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1.
The aim of this study is to survey the PM 10, PM 2.5, and PM 1 concentrations in rural and urban areas in Tehran province during cold, warm and dust storm days from December 22, 2016 to June 5, 2017 using Grimm Model aerosol spectrometer. During the study period, daily PM 10, PM 2.5, and PM 1 concentrations ranged from 27.2 to 244.96, 8.4 to 77.9, and 6.5 to 56.8 μg/m 3 in urban sites, and 22.8 to 286.4, 6 to 41.1, and 2.1 to 20.2 μg/m 3 in rural parts, respectively. Particularly, both daily WHO limits for outdoor PM 10 (50.0 μg/m 3) and PM 2.5 (25.0 μg/m 3) exceeded in 95% and 83% of the outdoor measurements in winter and 82% and 58% in total sampled days in urban site, respectively. The 24-h average PM 10 and PM 2.5 concentrations also exceeded by 59% and 18% in winter and by 36% and 14% of all sampling days in rural site, respectively. During the dust storm, the 24-h average PM 10, PM 2.5, and PM 1 concentrations were, respectively 4.7, 2, and 1.96 times higher than those in urban site and 2, 1.7, and 1.3 times more than those in rural site in all sampled days. 相似文献
2.
Fine particulate matters (PM 2.5) are known to pose serious health problems compared to other air pollutants. The current study employed air dispersion modeling system (AERMOD) to simulate the concentration of PM 2.5 from Tema Oil Refinery (TOR) and to assess the non-cancer risk and mortalities of the exposed population. In addition, the effects of local climatic factors on the distribution and concentration of PM 2.5 within the three main seasons (Major Raining Season (MRS), Low Raining Season (LRS) and Dry Season (DS)) were investigated. The AERMOD results showed that both 24-h (38.8 µ g m ?3) and annual (12.6 µ g m ?3) PM 2.5 concentration levels were in exceedance of the international limits. However, a decreasing trend in seasonal PM 2.5 concentrations was observed. Health risk assessment (HRA), indicated by hazard index (HI), revealed that the amount of Al 2O 3 present in the PM 2.5 caused a significant non-carcinogenic health risk to the exposed population (both adults and children) within the Metropolis (HI = 2.4 for adults and HI = 1.5 for children). Additionally, cardiopulmonary disease related mortalities due to PM 2.5 exposure (181 deaths for adults and 24 deaths for children) were found high compared to deaths caused by lung cancer (137 deaths for adults and 16 deaths for children). 相似文献
3.
During two intensive field campaigns in summer and autumn 2004 nitrogen (N 2O, NO/NO 2) and carbon (CO 2, CH 4) trace gas exchange between soil and the atmosphere was measured in a sessile oak ( Quercus petraea (Matt.) Liebl.) forest in Hungary. The climate can be described as continental temperate. Fluxes were measured with a fully automatic measuring system allowing for high temporal resolution. Mean N 2O emission rates were 1.5 μg N m −2 h −1 in summer and 3.4 μg N m −2 h −1 in autumn, respectively. Also mean NO emission rates were higher in autumn (8.4 μg N m −2 h −1) as compared to summer (6.0 μg N m −2 h −1). However, as NO 2 deposition rates continuously exceeded NO emission rates (−9.7 μg N m −2 h −1 in summer and −18.3 μg N m −2 h −1 in autumn), the forest soil always acted as a net NO
x
sink. The mean value of CO 2 fluxes showed only little seasonal differences between summer (81.1 mg C m −2 h −1) and autumn (74.2 mg C m −2 h −1) measurements, likewise CH 4uptake (summer: −52.6 μg C m −2 h −1; autumn: −56.5 μg C m −2 h −1). In addition, the microbial soil processes net/gross N mineralization, net/gross nitrification and heterotrophic soil respiration as well as inorganic soil nitrogen concentrations and N 2O/CH 4 soil air concentrations in different soil depths were determined. The respiratory quotient (ΔCO 2 resp ΔO 2 resp−1) for the uppermost mineral soil, which is needed for the calculation of gross nitrification via the Barometric Process Separation (BaPS) technique, was 0.8978 ± 0.008. The mean value of gross nitrification rates showed only little seasonal differences between summer (0.99 μg N kg −1 SDW d −1) and autumn measurements (0.89 μg N kg −1 SDW d −1). Gross rates of N mineralization were highest in the organic layer (20.1–137.9 μg N kg −1 SDW d −1) and significantly lower in the uppermost mineral layer (1.3–2.9 μg N kg −1 SDW d −1). Only for the organic layer seasonality in gross N mineralization rates could be demonstrated, with highest mean values in autumn, most likely caused by fresh litter decomposition. Gross mineralization rates of the organic layer were positively correlated with N 2O emissions and negatively correlated with CH 4 uptake, whereas soil CO 2 emissions were positively correlated with heterotrophic respiration in the uppermost mineral soil layer. The most important abiotic factor influencing C and N trace gas fluxes was soil moisture, while the influence of soil temperature on trace gas exchange rates was high only in autumn. 相似文献
4.
