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1.
1998/1999年南极普里兹湾邻近海域浮游植物的分布特征 总被引:3,自引:0,他引:3
中国第 1 5次南大洋考察从普里兹湾邻近海域获得 2 5个测站的浮游植物样品 ,主要研究了其种类组成、分布及其与环境的关系。浮游植物有 5门 1 6科 2 1属 48种 (变种和变型 ) ,浮游植物平均细胞密度为 2 2 .46× 1 0 3个 /dm3,其中以硅藻类占优势 (84.51 % )。浮游植物分布以近海岸陆架区的细胞密度最高 (4 6 .0 3× 1 0 3个 /dm3) ,其次为陆坡 (4 .40× 1 0 3个 /dm3) ,深海区最低 (3.34× 1 0 3个 /dm3)。表层叶绿素a浓度为 0 .1 6~ 3.99μg/dm3,普里兹湾内和湾西部四女士浅滩海域浓度在 3.5μg/dm3以上 ;平面分布趋势浓度从湾内向西北方向递减 ,深海区浓度在 0 .5μg/dm3以下。浮游植物优势种为硅藻的短拟脆杆藻 (Fragilariopsiscurta)。浮游植物垂直分布密集区位于 0~ 50m水层 ,1 0 0m或 1 0 0m以下水层随深度的增加而细胞密度逐渐减少 ,2 0 0m水层稀少或未见。其密集区位于普里兹湾近岸陆架区 ,而陆坡及深海区细胞密度显著减少。叶绿素a浓度的最大值同样分布在 2 5m或 50m层 ,50m以下的浓度随深度的增加而降低 ,2 0 0m层叶绿素a浓度分布范围为 0 .0 1~ 0 .95μg/dm3。粒径分级叶绿素a浓度以微小型浮游生物的贡献占优势 (56 % ) ,微型浮游生物的贡献占 2 4% ,微微型浮游生物的贡献占 2 0 %。经回 相似文献
2.
楚科奇海及其海台区粒度分级叶绿素a与初级生产力 总被引:1,自引:0,他引:1
2003年夏季中国第二次北极科学考察期间,在楚科奇海及其海台区进行了叶绿素a浓度与初级生产力的现场观测。结果表明,观测海区叶绿素a浓度范围为0.009~30.390μg/dm3。表层浓度为0.050~4.644μg/dm3,平均值为(0.875±0.981)μg/dm3;陆架区次表层和底层的浓度高于表层,海台区深层水的浓度较低,200m层的浓度为(0.015±0.007)μg/dm3。水柱平均叶绿素a浓度区域性特征明显,陆架区高于海台区。R断面进行3趟重复观测,平均叶绿素a浓度分别为(2.564±1.496)μg/dm3,(1.329±0.882)μg/dm3和(0.965±0.623)μg/dm3,浓度呈下降趋势。观测站潜在初级生产力为0.263~4.186mgC/(m.3h),陆架区平均潜在初级生产力((2.305±1.493)mgC/(m.3h))比海台区((0.527±0.374)mgC/(m.3h))高近4倍。平均同化数为(1.22±1.14)mgC/(mgChla.h)。观测区细胞粒径>20μm的小型浮游生物对总叶绿素a浓度和初级生产力的贡献率分别为63.13%和65.16%,细胞粒径2.0~20μm的微型浮游生物和细胞粒径<2.0μm的微微型浮游生物对总叶绿素a和初级生产力的贡献率相差甚小,其对总叶绿素a浓度的贡献率分别为19.18%和17.69%,对总初级生产力的贡献率分别为20.11%和14.73%。 相似文献
3.
