淀山湖富营养化过程的统计学特征

湖泊营养物输入及响应指标的统计学规律正在受到越来越广泛的关注。对淀山湖在不同富营养化阶段和近期总磷TP、总氮TN和叶绿素Chl a的频率分布以及TP-Chl a关系的经验方程进行了分析,结果表明:(1)淀山湖TP、TN和Chl a的平均浓度和离散程度随着湖泊富营养化程度的加剧而增加,其中以Chl a的增幅最大;(2)在富营养化条件下,即使营养物TP得到一定程度的控制,Chl a大于15μg/L的概率继续增加了20%以上。仅仅削减营养物的峰值,对降低湖泊初级生产力水平的贡献有限;(3)TP-Chl a对数回归方程的斜率随湖泊富营养化程度的升高而增加,由20世纪80年代的0.54增加到目前的2.46。淀山湖营养物输入及响应指标的统计学特征,可以用来表征水体富营养化程度,评价湖泊生态恢复的进程和效果,为湖泊营养物基准和标准的制定提供最为实际的统计学支持。     

巢湖叶绿素a浓度的时空分布及其与氮、磷浓度关系

基于巢湖水体2002~2007年水质监测资料,对叶绿素a浓度的分布、动态及与TN、TP的关系进行了统计分析。巢湖叶绿素a浓度与TN、TP的浓度分布存在明显的空间差异,西半湖叶绿素a浓度全年高于20μg/L,TN为1.94~3.84mg/L,TP为0.20~0.42mg/L;东半湖叶绿素a浓度全年小于5.5μg/L,TN为0.95~1.83mg/L,TP为0.08~0.14mg/L。在东半湖,叶绿素a含量与TN呈不明显的正线性关系,当TP浓度较低时,叶绿素a随TP的增加小幅上升,但是当TP>0.15mg/L时,叶绿素a随TP的增加而明显上升;在西半湖,当水体TN<5.8mg/L或者TP<2.0mg/L时,叶绿素a含量与TN、TP关系为正线性关系,当TN在5.8~9.4mg/L或者TP介于0.2~0.3mg/L间时,叶绿素a含量与TN、TP关系为不显著的负线性关系,当TP浓度>0.3mg/L时,叶绿素a含量与TP关系又为正线性关系。西半湖叶绿素a浓度的变化可能是藻类生物活动与沉积物及水体中营养盐的相互作用结果。在治理巢湖富营养化时,应优先控制西半湖的磷元素。     

钱塘江干流杭州段水体叶绿素a浓度及与环境因子的关系

2006年1月至2007年12月,对钱塘江干流杭州段水体的叶绿素a时空分布及其与环境因子的关系进行研究.结果表明钱塘江干流杭州段的叶绿素a浓度时间差异显著,空间差异不显著.叶绿素a浓度呈现夏秋季节高、冬春季节低的规律.叶绿素a浓度与温度呈显著正相关,叶绿素a与透明度在不同范围内表现出不同的相关关系,叶绿素a与TN、TP之间的相关关系在不同江段有所差异.钱塘江干流杭州段总氮和总磷浓度均很高,足够满足藻类生长需要;氮磷比较低,基本在8～30之间,说明氮磷含量可能不是钱塘江藻类生长的限制因子.     

珠江三角洲黄毛鼠种群数量动态的研究

本文研究农田黄毛鼠种群年度和季节数量动态。稻田区数量最高的季节为7～11月,冬春季12月～翌年6月相对来说密度较低,只是在3月份有一较小幅度增长。蕉田区黄毛鼠种群数量变化4～10月较低,11月～翌年3月数量相对较高,全年可以为呈马鞍形,即冬春较高密度,夏秋密度较低。山坡果园地小家鼠种群密度季节变化比较明显,也呈现冬春密度较高,夏秋密度较低的马鞍形曲线。     

