates and their volatile hydrolysis products, isothiocyanates, revealed that females detect glucosinolates by
contact chemoreception and isothiocyanates by antennal olfaction. In electroantennogram recordings, four isothiocyanates (allyl
[2-propenyl] isothiocyanate, benzyl isothiocyanate, butyl isothiocyanate and iberverin [3-methylthiopropyl isothiocyanate])
were active at all doses presented, including the lowest (0.1 μg), whilst the threshold for detection of three others, iberin
[3-methylsulphinylpropyl isothiocyanate], methyl isothiocyanate, and sulforaphane [4-methylsulphinylbutyl isothiocyanate],
was higher, at between 1 and 10 μg (source concentration of volatiles). Allyl isothiocyanate attracted experienced females
in a four-chambered olfactometer, whilst na?ve females showed no response. Allyl isothiocyanate also attracted mature females
to baited yellow water traps in field trials, although immature females were repelled at high isothiocyanate concentrations.
In laboratory behavioural bioassays the glucosinolates sinigrin (allyl [2-propenyl] glucosinolate) and sinalbin (p-hydroxybenzyl
glucosinolate), stimulated ovipositor probing in mature female A. rosae to an extent comparable to hot-water extracts of their host plants. These responses show that glucosinolates and isothiocyanates
play an important role in host finding and host recognition in A. rosae. 相似文献