中国第15次南大洋考察从普里兹湾邻近海域获得25个测站的浮游植物样品,主要研究了其种类组成、分布及其与环境的关系.浮游植物有5门16科21属48种(变种和变型),浮游植物平均细胞密度为22.46×103个/dm3,其中以硅藻类占优势(84.51%).浮游植物分布以近海岸陆架区的细胞密度最高(46.03×103个/dm3),其次为陆坡(4.40×103个/dm3),深海区最低(3.34×103个/dm3).表层叶绿素a浓度为0.16~3.99 μg/dm3,普里兹湾内和湾西部四女士浅滩海域浓度在3.5 μg/dm3以上;平面分布趋势浓度从湾内向西北方向递减,深海区浓度在0.5 μg/dm3以下.浮游植物优势种为硅藻的短拟脆杆藻(Fragilariopsis curta).浮游植物垂直分布密集区位于0~50 m水层,100 m或100 m以下水层随深度的增加而细胞密度逐渐减少,200 m水层稀少或未见.其密集区位于普里兹湾近岸陆架区,而陆坡及深海区细胞密度显著减少.叶绿素a浓度的最大值同样分布在25 m或50 m层,50 m以下的浓度随深度的增加而降低,200 m层叶绿素a浓度分布范围为0.01~0.95 μg/dm3.粒径分级叶绿素a浓度以微小型浮游生物的贡献占优势(56%),微型浮游生物的贡献占24%,微微型浮游生物的贡献占20%.经回归统计分析,浮游植物细胞丰度(y)与水温(T)、盐度成正相关,与营养盐(PO4 (P)、NO-3 (N)、SiO3 (Si))成显著负相关. 相似文献
4.
獐子岛及邻近海域秋季浮游植物的粒级结构及其影响因素 总被引:2,自引:0,他引:2
于2015年10月对獐子岛及邻近海域进行了航次调查,研究了獐子岛及邻近海域浮游植物粒级结构的空间分布特征及其环境影响因素。结果表明,秋季表层总叶绿素a、小型(20μm)、微型(2—20μm)和微微型(0.45—2μm)浮游植物叶绿素a浓度的范围分别为0.52—1.25、0.03—0.81、0.33—0.91、0—0.09μg/L,平均叶绿素a的浓度分别为0.76、0.19、0.53、0.03μg/L,对叶绿素a总量的贡献率分别为23.77%、72.26%和3.98%;底层总叶绿素a、小型(20μm)和微型(2—20μm)浮游植物叶绿素a浓度的范围分别为0.14—1.5、0.04—1.04、0.08—0.47μg/L,平均叶绿素a的浓度分别为0.46、0.22、0.24μg/L,对叶绿素a总量的贡献率分别为41.46%、58.50%。从垂直分布上来看,总叶绿素a浓度垂直变化为,表层底层;小型浮游植物垂直分布较为均匀;微型浮游植物垂直变化为,表层底层;微微型浮游植物垂直变化为,表层底层,且在表、底层均保持较低水平。秋季表层微型浮游植物(2—20μm)浓度与盐度呈正相关。底层总叶绿素a浓度与磷酸盐浓度呈正相关,小型浮游植物(20μm)浓度与磷酸盐和硅酸盐浓度均表现为正相关,微型浮游植物(2—20μm)浓度与温度呈正相关。统计分析结果表明,温度、盐度、磷酸盐及硅酸盐浓度是影响獐子岛及邻近海域秋季浮游植物粒级结构变动的重要因素。 相似文献
5.
白令海光合浮游生物现存量和初级生产力 总被引:3,自引:1,他引:2
2003年7~9月中国第2次北极科学考察在北太平洋和白令海的BR断面和白令海峡南口门的BS断面的初夏和夏末两航段进行叶绿素-a浓度和初级生产力的现场观测。结果表明,BR断面表层叶绿素-a浓度为0·199~1·170μg/dm3,平均值为(0·723±0·283)μg/dm3;水深10~30m次表层的叶绿素-a浓度明显高于真光层下的深层水。水柱平均叶绿素-a浓度呈现明显的区域性特征,白令陆架区>白令陆坡区>阿留申海盆区>北太平洋西部海域。BS断面叶绿素-a浓度高于BR断面,夏末的平均浓度((5·311±5·656)μg/dm3)是初夏浓度((1·605±1·194)μg/dm3)的3.3倍,是BR断面平均浓度的7·5倍。观测站真光层内初级生产力在0·471~19·046mgC/(m3·h),陆架海域的初级生产力明显高于陆坡和海盆区,BS断面的平均初级生产力比BR断面高约12倍。观测站光合作用同化数在0·45~2·80mgC/(mgChla·h)。 相似文献
6.
