The influence of the spectral composition of irradiance on primary production in the Eastern Scheldt (The Netherlands)

The error inin vivo ¹⁴C incubator measurements of primary production in the Eastern Scheldt when neutral density filters were used and the error obtained when no account was taken of the spectral changes in submarine irradiance that occur with increasing depth, were evaluated theoretically. By multiplying the photosynthetic action spectra of two marine algae by calculated irradiance in the euphotic layer using Kd and Kd() respectively, the gross primary production P[Ed(400–700)] and P[Ed()] was computed. In the green-brown waters of the Eastern Scheldt estuary the use of neutral density filters was sufficient to simulate the underwater light conditions. In clear waters it can cause an overestimation of the gross production.     

Effects of suspensoids (turbidity) on penetration of solar radiation in aquatic ecosystems

In mainland Australia and in southern Africa, the aridity of the climate and sparse vegetative cover increase the susceptibility of the soils to erosion, and as a consequence surface waters are usually turbid. The inanimate suspensoids in such waters, the tripton fraction of the limnologist, are responsible for virtually all the light scattering, and also, by virtue of the yellow-brown humic materials adsorbed on their surface, for a substantial part of the light absorption. Spectral absorption data for suspensoids in terms of theirin situ absorption coefficient values, and the contribution of suspensoids to absorption of photosynthetically available radiation (PAR) are given for certain Australian water bodies.To understand the effect of suspensoids on attenuation of the solar flux with depth, the scattering coefficient must also be known, and this can be determined from the nephelometric turbidity or from up- and down-welling irradiance measurements. The effect of particle size on scattering efficiency is discussed.An equation expressing the vertical attenuation coefficient for downward irradiance as a function of absorption coefficient, scattering coefficient and solar altitude is presented, and is used to explore the effects of absorption due to dissolved colour and suspensoids, and the effects of scattering by suspensoids, on the penetration of PAR.Suspensoids, by increasing the rate of attenuation of the solar flux with depth, can greatly diminish the euphotic depth of a water body, with a consequent decrease in the ratio of the euphotic to the mixed depth: thus turbidity can reduce productivity of a water body substantially below that which might be expected on the basis of nutrient availability. Shallow turbid waters of low intrinsic colour can, however, be highly productive. By diminishing the depth of the layer within which solar energy is dissipated as heat, suspensoids can greatly modify the hydrodynamic behaviour of water bodies, and this also has far-reaching ecological consequences.Suspensoids drastically impair the visual clarity of water, a fact of major significance for the aquatic fauna, as well of aesthetic significance for humanity. The reciprocal of the Secchi depth is more correctly thought of as a guide to the vertical contrast attenuation coefficient rather than to the vertical attenuation coefficient for irradiance. The reflectivity of a water body, being at any wavelength proportional to the backscattering coefficient divided by the absorption coefficient, is highly dependent on the concentration, and optical character, of the suspensoids present. This has implications not only for the appearance (colour, muddiness) of the water to an observer, but also for the remote sensing of water composition by air- or satellite-borne radiometric sensors.     

从超声波破碎的蓝藻类囊体膜中分离的叶绿素蛋白复合物

当蓝藻的类囊体膜用超声波进行破碎,并在4℃下用聚丙烯酰胺凝胶电泳进行分离,有6条叶绿素带被分离出来,它们分别是 CPIa,CPIb,CP1,CPa1 CPa2,FC。CP1 在红区和蓝区的吸收峰分别位于674和435 nm 处。在液氮甲该组分在725和680 nm 处有两个荧光发射带。CPa1和 CPa2的吸收光谱相似,其红峰和蓝峰的位置分别位于667和431.5nm 处。它们在77 K 的荧光发射峰都位于684 nm 处。用超声破碎法分离的叶绿素蛋白复合物的光谱特性,除 CPa1和 CPa2在红峰和蓝峰的吸收位置蓝移了3—5 nm 之外,其余与用 SDS 增溶法分离的相应复合物相似。属于光系统Ⅰ的 CPIa-CPI 的叶绿素含量占总叶绿素的40.93%,而属于光系统Ⅱ的 CPa1和 CPa2的叶绿素则占总叶绿素的38.78%,二者之差仅有2.15%。     

Dynamics and attenuation characteristics of periphyton upon artificial substratum under various light conditions and some additional observations on periphyton upon Potamogeton pectinatus L.