The indoor air quality (IAQ) in classrooms highly affects the health and productivity of students. This article aims to clarify seasonal variation in indoor environment and sick building syndromes (SBS) symptoms in an Eastern Mediterranean climate. A series of field measurements were conducted during the fall and winter seasons from October 2011 to March 2012 in 12 naturally ventilated schools located in the Gaza Strip. Data on environmental perception and health symptoms were obtained from 724 students by using a validated questionnaire. The results showed that indoor PM 10 and PM 2.5 concentrations were 426.3 ± 187.6 μg/m 3 and 126.6 ± 94.8 μg/m 3, respectively. The CO 2 concentrations and ventilation rate widely exceeded their reference values during the winter season. The prevalence rates of general symptoms were relatively high at baseline assessment in the fall season and increased significantly during follow-up in the winter season. Significant increases in disease symptoms such as mucosal irritation and pre-existing asthma symptoms among students could be related to poor indoor air quality. Five distinct groups of SBS symptoms from factor analysis of students’ related symptoms were significantly correlated with PM 10 and PM 2.5, CO 2, ventilation rate, and indoor temperature. As vulnerable children, this situation negatively affects their school performance and health. 相似文献
5.
The characterization of indoor (a naturally ventilated office) and outdoor (adjacent courtyard) metals in PM 2.5 during a winter period in Xi'an, China were carried out. The results indicated that the average mass concentrations of PM 2.5 in indoor and outdoor environments all exceeded the daily average limit of 75 µg m –3 set by the Chinese government. The dominant metals in PM 2.5 were Ca, Al, Zn, Mg, Fe, and Pb in both indoor and outdoor air. Concentration of As was much higher than the standard of 6 ng m –3 issued by the government. Enrichment factor analysis showed that anthropogenic emissions might be the primary sources of As, Cd, Pb, and Zn, while crust was the main origin of Co. A majority of indoor-to-outdoor concentration ratios of metal were lower than 1 indicating mostly the contribution of outdoor sources rather than indoor ones. As and Cr in both indoor and outdoor air posed the highest noncarcinogenic and carcinogenic risks, respectively. The noncarcinogenic and carcinogenic risks were 2.74 and 2.54 × 10 ?4 indoor and 4.04 and 3.87 × 10 ?4 outdoor, which suggested that possible adverse health effects should be of concern. 相似文献
6.
