基于互信息法的北部太湖Chl.a与环境因子的关系

以北部太湖竺山湾、梅梁湾、贡湖湾为研究区域,基于2013—2018年蓝藻暴发期三湖湾出入湖河道的水量数据和湖湾的水质及气象数据,采用Pearson相关法及互信息法分析了三湖湾Chl.a与环境因子的相关关系,分别建立三个湖湾Chl.a与由Pearson相关法确定的主要环境影响因子之间的线性解释回归方程以及与由互信息法确定的主要环境影响因子之间的非线性方程。结果表明：(1)互信息法显示三湖湾的Chl.a浓度与水温、风速、TN、TP浓度均有较好的相关性,梅梁湾和贡湖湾的Chl.a浓度与出湖水量有较好相关性,而竺山湾的Chl.a浓度则与入湖水量有较好相关性;Pearson相关系数法表明除梅梁湾Chl.a浓度与出湖水量存在弱相关性外,三湖湾的Chl.a浓度仅与水温、TP浓度有较好的相关性。(2)对于梅梁湾和贡湖湾,水温风速等气象因子与营养盐浓度共同影响藻类的生长;而在营养盐水平最高的竺山湾,水温风速等气象因子成为蓝藻水华暴发的最主要驱动因子。(3)拟合三湖湾Chl.a浓度与其主要影响因子关系的非线性方程R~2均在0.9以上,而线性方程R~2均小于0.7,表明互信息法能更加全面地筛选出蓝藻水华的主...     

太湖东部湖湾水生植物生长区底泥氮磷污染特征

为了解太湖东部湖湾(贡湖湾、光福湾、渔洋湾)表层底泥中氮、磷的污染特征及其与水生植物生长的关系,采集了各湖湾滨岸带水生植物生长区的表层底泥,探讨了水生植物的生长与分布对表层底泥中总氮(TN)、总磷(TP)及总有机碳(TOC)等含量的影响,并对表层底泥进行营养评价.结果表明,水生植物生长密集区底泥中TN、TP、TOC的含量均显著低于水生植物零星生长区,说明水生植物的生长对太湖东部湖湾表层底泥中营养盐与有机碳含量具有较为明显的影响;相关性分析显示,表层底泥中TOC与TN含量呈显著相关性(R2=0.832 8),而与TP的相关性则较弱(R2=0.166 5),反映了TOC在湖泊底泥中的沉积可能成为湖泊氮的重要来源,而对磷的影响较小.利用有机指数与有机氮指数两种方法分别对东部各湖湾底泥进行污染评价,贡湖湾、光福湾、渔洋湾底泥有机指数平均值分别为0.142 7、0.228 6与0.208 6,均属较清洁与尚清洁水平,而各湖湾有机氮指数平均值均为Ⅲ与Ⅳ级,说明底泥已遭受了一定程度的氮污染.因此,对水生植物零星生长区表层底泥中氮含量的控制与削减有利于湖泊富营养化的预防与治理.     

甘肃永靖黑方台灌区潜水渗流场与斜坡稳定性耦合分析

渗流场与斜坡稳定性的耦合分析是揭示灌溉诱发型黄土滑坡机理的重要途径,也是后续开展基于水位的滑坡灾害风险控制的基础.在综合分析研究区地质结构和水文地质条件的基础上,以调查、钻探、测量、三维激光扫描和监测资料为依据,联合应用Visual Modflow和FLAC3D数值模拟软件,开展潜水渗流场与斜坡稳定性的耦合分析,模型计算结果与监测及野外调查结果吻合较好,潜水渗流场的演化对斜坡稳定性具有控制作用,随着潜水位的升高,台塬周边不稳定区域逐年增加,1990、2000和2010年焦家崖头附近最大位移值分别为0.85、1.19和1.80m.     