The seasonal variation in periphyton dynamics has been studied upon artificial substratum (microscopic glass slides) under various light conditions during the periods May–October 1986 and May–September 1987, in Lake Veluwe. Some additional observations on the periphyton development upon leaves of Potamogeton pectinatus L. have been made simultaneously. Four different light conditions were created in an experimental setup by manipulating the photon flux density through artificial shading.Periphyton upon artificial substratum exhibited a relatively high abundance with a distinct seasonal pattern. Periphyton accrual rates were highest at the beginning of June and in August and September upon slides which were incubated for two weeks. Periphyton mass increased during May and June, decreased or remained about the same during July and subsequently increased until an upper plateau was reached upon slides which were incubated from the beginning of May onwards.Generally, periphyton mass was lower upon slides than upon P. pectinatus. The seasonal variation in periphyton mass was more pronounced upon P. pectinatus leaves than upon the slides.Attenuation by periphyton upon slides ranged from 5 to 65% after two weeks of incubation. Periphyton upon slides which had been incubated for more than two weeks demonstrated an attenuation of more than 85%.Water quality parameters other than photon flux density were probably more important in determining the periphyton dynamics, since only minor differences were observed in periphyton mass between the various light conditions. Chlorophyll-a content was higher with increased shading on various sampling dates.Periphyton, especially older periphyton consisted largely of settled silt and clay particles and to a lesser extent of detrital matter on both substrata. Living epiphytes were only a relatively small fraction.It is concluded that a reduction of resuspension of sediment particles, giving less suspended matter in the water column, will result in lower periphytic mass. Consequently, the quantity of photosynthetically active radiation reaching the submerged macrophytes is expected to increase considerably.     

The challenge of estimating kelp production in a turbid marine environment

Coastal kelp forests produce substantial marine carbon due to high annual net primary production (NPP) rates, but upscaling of NPP estimates over time and space remains difficult. We investigated the impact of variable underwater photosynthetically active radiation (PAR) and photosynthetic parameters on photosynthetic oxygen production of Laminaria hyperborea, the dominant NE-Atlantic kelp species, throughout summer 2014. Collection depth of kelp had no effect on chlorophyll a content, pointing to a high photoacclimation potential of L. hyperborea towards incident light. However, chlorophyll a and photosynthesis versus irradiance parameters differed significantly along the blade gradient when normalized to fresh mass, potentially introducing large uncertainties in NPP upscaling to whole thalli. Therefore, we recommend a normalization to kelp tissue area, which is stable over the blade gradient. Continuous PAR measurements revealed a highly variable underwater light climate at our study site (Helgoland, North Sea) in summer 2014, reflected by PAR attenuation coefficients (K_d) between 0.28 and 0.87 m⁻¹. Our data highlight the importance of continuous underwater light measurements or representative average values using a weighted K_d to account for large PAR variability in NPP calculations. Strong winds in August increased turbidity, resulting in a negative carbon balance at depths >3–4 m over several weeks, considerably impacting kelp productivity. Estimated daily summer NPP over all four depths was 1.48 ± 0.97 g C · m⁻² seafloor · d⁻¹ for the Helgolandic kelp forest, which is in the range of other kelp forests along European coastlines.     