Many coastal plain wetlands receive nutrient pollution from agricultural fields and are particularly vulnerable to saltwater incursion. Although wetlands are a major source of the greenhouse gases methane (CH 4) and nitrous oxide (N 2O), the consequences of salinization for greenhouse gas emissions from wetlands with high agricultural pollution loads is rarely considered. Here, we asked how saltwater exposure alters greenhouse gas emissions from a restored freshwater wetland that receives nutrient loading from upstream farms. During March to November 2012, we measured greenhouse gases along a ~2 km inundated portion of the wetland. Sampling locations spanned a wide chemical gradient from sites receiving seasonal fertilizer nitrogen and sulfate (SO 4 2?) loads to sites receiving seasonal increases in marine salts. Concentrations and fluxes of CH 4 were low (<100 µg L ?1 and <10 mg m ?2 h ?1) for all sites and sampling dates when SO 4 2? was high (>10 mg L ?1), regardless of whether the SO 4 2? source was agriculture or saltwater. Elevated CH 4 (as high as 1,500 µg L ?1 and 45 mg m ?2 h ?1) was only observed on dates when air temperatures were >27 °C and SO 4 2? was <10 mg L ?1. Despite elevated ammonium (NH 4 +) for saltwater exposed sites, concentrations of N 2O remained low (<5 µg L ?1 and <10 µg m ?2 h ?1), except when fertilizer derived nitrate (NO 3 ?) concentrations were high and N 2O increased as high as 156 µg L ?1. Our results suggest that although both saltwater and agriculture derived SO 4 2? may suppress CH 4, increases in N 2O associated with fertilizer derived NO 3 ? may offset that reduction in wetlands exposed to both agricultural runoff and saltwater incursion. 相似文献
7.
AbstractQuantification of PM 2.5 (particulate matter <2.5?µm) bound heavy metals and their potential health risks were carried out around a cement manufacturing company in Ewekoro, Nigeria. The PM 2.5 samples were collected using Environtech gravimetric sampler. A four-staged sequential extraction procedure was used to fractionate PM 2.5 bound chromium (Cr), lead (Pb), aluminum (Al), copper (Cu), and silver (Ag), and further analyzed using inductively coupled plasma mass spectrometry. Chemical speciation results reveal bioavailable levels of Pb (4.05?µg/m 3), Cr (10.75?µg/m 3), Al (16.47?µg/m 3), Cu (4.38E-01?µg/m 3), and Ag (1.22E-02?µg/m 3) in the airborne particulates. Pb and Cr levels exceeded the World Health Organization allowable limit of 0.5 and 2.5E-05?µg/m 3, respectively. The labile phases showed strong indication of the presence of Cr and Cu metal. Excess cancer risks exposure for adults, outdoor workers and children were higher than the acceptable risk target level of 1E-06. Non-carcinogenic health risk estimated using hazard quotients (HQs) and hazard indices (HIs) showed ingestion route within the safe level of HI <1 implying no adverse effect while inhalation route exceeded the safe level for all receptors. Enforcement of pollution control by authorized agencies, and screening of greenbelts as sinks for air pollutants is strongly recommended. 相似文献
8.
We evaluated the nighttime CO 2 flux (ecosystem respiration) on Rishiri Island, located at the northern tip of Hokkaido, Japan, from 2009 to 2011, by using the relationship between atmospheric 222Rn and CO 2 concentrations. The annual mean CO 2 flux was 1.8 μmol m ?2 s ?1, with a maximum monthly mean in July (4.6 ± 2.6 μmol m ?2 s ?1) and a broad minimum from December to March (0.33 ± 0.29 μmol m ?2 s ?1). The annual mean was comparable to fluxes at the JapanFlux sites in northern Japan. During the season of snow cover (mid-December to early April), the CO 2 flux was low (0.45 ± 0.43 μmol m ?2 s ?1). Total annual respiration was estimated at 679 ± 174 g cm ?2, about 8 % of which occurred during the season of snow cover. 相似文献
9.
