Evaluating anthropogenic N inputs to diverse lake basins: A case study of three Chinese lakes

The environmental degradation of lakes in China has become increasingly serious over the last 30 years and eutrophication resulting from enhanced nutrient inputs is considered a top threat. In this study, a quasi-mass balance method, net anthropogenic N inputs (NANI), was introduced to assess the human influence on N input into three typical Chinese lake basins. The resultant NANI exceeded 10 000 kg N km⁻² year⁻¹ for all three basins, and mineral fertilizers were generally the largest sources. However, rapid urbanization and shrinking agricultural production capability may significantly increase N inputs from food and feed imports. Higher percentages of NANI were observed to be exported at urban river outlets, suggesting the acceleration of NANI transfer to rivers by urbanization. Over the last decade, the N inputs have declined in the basins dominated by the fertilizer use but have increased in the basins dominated by the food and feed import. In the foreseeable future, urban areas may arise as new hotspots for nitrogen in China while fertilizer use may decline in importance in areas of high population density.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0638-8) contains supplementary material, which is available to authorized users.     

Toxicity of sediment cores from Yangtze River estuary to zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) embryos

Toxicity evaluation is an important segment in sediment quality monitoring in order to protect aquatic organisms and human health. The purpose of this study is to assess the toxicity of sediments from three sediment cores in Yangtze River Estuary, China, using the zebrafish (Danio rerio) embryo tests. Fertilized zebrafish eggs were exposed to both whole sediments and sediment organic extracts prepared from collected sediments, in order to provide a comprehensive and realistic insight into the bioavailable toxicity potential of the sediments. As end points, development parameters (mortality, hatching rate, and abnormality) in the developing embryos were recorded during the 96-h exposure. The results showed that some samples increased mortality, inhibited the hatching of embryos, and induced morphological abnormalities. The embryonic toxicities presented serrated changes and irregular distribution with depth, which may be related to hydrodynamic effect and unstable environmental input. However, lethal and sub-lethal effects were more significant at the sub-surface sediments (10～40 cm), which indicated that the pollution is more serious in recent decades.     

微生物絮凝剂M-C11处理高岭土悬浊液的响应曲面优化

采用响应曲面法对微生物絮凝剂M-C11处理高岭土悬浊液的过程参数进行优化,选取中心复合实验设计(CCD),以p H、M-C11投加量和Ca Cl2投加量等因素为自变量,以处理后的高岭土悬浊液絮凝率(Fr)为响应值,并借助扫描电镜对絮凝剂的作用机理进行初步探讨。结果表明,微生物絮凝剂M-C11可显著改善高岭土悬浊液的絮凝性能,且选取的3种单因素水平均可影响絮凝剂活性。经多元回归拟合分析,在M-C11投加量为2.56 m L,Ca Cl2投加量为0.37 g/L的最优条件下,微生物絮凝活性实验值可达92.37%,接近模型预测值(92.30%)。Ca Cl2投加量对絮凝效果的影响高于M-C11投加量(PCa Cl2相似文献   

中国工业水污染及其成因的de Bruyn模型分析

选取废水、挥发酚、氰化物、COD、石油类和氨氮为中国工业水污染指标,利用分解分析方法将2004—2010年间的污染变化分解为规模效应、结构效应、污染治理效应、清洁技术效应和广义技术效应。结果显示,这5类效应的平均作用强度分别为2.08%、3.04%、15.61%、17.37%和32.88%,其中规模效应和广义技术效应是影响工业水污染的主导效应。各类效应对不同污染物的作用方向并不完全一致,规模效应促进污染物排放量的增加;结构效应以加重污染为主,污染治理效应和清洁技术效应以减轻污染为主;广义技术效应的平均作用强度和负向作用概率均最大,是现阶段中国工业水污染控制最为有效的手段。     

