三峡库区澎溪河与磨刀溪电导率等水质特征与水华的关系比较

三峡库区北岸最大一级支流自三峡大坝2003年蓄水以来,频繁暴发水华,而毗邻的一级支流磨刀溪却少有水华暴发.本文以澎溪河和磨刀溪作为研究对象,于2014年春季和夏季三峡库区水华高发期对两条河流同时采样,对比分析两条河流水体水质以及叶绿素a(Chl-a)含量的时空变化,探索澎溪河水华暴发机理.结果表明:澎溪河Chl-a含量较磨刀溪高,澎溪河春季Chl-a最大值为60.5μg·L~(-1),夏季Chl-a最大值仅7.8μg·L~(-1);磨刀溪Chl-a变化趋势与澎溪河相反,磨刀溪春季Chl-a含量为2.92μg·L~(-1),夏季Chl-a达到7.48μg·L~(-1).澎溪河与磨刀溪春季和夏季节水体温度分层,为温跃层+滞温层模式,而没有混合层;两条河流Chl-a含量均位于水深10 m温跃层.澎溪河春季总氮(TN)、总磷(TP)平均值为2.305 mg·L~(-1)和0.053 mg·L~(-1),夏季为1.673 mg·L~(-1)和0.097 mg·L~(-1);磨刀溪春季为1.875 mg·L~(-1)和0.075 mg·L~(-1),夏季为1.79 mg·L~(-1)和0.054 mg·L~(-1).TN、TP水平均超过了国际公认发生富营养化的阈值;水体氮磷含量与Chl-a浓度并无显著相关性,营养盐并不是藻类生物量的限制性因素.然而在水体电导率的规律方面,两条河却存在很大的差异;春季,磨刀溪上游上层水体(0~10 m)电导率只有下游和长江干流的75%,来自长江干流的回水可覆盖至磨刀溪中游(断面MD03),与Chl-a在此处密集保持一致;夏季电导率和回水区分布与春季相似.与磨刀溪不同,澎溪河春季上游电导率为下游和干流的150%,长江干流回水可到PX04与PX05之间,上游高电导率对应着高Chl-a含量;澎溪河电导率与藻类生长分布表现出显著正相关关系,水体中除N、P营养盐外的其它离子对澎溪河水华暴发起重要作用.     

Decadal changes in a NW Mediterranean Sea food web in relation to fishing exploitation

We analysed changes in the ecological roles of species, trophic structure and ecosystem functioning using four standardized mass-balance models of the South Catalan Sea (North-western Mediterranean). Models represented the ecosystem during the late 1970s, mid 1990s, early 2000s, and a simulated no-fishing scenario. The underlying hypothesis was that ecosystem models should quantitatively capture the increasing exploitation in the ecosystem from the 1970s to 2000s, as well as differences between the exploited and non-exploited scenarios. Biomass showed a general decrease, while there was an increase in biomass at lower trophic levels (TL) from the 1970s to 2000s. The efficiency of energy transfer (TE) from lower to higher TLs significantly increased with time. The ecosystem during the 1990s showed higher biomass and flows than during the 1970s and 2000s due to an increase in small pelagic fish biomass (especially sardines). Exploited food webs also showed similarities in terms of general structure and functioning due to high intensity of fishing already in the 1970s. This intensity was highlighted with low trophic levels in the catch, high consumption of production by fisheries, medium to high primary production required to sustain the catches and high losses in secondary production due to fishing. Significant differences on ecosystem structure and functioning were highlighted between the exploited and no-fishing scenarios. Biomass of higher TLs increased under the no-fishing scenario and the mean trophic level of the community and the fish/invertebrate biomass ratios were substantially lower in exploited food webs. The efficiency of energy transfer (TE) from lower to higher TLs was lower under the no-fishing scenario, and it showed a continuous decrease with increasing TL. Marine mammals, large hake, anglerfish and large pelagic fish were identified as keystone species of the ecosystem when there was no fishing, while their ecological importance notably decreased under the exploited periods. On the contrary, the importance of small-sized organisms such as benthic invertebrates and small pelagic fish was higher in exploited food webs.     

