生物炭施用对紫色土旱坡地土壤氮流失形态及通量的影响

明确生物炭施用对紫色土旱坡地土壤氮流失形态及通量的影响,为提升紫色土旱坡地耕地质量及减少紫色土旱坡地农业面源污染发生风险提供科学依据.以油菜/玉米轮作农田生态系统为研究对象,通过田间试验,研究了不施肥(对照)、常规施肥、优化施肥及生物炭(化肥减量配施生物炭)这4个处理对紫色土旱坡地地表径流和壤中流氮素流失形态及通量的影响.结果表明:①在各施肥处理中,常规处理总径流量最大,为16 133 L·a~(-1),生物炭处理总径流量最小,为11 893 L·a~(-1).各施肥处理以壤中流为主要径流方式,壤中流流失量占总流失量的61.80%～68.60%;与对照(不施肥处理)相比,其余各施肥处理泥沙流失量均有所降低,其中常规处理降低的效果最明显.②铵态氮主要通过地表径流流失,占总流失通量的86.51%～96.58%;铵态氮流失通量最大的为施生物炭处理[0.69 kg·(hm~2·a)~(-1)].③各施肥处理产流中的颗粒态氮浓度均高于对照处理,且常规施肥处理的颗粒态氮流失通量最大,为2.87 kg·(hm~2·a)~(-1).④各施肥处理的壤中流和地表径流中的全氮浓度和硝态氮浓度均存在极显著正相关关系(P0.01).硝态氮是全氮流失的主要形态,且二者均以壤中流为主要流失途径;全氮通过壤中流流失占比为72.86%～89.13%,且常规施肥处理的全氮总流失通量最大,为35.58 kg·(hm~2·a)~(-1),而施生物炭处理全氮总流失通量最小,为21.49 kg·(hm~2·a)~(-1).化肥减量配施生物炭能明显降低径流量和氮的流失通量,可有效阻控农业面源污染发生的风险.     

基于LCA的聚乳酸快递包装环境友好性评价

以聚乳酸快递包装为研究对象,运用生命周期评价（LCA）方法对聚乳酸快递包装的原料获取、加工、使用及5种处置情景的环境影响进行比较,并采用累积能源需求（CED）方法对能源消耗情况进行分析.功能单位（1000个规模为25×35cm的聚乳酸快递袋,918kg）快递袋原材料获取、加工及使用阶段的环境影响潜能值分别为1.09×10^-9、5.64×10^-10、1.24×10^-10.海洋水生态毒性是聚乳酸快递袋环境影响的主要类型,占77%;非生物资源耗竭潜能值、人类毒性次之,分别占9%和6%.能源消耗主要类型为不可再生能源,占总能源消耗的89%,其中,快递袋使用阶段为主要贡献阶段,占比为91%.处理阶段5种处置情景中情景Ⅴ（焚烧47%,填埋13%,回收40%）对环境最为友好,通过增加焚烧和回收处置的比例,减少填埋比例对环境有着更为积极的影响.     

Marine aquaculture regulates dissimilatory nitrate reduction processes in a typical semi-enclosed bay of southeastern China

Marine aquaculture in semi-enclosed bays can significantly influence nutrient cycling in coastal ecosystems. However, the impact of marine aquaculture on the dynamics of dissimilatory nitrate reduction processes (DNRPs) and the fate of reactive nitrogen remain poorly understood. In this study, the rates of DNRPs and the abundances of related functional genes were investigated in aquaculture and non-aquaculture areas. The results showed that marine aquaculture significantly increased the denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) rates and decreased the rate of anaerobic ammonium oxidation (ANA), as compared with non-aquaculture sites. DNF was the dominant pathway contributing to the total nitrate reduction, and its contribution to the total nitrate reduction significantly increased from 66.72% at non-aquaculture sites to 78.50% at aquaculture sites. Marine aquaculture can significantly affect the physicochemical characteristics of sediment and the abundances of related functional genes, leading to variations in the nitrate reduction rates. Although nitrate removal rates increased in the marine aquaculture area, ammonification rates and the nitrogen retention index in the aquaculture areas were 2.19 and 1.24 times, respectively, higher than those at non-aquaculture sites. Net reactive nitrogen retention exceeded nitrogen removal in the aquaculture area, and the retained reactive nitrogen could diffuse with the tidal current to the entire bay, thereby aggravating N pollution in the entire study area. These results show that marine aquaculture is the dominant source of nitrogen pollution in semi-enclosed bays. This study can provide insights into nitrogen pollution control in semi-enclosed bays with well-developed marine aquaculture.     

