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.     

Radiation-induced degradation of methyl orange in aqueous solutions

Degradation of methyl orange under gamma-irradiation was investigated. The reactions followed pseudo first-order kinetics. Apparent degradation rate constant, estimated through linear regression analysis, increased with an increase of dose rate and a decrease of initial methyl orange concentration. Degradation of methyl orange was significantly accelerated under oxidative condition, but was slightly enhanced under reductive condition. However, the result of decoloration was better under reductive condition than oxidative one. An analysis on the intermediates using Fourier transform infrared and gas chromatography/mass spectrometry demonstrates that the radiolytic degradation of methyl orange was processed with different C-N cleavages under oxidative and reductive conditions.     

Effect of manganese ion on the mineralization of 2,4-dichlorophenol by ozone

Mineralization of 2,4-dichlorophenol (DCP) was studied by ozone with Mn(2+) as an ozonation catalyst. Laboratory scale semi-batch ozonation experiments were conducted at room temperature. The results showed that trace amount of Mn(2+) accelerated the mineralization of DCP. Total organic carbon removal rate was independent on Mn(2+) dosage at its range of 0.1-0.5 mgL(-1). Dissolved ozone concentration in the solution remained low level in the catalytic ozonation process, which indicated that Mn(2+) catalyzed decomposition of ozone. DCP mineralization was inhibited in catalytic ozonation by the addition of carbonate. Electron spin resonance/spin-trapping technique was used to determine hydroxyl radicals, and the results showed that larger amounts of hydroxyl radicals were produced in catalytic ozonation system than those of single ozonation. Intermediates mainly including aliphatic carboxylic acids were determined qualitatively and semi-quantitatively by GC-MS. And, a general pathway for mineralization of DCP was proposed.     

四氯乙烯污染对小麦幼苗抗氧化酶系的影响

通过室内模拟试验,采用愈创木酚法、高锰酸钾滴定法、氮蓝四唑法分别测定了四氯乙烯(PCE)污染小麦幼苗的过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物岐化酶(SOD)等抗氧化物酶系,研究了PCE污染对植物生物学指标的影响,以评价土壤PCE污染的生态毒性效应,为土壤性质的变化趋势提供依据.结果表明,PCE浓度较低时,POD、SOD活性被激活,表现出明显的抗氧化能力,但PCE浓度过高时则抑制POD和SOD的活性诱导作用;小麦幼苗中CAT活性只有在PCE为0.10mg/kg时被激活,其他浓度时CAT活性均受到抑制;随着时间的延长,POD、CAT的活性均呈激活态势,而SOD活性在PCE浓度较低时呈降低趋势,在PCE浓度较高时,SOD活性升高.     

黄铁矿焙烧过程中铊析出影响因素及其烧渣中重金属的相态分布研究

通过模拟硫酸厂的沸腾焙烧炉,考察了黄铁矿焙烧过程中铊(T1)析出的影响因素.并通过分级提取法考察了黄铁矿烧渣中重金属的相态分布.结果表明,T1释放率随焙烧温度的升高而增加,随停留时间的增长而增加;当O2流量在20～300 mL/mi.范围变化时,T1释放率先增后减.环境中备受关注的重金属(如Pb、Cd、Cr等)在黄铁矿烧渣中以Pb为主,各相态Pb的总量达到1 429.20 μg/g,且黄铁矿烧渣中的重金属(除Cu和Sr外)主要是以分布于硅酸盐矿物相中的残余态形式存在,因此在环境中不易迁移释放.尽管黄铁矿烧渣中的重金属(除Cu和Sr外)不是以非残余态分布为主,但非残余态重金属的总量也不少,因此黄铁矿烧渣在环境中的潜在污染风险应当引起重视.     