环保部国土资源部负责人就土壤污染状况调查答记者问

环境保护部和国土资源部日前向媒体发布了全国土壤污染状况调查公报。调查结果显示,全国土壤环境状况总体不容乐观,部分地区土壤污染较重,耕地土壤环境质量堪忧,工矿业废弃地土壤环境问题突出。为全面认识和正确理解公报内容,环境保护部和国土资源部等相关负责人回答了记者提问。问：全国土壤污染状况调查成果有什么重要意义？答：本次调查是我国首次开展的全国范围土壤环境质量综合调查,填补了我国土壤环境领域的空白。     

青海省侏罗系油页岩成矿模式研究

通过"青海省侏罗系油页岩资源调查评价项目"工作的开展,以及对以往施工煤炭钻孔资料的系统梳理,认为青海省侏罗系油页岩主要赋存于以A、B两类型为代表的江仓组上段、石门沟组上段半深湖-深湖环境,其次为以C、D两类型为代表的窑街组及小煤沟组的湖湾沼泽环境。小峡矿区主体以湖湾环境为主,油页岩主要在湖湾环境的中心附近发育富集。鱼卡矿区主要为三角洲平原、三角洲前缘、滨浅湖、半深湖-深湖环境,油页岩分布在半深湖-深湖、滨浅湖、三角洲前缘单元中,主要在滨浅湖-半深湖-深湖环境中富集。     

冰岛地热资源开发利用现状

文章介绍了冰岛地热资源最新调查结果、地热资源管理模式与开发利用现状。提出了我国地热资源当务之急是理顺管理体系、加强地热资源基础调查评价、开展地热应用新技术新方法研究以及国家应予以适当资金扶持等建议。     

沉水植物黑藻对沉积物磷吸附动力学的影响

在室内模拟条件下,通过吸附动力学实验,研究了沉水植物黑藻对沉积物吸附磷动力学模型拟合和吸附速度的影响,并从有机质和铁铝氧化物含量的角度,讨论了沉水植物黑藻对沉积物吸附磷动力学的影响机理。初步得出如下结论:(1)一级反应动力学模型虽然从模型拟合的角度达到了极显著水平,但不能真实地反映沉水植物对沉积物吸附磷动力学过程的影响。其余三个模型均能很好地反映,其中抛物线扩散模型的拟合效果最好,修正的Elovich模型和双常数速率模型的拟合效果较好。种植沉水植物与否并不影响这一趋势;(2)沉水植物黑藻提高了沉积物吸附磷的强度和速度,特别是提高了0～0.5h内的吸附速度,沉水植物影响有机质和铁铝氧化物含量是增强沉积物吸附磷强度和速度的重要机理。     

地下水和干旱指数对植被指数空间分布的联合影响:以鄂尔多斯高原为例

鄂尔多斯高原无定河与都思兔河之间的地段属于我国西北地区典型的干旱-半干旱过渡带,覆盖毛乌素沙地,存在大量的地下水浅埋区,为植被生长创造了有利条件。前人研究表明鄂尔多斯高原沙地植被的盖度随着地下水埋深的减小而增大,但没有充分考虑气候梯度的影响。本研究依托大量井孔调查资料建立了研究区地下水埋深的高分辨率栅格数据,与区内增强型植被指数EVI的遥感数据和气候数据进行相关分析,并建立地下水埋深与干旱指数双因素坐标系来确定区域植被指数对地下水和气候背景的联合响应。研究结果表明:干旱指数和地下水埋深的增大都会导致植被指数的概率统计值减小。干旱指数介于3~5时,地下水埋深对植被指数的影响比较显著,且地下水埋深介于1~3m最有利于高盖度植被的出现。地下水显著影响植被分布的临界埋深约为7m。这一结果改进了前人关于鄂尔多斯生态水文地质特征的认识。     

青藏公路对其邻近土壤细菌丰度影响的研究

以垂直青藏公路不同距离样带土壤为研究样本,研究了距青藏公路10~500 m范围内土壤细菌丰度的变化及其影响因素. 结果表明：青藏公路沿线土壤细菌丰度为2.71×10⁷~7.20×10⁸copies·g^-1dw;距公路10~500 m土壤细菌丰度呈现出递增趋势,且以50 m为界限,50~500 m细菌丰度没有显著差异. 土壤细菌丰度与环境因子的相关性表明：青藏公路沿线土壤细菌丰度主要受土壤总氮、总有机碳以和植被盖度的影响,表现为细菌丰度与土壤总氮极显著正相关,与总有机碳显著正相关,与植被盖度极显著正相关. 上述结果说明,青藏公路对土壤细菌丰度的影响范围在50 m左右.     