To reduce CO 2 emissions from alcoholic fermentation, Arthrospira platensis was cultivated in tubular photobioreactor using either urea or nitrate as nitrogen sources at different light intensities (60 μmol m ?2 s ?1?≤? I?≤?240 μmol m ?2 s ?1). The type of carbon source (pure CO 2 or CO 2 from fermentation) did not show any appreciable influence on the main cultivation parameters, whereas substitution of nitrate for urea increased the nitrogen-to-cell conversion factor ( Y X/N ), and the maximum cell concentration ( X m ) and productivity ( P X ) increased with I. As a result, the best performance using gaseous emissions from alcoholic fermentation ( X m ?=?2,960?±?35 g m ?3, P X ?=?425?±?5.9 g m ?3 day ?1 and Y X/N ?=?15?±?0.2 g g ?1) was obtained at I?=?120 μmol m ?2 s ?1 using urea as nitrogen source. The results obtained in this work demonstrate that the combined use of effluents rich in urea and carbon dioxide could be exploited in large-scale cyanobacteria cultivations to reduce not only the production costs of these photosynthetic microorganisms but also the environmental impact associated to the release of greenhouse emissions. 相似文献
10.
Abstract Ambient PM 2.5 data in the Central Business District (CBD) of Bangkok monitored by Pollution Control Department and Bangkok Metropolitan Administration were collected over three years in Bangkok from 2015 to 2017. The other air pollutions data were used as the dependent variables to develop mathematic models with statistical distribution technique. Multiple linear regression technique was selected as the main statistical distribution methodology for estimating PM 2.5 concentrations in non-monitored areas. The predicted PM 2.5 concentrations were validated against the measured PM 2.5 concentrations by various statistical techniques. The validation found that the model had strong significant correlations for ambient and roadside area with R 2?=?0.88 and 0.96, respectively. The non-carcinogenic health risk assessment of PM 2.5 was quantified as the hazard quotient (HQ) from both the measured and predicted data. The risk areas and HQ were compared using the inverse distance weighting interpolation technique and illustrated as GIS-based maps. During December to February, the HQ values of PM 2.5 were exceed 1 (HQs?>?1) at all area of CBD; however, the highest HQ was found in the southern part of CBD. The finding could be used for residential health awareness in that area. 相似文献
11.
Indigenous broadleaf plantations are increasingly developing as a prospective silvicultural management approach for substituting in place of large pure conifer plantations in subtropical China. However, little information is known about the effects of tree species conversion on soil-atmosphere greenhouse gas (GHG) exchanges. Four adjacent monospecific plantations were selected in subtropical China to examine the effects of tree species on soil-atmosphere exchanges of N 2O, CH 4 and CO 2. One coniferous plantation was composed of Pinus massoniana (PM), and the three broadleaf plantations were Castanopsis hystrix (CH), Michelia macclurei (MM) and Mytilaria laosensis (ML). We found that mean soil N 2O and CO 2 emissions in the PM plantation were 4.34 μg N m ?2?h ?1 and 43.25 mg C m ?2?h ?1, respectively, lower than those in the broadleaf plantations (>5.25 μg N m ?2?h ?1 and >56.38 mg C m ?2?h ?1). The PM plantation soil had higher mean CH 4 uptake (39.03 μg C m ?2?h ?1) than the broadleaf plantation soils (<32.67 μg C m ?2?h ?1). Variations in soil N 2O emissions among tree species could be primarily explained by the differences in litter C:N ratio and soil total N stock. Differences in soil CH 4 uptake among tree species could be mostly attributed to the differences in mean soil CO 2 flux and water filled pore space (WFPS). Litter C:N ratio could largely account for variations in soil CO 2 emissions among tree species. This study confirms that there is no GHG benefit of converting PM plantation to broadleaf plantations in subtropical China. Therefore, the future strategy of tree species selection for substituting in place of large coniferous plantations in subtropical China needs to consider the potential effects of tree species on soil-atmosphere GHG exchanges. 相似文献
12.