桑沟湾春季叶绿素a浓度分布及其影响因素 总被引:1,自引:0,他引:1
依据2014年5月走航和定点连续调查资料,分析了桑沟湾叶绿素a的空间分布及昼日变化特征,结合理、化环境因素的相关性分析,探讨影响叶绿素a浓度的主要因素。(1)走航调查的结果显示,桑沟湾春季叶绿素a浓度较低,叶绿素a浓度范围为0.11—1.40μg/L,平均为(0.64±0.36)μg/L。叶绿素a浓度从湾内向湾外逐步降低,贝类区混养区海带区外海区;湾内表层叶绿素a浓度均高于底层,而湾外的非养殖区则相反(2)网箱区叶绿素a浓度最高,日平均为1.70μg/L,显著高于其它3个区;海草区最低,为0.57μg/L,与海带养殖区无显著性差异,显著低于贝类养殖区和网箱区。叶绿素a浓度的总体趋势为:网箱区贝类区海带区和海草区。而且,不同养殖区域,叶绿素a浓度昼夜变化规律各不相同,反映了养殖活动的影响。海草区白天表层高于底层,而夜间则相反;网箱区底层均高于表层;贝类区表层均高于底层;海带区表底层叶绿素a浓度呈现出升降交替的规律。(3)叶绿素a浓度与硅酸盐、水温显著正相关,与其他环境因子,如氨氮、亚硝酸盐、磷酸盐等无显著相关性。硅酸盐和温度可能为影响桑沟湾春季浮游植物生长的主要限制性因素。(4)桑沟湾春季浮游植物生长受多重因素的限制,湾内营养盐浓度与叶绿素a浓度并未呈现显著的规律性,营养盐的上行控制和贝类摄食的下行控制均能影响浮游植物的生长。 相似文献
7.
2006年夏季南黄海浮游植物叶绿素a分布特征及其环境调控机制 总被引:7,自引:0,他引:7
根据2006年夏季南黄海生态调查资料,分析了浮游植物现存量(叶绿素a)的空间分布特征及其主要环境调控机制.结果表明:南黄海浮游植物叶绿素a浓度范围为0.07~12.17 mg/m3,平均值为1.42 mg/m3;浮游植物叶绿素a平面分布呈近岸混合区高于外海层化区的特征,总体上随水体盐度和营养盐梯度的变化而变化,其中浅海陆架锋区对浮游植物有明显的聚集作用,垂直结构中层化区叶绿素次表层最大值现象明显,且最大值的深度和量值具有明显的区域差异;叶绿素a浓度与主要环境因子的相关性分析表明,在较大空间尺度上营养盐是浮游植物的主要调控因子,温度、光照和浮游动物摄食等也在一定空间和程度上对浮游植物的生长产生影响. 相似文献
8.
春季季风转换期间孟加拉湾的初级生产力 总被引:1,自引:0,他引:1
2010年中国科学院东北印度洋科学考察期间,对孟加拉湾水域初级生产力展开了研究.孟加拉湾表层水体的水温较高,盐度变化范围较大,且上层水体营养盐含量较低,在真光层底部营养盐浓度突然增加.表层叶绿素a浓度较低(<0.1 mg/m3),叶绿素a最大值常出现在75 m水深处,上层水体浮游植物的生长受氮限制明显.表层潜在初级生产力低于0.2mgcm-3h-1,且初级生产速率在50-75 m出现最大值.水柱中初级生产力变化范围为199-367 mgCm-2d-1,高值出现在88°-89°(E)附近.浮游植物固碳的主要贡献者是微微型浮游生物(<3 μm),其次是小型浮游生物(>20 μm)和微型浮游生物(3-20 μm),但表层与75 m水深处固碳浮游植物的结构有一定差异.将孟加拉湾与阿拉伯海初级生产力进行对比,孟加拉湾水体初级生产力显著低于阿拉伯海,且初级生产力的影响因素有着显著的差异. 相似文献
9.