草地植被盖度的多尺度遥感与实地测量方法综述

植被盖度作为一个重要的生态学参数被用在许多气候模型和生态模型中。地表实测和遥感测量是获取植被盖度的两种基本途径。以草地植被盖度的测量为研究对象,综合讨论了目前地表实测和遥感测量常用的方法,分析了它们的优缺点,并对如何提高草地植被盖度的测量精度做出展望。数码相机、高光谱遥感以及多尺度遥感数据的综合使用可能是未来草地植被盖度测量发展的趋势。     

Antibiotics pollution in Gonghu Bay in the period of water diversion from Yangtze River to Taihu Lake

As a famous project in China, the water diversion from Yangtze River to Taihu Lake Project has impacts on the water quality of Taihu Lake, especially Gonghu Bay, which is the entrance of the diversion water and the drinking water source for Wuxi and Suzhou. To investigate contamination of the antibiotics in Gonghu Bay in the period of water diversion, 16 antibiotics in 14 water samples collected from Wangyu River and Gonghu Bay in China were analyzed by liquid chromatography–tandem mass spectrometry. The results indicated that the concentration of total antibiotics in Wangyu River and Gonghu Bay ranged from 1320 to 17,209 ng/L (mean: 3920?±?3841 ng/L). The average level of different antibiotics was tetracyclines (range 1082–15,310 ng/L, mean 3161?±?3479 ng/L)?>?quinolones (range 225–1325 ng/L, mean 463?±?276 ng/L)?>?sulfonamides (range n.d.–888 ng/L, mean 402?±?248 ng/L)?>?macrolides (range 12–17 ng/L, mean 14?±?2 ng/L), and levels of the detected antibiotics in Gonghu Bay were higher than that in Wangyu River, indicating that the antibiotics pollution in Gonghu Bay were much severer than Wangyu River. Ecological risk evaluation showed that in the Wangyu and Gonghu water, trimethoprim (TMP), sulfacetamide (SAAM), sulfamethoxypyridazine (SMP), and sulfamerazine (SMRZ) presented low ecological risk levels, chlortetracycline (CTC), tetracycline (TC), roxithromycin (ROM), and sulfamethoxazole (SMX) had medium level of risk, and oxytetracycline (OTC), norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP), and enrofloxacin (ENR) had high level of ecological risk. The total hazard quotient of antibiotic mixtures for each sample site indicated high risk of antibiotics in Wangyu River and Gonghu Bay. In summary, the water diversion could mitigate antibiotic pollution in Gonghu Bay to a certain degree. However, the risk of antibiotics in the Wangyu River and Gonghu Bay is still high.     

引江济太对太湖水体碱性磷酸酶动力学参数的影响

采用野外定点采样、室内同步分析水体碱性磷酸酶活性及水化学指标的方法,研究引江济太调水对太湖各湖区水体碱性磷酸酶最大反应速率(v_max)、米氏常数(Km_m)值的影响。结果表明:在引江济太调水试验期间,各湖区水体中v_max及Km_m值时空分布存在差异性。调水稀释了各湖区蓝藻浓度,抑制了水体碱性磷酸酶v_max;贡湖区、西岸河口区及湖心区水体中Km_m值与入湖累积水量之间有显著的二次函数关系(p=0.007)。梅梁湖、竺山湖、贡湖及西岸河口区水体碱性磷酸酶v_max/Km_m随着总磷浓度升高而增加,但竺山湖、贡湖、草型湖、湖心及西岸河口区水体v_max/K随生物可利用磷(PO₃--P)浓度增加而下降。除草型湖区外,其它湖区水体v/K随叶绿素a浓度升高而增加。     

The distribution of nitrogen speciation and sources of nitrate in the north of Taihu Lake