In recent years, monitoring of airborne bacteria and fungi concentrations has obtained increasing universal attraction not only for influences on ecological balance but also for evaluating their public health consequences. In this study, we aimed to investigate culturable airborne bacteria and fungi levels in different sites of Abadan, and their association with meteorological parameters and PM2.5 levels. Abadan is one of the most industrialized cities in the southwest of Iran where over the current decade has experienced lots of dust storm episodes. In total, 400 air samples were collected in 6 months (autumn and winter) using a single-stage viable Andersen cascade impactor for sampling airborne bacteria and fungi and portable DustTrak Aerosol Monitor 8520 for measuring PM2.5 concentrations and meteorological parameters. Microbial concentrations showed a significant difference between various sites over the study period with averages of 569.57?±?312.64 and 482.73?±?242.86 CFU/M3 for bacteria and fungi, respectively. The air temperature had a significant effect on the concentration of both airborne bacteria and fungi. A significant positive correlation between relative humidity and fungi but no correlation between relative humidity and bacteria concentrations were observed. The average airborne PM2.5 concentrations of all sites among the study period was 93.24?±?116.72 μg/m3. The atmospheric bacterial and fungal communities were strongly positively correlated with the ambient PM2.5 level. The levels of airborne bacteria and fungi along with PM2.5 in the air of the city were relatively higher than the recommended levels. Therefore, the best course of action is needed to control emission sources. Further studies are also needed to evaluate the clinical analysis of the health effects of exposure to these pollutants. 相似文献
13.
The air PM 2.5 concentration and its heavy metal content (Fe, Pb, Mn, Ni, As) were measured in the Metropolitan Area of Monterrey, Méxicoin Mexico, an area that is characterized by both very active and diverse industrial activity and intense highway traffic and industrial activity. The 24-h PM 2.5 samples were collected in two different zones during a 1-year-long measurement program (February 2008–February 2009). The year PM 2.5 average was above 15 μg/m 3 exceeding Mexican and international standards. The difference of PM 2.5 in each zone was not statistically significant. The greatest metal content was for iron, followed by lead, manganese, nickel and arsenic. The difference in metal content for Pb, Mn, and As was statistically significant. 相似文献
14.
The transfer of carbon (C) from Amazon forests to aquatic ecosystems as CO 2 supersaturated in groundwater that outgases to the atmosphere after it reaches small streams has been postulated to be an important component of terrestrial ecosystem C budgets. We measured C losses as soil respiration and methane (CH 4) flux, direct CO 2 and CH 4 fluxes from the stream surface and fluvial export of dissolved inorganic C (DIC), dissolved organic C (DOC), and particulate C over an annual hydrologic cycle from a 1,319-ha forested Amazon perennial first-order headwater watershed at Tanguro Ranch in the southern Amazon state of Mato Grosso. Stream pCO 2 concentrations ranged from 6,491 to 14,976 ??atm and directly-measured stream CO 2 outgassing flux was 5,994 ± 677 g C m ?2 y ?1 of stream surface. Stream pCH 4 concentrations ranged from 291 to 438 ??atm and measured stream CH 4 outgassing flux was 987 ± 221 g C m ?2 y ?1. Despite high flux rates from the stream surface, the small area of stream itself (970 m 2, or 0.007% of watershed area) led to small directly-measured annual fluxes of CO 2 (0.44 ± 0.05 g C m 2 y ?1) and CH 4 (0.07 ± 0.02 g C m 2 y ?1) per unit watershed land area. Measured fluvial export of DIC (0.78 ± 0.04 g C m ?2 y ?1), DOC (0.16 ± 0.03 g C m ?2 y ?1) and coarse plus fine particulate C (0.001 ± 0.001 g C m ?2 y ?1) per unit watershed land area were also small. However, stream discharge accounted for only 12% of the modeled annual watershed water output because deep groundwater flows dominated total runoff from the watershed. When C in this bypassing groundwater was included, total watershed export was 10.83 g C m ?2 y ?1 as CO 2 outgassing, 11.29 g C m ?2 y ?1 as fluvial DIC and 0.64 g C m ?2 y ?1 as fluvial DOC. Outgassing fluxes were somewhat lower than the 40?C50 g C m ?2 y ?1 reported from other Amazon watersheds and may result in part from lower annual rainfall at Tanguro. Total stream-associated gaseous C losses were two orders of magnitude less than soil respiration (696 ± 147 g C m ?2 y ?1), but total losses of C transported by water comprised up to about 20% of the ± 150 g C m ?2 (±1.5 Mg C ha ?1) that is exchanged annually across Amazon tropical forest canopies. 相似文献
15.