于2016年1月对獐子岛海域进行了航次调查,研究了獐子岛海域浮游植物粒级结构的空间分布特征及其环境影响因素。结果表明:冬季表层总叶绿素a、小型(20μm)、微型(2~20μm)和微微型(0.45~2μm)浮游植物叶绿素a浓度的范围分别为0.24~0.92、0.15~0.58、0.09~0.46、0~0.03μg·L-1,平均叶绿素a的浓度分别为0.69、0.36、0.33、0.002μg·L-1,小型、微型和微微型浮游植物对浮游植物总量的贡献率分别为51.72%、48.01%、0.26%;底层总叶绿素a、小型、微型和微微型浮游植物叶绿素a浓度的范围分别为0.29~1.77、0.12~1.45、0.17~0.50、0μg·L-1,平均叶绿素a的浓度分别为0.78、0.43、0.34、0μg·L-1,小型、微型和微微型浮游植物对浮游植物总量的贡献率分别为52.97%、47.03%、0;从垂直分布上来看,表、底层总叶绿素a及两种粒级浮游植物(20μm、2~20μm)的浓度均差异不显著,分布较为均匀;从水平分布上来看,总叶绿素a及两种粒级浮游植物(20μm、2~20μm)浓度的表、底层空间分布趋势相近,均呈现出由獐子岛海域西北部向南部逐渐降低的趋势。RDA分析表明,温度、盐度、溶解氧、颗粒态有机物、NO2--N和NH4+-N是影响獐子岛海域冬季浮游植物粒级结构变动的重要因素。 相似文献
10.
胶州湾叶绿素a浓度及浮游植物的粒级组成 总被引:2,自引:0,他引:2
2008年2、5、8和11月对胶州湾及邻近水域中表层叶绿素a浓度和浮游植物粒级组成进行了调查.结果表明:胶州湾内和湾外表层叶绿素a年平均浓度分别为4.90和2.03 mg·m-3;叶绿素a浓度的平面分布呈现自东北部及近岸向中部、南部及湾外递减的趋势;叶绿素a浓度季节变化明显,冬季和夏季浓度较高,春季次之,呈现温带海域双峰型的变化趋势.胶州湾浮游植物粒级组成以微型浮游植物为主,平均占叶绿素a总量的60.9%,其次是小型浮游植物,超微型浮游植物所占比例最低,与我国近海浮游植物粒级组成基本一致.与历史资料相比,微型浮游植物所占比例有所增加,超微型浮游植物所占比例降低. 相似文献
11.
R.J. Murphy T.J. Tolhurst M.G. Chapman A.J. Underwood 《Journal of experimental marine biology and ecology》2005,316(1):69-77
During low tide, field spectrometric data (350-1050 nm) were acquired from intertidal mudflats in the upper reaches of Sydney Harbour, after which samples of sediment were taken using a small contact core. A total of 103 spectra/sediment pairs of samples were acquired. In the laboratory, amounts of chlorophyll in the contact cores were determined spectrophotometrically. The proportion of fine sediment (<63 μm), a major factor influencing bulk-density of sediment, was measured.The relationship between the remotely sensed observations and the amounts of chlorophyll was investigated by comparing chlorophyll expressed as a mass per unit area (area-normalised values) and as a mass per unit mass (content or weight-normalised values) with: (i) reflectance between 350 and 1050 nm and (ii) a ratio of reflectance at 562 and 647 nm (R562/R647). The reflectance at wavelengths >400 nm were found to be more tightly correlated with area-normalised chlorophyll (maximal correlation=−0.51 at 666 nm) than with weight-normalised chlorophyll (maximal correlation=−0.41 at 664 nm). The relationship between R562/R647 and area-normalised chlorophyll was stronger (R2=0.66) than for weight-normalised chlorophyll (R2=0.47). The residuals from the regression of weight-normalised chlorophyll on R562/R647 were strongly correlated with the mass per unit mass of sediment that was <63 μm. There was no such relationship for residuals from the regression of area-normalised chlorophyll on R562/R647. The results demonstrate conclusively that chlorophyll measured as mass per unit mass of sediment, is inappropriate for ground-truthing remotely sensed observations of chlorophyll in intertidal benthic sediments. 相似文献
12.
