Monitored and Modeled Correlations of Sediment and Nutrients with Chesapeake Bay Water Clarity

This article analyzes the correlations of the observed and modeled light attenuation coefficient, Kd, with in situ total suspended solids (TSS) and chlorophyll‐a concentrations in Chesapeake Bay (CB) tidal waters, and with sediment and nutrient loads from the Chesapeake watershed. Light attenuation is closely related to in situ TSS and chlorophyll‐a concentrations, however, the strength of the correlation differs among the CB segments. There are distinct differences between saline and tidal fresh segments in the main Bay, but less distinction among saline and tidal fresh segments in the tidal tributaries. The correlation between Kd with sediment and nutrient loads is complicated by the lag times of TSS and the chlorophyll‐a responses to reductions in nutrient and sediment loads from the watershed, and also due to the diverse load sources. Three sets of model sensitivity scenarios were performed with: (1) differential sediment and nutrient loads; (2) selective sediment source types; and (3) geographically isolated inputs. The model results yield similar findings as those based on observed data and provide information regarding the effect of sediment on specific water bodies. Based on the model results a method was developed to determine sediment and nutrient load reductions needed to achieve the water clarity standards of the CB segments.     

Net primary productivity of China's terrestrial ecosystems from a process model driven by remote sensing

The terrestrial carbon cycle is one of the foci in global climate change research. Simulating net primary productivity (NPP) of terrestrial ecosystems is important for carbon cycle research. In this study, China's terrestrial NPP was simulated using the Boreal Ecosystem Productivity Simulator (BEPS), a carbon-water coupled process model based on remote sensing inputs. For these purposes, a national-wide database (including leaf area index, land cover, meteorology, vegetation and soil) at a 1 km resolution and a validation database were established. Using these databases and BEPS, daily maps of NPP for the entire China's landmass in 2001 were produced, and gross primary productivity (GPP) and autotrophic respiration (RA) were estimated. Using the simulated results, we explore temporal-spatial patterns of China's terrestrial NPP and the mechanisms of its responses to various environmental factors. The total NPP and mean NPP of China's landmass were 2.235 GtC and 235.2 gCm(-2)yr(-1), respectively; the total GPP and mean GPP were 4.418 GtC and 465 gCm(-2)yr(-1); and the total RA and mean RA were 2.227 GtC and 234 gCm(-2)yr(-1), respectively. On average, NPP was 50.6% of GPP. In addition, statistical analysis of NPP of different land cover types was conducted, and spatiotemporal patterns of NPP were investigated. The response of NPP to changes in some key factors such as LAI, precipitation, temperature, solar radiation, VPD and AWC are evaluated and discussed.     

梯级水库建设下的水沙营养盐协同变化规律研究：以嘉陵江为例

水库建设在兴利防洪的同时对多个环境要素造成了影响,现有研究主要分析水、沙、营养盐等单一要素变化,缺乏不同要素间的协同分析.本研究基于IHA指标、MK分析、Spearman相关分析等方法讨论了1995—2017年嘉陵江梯级水库建设对流域水-沙-污染物等单个要素和多个要素协同性的综合影响.结果表明,水库建设对河流流量具有"削峰填平"作用,其中枯水期流量增加13.3%～47.0%,丰水期流量下降率最高则达19.4%;相对于流量,水库建设对泥沙的削减作用更为明显,且对上游河流泥沙输移影响更大.同时,水库建设后其下游水、沙、营养盐过程线趋同,尤其是丰水期,水、沙、营养盐指标相关系数显著提升,均达0.75以上.该结果补充了目前水库建设对水、沙、营养盐综合影响研究的不足,为水利工程影响下的水环境综合管理提供了支撑.     

Response mechanism of Chlamydomonas reinhardtii to nanoscale bismuth oxyiodide (nano-BiOI): Integrating analysis of mineral nutrient metabolism and metabolomics

Nanoscale bismuth oxyiodide (nano-BiOI) is widely studied and applied in environmental applications and biomedical fields, with the consequence that it may be deposited into aquatic environments. However, the impact of nano-BiOI on aquatic ecosystems, especially freshwater microalga, remains limited. Herein, the nano-BiOI was synthesized and its response mechanism towards microalga Chlamydomonas reinhardtii was evaluated. Results showed that a low concentration of nano-BiOI (5 mg/L) could stimulate algal growth at the early stage of stress. With the increase in concentration, the growth rate of algal cells was inhibited and showed a dose effect. Intracellular reactive oxygen species (ROS) were significantly induced and accompanied by enhanced lipid peroxidation, decreased nonspecific esterase activity, and significantly upregulated glutathione S-transferase activity (GST) activity. Mineral nutrient metabolism analysis showed that nano-BiOI significantly interfered with the mineral nutrients of the algae. Non-targeted metabolomics identified 35 different metabolites (DEMs, 22 upregulated, and 13 downregulated) under 100 mg/L BiOI stress. Metabolic pathway analysis demonstrated that a high concentration of nano-BiOI significantly induced metabolic pathways related to amino acid biosynthesis, lipid biosynthesis, and glutathione biosynthesis, and significantly inhibited the sterol biosynthesis pathway. This finding will contribute to understanding the toxicological mechanisms of nano-BiOI on C. reinhardtii.     