上流式多级厌氧反应器中厌氧颗粒污泥特性研究

高品质厌氧颗粒污泥是厌氧反应器实现高效、稳定运行的关键和基础.在实现上流式多级厌氧反应器(UMAR)处理木薯变性淀粉废水高效运行的基础上,对厌氧颗粒污泥的浓度分布、粒径分布、沉降速度、产甲垸活性,辅酶F420和生物相等作进一步的研究.根据在实验工艺条件下培养得到的厌氧颗粒污泥的性能,探讨厌氧颗粒污泥的可能形成机制.     

umu试验菌种保存条件优化研究

研究了umu试验菌株(Salmonella typhimurimu TA1535/pSK1002)的菌种在普通冰箱中保存时其生长曲线和活性的变化,菌种经活化后可以得到稳定的活化生长曲线以及比较稳定的4-NQO活性曲线.通过菌种活化,使得umu试验菌种在普通冰箱中保存就能具有很好的活性和稳定性,极大地降低了保存难度,简化了菌种保存操作步骤,增加了试验的可重复性,有利于umu试验在实际环境样品检测中的应用.     

Assessing heavy metal pollution in the surface soils of a region that had undergone three decades of intense industrialization and urbanization

Heavy metals in the surface soils from lands of six different use types in one of the world’s most densely populated regions, which is also a major global manufacturing base, were analyzed to assess the impact of urbanization and industrialization on soil pollution. A total of 227 surface soil samples were collected and analyzed for major heavy metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) by using microwave-assisted acid digestion and inductively coupled plasma–mass spectrometry (ICP-MS). Multivariate analysis combined with enrichment factors showed that surface soils from the region (>7.2?×?10⁴ km²) had mean Cd, Cu, Zn, and As concentrations that were over two times higher than the background values, with Cd, Cu, and Zn clearly contributed by anthropogenic sources. Soil pollution by Pb was more widespread than the other heavy metals, which was contributed mostly by anthropogenic sources. The results also indicate that Mn, Co, Fe, Cr, and Ni in the surface soils were primarily derived from lithogenic sources, while Hg and As contents in the surface soils were controlled by both natural and anthropogenic sources. The pollution level and potential ecological risk of the surface soils both decreased in the order of: urban areas?>?waste disposal/treatment sites?～?industrial areas?>?agricultural lands?～?forest lands?>?water source protection areas. These results indicate the significant need for the development of pollution prevention and reduction strategies to reduce heavy metal pollution for regions undergoing fast industrialization and urbanization.     

The acute effects of fine particles on respiratory mortality and morbidity in Beijing, 2004–2009

Recent epidemiological and toxicological studies have shown associations between particulate matter and human health. However, the estimates of adverse health effects are inconsistent across many countries and areas. The stratification and interaction models were employed within the context of the generalized additive Poisson regression equation to examine the acute effects of fine particles on respiratory health and to explore the possible joint modification of temperature, humidity, and season in Beijing, China, for the period 2004–2009. The results revealed that the respiratory health damage threshold of the PM_2.5 concentration was mainly within the range of 20–60 μg/m³, and the adverse effect of excessively high PM_2.5 concentration maintained a stable level. In the most serious case, an increase of 10 μg/m³ PM_2.5 results in an elevation of 4.60 % (95 % CI 3.84–4.60 %) and 4.48 % (95 % CI 3.53–5.41 %) with a lag of 3 days, values far higher than the average level of 0.69 % (95 % CI 0.54–0.85 %) and 1.32 % (95 % CI 1.02–1.61 %) for respiratory mortality and morbidity, respectively. There were strong seasonal patterns of adverse effects with the seasonal variation of temperature and humidity. The growth rates of respiratory mortality and morbidity were highest in winter. And, they increased 1.4 and 1.8 times in winter, greater than in the full year as PM_2.5 increased 10 μg/m³.     

Toxicological responses of earthworm (Eisenia fetida) exposed to metal-contaminated soils

The aim of this study was to evaluate the toxicological responses of earthworm (Eisenia fetida) induced by field-contaminated, metal-polluted soils. Biochemical responses and DNA damage of earthworm exposed to two multi-metal-contaminated soils in a steel industry park and a natural reference soil in Zijin Mountain for 2, 7, 14, and 28 days were studied. Results showed that three enzyme activities, including superoxide dismutase (SOD), acetylcholinesterase (AChE), and cellulase, in earthworm in metal-contaminated soils were significantly different from those of the reference soil. Cellulase and AChE were more sensitive than SOD to soil contamination. The Olive tail moment of the comet assay after 2-day exposure increased 56.5 and 552.0 % in two contaminated soils, respectively, compared to the reference soil. Our findings show that cellulase and DNA damage levels can be used as potential biomarkers for exposure of earthworm to metal-polluted soils.