东海赤潮高发区沉积物中叶绿素的分析 总被引:11,自引:3,他引:8
研究分析了2002年8~9月“赤潮973”航次所采集的沉积物中叶绿素a及其降解产物脱镁叶绿酸含量与分布.结果表明。叶绿素a和脱镁叶绿酸是同源的;随深度增加叶绿素a和脱镁叶绿酸的含量呈递减趋势,到一定深度后含量不再变化。个别站位叶绿素a和脱镁叶绿酸的垂直分布出现了许多小突跃,可能是由生物扰动引起;表层沉积物(0~0.5cm)中的叶绿素a和脱镁叶绿酸的变化幅度分别为0.14~1.17和0.83~5.58μg·g-1。平均值分别为0.54和2.45μg·g-1;并初步探讨水深(光强)、盐度、温度、含水量对叶绿素水平分布的影响;脱镁叶绿酸作为叶绿素的主要降解产物,到一定深度后,成为叶绿素的主要存在形式,约占80%~90%;由于水温的不同,夏季沉积物中的叶绿素a和脱镁叶绿酸含量是春季的3倍之多;比较了上层水柱中的叶绿素和沉积物中的叶绿素的相对含量,平均而言,沉积物中叶绿素占上层水柱中叶绿素的31%. 相似文献
13.
SUMMARY The presence of sediment at concentrations of 0,2% by mass in water samples significantly lowered the amount of chlorophyll a that could be measured. Two types of sediment differed in their ability to lower the chlorophyll a concentration. The chemically more active sediment had a marked depressive effect on the chlorophyll a concentration and the relationship between chlorophyll a and cell numbers in the samples was non-linear. It is recommended that the use of chlorophyll a as an indicator of biomass in water containing sediment should be approached with care. 相似文献
14.
How does the vertical distribution of chlorophyll vary in littoral sediments of small lakes? 总被引:1,自引:0,他引:1
Hélène Cyr 《Freshwater Biology》1998,40(1):25-40
1. In this study, sediment chlorophyll profiles at twenty littoral stations in three oligo‐mesotrophic lakes were compared to test whether the vertical distribution of chlorophyll is related to site characteristics (light availability, temperature, physical disturbances) and whether these profiles differ between shallow and deep portions of the littoral zone.
2. The magnitude of chlorophyll peaks at the sediment surface did not vary with light intensity. Chlorophyll peaks in the shallow littoral zone had a weak tendency to decrease with increasing effective fetch. The magnitude of chlorophyll peaks at deeper sites was more closely related to water temperature than to substrate slope.
3. High chlorophyll concentrations were measured down to 1–3 cm in the sediments, both at shallow (< 2.5 m) and deep (4–10 m) stations. The depth to which high chlorophyll was found in sediments did not vary with effective fetch or sediment water content, two indices of wave disturbance in the shallow littoral zone, or with substrate slope, an index of sediment stability in the deep littoral zone. Sediment mixing is apparently not related to common indices of physical disturbances.
4. Between 8 and 100% of sediment surface chlorophyll was 'retained' 4–5 cm into the sediments. The proportion of chlorophyll 'retained' in littoral sediments increased with increasing depth, increasing lake productivity (total phosphorus concentration) and increasing lake pH.