灌河口邻近海域春季浮游植物的生态分布及其营养盐限制

2011年4月通过灌河口邻近海域的现场调查及营养加富培养实验,研究了春季灌河口邻近海域浮游植物生态分布特征以及硝酸盐、磷酸盐对浮游植物生长的限制作用,结果表明:共发现浮游植物68种,其中硅藻61种,优势度最高的为中肋骨条藻(Skeletonema costatum,Y=0.53),各个站位浮游植物的丰度介于0.84× 106-2.25×106个/L,均值为1.54×106个/L,种类范围为29-39种,均值为35种,叶绿素a浓度呈现近岸高外海低的特征,在2.66-6.67 μg/L变化,均值为3.89 μg/L,多样性指数介于2.60-3.79,均值为3.20,海域环境基本适宜浮游植物的生长;调查海域磷酸盐浓度的范围为0.35-0.90μmol/L,均值为0.58μmol/L,亚硝酸盐浓度范围为1.57-3.93 μmol/L,均值为3.08 μmol/L,两者分布均具有近岸高外海低的特征;铵盐浓度范围为3.145.43μmol/L,均值为3.95 μmol/L,其分布则是近岸低外海高;硝酸盐浓度严重偏高,在31.21-37.00μmol/L之间变化,均值为34.55 μmol/L,导致调查区域具有高N/P比(42-112),且浮游植物叶绿素a与磷酸盐浓度有显著的正相关(R2=0.80),而与无机氮线性关系不明显(R2=0.11);在P加富培养实验中,磷酸盐在3个培养组(对照,+P,++P)中的比吸收速率分别为0.36、0.43、0.51d-1,加P促进了P本身的吸收,硝酸盐和亚硝酸盐的吸收也得以促进,但没有磷酸盐那么显著,而铵盐浓度基本呈增加趋势,P的添加也促进了藻类的生长,培养结束后叶绿素a浓度最大值分别为77.24、90.57、96.49μg/L.在N加富培养实验中,硝酸盐的比吸收速率分别为0.39、0.049、0.025d-1,加N未促进硝酸盐本身的吸收,磷酸盐浓度在3个实验组变化曲线相似,其吸收也没有得到促进,亚硝酸盐在加N组中浓度是增加的,培养结速后加N组(+N,++N)叶绿素a浓度最大值分别为72.31、69.62μg/L,都小于对照组,N的添加也未促进藻类的生长.上述研究表明了春季灌河口邻近海域浮游植物的生长主要受到P的限制,而不是N限制.     

大亚湾大辣甲水域叶绿素a及营养盐的垂直分布与季节变化

为了较为系统地研究大亚湾水域叶绿素a和营养盐的垂直分层状况, 并为大亚湾海洋生态系统的数值模拟提供基础数据, 作者于大亚湾大辣甲和桑洲之间连线的中间点附近海域选点, 在2007年～2008年进行了4个季度的垂直采样监测。本次研究分析了大亚湾大辣甲水域叶绿素a及营养盐的垂直分布与季节变化, 并分析了叶绿素a与DIN、PO₄-P和SiO₃-Si的关系。结果表明:在整个监测时段内, 叶绿素a和DIN、PO₄-P、SiO₃-Si的浓度范围分别为0.50～5.80 mg·m^-3、0.023～0.159 mg·L^-1、1.606～19.69μg·L^-1和0.065～1.13 mg·L^-1, 营养盐和叶绿素a在4个季度里的垂直变化趋势各有不同;在季节变化上, SiO₃-Si与DIN比较相似, 总体呈现夏、冬、秋季高, 春季较低的特征, PO₄-P恰好相反, 夏季的浓度最低, 叶绿素a总体呈现夏、春、冬季高, 秋季较低的特征;在整个垂直水柱内, DIN和SiO₃-Si对叶绿素a的影响相对较小, PO₄-P和叶绿素a呈显著正相关关系。     

基于PCA和SOM模型的龙感湖水质时空动态研究

为评估湖泊渔业模式转型阶段水环境的时空动态, 选择长江中下游典型湖泊龙感湖为研究地点, 于2017—2018年对该湖的黄梅水域和宿松水域进行周年季度水质监测, 通过主成分分析(PCA)和自组织特征映射人工神经网络(SOM)模型定量分析了水体理化参数的时空变化特征, 采用综合营养状态指数法(TLI)对水体富营养化状况进行了评价。PCA分析结果表明, 龙感湖宿松水域和黄梅水域的水质差异较小, 季节动态明显。全湖氨氮夏季平均浓度高达0.64 mg/L; 总氮夏季平均浓度为2.30 mg/L, 冬季平均浓度为1.04 mg/L; 叶绿素a夏季平均含量达95.28 μg/L, 秋季平均浓度为28.30 μg/L; pH夏季最高, 达9.27; 总磷冬季最高, 平均为0.22 mg/L; TLI指数表明龙感湖除秋季属于轻度富营养水体外, 其他3个季节均属于中度富营养状态。SOM模型结果具有可视化强的优点, 能够更清晰和直观地反映龙感湖水质的时空分布动态。围栏拆除和禁渔等管理措施有助于湖泊渔业环境修复和资源恢复, 建议对渔业模式转型后的湖泊生态系统变化进行长期跟踪监测评估。     