Meiliang Bay and Gonghu Bay, in the north of Taihu Lake, are important water sources for the city of Wuxi, and increased eutrophication now threatens the safety of drinking water. The distribution of nitrogen (N) speciation and source of N in the surface waters in the north of Taihu Lake is studied, which was an important first step in controlling N pollution. The result shows that the average concentration of ammonia (NH₄ ⁺) and nitrate (NO₃ ^?) of surface water in Meiliang Bay was 0.32 and 0.35 mg/L, while 0.21 and 0.74 mg/L of Gonghu Bay, in which both bays had serious nitrate pollution. The concentrations of NH₄ ⁺ and NO₃ ^? in the surface water of the two bays had a trend of gradual decrease from north to south. The maximum concentrations of NH₄ ⁺ and NO₃ ^? of two bays were observed near the inflowing rivers, and the maximum concentrations of NH₄ ⁺ in surface water of two bays were 0.49 and 0.61, and 0.77 and 1.38 mg/L of NO₃ ^?. The concentration of NH₄ ⁺ in the interstitial water of the two bays had a trend of gradual decrease from west to east, but NO₃ ^? had the opposite tendency. The maximum concentrations of NH₄ ⁺ in the interstitial water of the two bays were 5.88 and 4.64, and 3.58 and 7.18 mg/L of NO₃ ^?. The exchangeable NH₄ ⁺ content in the sediment of Meiliang Bay had a trend of gradual decrease from north to south, but Gonghu Bay showed the reverse. The exchangeable NO₃ ^? content in the sediment of Meiliang Bay had a trend of gradual decrease from east to west, but a decreasing trend from north to south was observed in Gonghu Bay. The maximum concentrations of exchangeable NH₄ ⁺ were determined, and the values were 96.25 and 74.90 mg/kg, as well as NO₃ ^? with the values of 12.06 and 7.08 mg/kg. Chemical fertilizer and domestic sewage were the major sources of nitrate in surface water of Gonghu Bay, contributing 39.16 and 47.79%, respectively. Domestic sewage was the major source of nitrate in Meiliang Bay, contributing 84.79%. The denitrification process in Gonghu Bay was more apparent than in Meiliang Bay. Mixing and dilution processes had important effects on changing the concentration of nitrate transportation in the two bays.     

Benthic Macrophyte Distribution and Abundance in Estuarine Mangrove Lakes and Estuaries: Relationships to Environmental Variables

Annual mean salinity, light availability, and sediment depth to bedrock structured the submerged aquatic vegetation (SAV) communities in subtropical mangrove-lined estuaries. Three distinct SAV communities (i.e., Chara group, Halodule group, and Low SAV coverage group) were identified along the Everglades–Florida Bay ecotone and related to water quality using a discriminant function model that predicted the type of plant community at a given site from salinity, light availability, and sediment depth to bedrock. Mean salinity alone was able to correctly classify 78% of the sites and reliably separated the Chara group from the Halodule group. The addition of light availability and sediment depth to bedrock increased model accuracy to 90% and further distinguished the Chara group from the Halodule group. Light availability was uniquely valuable in separating the Chara group from the Low SAV coverage group. Regression analyses identified significant relationships between phosphorus concentration, phytoplankton abundance, and light availability and suggest that a decline in water transparency, associated with increasing salinity, may have also contributed to the historical decline of Chara communities in the region. This investigation applies relationships between environmental variables and SAV distribution and provides a case study into the application of these general principals to ecosystem management.     

Sediment phosphorus fractions and profile distribution at different vegetation growth zones in a macrophyte dominated shallow Wuliangsuhai Lake,China

Sediment phosphorus (P) fractions and profile distribution at submerged macrophyte growth zone, emergent macrophyte growth zone and open-water zone were studied in Wuliangsuhai Lake, China, as well as the correlations among water content, grain size, and organic matter and P fractions. Among the three surveyed zones, the highest concentrations of most P forms occurred in the surface sediment and the lowest between a depth of 12 and 22 cm, except HCl-P and NaOH-P. Sediment phosphorus was mainly associated to inorganic forms (>50%) in three surveyed areas, and the highest value of inorganic phosphorus (IP) in the surface sediment was obtained from submerged macrophyte growth zone. Submerged and emergent macrophytes increased the IP content by 107 and 44 μg/g, respectively, in the surface sediment compared with open-water zone. Vertical profiles of IP in the three surveyed zones showed that the concentrations decreased from surface to 12 cm depth and then increased. There was a similar trend in the sediment profiles of organic phosphorus (OP) and total phosphorus (TP), but the highest concentration of OP and TP in surface sediment was obtained from the emergent macrophyte growth zone. Compared with open-water zone, the emergent macrophyte increased TP content in surface sediment by 1.73 times to 1,320 μg/g, while submerged macrophyte enhanced TP content in the surface sediment by 1.13 times to 865 μg/g. It was observed that in macrophyte growth zones, a strong linear correlation existed between organic matter and OP (r > 0.98), and the maximum concentrations of OP were present in the areas with maximum concentrations of organic matter. Results show that, although rooted macrophyte could uptake directly P from sediments, it is responsible for increasing the internal P loading especially OP by reducing current velocities, attenuating wave energy and generating organic residue in Wuliangsuhai Lake.     

