珠江口夏季海陆源有机碳的模拟研究——分布特征、贡献比重及其迁移转化过程

基于经过验证的三维水动力-水质模型,对珠江口夏季有机碳进行海陆源区分,并对海陆源有机碳的分布特征、贡献比重及其通量过程进行研究.结果表明,水平方向上,珠江口夏季陆源(海源)有机碳浓度从口门到外海逐渐降低(升高),在表、底层海水中平均浓度分别为1.45和0.87mg/L(0.97和1.05mg/L);垂直方向上,在层化水域陆源(海源)有机碳浓度从上到下逐渐递减(升高),在非层化水域海陆源有机碳浓度垂向分布较为均匀.珠江口夏季海源有机碳贡献率表层海水低于底层海水,平均贡献率为48.26%,沿向海方向海源有机碳贡献率逐渐增加——从内伶仃洋水域的4.43%逐渐提升到外伶仃洋东侧水域的81.20%.珠江口水动力条件复杂,在径流、潮汐、季风等因素的作用下陆源有机碳向海输送且向海输送量逐渐递减;海源有机碳在不同水域动力输送特征不同,西南水域向海输送,向海输送量逐渐递增;东北水域向岸输送,向岸输送量逐渐递减.陆源有机碳生化反应活性较弱,只有小部分被生化过程消耗,其迁移转化主要由沉降过程控制,而海源有机碳的迁移转化,则由口门的动力输送过程主控向外海的生化耗碳过程主控过渡.此外,海源有机碳沉降作用明显低于陆源有机碳,生化作用明显高于陆源有机碳.

Al-Zn-In系牺牲阳极在间浸环境中的性能研究

目的探究4种常用Al-Zn-In系牺牲阳极(Al-Zn-In、Al-Zn-In-Cd、Al-Zn-In-Mg-Ti、Al-Zn-In-Mg-Ga-Mn)在海水间浸环境中的电化学性能。方法采用恒电流法对4种阳极的开路电位、工作电位、实际电容量、电流效率及溶解形貌等进行研究,并结合电化学阻抗谱、动电位极化曲线等方法进行分析。结果在间浸环境中,Al-Zn-In、Al-Zn-In-Mg-Ti、Al-Zn-In-Mg-Ga-Mn的电流效率均在88.92%以上,3种阳极的工作电位在-0.96~-1.10 V波动,能满足碳钢在间浸环境中的保护需要。Al-Zn-In-Mg-Ga-Mn阳极溶解形貌均匀,Al-Zn-In和Al-Zn-In-Mg-Ti阳极溶解形貌略差。Al-Zn-In-Cd阳极电流效率仅为80.95%,工作电位在-0.93~-1.10 V波动,溶解形貌不均匀,电化学性能最差。研究发现,Al-Zn-In-Cd阳极表面附着的腐蚀产物多次在空气环境中脱水,并形成壳层,导致电位正移,阻碍阳极的进一步活化。结论在间浸环境中,4种阳极的电化学性能由好到差依次为Al-Zn-In-Mg-Ga-Mn阳极、Al-Zn-In阳极、Al-Zn-In-Mg-Ti阳极、Al-Zn-In-Cd阳极,前3种阳极适用于间浸环境中海洋结构物的阴极保护。

SPEI_(PM)-based research on drought impact on maize yield in North China Plain

The calculation method of potential evapotranspiration（PET） was improved by adopting a more reliable PET estimate based on the Penman-Monteith equation into the standardized precipitation evapotranspiration index（SPEI） in this study（SPEI PM）. This improvement increased the applicability of SPEI in North China Plain（NCP）. The historic meteorological data during 1962–2011 were used to calculate SPEI PM. The detrended yields of maize from Hebei, Henan, Shandong, Beijing, and Tianjin provinces/cities of NCP were obtained by linear sliding average method. Then regression analysis was made to study the relationships between detrended yields and SPEI values. Different time scales were applied, and thus SPEI PM was mentioned as SPEI PMk-j（k=time scale, 1, 2, 3, 4,…, 24 mon; j=month, 1, 2, 3,..., 12）, among which SPEI PM3-8 reflected the water condition from June to August, a period of heavy precipitation and vigorous growth of maize in NCP. SPEI PM3-8 was highly correlated with detrended yield in this region, which can effectively evaluate the effect of drought on maize yield. Additionally, this relationship becomes more significant in recent 20 yr. The regression model based on the SPEI series explained 64.8% of the variability of the annual detrended yield in Beijing, 45.2% in Henan, 58.6% in Shandong, and 54.6% in Hebei. Moreover, when SPEI PM3-8 is in the range of –0.6 to 1.1, –0.9 to 0.8 and –0.8 to 2.3, the detrended yield increases in Shandong, Henan and Beijing. The yield increasing range was during normal water condition in Shandong and Henan, where precipitation was abundant. It indicated that the field management matched well with local water condition and thus allowed stable and high yield. Maize yield increase in these two provinces in the future can be realized by further improving water use efficiency and enhancing the stress resistance as well as yield stability. In Hebei and Beijing, the precipitation is less and thus the normal water condition cannot meet the high yield target. Increasing of water input and improving water use efficiency are both strategies for future yield increase. As global climate change became stronger and yield demands increased, the relationship between drought and maize yield became much closer in NCP too. The research of drought monitoring method and strategies for yield increase should be enhanced in the future, so as to provide strong supports for food security and agricultural sustainable development in China.