高血压前期患者颈动脉血管弹性超声参数与左室舒张功能的关系研究

摘要 目的：研究高血压前期患者颈动脉血管弹性超声参数与左室舒张功能的关系。方法：选取2019年12月-2020年12月因血压异常于河北北方学院附属第一医院接受诊断与治疗的161例患者,根据血压水平分为高血压前期组（82例）与高血压组（79例）;另选取同期于我院体检的80例健康志愿者作为对照组。收集三组临床资料,检测生化指标与血压;通过超声诊断仪中超声射频信号血管内中膜定量分析（QIMT）与动脉僵硬度定量分析（QAS）软件测量颈动脉血管弹性超声参数[颈动脉内中膜厚度（IMT）、顺应性系数（CC）、扩张性系数（DC）、血管弹性指数（α、β）、脉搏波传导速度（PWV）];超声心动图检查左室功能指标[左室射血分数（LVEF）、左室质量指数（LVMI）、舒张早期血流速度峰值（E）/舒张晚期血流速度峰值（A）、等容舒张时间（IVRT）、舒张期减速时间（DT）];采用Pearson相关性法分析颈动脉血管弹性超声参数与心室指标的相关性。结果：三组收缩压与舒张压水平存在统计学意义（P＜0.05）。高血压前期组与高血压组IMT、α、β、PWV高于对照组,DC、CC低于对照组（P＜0.05）,且高血压前期组IMT、α、β、PWV低于高血压组,DC、CC高于高血压组（P＜0.05）。高血压前期与高血压组E/A低于对照组,IVRT、DT高于对照组（P＜0.05）,且高血压前期组E/A高于高血压组,IVRT、DT低于高血压组（P＜0.05）。经Peason相关性分析显示,IMT、α、β、PWV与E/A呈负相关,与IVRT、DT呈正相关（P＜0.05）;DC、CC与E/A呈正相关,与IVRT、DT呈负相关（P＜0.05）。结论：高血压前期患者颈动脉血管弹性功能下降,且伴有左室舒张功能受损,颈动脉血管弹性超声参数与左室舒张功能密切相关。     

乳腺良恶肿瘤患者超声弹性成像定量参数与临床分期、病理分子分型的相关性分析

摘要 目的：探讨乳腺良恶肿瘤患者超声弹性成像定量参数与临床分期、病理分子分型的相关性。方法：选择2020年1月至2022年12月来我院诊治的乳腺肿块患者85例,均行超声弹性成像检查,分析85例乳腺肿块患者的病理检查结果,对比良恶性肿瘤患者的弹性成像参数,对弹性应变率、直径变化率、面积比及三者联合绘制ROC曲线,分析不同乳腺肿瘤患者临床分期的弹性成像参数,分析乳腺肿瘤患者病理分子分型的弹性成像参数。结果：85例乳腺肿块患者中,良性肿块35例,恶性肿块50例。恶性组的弹性应变率、肿块直径、直径变化率、肿块面积、面积比明显较良性组低（P<0.05）。面积比ROC曲线AUC为0.580,以1.73为临界值,乳腺恶性肿瘤的诊断灵敏度为73.5 %,特异度为38.5 %;直径变化率ROC曲线AUC为0.630,以0.28为临界值,诊断灵敏度为75.5 %,特异度为47.5 %;弹性应变率ROC曲线AUC为0.790,以15.2 cm²为临界值,诊断灵敏度为64.5 %,特异度为83.5 %,以三者联合绘制ROC曲线,AUC为0.920,诊断灵敏度为82.5 %,特异度为92.5 %。乳腺恶性肿瘤患者TNM分期Ⅰ、Ⅱ、Ⅲ、Ⅳ期者的弹性应变率、肿块直径、直径变化率、肿块面积、面积比对比有统计学意义（P<0.05）;其中Ⅳ期者的弹性应变率、肿块直径、直径变化率、肿块面积、面积比明显较Ⅲ、Ⅱ、Ⅰ期者高,Ⅲ期者明显较Ⅱ、Ⅰ期者高,Ⅱ期者明显较Ⅰ期高。乳腺恶性肿瘤患者Luminal A型者、Liminal B型者、Her2过表达型者、基底样型者的弹性应变率、肿块直径、直径变化率、肿块面积、面积比对比有统计学意义（P<0.05）;其中Liminal B型者的弹性应变率、肿块直径、直径变化率、肿块面积、面积比明显较Luminal A型者、Her2过表达型者、基底样型者高,Her2过表达型者明显较Luminal A型者、基底样型者高（P均<0.05）,Luminal A型者与基底样型者对比无统计学意义（P>0.05）。结论：超声弹性成像可用于乳腺良恶肿瘤的诊断,超声弹性成像定量参数可用于恶性乳腺肿瘤临床分期、Liminal B型、Her2过表达型的判断。     

生物组织散射元平均间距估计的一种新方法

生物组织散射元平均间中划描述生物组织微观结构特性和生物组织超微散射特性的重要参数。本文在对生物组织超声背向散射随机模的基础上,提出了基于生物组织超声背向散射信号突变点检测的工用射元平均间距估计的新方法。该方法是生物组织超声散射分析的有效方法。