The nursery role of seagrass meadows in the upper and lower reaches of the Chesapeake Bay

A two-year trawling and gill-netting study of vegetated and unvegetated bottoms near Parson’s Island, Maryland and near the mouth of the York River, Virginia was carried out to assess the nursery function of submerged vegetation for populations of fishes and decapod crustaceans in the Chesapeake Bay. Results revealed that vegetated bottoms supported substantially larger numbers of decapods, but not fishes, than unvegetated substrates. The lower Bay grassbed was an important nursery area for juvenile blue crabs, although neither of the grassbeds functioned as a nursery for commercially or recreationally valuable fishes. Our results suggest that: (1) further decreases in lower Bay Seagrass biomass would result in reduced numbers of adult blue crabs, but should not substantially affect populations of valuable fish species; (2) additional decreases in Upper Bay submerged vegetation should not produce dramatic change in the population sizes of either adult blue crabs or fishes.     

灵水岩溶泉浮游植物群落结构及其对水环境的指示作用

灵水湖内沉水植物自2010年逐渐消亡,至2013年已基本消失,为探究岩溶水生态系统退化的原因,于2016年4、7、10月对灵水和罗波潭两个水环境相似的岩溶泉进行浮游植物调查和水环境监测。结果显示:灵水优势种共3门16种,罗波潭优势种共3门13种,两者的浮游植物相似性为60%。3次调查种类数基本不变,丰度均表现为4月>7月>10月。生物多样性指数和叶绿素水质评价均显示罗波潭优于灵水,说明沉水植物消亡会引发水环境退化。浮游植物与环境因子的RDA和相关性分析显示,总氮(TN)是浮游植物群落的决定性因子,而浮游植物对氮营养盐更强的摄食能力可能是灵水沉水植物消亡的原因之一。岩溶水环境的HCO-3 和Ca2+浓度可以指示浮游植物的生长状态。      

Temporal and spatial distribution and production of dissolved gaseous mercury in the Bay St. François wetland, in the St. Lawrence River, Quebec, Canada

Wetlands are valued for their high biodiversity and for their ecosystem services. However, we still do have a poor understanding of their role in the redox transformation of contaminants such as mercury, particularly in fluvial settings. Seasonal and spatial variations in dissolved gaseous mercury (DGM) distribution and production were studied in the Bay St. François, a wetland in the St. Pierre Lake, a fluvial lake of the St. Lawrence River, in Quebec, Canada. A high spatial resolution for DGM, with samples taken every 10-cm depth, was used in field measurements. Through a series of parallel field and incubation experiments, we assessed the main factors determining Hg(0) transformations as a function of depth, seasons, and presence/absence of macrophyte beds. Besides light penetration in the water column and water temperature, iron and dissolved organic carbon likely stimulated Hg(II) reduction. Inversely, chloride favored Hg(0) oxidation. Macrophytes and associated epiphytes appeared to be important sites of adsorption/absorption of Hg(II) and likely of DGM. It seems however that the effects of macrophytes were restricted to immediately adjacent waters. Near the bottom, under anoxic conditions, the reduction of Hg(II) was highly promoted. In addition, sediments and decomposing macrophytes seemed to release DGM and/or reducible Hg to bottom waters. Overall, differences in DGM between surface and bottom waters tended to be more accentuated than observed differences in DGM between macrophyte beds and sites devoid of plant.     

长江源区高寒生态与气候变化对河流径流过程的影响分析

近40 a来长江源区气候变化剧烈,是青藏高原增温最为显著的地区之一,高寒生态系统与冻土环境不断退化.采用多因素逐次甄别方法与半经验理论方法相结合,基于多年冻土的不同植被覆盖降水-径流观测场观测试验结果,分析了长江源区气候-植被-冻土耦合系统中各要素变化对河川径流的不同影响.结果表明:近40 a来长江源区河川径流呈持续递减趋势,年均径流量减少了15.2%,频率>20%的径流量均显著减少,而>550 m³·s^-1的稀遇洪水流量发生频率增加;气候变化与高寒草甸覆盖变化对源区径流变化的影响较大,分别占5.8%和5.5%;气候与植被覆盖变化对径流的显著影响是与冻土耦合作用的结果,但冻土环境与冰川变化对径流的贡献尚不能准确评价.高寒沼泽湿地和高寒草甸生态系统对于源区河川径流的形成与稳定起到关键作用,这两类生态系统的显著退化是驱动河川径流过程中变差增大、降水-径流系数减少以及洪水频率增加的主要原因.保护源区高寒草甸与独特的高寒湿地生态,对于维护源区水涵养功能和流域水安全意义重大.