5. Among‐core variability (standard error/mean) in chlorophyll concentration at the sediment surface ranged from less than 1% to 33% at different stations and was highest at shallow, exposed sites. These levels of variability are similar to those found in other periphytic communities. 相似文献
2. The magnitude of chlorophyll peaks at the sediment surface did not vary with light intensity. Chlorophyll peaks in the shallow littoral zone had a weak tendency to decrease with increasing effective fetch. The magnitude of chlorophyll peaks at deeper sites was more closely related to water temperature than to substrate slope.
3. High chlorophyll concentrations were measured down to 1–3 cm in the sediments, both at shallow (< 2.5 m) and deep (4–10 m) stations. The depth to which high chlorophyll was found in sediments did not vary with effective fetch or sediment water content, two indices of wave disturbance in the shallow littoral zone, or with substrate slope, an index of sediment stability in the deep littoral zone. Sediment mixing is apparently not related to common indices of physical disturbances.
4. Between 8 and 100% of sediment surface chlorophyll was 'retained' 4–5 cm into the sediments. The proportion of chlorophyll 'retained' in littoral sediments increased with increasing depth, increasing lake productivity (total phosphorus concentration) and increasing lake pH.
5. Among‐core variability (standard error/mean) in chlorophyll concentration at the sediment surface ranged from less than 1% to 33% at different stations and was highest at shallow, exposed sites. These levels of variability are similar to those found in other periphytic communities. 相似文献
15.
Reconstruction of historical productivity using visible-near-infrared (VNIR) reflectance properties from boreal and saline lake sediments 总被引:2,自引:0,他引:2
Biplob Das 《Aquatic Ecology》2007,41(2):209-220
Chlorophylls preserved in lake sediments have been used as a proxy to infer past trophic status. Recently, it has been demonstrated
that visible-near-infrared (VNIR) reflectance spectroscopy can provide a rapid and non-destructive estimation of fossil chlorophylls
from alpine lake sediments. The present study explores, (a) the applicability of VNIR reflectance spectroscopy to reconstructing
historical productivity from boreal and saline lakes, and (b) the ability of an inference model combining all lake types to
reconstruct historical chlorophyll concentrations from lake sediments. Results revealed that regardless of the lake type,
a common sediment spectral feature of a reflectance trough centered near 675 nm, was observed. Additionally, the amplitude
of reflectance in the VNIR region differs within and among lakes depending on their trophic states. The inferred concentration
of total chlorophylls and derivatives from sediment spectral properties reflected a recent nutrient enrichment in most of
the study lakes. Predicted chlorophyll concentration, when plotted against high-pressure liquid chromatography (HPLC) measured
concentration combining all lake types, was found to be statically significant (r
2 = 0.80, P < 0.01). Collectively, results from this study indicate that regardless of the lake type, a common chlorophyll absorption
feature near 675 nm can be detected, which is associated with contrasting limnological settings and, therefore, can be used
as a viable tool to reconstruct paleoproductivity. A similar approach can be implemented for rapid and non-destructive detection
of historical lake water quality in a wide range of lake sediments. 相似文献
16.