MICROBIOLOGICAL QUALITY OF PUGET SOUND BASIN STREAMS AND IDENTIFICATION OF CONTAMINANT SOURCES1

ABSTRACT: Fecal coliforms, Escherichia coli, enterococci, and somatic coliphages were detected in samples from 31 sites on streams draining urban and agricultural regions of the Puget Sound Basin Lowlands. Densities of bacteria in 48 and 71 percent of the samples exceeded U.S. Environmental Protection Agency's freshwater recreation criteria for Escherichia coli and enterococci, respectively, and 81 percent exceeded Washington State fecal coliform standards. Male‐specific coliphages were detected in samples from 15 sites. Male‐specific F⁺RNA coliphages isolated from samples taken at South Fork Thornton and Longfellow Creeks were serotyped as Group II, implicating humans as potential contaminant sources. These two sites are located in residential, urban areas. F⁺RNA coliphages in samples from 10 other sites, mostly in agricultural or rural areas, were serotyped as Group I, implicating non‐human animals as likely sources. Chemicals common to wastewater, including fecal sterols, were detected in samples from several urban streams, and also implicate humans, at least in part, as possible sources of fecal bacteria and viruses to the streams.     

Changing scenario of Himalayan agroecosystems: loss of agrobiodiversity, an indicator of environmental change in Central Himalaya, India

Environmental, biological, socio-cultural and economic variations in the Himalayas have led to the evolution of diverse and unique traditional agroecosystems, crop species, and livestock, which help the traditional mountain farming societies to sustain themselves. During the recent past, as a result of rapid changes in land use caused by socio-cultural and economic changes and various environmental perturbations, the agrobiodiversity of the Central Himalayan agroecosystems has changed steadily. A recent survey conducted in 150 different villages located along an elevated transect of the Alaknanda catchment of the Central Himalaya revealed that over a period of two decades (1970–74 and 1990–94) the cultivated area under many traditional crops had declined significantly. A micro-level study carried out in 30 villages revealed that a series of changes had occurred in land use practices over a period of 25–30 years.The loss of agrobiodiversity and the changing socio-cultural and economic dimensions and their impacts on the sustainability of Himalayan agroecosystems are emerging as major causes of concern at local/regional/national scale, and appropriate options to meet these challenges are discussed in this paper.     

辽河流域河流栖息地评价指标与评价方法研究

建立了由底质、栖息地复杂性、速度-深度结合特性、堤岸稳定性、河道变化、河水水量状况、植被多样性、水质状况、人类活动强度和河岸土地利用类型所构成的河流栖息地评价指标体系,确定了各指标的等级划分以及栖息地综合指数的计算方法.结合2005年辽河流域河流生态调查结果,对流域内所调查的28个河段的栖息地质量状况进行了具体评价,并进一步分析了河道栖息地综合指数与河流理化因子、底栖生物以及小流域土地利用状况的相关关系.结果表明:①辽河流域28个河段的栖息地质量状况差异显著,其中10个河段达到了较好等级以上,6个仅为中等水平,12个河段为较差等级以下;②栖息地质量与理化因子、底栖生物指标具有显著相关性,表明栖息地质量是影响水质与生物状况的重要因素;③小流域的人类未利用土地比例与栖息地质量显著相关,表明小流域土地利用程度对栖息地环境质量影响较大,是恢复与保护河流栖息地质量的重要条件.     