密云水库及其流域营养物集成模拟的情景分析研究

在密云水库水环境模拟预测集成模型的支持下,考察了不同点源、非点源污染负荷控制措施对水库水质的影响和作用,制定了4个情景方案.基础情景分析表明,密云水库TN超标严重,TP相对较好,叶绿素浓度超过10μg/L的区域主要集中在潮河库区,而且面积较大.情景1、情景2和情景3是考虑了不同点源、非点源管理措施后的密云水库水质状况.结果表明,营养负荷的下降能显著地改善水体水质,尤其是磷负荷的降低可有效地制约藻类生长,叶绿素浓度显著降低,超过10μg/L的区域缩小甚至消失.这一结论说明了加强密云水库流域及周边地区工业、生活和畜禽养殖等点源和农业非点源污染控制对改善密云水库水质的有效性和必要性.     

EUTROPHICATION MEASURES FOR SMALL LAKE WATER QUALITY MANAGEMENT1

ABSTRACT: Continuous measures of water quality responsiveness to changes in nutrient loadings are developed for use by environmental regulators attempting to achieve the greatest degree of water quality improvement consistent with competing uses of scarce resources. Recent contributions to the literature, based upon the nutrient loading concept, provide statistical relationships applicable to broad categories of lakes. In order to meet the requirements of water quality regulators, equations based upon USEPA survey data are developed in terms of the functional forms formulated and tested in the literature. Since recent authors have observed that much existing survey data are inappropriate for the formulation and testing of nutrient loading relationships, we have utilized results from the literature that work best with the existing data base, on grounds that such data are most inexpensively available to water quality managers. The nature of existing data limitations is discussed, and approaches to the revision of current results in light of improvements in the data base are indicated.     

生物脱氮除磷新工艺的研究进展

传统的脱氮除磷工艺存在许多不足之处 ,经济、高效、低耗的可持续脱氮除磷工艺已成为污水处理的发展方向。在分析中 ,介绍了运用短程硝化反硝化、厌氧氨氧化、反硝化除磷理论的工艺 :SHARON工艺、CANON工艺、ANAMMOX工艺、SHARON与ANAMMOX联合工艺、DEPHANOX工艺、BCFS○R工艺的机理和研究进展     

BAT and BEP as instruments for reducing emissions of unintentionally produced POPs and development of guidelines under the stockholm convention

The 6th Intergovernmental Negotiating Committee (INC 6), under the Stockholm Convention on POPs, gave an expert group the mandate to develop guidelines for the application and implementation of best available techniques (BAT) and best environmental practices (BEP) for the prevention and reduction of unintentionally produced and emitted POPs, including polychlorinated dibenzodioxins/-furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB). Measures to reduce or eliminate the release of these POPs to the environment can be found in Article 5 of the Convention. BAT and BEP are already being applied as emission reduction instruments in a number of industrialised countries and are elements of other major international treaties, e.g. the UN ECE Protocol on POPs and the Marine Convention's OSPAR and HELCOM, and of the EU Directive for Integrated Pollution Prevention and Control (IPPC Directive). Existing concepts are presented and compared with the requirements of the Stockholm Convention. Consequences, perspectives and questions for the future intersessional work of the above-mentioned Expert Group are discussed.     

黑藻与金鱼藻自然衰亡过程中营养盐释放规律研究

为研究在自然衰亡状态下黑藻（Hydrilla verticillata）与金鱼藻（Ceratophyllum demersum）营养盐释放规律,采用人工模拟的方式,于黑藻和金鱼藻进入衰亡期时,采用塑料薄膜捆扎植物根部的方式,阻隔水和底泥界面之间的物质交换,避免底泥释放对水营养盐的影响;同时,监测水中环境因子和营养盐的动态变化,分析营养盐的释放与环境因子之间的关系.结果表明:①黑藻和金鱼藻两种沉水植物在模拟自然状态下分解速率和生物量无显著性差异（P>0.05）,Olson指数的分解速率分别为0.011、0.010 d-1.②水中氮、磷质量浓度峰值在试验的第40~50天.水中磷形态以DTP（溶解性总磷）和SRP（溶解性活性磷）为主,氮形态以DTN（溶解性总氮）和NO₃--N为主.由于SRP、NO₃--N分别是DTP、DTN的组分之一,因此黑藻和金鱼藻在衰亡期向水中释放的氮、磷形态主要为NO₃--N和SRP.③环境因子pH、DO、ORP（氧化还原电位）均呈不同程度的先降后升趋势.主成分分析结果表明,金鱼藻和黑藻环境因子主成分F_j和F_h、生物量剩余百分比分别与两植物组营养盐第一主成分之间二次曲线拟合效果较好,因此通过对数据进行降维处理,可建立二者之间的函数方程.研究显示,黑藻和金鱼藻两种沉水植物自然分解速率基本一致,衰亡期间向水中主要释放NO₃--N和SRP,水中氮、磷质量浓度呈单峰变化,通过主成分分析可以建立环境因子和营养盐之间的函数关系.      

1951—2017年滇池流域极端降水变化及湖体水质响应

极端降水是流域水文水质变化的重要驱动事件.本研究使用RclimDex、随机森林回归和Mann-Kendall等方法分析了滇池流域多年极端降水指标变化特征及其对滇池湖体水质的影响,评估了不同极端降水指标、经济社会指标、人为氮磷输入量、调水量等驱动因子对滇池TP、TN浓度的重要性.结果表明：近67年间,滇池流域的总降水量没有显著变化,极端降水的频次及强度显著降低,但由于极端降水对流域总降水量的贡献较大,流域面临的极端降水风险较大.近20年来,滇池湖体TP、TN浓度呈显著降低趋势,水质显著好转,但极端降水将持续影响滇池水质,并且,在人为氮磷输入与极端降水变化的双重作用下,滇池水质持续好转的压力较大.