Laurent Barillé Vona Méléder Jean-Philippe Combe Patrick Launeau Véronique Carrère 《Journal of experimental marine biology and ecology》2007,343(2):197-209
Benthic diatom biomass on an intertidal mudflat was estimated by field spectrometry, a non-intrusive optical method operating in the visible-infrared wavelength range. Spectral reflectance (400-900 nm) of natural assemblages was related to the amount of principal photosynthetic and accessory pigments measured by high-performance liquid chromatography (HPLC) in the top 2 mm of sediment. Relationships established in situ were compared with those obtained in the laboratory with monospecific cultures. However, to compare both types of reflectance spectra differing in their overall shape (continuum) and to isolate the pigment absorption features from other effects, we applied hyperspectral data processing, the Modified Gaussian Model (MGM), to remove the continuum and model the main absorption bands by a succession of Gaussian curves. The Gaussian band depths associated with the absorption by chlorophyll a and the pigments specific to diatoms (chlorophyll c, fucoxanthine, diadinoxanthin) displayed linear relationships with the logarithm of chlorophyll a.The most relevant spectral feature to quantify the microalgal biomass in situ was the 632 nm absorption band associated with chlorophyll c. A significant but equivocal statistical relationship was obtained at 675 nm, due to the overlapping absorption by chlorophyll breakdown products (pheophytine a and pheophorbide a) present in all the samples analyzed in the field. Fucoxanthin absorption at 550 nm can become an indicator of chlorophyll a biomass for benthic diatoms, but the effect of seasonal photophysiological adaptation should be considered. The comparative analysis of field and laboratory reflectance showed that the chlorophyll a present in the top 2 mm was not a good estimator of the photosynthetic active biomass (PAB) and that a shallower depth should be sampled in muddy sediments colonized by microphytobenthos. The approach of MGM band depth retrieval offers the possibility of quantifying PAB and has the potential to characterize (by accessory pigments) microalgae present in the photic zone of different sediment types, removing albedo variability due to grain-size scattering effects or sediment moisture content. Its accuracy relies, however, on an appropriate ground-truth sampling, excluding the contribution of redundant pigments not detected by the sensor. 相似文献
17.
D. A. Scruton C. J. Pennell C. E. Bourgeois R. F. Goosney L. King R. K. Booth W. Eddy T. R. Porter L. M. N. Ollerhead K. D. Clarke 《Hydrobiologia》2008,596(1):225-239
Microalgal biofilms are associated with considerable variability in the properties of natural sediments, yet little effort
has been made to isolate micro-scale spatial and temporal changes in sediment properties caused by the growth of a biofilm.
Understanding the changes associated with biofilm growth and quantifying the time scales over which these changes occur is
important for developing suitable experimental designs and for understanding how biofilms mediate sediment properties and
processes. The development of a microphytobenthic biofilm and associated changes in the sediment was investigated over 45 days
in the laboratory. The biogeochemical properties of the sediment: bulk density, water content, chlorophyll a concentration and colloidal carbohydrate concentration were measured on a sub-millimetre scale in the top 2 mm. The erosion
threshold was measured with a Cohesive Strength Meter (CSM). Biofilm development was rapid, with changes in the properties
occurring after 1 day and a visible film forming after just 3 days. The largest changes in sediment properties tended to occur
in the surface 200 μm through time, with some variables also showing a differing response with depth. There were significant
changes in water content, chlorophyll a concentration, colloidal carbohydrate concentration and erosion threshold in the surface 2 mm, with a general trend to increase
with time. Bulk density was highly variable and did not show a consistent pattern of change with time. Erosion threshold was
positively correlated with water content, chlorophyll a and colloidal carbohydrate in the surface 200 μm and these were also positively correlated with each other. Low Temperature
Scanning Electron Microscopy (LTSEM) images revealed changes in the surface sediment structure and the formation of a thick
multi-layer biofilm. The rapidity of biofilm growth and development and the associated changes to the sediment should be considered
when designing experiments that investigate biofilms and properties of sediments and/or that involve biocide treatments or
disturbance to the sediment. 相似文献
18.