Netrium digitus is a representative of the species-rich class Zygnematophyceae (Streptophyta). Its intensive extracellular polysaccharide (EPS) production makes this alga interesting for biotechnological applications with a focus on cosmetics and food additives. Quantitative data on growth and EPS production in suspension and, for the first time, in immobilized culture using lab-scale porous substrate bioreactors, so-called Twin-Layer (TL) systems, is presented. It is shown that the cell as well as the EPS dry weight content is increased at least sixfold in immobilized compared to suspension culture. Due to the high amount of EPS, the biofilms reach a thickness of more than 8 mm after 27 days at 70 μmol photons m ?2 s ?1 and with 1.5% CO 2 supply. Frequent exchange of the growth medium results in a linear cell biomass increase of 2.02?±?0.09 g m ?2 growth area day ?1 compared to 2.99?±?0.09 g m ?2 day ?1, when the medium is not exchanged. Under this mode of cultivation, the EPS production is lower and a final concentration of 12.18?±?1.25 g m ?2 compared to 20.76?±?0.85 g m ?2, when medium was exchanged, is reached. It is clearly demonstrated that the relatively slow growing, but excessively EPS producing, microalgal species N. digitus can be grown in porous substrate bioreactors and that this culturing technique is a promising alternative to suspension culture for the Zygnematophyceae. 相似文献
16.
The biomass productivity of Scenedesmus obliquus was investigated outdoors during all seasons in solar tracked flat panel photobioreactors (PBR) to evaluate key parameters for process optimization. CO 2 was supplied by flue gas from an attached combined block heat and power plant. Waste heat from the power plant was used to heat the culture during winter. The parameters pH, CO 2, and inorganic salt concentrations were automatically adjusted to nonlimiting levels. The optimum biomass concentration increased directly with the photosynthetic active radiation (PAR) from 3 to 5 g dry weight (DW)?L ?1 for a low PAR of 10 mol photons m ?2 day ?1 and high PAR of 40–60 mol photons m ?2 day ?1, respectively. The annual average biomass yield (photosynthetic efficiency) was 0.4?±?0.5 g DW mol ?1 photons. However, biomass yields of 1.5 g DW mol ?1 photons close to the theoretical maximum were obtained at low PAR. The productivity (including the night biomass losses) ranged during all seasons from ?5 up to 30 g DW m ?2 day ?1 with a mean productivity of 9?±?7 g DW m ?2 day ?1. Low night temperatures of the culture medium and elevated day temperatures to the species-specific optimum increased the productivity. Thus, continuous regulation of the biomass concentration and the culture temperature with regard to the fluctuating weather conditions is essential for process optimization of outdoor microalgal production systems in temperate climates. 相似文献
17.
This study evaluated the effects of supplemental dietary chromium (Cr) on the performance, carcass traits, and some serum parameters of broilers under a heat stress (23.9 to 37 °C cycling) condition. A total of 150 1-day-old broiler chicks (Cobb 500) according to a completely randomized design were assigned into five treatment groups. Each treatment consisted of three replicates and each replicate contained ten chicks. Treatments were supplemented with 0 (control), 600, and 1,200 μg kg ?1 Cr in the form of Cr chloride (CrCl 3) and Cr L-methionine from 1 to 49 days of age. Blood samples were collected from two birds in each replicate to determine serum parameters at 35 and 49 days of age. The body mass, feed intake, and conversion ratio were not influenced by dietary Cr ( P?>?0.05). Dietary supplementation of Cr from either CrCl 3 or Cr L-methionine caused increased serum concentrations of Cr ( P?<?0.05), but had no effect on serum insulin and glucose concentrations at both sampling times ( P?>?0.05). Serum triglycerides, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were also not significantly affected ( P?>?0.05) by dietary treatments, whereas total cholesterol concentration decreased in chicks fed Cr L-methionine compared to the control ( P?<?0.05). 相似文献
18.