基于ETM+影像的千岛湖叶绿素a浓度卫星遥感反演研究

以千岛湖为研究对象,利用Landsat 7 ETM+遥感影像与野外实测数据,建立叶绿素a浓度的遥感定量反演模型。将叶绿素a浓度与波段反射率组合进行Pearson相关性分析,选择(B4+B2)/B3波段组合构建叶绿素a反演模型,并得到千岛湖叶绿素a浓度的时空分布。结果表明:(1)2007年千岛湖叶绿素a浓度低于4μg/L的水体面积占水体总面积达到99%以上,整体水质优良;(2)千岛湖叶绿素a浓度随季节变化特征明显,夏季容易出现局地高值,秋季平均浓度整体升高;(3)通过反演不同时期的叶绿素a浓度分布,可以刻画出千岛湖藻类的消长过程,从空间上发现易爆发富营养化的区域。该反演模型能较为精确地估算千岛湖的叶绿素a浓度,对今后水体富营养化的监测和预警具有重要意义。     

抚仙湖叶绿素a的生态分布特征

2001年5月、8月和9月,对云南抚仙湖水体、沉积物、沉积物与水界面的叶绿素a,浮游植物的优势种类、细胞密度的分布和时空变化及其与环境因子的关系进行了研究。采用分光光度法测定叶绿素a浓度。结果表明,水体叶绿素a浓度的分布存在着明显的季节变化,真光层中的动态变化尤其显著,且光照强度对水体中叶绿素a浓度的分布起主导作用。在观测的3个不同季节中,表层叶绿素a浓度,秋季最高,平均为(2.27±0.12)μg/dm3;春季次之,为(1.85±0.20)μg/dm3;夏季最低,为(1.38±0.15)μg/dm3。分析水体中营养元素的分布特征及其与叶绿素a之间的关系,表明磷是抚仙湖浮游植物生长的主要限制因子。沉积物叶绿素a浓度的垂直分布存在明显差异,其浓度在表层和次表层较高,并随沉积深度的增加而降低;浮游植物的分析表明,硅藻门的小环藻是抚仙湖沉积物中叶绿素a的主要来源。而上覆水中叶绿素a浓度与真光层叶绿素a浓度相当的原因,则可能是由水底微型藻类的再悬浮和浮游植物的沉降聚集而导致的。     