应用LOPEX'93(Leaf Optical Properties Experiment)数据,分析了统计回归模型在进行植被叶绿素和水分反演中抗土壤背景影响的能力,模型参数分别使用了:反射率及其变化形式、光谱位置变量、植被指数。在LOPEX'93数据库的植被波谱中分别加入10%-90%的实测土壤光谱信息,得到植被与土壤的混合光谱,并分析混合光谱对植被生化组分的响应。结果表明:应用反射率及其变化形式进行植被叶绿素反演时,以730nm和400nm组合的反射率和反射率倒数的对数为参数的模型具有最高的抗土壤背景能力,在土壤背景所占比例从低到高的变化过程中,以二者反射率组合为参数的模型与叶绿素的相关系数,始终保持在0.645附近,以二者反射率倒数的对数为参数的模型与植被叶绿素的相关系数保持在0.650附近;应用反射率及其变化形式进行植被含水量反演时,以1100,1170,1000,1040,1080nm组合的反射率为参数的模型以及以1170,960,1210,1090,1080,950,1220,1210nm反射率倒数的对数组合为参数的模型具有较高的稳定性,在土壤组分变化的过程中,以上模型与植被含水量的相关系数均稳定的高于0.99;对于光谱位置变量的分析中,以红边-绿峰-红谷组合的模型与植被叶绿素含量具有较高、而且稳定的相关系数,在土壤背景所占比例变化的情况下,相关系数稳定在0.53附近;在应用植被指数进行叶绿素的反演过程中,植被指数与叶绿素的相关系数在土壤背景所占比例变化的情况下变化较大,抗土壤背景的能力均较差;在应用植被指数进行植被水分含量的反演时,以水分指数Ratio975和Ratio1200相关系数最高,且在不同比例土壤背景变化下稳定,相关系数分别分布在0.980附近和0.960附近。该结果可用于指导不同植被覆盖条件下植被冠层参数的反演,提高反演的稳定性和准确性。 相似文献
19.
The relationship between chlorophyll a and fractionation of sediment phosphorus, inorganic phosphate-solubilizing bacteria (IPB), and organic phosphate-mineralizing bacteria (OPB) was evaluated in a large Chinese shallow eutrophic lake (Lake Taihu) and its embayment (Wuli Bay). At the three study sites, the increase of chlorophyll a concentrations in April paralleled those of the iron bound phosphate accounting for major portion of sediment inorganic phosphate, and in June significantly higher OPB and IPB numbers (especially OPB) in sediment were main contributors to the peaks of chlorophyll a concentration. Even though IPB peaked from February to June, it should serve as an unimportant P source due to the irrelevancy with chlorophyll a and soluble reactive phosphorus (SRP). By contrast, at the other site in the embayment, the calcium-bound phosphate was predominant and solid, which was difficult to be released, and neither IPB nor OPB were detectable in the sediment, indicating weak potential for phosphorus release from the sediment, which was reflected in the small seasonal variation in SRP concentration in water column. Hence, the extents to which the three general mechanisms behind phosphate release from sediment (desorption of iron bound phosphate, solubilization by IPB and enzymatic hydrolysis by OPB) operated were different depending on seasons and sites in Lake Taihu, they may jointly drive phosphate release and accelerate the eutrophication processes. 相似文献
20.
Spatial patterns of benthic diatoms,carbohydrates and mud on a tidal flat in the Ems-Dollard estuary 总被引:1,自引:0,他引:1
Staats Natascha de Deckere Eric M.G.T. de Winder Ben Stal Lucas J. 《Hydrobiologia》2001,448(1-3):107-115
The chlorophyll a content and two operational fractions of carbohydrate (water extractable and EDTA extractable) were measured every three months during one year along transects on a tidal flat in the Ems-Dollard estuary (The Netherlands). Chlorophyll a was used as an indicator of microphytobenthos biomass, which was composed predominantly of epipelic diatoms. Both carbohydrate fractions correlated significantly with chlorophyll a. EDTA extractable carbohydrates were more resistant towards degradation than the water extractable fraction. During most of the year, concentrations of chlorophyll a and carbohydrates were low, but in June, high concentrations of up to 90 g chlorophyll a/g sediment were found in a narrow zone running parallel to the channel. Maximum concentrations of water extractable carbohydrates and EDTA extractable carbohydrates ranged between 800–1200 and 600–800 g/g sediment, respectively. The mud content was high (± 90%) at the margin of the tidal flat. This was not limited to the growth season of the diatoms, but was observed throughout the year. This indicated that the high mud content at the mudflat margin was mainly caused by hydrodynamic factors, and not by biostabilization. In June, exceptionally high diatom densities were found in sediment with a high mud content. There was only minor evidence that biostabilization by epipelic diatoms lead to a further increase in the mud content of the sediment. 相似文献