Long-term joint effect of nutrients and temperature increase on algal growth in Lake Taihu, China

To study how global warming and eutrophication affect water ecosystems, a multiplicative growth Monod model, modified by incorporating the Arrhenius equation, was applied to Lake Taihu to quantitatively study the relationships between algal biomass and both nutrients and temperature using long-term data. To qualitatively assess which factor was a limitation of the improved model, temperature variables were calculated using annual mean air temperature (AT), water temperature (WT), and their average temperature (ST), while substrate variables were calculated using annual mean total nitrogen (TN), total phosphorus (TP), and their weighted aggregate (R), respectively. The nine fitted curves showed that TN and AT were two important factors influencing algal growth; AT limited growth as algal photosynthesis is mainly carried out near the water surface; N leakage of phytoplankton and internal phosphorus load from sediment explains why TN was the best predictor of peak biomass using the Monod model. The fitted results suggest that annual mean algal biomass increased by 0.145 times when annual mean AT increased by 1.0℃. Results also showed that the more eutrophic the lake, the greater the effect AT had on algal growth. Subsequently, the long-term joint effect of annual temperature increase and eutrophication to water ecosystems can be quantitatively assessed and predicted.     

东海赤潮及其监视监测

赤潮是一种海洋生态异常现象，是海洋生态系统受损与退化的表征与警示。近20a以来，东海赤潮频发，且影响范围不断扩大、持续时间增长，并呈逐年上升趋势，在一定程度上制约了东海区沿海省市海洋经济的发展。开展有害赤潮常规监测和应急监视监测是当前赤潮监控中最为有效手段。本文系统回顾和总结了近20a来东海区赤潮发生特点，以及在东海区开展的赤潮监视监测工作，并对21世纪东海赤潮监视监测进行了简要展望。     

Sulfur-containing amino acid methionine as the precursor of volatile organic sulfur compounds in algea-induced black bloom

After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds (VOSCs): methanethiol (MeSH), dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and dimethyl tetrasulfide (DMTeS). Even in the untreated control without a methionine addition, methionine and its catabolites (VOSCs, mainly DMDS) were found in considerable amounts that were high enough to account for the water’s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine+glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.     

酸雨与镧对大豆幼苗生长的复合伤害效应研究

为探索酸雨与稀土镧对大豆幼苗生长的复合影响及其内在机制,以重要油粮作物大豆(Glycine max)为材料,研究在模拟酸雨pH分别为3.0、3.5、4.5与稀土镧La(Ⅲ)浓度分别为60、100和300mg·L-1处理下大豆幼苗生长及光合作用的变化.结果表明,相对单一酸雨与镧处理,酸雨与La(Ⅲ)复合处理组中大豆幼苗的生长受抑制程度增大,两者呈协同效应,且pH越低,La(Ⅲ)浓度越高,抑制效应越明显.光合参数的变化规律与生长指标近同,相同处理组各光合参数的降幅不一致,其中最大荧光(Fv/Fm)和叶绿素含量(Chl)的降幅范围分别为9.53%～22.75%和9.14%～24.53%,较净光合速率Pn(22.78%～84.7%)、希尔(Hill)反应速率(15.52%～73.38%)和Mg2+-ATPase活性(14.51%～71.54%)小,表明各光合参数对2个胁迫因子的敏感程度存在差异.进一步相关性分析发现,Pn变化主要受Hill反应速率与Mg2+-ATPase活性的影响,而Chl、Fv/Fm次之.表明酸雨与La(Ⅲ)对植物光合过程各环节的作用机制不同,光合作用受阻是影响植物生长的重要因素之一.     

松花江佳木斯江段水环境质量变化状况及趋势分析研究

根据近十年来的松花江佳木斯江段水环境质量监测数据,介绍了松花江佳木斯江段水质现状,探讨了松花江佳木斯江段水质的主要污染物,从理化指标对松花江佳木斯江段水环境质量变化趋势进行了评价分析,分析结果表明：主要污染指标高锰酸盐指数、化学需氧量、氨氮、生化需氧量浓度值均有不同幅度的下降,2005年水质状况为轻度污染,2013年已达到良好水平.水环境质量呈规律性的逐年提高和改善,确保了松花江更好地休养生息.