象山港小型底栖动物群落结构及其与环境因子的相关性

为阐明象山港小型底栖动物群落的结构和组成,于2011年10月(秋)、2012年2月(冬)、5月(春)和8月(夏),对小型底栖动物进行12个站位的取样分析,结果表明:共鉴定出12个类群,包括线虫、介形类、双壳类、腹足类、寡毛类、多毛类、涡虫类、桡足类、端足类、涟虫类、水螅幼体和其他类。春、夏、秋、冬各季节的小型底栖动物平均丰度分别为(22.3±34.4)个/10 cm~2、(74.8±140.8)个/10 cm2、(31.4±64.5)个/10 cm~2和(97.4±206.5)个/10 cm~2,且以线虫和介形类为主要优势类群;相应季节的平均生物量分别为(73.0±144.4)μg/10 cm~2、(1261.7±2244.1)μg/10 cm~2、(440.7±1003.7)μg/10 cm~2和(1010.5±2365.6)μg/10cm~2,介形类为主要贡献类群。相似性分析(ANOSIM)显示,各季节间小型底栖动物群落结构差异显著(R=0.085,P=0.001)。据小型底栖动物全年平均丰度的MDS分析,在空间上将12个站位分成3组,其中,港底区组分别与其他2组群落结构差异显著,这些组间的主要差异类群是介形类、线虫、腹足类和多毛类。同时,对相应样品的14个沉积环境因子(水深、温度、盐度、水份、有机碳、叶绿素a、pH值、氧化还原电位、电导率、溶解固体,以及沉积物的砂、粉砂、粘土含量和中值粒径)进行了监测,结果发现,象山港沉积物以粘土和粉砂为主,中值粒径在港口区较高。沉积物中,有机碳季节间差异明显,春、夏有机碳含量高于秋、冬季节;而叶绿素a含量在春季和港底区较高。据生物-环境(BIOENV)分析,小型底栖动物与环境因子间相关系数仅为0.270,筛选的变量子集为砂含量、含水率、水深和中值粒径。进一步的spearman相关分析显示,小型底栖动物丰度与叶绿素a和砂含量呈显著正相关,与水深、盐度呈显著负相关;小型底栖动物生物量与砂含量呈显著正相关,分别与盐度、粉砂含量呈显著负相关。主要类群线虫丰度与叶绿素a呈显著正相关,而介形类丰度与砂含量呈显著正相关,分别与氧化还原电位、盐度呈显著负相关。寡毛类、桡足类与环境因子间均未检出显著相关性。     

长白山阔叶红松林土壤水分动态研究

在1990～1992年和2003年对长白山阔叶红松林土壤水分动态进行定位观测研究.结果表明,土壤水分年内变化可划分为5个时期：春季聚水阶段、旱季耗水阶段、雨季蓄墒阶段、秋季失墒阶段和冬春土壤水分相对稳定阶段.利用标准差和变异系数对土壤水分垂直变化进行分层,得出土壤水分剖面分布分为速变层、活跃层和次活跃层,并用相关分析方法分析了各层次间土壤水分及其与其间降水量的关系.     

太湖水色因子空间分布特征及其对水生植物光合作用的影响

利用太湖全湖64个采样点的数据,分析了各水色因子及真光层深度的空间分布和变化特征,并探讨了其对水生植物光合作用的影响.结果表明:叶绿素a浓度在全湖间的差异最大,其变化范围为1.67～159.94μg.L-1,均方差为41.03μg.L-1,在梅梁湾、竺山湖、夹浦港和小梅口附近湖区,叶绿素a浓度较高且空间变化明显,等值线在这些湖区密集分布;悬浮物浓度变化次之,其含量在6.47～143.47mg.L-1之间变化,均方差为31.63mg.L-1,其在大浦港和小梅口入湖口附近湖区的空间变化明显,等值线分布密集;有色可溶性有机物(CDOM)吸收系数在全湖变化较小,没有明显的空间变化特征;真光层深度受悬浮物和叶绿素的共同影响,其空间分布特征与悬浮物相反.     

Leaf growth dynamics in four plant species of the Patagonian Monte, Argentina

Studying plant responses to environmental variables is an elemental key to understand the functioning of arid ecosystems. We selected four dominant species of the two main life forms. The species selected were two evergreen shrubs: Larrea divaricata and Chuquiraga avellanedae and two perennial grasses: Nassella tenuis and Pappostipa speciosa. We registered leaf/shoot growth, leaf production and environmental variables (precipitation, air temperature, and volumetric soil water content at two depths) during summer-autumn and winter-spring periods. Multiple regressions were used to test the predictive power of the environmental variables. During the summer-autumn period, the strongest predictors of leaf/shoot growth and leaf production were the soil water content of the upper layer and air temperature while during the winter-spring period, the strongest predictor was air temperature. In conclusion, we found that the leaf/shoot growth and leaf production were associated with current environmental conditions, specially to soil water content and air temperature.     