进水模式对SBBR性能及氮形态转化的影响

通过对4种不同进水模式下序批式生物膜反应器(SBBR)的性能、微生物群落结构以及氮形态转化的差异分析, 比较不同进水模式对SBBR性能和氮形态转化的影响及其产生的机制. 结果表明, 分散式进水模式表现出比一次性进水更好的脱氮效率和更高的抗冲击负荷能力, 在达到相同的处理效率的前提下, 分散式进水模式M₄的COD和氨氮负荷最高可达2 540和540 mg·(L·d)^-1, 而一次性进水模式M₁仅能分别达到2 000和420 mg·(L·d)^-1;分散进水模式能降低一次性进水所带来的冲击性负荷, 将负荷均化分散到周期内的各个时段, 同时也减少了进水对微生物的稀释作用, 使得单位体积内有效微生物的数量相对充足, 从而提高反应器的负荷能力. 在分散进水模式下, 从M₄与M₂、M₃的对比来看, 分散模式的进水规律越接近运行模式的循环规律, 反应器的氮素转化效率就越高, 残留的氮素总量也就越低.     

Recovery elemental sulfur from calcium sulfide prepared by red gypsum in sulfuric acid wastewater treatment

Journal of Material Cycles and Waste Management - Red gypsum comes from TiO2 production industry by sulfate method, which comes from the low acidic liquid stream treatment using lime or limestone....     

Improving protected area effectiveness through consideration of different human-pressure baselines

Previous assessments of the effectiveness of protected areas (PAs) focused primarily on changes in human pressure over time and did not consider the different human-pressure baselines of PAs, thereby potentially over- or underestimating PA effectiveness. We developed a framework that considers both human-pressure baseline and change in human pressure over time and assessed the effectiveness of 338 PAs in China from 2010 to 2020. The initial state of human pressure on PAs was taken as the baseline, and changes in human pressure index (HPI) were further analyzed under different baselines. We used the random forest models to identify the management measures that most improved effectiveness in resisting human pressure for the PAs with different baselines. Finally, the relationships between the changes in the HPI and the changes in natural ecosystems in PAs were analyzed with different baselines. Of PAs with low HPI baselines, medium HPI baselines, and high HPI baselines, 76.92% (n=150), 11.11% (n=12), and 22.86% (n=8) , respectively, showed positive effects in resisting human pressure. Overall, ignoring human-pressure baselines somewhat underestimated the positive effects of PAs, especially for those with low initial human pressure. For PAs with different initial human pressures, different management measures should be taken to improve effectiveness and reduce threats to natural ecosystems. We believe our framework is useful for assessing the effectiveness of PAs globally, and we recommend it be included in the Convention on Biological Diversity Post-2020 Strategy.     

Numerical simulation of overtopping breach processes caused by failure of landslide dams

Environmental Fluid Mechanics - Based on the mechanism of landslide dam failure caused by overtopping, a simplified mathematical model for simulating dam breach overtopping flow processes was...     

Generation estimation and material flow analysis of retired mobile phones in China

The generation estimation of retired mobile phones is launched with the sales and new method using the revised sales data and amount of the subscribers. Several assumptions have been made due to the insufficient sources of the data. The sales data of legal mobile phones are calculated with the authoritative and continuous official data. The sales data of smuggled and counterfeit mobile phones in China are also estimated based on the behavior data collected from the questionnaires. The results of generation estimation show that there are 636.52 million mobile phones retired in 2020, compared with 14.44 million in 1999 and several negative values in 2000, 2001, and 2008. The annual total mass of retired mobile phones in China escalated with the contributions of both the increasing generation amount and constant mass of the single unit. There are 50,921.60 ton of mobile phones retired in 2020 compared with 1155.20 ton in 1999, while the peak is 58,131.20 ton in 2019. There are 26,066.80 ton of retired mobile phones are stockpiled in 2020, while 16,152.40 ton and 8702.40 ton of retired mobile phones are reused as a whole unit and recycled, respectively. In the retired mobile phones that are recycled, 4600.50 ton material is recovered and 1216.50 ton components are reused, while 2885.40 ton residues need final disposal. The amount and dynamic characteristics of metals in the retired mobile phones are also calculated. Based on the results, several policy implications are made to improve sustainable management system of retired mobile phones in China.

     

One-part alkali-activated slag binder for cemented fine tailings backfill: proportion optimization and properties evaluation

In this study, a one-part alkali-activated slag (AAS) composed of ground-granulated blast furnace slag, desulfurized gypsum, and hydrated lime is proposed as alternative to cement for the production of cemented fine tailings backfill (CFTB), which is an environmentally friendly binder consisting of 93.72 wt.% industrial solid waste. Results show that AAS with 67.83 wt.% slag, 25.92 wt.% desulfurized gypsum, and 6.25 wt.% hydrated lime yields the highest strength, which is 1.7–3.2 times that of ordinary Portland cement (OPC). Aside from calcium silicate hydrate gel, appreciable quantity of ettringite characterized by interlocking needles structure and high bound water is also produced during the AAS hydration process. In addition, the hydration heat of the AAS binder is 48% less than that of OPC. Moreover, CFTB made of AAS provides better workability than that of CFTB with OPC up to 20 h. The findings of this study will contribute to the production of more cost-effective, durable, and environmental-friendly cemented fine tailings backfill.