Objective: The influence of different exposures to PM 2.5 (particulate matter with an aerodynamic diameter below 2.5?μm) on the concentrations of biomarkers of exposure and oxidative stress should be investigated. For this purpose, urine samples from individuals travelling from Germany to China were collected and analysed. Materials: Robust LC and LC-MS/MS methods were established for the determination of biomarkers including 8-hydroxy-2′-deoxyguanosine, malondialdehyde, F2α-isoprostanes and hydroxylated polycyclic aromatic hydrocarbons. As a pilot study, nine volunteers travelled from Germany (mean daily concentration of PM2.5: 21?μg/m3) to China (mean daily concentration of PM2.5: 108?μg/m3). Urine samples were collected before and after the trip. Results: In samples collected after return to Germany, the median concentrations of oxidative stress biomarkers were observed to be higher than in samples collected before leaving Germany. Decreasing trends were observed in the sequences of samples collected after return in the following weeks. Correlations were found between exposure and oxidative stress biomarkers. Conclusion: Travellers are ideal models for PM pollution-induced acute health effects study. Exposure to PM pollution can cause oxidative stress and damage. 相似文献
19.
Respiration and calcification rate were estimated to quantify the effect of Zhikong scallop Chlamys farreri on marine CO 2 system in Sanggou Bay, China. The C. farreri population in Sanggou Bay sequestered 78.06?±?5.76 g C m ?2 y ?1 for shell formation, while the CO 2 fluxes due to calcification and respiration were 53.95?±?3.98 and 71.69?±?6.51 g C m ?2 y ?1, respectively. In order to eliminate the additional CO 2 released from calcification and respiration process of C. farreri, Gracilaria lemaneiformis were introduced into the integrated system and its role was validated by in situ mesocosm methods. Eight mesocosms (1,000 L) were deployed over 42-h period and consisted of four treatments: seaweed-only, scallop-only (SP), seaweed integrated with scallop (SS), and control (C). The aqueous CO 2 concentration and partial pressure of CO 2 in SP treatments were significantly higher than the other three treatments ( p?<?0.01), while there were no difference between SS treatments and C treatments ( p?>?0.05). Furthermore, compared with the SP treatments, the presence of the G. lemaneiformis can keep the seawater pH stable. These findings suggest that seaweed and shellfish integrated aquaculture practice cannot only reduce dissolved inorganic carbon but also can alleviate ocean acidification. 相似文献
20.
Response of Aphanizomenon ovalisporum to certain environmental parameters was studied to gain a better understanding of the conditions which may have stimulated its autumnal bloom in Lake Kinneret. Optimal temperature for A. ovalisporum growth was 26–30?°C, resulting in growth rates of 0.2–0.3?day ?1, similar to those observed in the lake. Maximal rate of CO 2 fixation (assimilation numbers of 6–8?μg?C?μg ?1?Chl?h ?1) was obtained at low irradiances ( I k of 40–100?μmol?photons?m ?2?s ?1), 200?μM Pi and low N:Pi ratios. Growth was strongly affected by phosphorus availability, reaching a maximum at Pi concentrations above 40?μM. The high demand for phosphorus was indicated by an increase in alkaline phosphatase activity. The relative abundance of Pi in the cells increased by 4-fold in Pi-rich compared with Pi-limited cultures. Uptake of Pi was faster in Pi-depleted compared with Pi-sufficient cells. Maximal photosynthetic rates and K 1/2(HCO 3 ?) were 140–220?μmol?O 2?mg ?1?Chl?h ?1 and 10–24?μM, respectively. At pH 7.0 the K 1/2(CO 2) was 2.2 and fell to 0.04?μM at pH 9.0. These data indicated that A. ovalisporum is a HCO 3 ? user, and can explain its high photosynthetic rates during the bloom, under high pH and low dissolved CO 2 conditions. Na + concentrations of about 5?mM were essential for A. ovalisporum growth at high pH approaching values in the lake. 相似文献
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