保安湖菹草种群的时空分布特征及环境效应分析

为了解近20年来保安湖菹草(Potamogeton crispus L.)种群的变化特征及其对水环境的影响, 研究以保安湖最大的湖区, 即主体湖为研究对象, 分季节对其沉水植物种类组成、生物量及水深(Z_M)、透明度(Z_SD)、水中总氮(TN)、总磷(TP)和浮游藻类叶绿素a(Chl. a)等环境指标进行了监测, 并分析了菹草在不同生活史阶段对环境影响的差异。结果表明: (1)2002年春季菹草生物量(B_P.c)均值为356 g/m2, 2012年上升至974 g/m2, 2019年为1901 g/m2, 菹草种群分布范围由中部扩展至整个湖区; (2)在春季菹草快速生长时, B_P.c与Z_M(Z_M≤3 m)呈显著正相关(r= 0.52, P<0.01), 与Chl. a呈显著负相关(r= –0.42, P<0.01), 与Z_SD、Z_SD/Z_M、TN、TP无相关关系; 有草区的Z_M(中位数为2.1 m)、Z_SD(中位数为0.93 m)和Z_SD/Z_M(中位数为0.48)显著高于无草区(1.8 m、0.45 m和0.28; P<0.05), 有草区的Chl. a(中位数为8.13 μg/L)显著低于无草区(14.10 μg/L; P<0.05); 有草区的Chl. a和TP的关系不明显, 无草区的Chl. a的含量随TP上升而增加, 且在相同TP条件下, 无草区Chl. a多数高于有草区; (3)在夏季菹草衰亡后, 夏季Z_SD/Z_M与B_P.c呈显著负相关(r= –0.47, P<0.01), Z_SD、TN、TP、Chl. a与B_P.c无相关关系; 无草区TN(中位数为1.30 mg/L)显著高于有草区(0.72 mg/L; P<0.05); 有草区和无草区的Chl. a均随TP的上升而增加, 在相同TP条件下, 无草区Chl. a和有草区差异不显著。以上结果表明近20年来保安湖菹草种群生物量呈上升趋势, 分布范围也在不断增加。在快速生长期(春季), 大量菹草的存在有利于水质的改善。在菹草衰亡(春末夏初)后, 其对水质产生的不利效应未持续整个夏季。     

Early disruption of pregnancy as a manifestation of seasonal infertility in pigs

All gilts and sows in production from which the detailed production information was available in a 160-sow unit were included to the study. In winter-spring, there were complete data available from 47 animals and in summer-autumn from 64 animals. The farm had a consistent history of the seasonally reduced farrowing rate in summer-autumn. Success of inseminations was monitored during a 4-month breeding period in winter-spring and in summer-autumn. Each animal was bled twice a week for 6 weeks starting a day before insemination and the blood samples were assayed to determine serum progesterone concentration. The blood samples were also assayed for cortisol to detect any acute infectious response. Starting on day 18, animals were pregnancy tested by transcutaneous real time ultrasound twice a week. In winter-spring, the farrowing rate was 72% (58 inseminations, 1.2 inseminations/sow) and in summer-autumn 63% (81 inseminations, 1.3 inseminations/sow). In winter-spring, there was only one detected case of early disruption of pregnancy (EDP), whereas nine such cases were recognised in summer-autumn. Five out of those nine animals returned to oestrus with a mean insemination to oestrus interval of 25.8+/-1.6 days. One sow returned to oestrus 35 days after insemination and three sows did not return to oestrus within 45 days. However, two of these sows had progesterone profiles that indicated an undetected oestrus around day 25. In those nine animals, no acute phase infectious response as indicated by a rise in serum cortisol was evident. Serum progesterone concentrations in the animals eventually loosing the pregnancy tended to be lower on day 13 (no significant difference) and were significantly lower on day 20 when compared with animals remaining pregnant. There was no difference in serum progesterone levels of pregnant animals between winter-spring and summer-autumn. Litter size was not affected by the season. The weaning to oestrus interval tended to be longer in summer-autumn. This study showed that the seasonally decreased farrowing rate is partly caused by EDP. The lowered progesterone concentrations in summer-autumn were demonstrable only in "problem animals".     