添加炭基材料对蔬菜废物好氧堆肥进程和腐熟度的影响

以蔬菜废弃物辣椒秸秆和树叶为堆肥原料(CK),采用密闭式好氧堆肥工艺,研究了添加5%木本泥炭(T1)、5%活性炭(T2)和10%木本泥炭(T3)等炭基材料对堆肥p H、EC、CO2累积量、物料损失率、T值、C/N和发芽率指数的影响。结果显示,T2处理的p H在60 d后维持在8~9之间;EC值随着堆肥进行呈现先下降后升高再下降的趋势,最终CK、T1、T2和T3处理的EC值(m S/cm)分别降低了1.02、0.76、0.33和0.48;T2和T3处理的CO2累积量一直高于其他处理;所有处理的物料损失率均在20%以上;4个处理堆肥产品的T值分别为0.56、0.65、0.68和0.69;堆肥产品的发芽率指数分别为63.2%、69.3%、93.5%和86.1%。T值和发芽率指数显示T2和T3处理达到了腐熟阶段。结果表明,在蔬菜堆肥处理中添加炭基材料可改善堆肥产品的理化性质,加速堆肥物料的分解,有效地缩短堆肥周期和提高堆肥产品的腐熟度。     

阳宗海沉积物中磷的稳定性

絮凝剂(Fe Cl3)治理阳宗海砷污染的过程中,水体中的磷被大量沉积进入底泥,弄清其是否会在环境条件变化后发生反溶形成二次污染对湖泊富营养化防治具有重要意义。通过模拟实验模拟泥-水界面p H变化、物理扰动和微生物活动的变化,旨在分析这些环境因子变化对沉积物中磷溶出的影响。结果表明,阳宗海水体在目前这种磷浓度下,底泥的磷会随时间的增加而溶出再次造成水体磷污染,当暴露在清洁水条件下时磷的释放率会增加;这种由于絮凝剂吸附沉淀到湖底的磷,在上覆水p H增加0.5时底泥磷解吸附释放速率增加;每年秋季湖泊上下层水的交换活动会造成水体磷浓度的季节性升高,形成不可忽视的磷内源。而夏季水温分层导致湖泊底部厌氧,使厌氧微生物活性增强,这将进一步促进底泥中磷的释放。     

Degradation of the potential rodent contraceptive quinestrol and elimination of its estrogenic activity in soil and water

Quinestrol has shown potential for use in the fertility control of the plateau pika population of the Qinghai–Tibet Plateau. However, the environmental safety and fate of this compound are still obscure. Our study investigated degradation of quinestrol in a local soil and aquatic system for the first time. The results indicate that the degradation of quinestrol follows first-order kinetics in both soil and water, with a dissipation half-life of approximately 16.0 days in local soil. Microbial activity heavily influenced the degradation of quinestrol, with 41.2 % removal in non-sterile soil comparing to 4.8 % removal in sterile soil after incubation of 10 days. The half-lives in neutral water (pH 7.4) were 0.75 h when exposed to UV light (λ?=?365 nm) whereas they became 2.63 h when exposed to visible light (λ?>?400 nm). Acidic conditions facilitated quinestrol degradation in water with shorter half-lives of 1.04 and 1.47 h in pH 4.0 and pH 5.0 solutions, respectively. Moreover, both the soil and water treatment systems efficiently eliminated the estrogenic activity of quinestrol. Results presented herein clarify the complete degradation of quinestrol in a relatively short time. The ecological and environmental safety of this compound needs further investigation.     

Comparison of lignin peroxidase and horseradish peroxidase for catalyzing the removal of nonylphenol from water

Concentrations of aqueous-phase nonylphenol (NP), a well-known endocrine-disrupting chemical, are shown to be reduced effectively via reaction with lignin peroxidase (LiP) or horseradish peroxidase (HRP) and hydrogen peroxide. We systematically assessed their reaction efficiencies at varying conditions, and the results have confirmed that the catalytic performance of LiP toward NP was more efficient than that of HRP under experimental conditions. Mass spectrum analysis demonstrated that polymerization through radical–radical coupling mechanism was the pathway leading to NP transformation. Our molecular modeling with the assistance of ab initio suggested the coupling of NP likely proceeded via covalent bonding between two NP radicals at their unsubstituted carbons in phenolic rings. Data from acute immobilization tests with Daphnia confirm that NP toxicity is effectively eliminated by LiP/HRP-catalyzed NP removal. The findings in this study provide useful information for understanding LiP/HRP-mediated NP reactions, and comparison of enzymatic performance can present their advantages for up-scale applications in water/wastewater treatment.