Deep-water aquatic plant communities in an oligotrophic lake: physiological responses to variable light

1. Oligotrophic Lake Waikaremoana, New Zealand, is used for hydroelectric power generation and the lake levels are manipulated within an operating range of 3 m. There was concern that rapidly changing water levels adversely affected the littoral zone by decreasing light availability in two ways: local turbidity caused by shoreline erosion at low water levels; and decreased light penetration to the deep littoral zone caused by high water levels in summer. 2. The littoral zone was dominated by native aquatic plants with vascular species to 6 m and a characean meadow below this to 16 m. The biomass and heights of the communities in the depth zone 0–6 m were reduced at a site exposed to wave action relative to those at a sheltered site. However, the community structure below 6 m was similar at exposed and sheltered sites. The lower boundary of the littoral zone was sharply delimited at 16 m and this bottom boundary remained constant throughout the year despite large seasonal changes in solar radiation and the 3 m variation in lake level. 3. There was evidence that the deep-water community consisting of Chara corallina had adapted physiologically to low-light conditions. Net light saturated photosynthesis (CO₂ exchange) per unit chlorophyll a (Chl a) was reduced to 1.7 μg C (μg Chl a)^?1 h^?1 at the lower boundary, half of that recorded at 5 m. The concentration of Chi a per gram of biomass (dry weight), was considerably greater at the lower boundary than higher in the profile [c. 7 mg Chl a (g dry wt)^?1 at 16 m vs. 4 mg Chl a (g dry wt)^?1 at 5 m]. Chl b also increased with depth and there was no change in the ratio of Chl a and Chl b with increasing depth. The saturation light intensity (I_k) of the community at the lower boundary was only 78 μmol photons m^?2 s^?1. Photosynthetic parameters (I_k and α) as well as the Chl a content remained relatively constant throughout the seasonal and short-term changes in radiation. 4. The photosynthetic characteristics of the littoral community were therefore not greatly affected by the lake level change caused by the present hydroelectric operations. However, the sharpness of the lower boundary and its extreme shade characteristics imply that the deep-water community would be sensitive to any further changes in underwater light availability.     

Cyclic Seasonal Variation of G-6-PD Deficiency in Newborn Infants from Sardinia

Glucose-6-Phosphate Dehydrogenase has been studied in 5267 consecutive newborn infants from Sardinian population during a four years period. The proportion of G-6-PD deficient female infants is much higher in those conceived in the winter-spring than among those conceived in summer-autumn, resulting in a lower sex ratio among G-6-PD deficient infants conceived in winter-spring as compared to G-6-PD deficient infants conceived in the summer-autumn. The overall frequency of the gene for G-6-PD deficiency is much lower in infants conceived in the summer period than in infants conceived in the other seasons. A greater reproductive efficiency of G-6-PD deficient males in the winter-spring season and/or some effect at post zygotic level favouring the survival of heterozygous G-6-PD deficient females conceived in the winter-spring period could contribute to the pattern described. Fresh vegetables containing oxidative substances are more abundant in the spring time. These substances may interact with seasonal reproductive cycles influencing reproduction efficiency of G-6-PD deficient males and/or the relative survival rate of heterozygous female embryos.     

伊维菌素在环境中的降解及其对七种水生生物的急性毒性研究

伊维菌素作为一种高效的抗寄生虫兽药,在畜禽业有着广泛的应用。但药物随着畜禽动物的代谢产物的排放而进入自然生态系统也成为逐渐显现的环境问题。由于药物具有在自然环境中难以快速降解和对水生枝角类高毒性的特点,因此流入天然水体的伊维菌素存在着影响水生态平衡的风险。为了比较全面评估药物对水生动物潜在的毒害作用,研究模拟天然河道环境,对药物在底质中的降解速率进行了测定,并选取7种占据不同生态位的水生生物作为试验对象,通过关于急性毒性的国家标准试验方法来初步评价药物对水生态系统的风险。结果显示伊维菌素在自然水体中降解缓慢,在泥水混合25℃恒温条件下,70d的降解率仅为28.3%。急性毒性试验结果显示伊维菌素对发光细菌(Photobacterium)并不表现出毒性,对淡水小球藻(Chlorella vulgaris)的96h EC50=19.80 mg/L,属中毒;而对其他实验生物则表现出了较高的毒性,伊维菌素对斑马鱼(Brachydanio rerio)、食蚊鱼(Gambusia affinis)和鲫鱼鱼苗(Carassius carassius)的96h LC50分别为40.48、34.81和13.79μg/L,对罗氏沼虾(Macrobrachium rosenbergii)的96h LC50=7.87μg/L,对大型溞(Daphniamagna)的24h LC50=4.81 ng/L,均属极高毒。因此残留在天然水体的伊维菌素对水生态中的生物有较大影响,对含伊维菌素的废弃物排放进行监控和科学管理非常必要。