Influence of Model Parameters on Hadron-Quark Phase Transition in Neutron Star Matter

We study the influence of the model parameters on the phase transitions, the equation of state （EOS）, and the corresponding mass-radius relations in the interior of neutron stars. The numerical analysis shows that the coupling constants of hyperons have a slight influence on the phase transitions and EOS, but an obvious influence on the particle fractions, while the bag constant B and coupling constant g have an important influence on the phase transitions, the EOS, and the mass-radius relations. We find that both the bag constant B and coupling constant g play the same role in the description of the interactions between quarks of hybrid stars. The maximum mass calculated by using the bag constant determined with experimental data （ranging from 175 to 200 MeV） falls in the interval of 1.4 ～1.7 solar mass. The corresponding radius is between 9.3 and 12 km. These results are in agreement with observed values of neutron stars. The possibility of the existence of a third family is discussed. The detection of a third family may provide a signature for a phase transition inside neutron stars.

Reducing maize yield gap by matching plant density and solar radiation

Yield gap exists because the current attained actual grain yield cannot yet achieve the estimated yield potential. Chinese high yield maize belt has a wide span from east to west which results in different solar radiations between different regions and thus different grain yields. We used multi-site experimental data, surveyed farmer yield data, the highest recorded yield data in the literatures, and simulations with Hybrid-Maize Model to assess the yield gap and tried to reduce the yield gap by matching the solar radiation and plant density. The maize belt was divided into five regions from east to west according to distribution of accumulated solar radiation. The results showed that there were more than 5.8 Mg ha^(–1) yield gaps between surveyed farmer yield and the yield potential in different regions of China from east to west, which just achieved less than 65% of the yield potential. By analyzing the multi-site density experimental data, we found that the accumulated solar radiation was significantly correlated to optimum plant density which is the density with the highest yield in the multi-site density experiment(y=0.09895 x–32.49, P<0.01), according to which the optimum plant densities in different regions from east to west were calculated. It showed that the optimum plant density could be increased by 60.0, 55.2, 47.3, 84.8, and 59.6% compared to the actual density, the grain yield could be increased by 20.2, 18.3, 10.9, 18.1, and 15.3% through increasing plant density, which could reduce the yield gaps of 33.7, 23.0, 13.4, 17.3, and 10.4% in R(region)-1, R-2, R-3, R-4, and R-5, respectively. This study indicates that matching maize plant density and solar radiation is an effective approach to reduce yield gaps in different regions of China.

The effect of solar radiation change on the maize yield gap from the perspectives of dry matter accumulation and distribution

The uneven distribution of solar radiation is one of the main reasons for the variations in the yield gap between different regions in China and other countries of the world.In this study,different solar radiation levels were created by shading and the yield gaps induced by those levels were analyzed by measuring the aboveground and underground growth of maize.The experiments were conducted in Qitai,Xinjiang,China,in 2018 and 2019.The maize cultivars Xianyu 335 (XY335)and Zhengdan 958 (ZD958) were used with planting density of 12×10^(4) plants ha^(–1) under either high solar radiation (HSR)or low solar radiation (LSR,70%of HSR).The results showed that variation in the solar radiation resulted in a yield gap and different cultivars behaved differently.The yield gaps of XY335 and ZD958 were 8.9 and 5.8 t ha^(–1) induced by the decreased total intercepted photosynthetically active radiation (TIPAR) of 323.1 and 403.9 MJ m^(–2) from emergence to the maturity stage,respectively.The average yield of XY335 was higher than that of ZD958 under HSR,while the average yield of ZD958 was higher than that of XY335 under LSR.The light intercepted by the canopy and the photosynthetic rates both decreased with decreasing solar radiation.The aboveground dry matter decreased by 11.1% at silking and 21% at maturity,and the dry matter of vegetative organs and reproductive organs decreased by 9.8 and 20.9%at silking and by 12.1 and 25.5% at physiological maturity,respectively.Compared to the HSR,the root weights of XY335 and ZD958 decreased by 54.6 and 45.5%,respectively,in the 0–60 cm soil layer under LSR at silking stage.The aboveground and underground growth responses to different solar radiation levels explained the difference in yield gap.Selecting suitable cultivars can increase maize yield and reduce the yield gaps induced by variation of the solar radiation levels in different regions or under climate change.

The Nucleon Direct Urca Processes in a Cooling Neutron Star

In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchangingδmeson on the nucleon direct Urca processes in neutron star matter.The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes,while it has only a little influence on the neutrino luminosity for a fixed neutron star whetherδmesons appear in a neutron star or not.However,the presence ofδmesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.

Bulk Properties of Hybrid Stars with the Color-Flavor Locked QuarkMatter Core

We investigate the influence of the energy gap(Δ)of the color-flavor locked(CFL)quark phase on the bulk properties of hybrid stars.The relativistic mean field model is used for hadronic matter and the MIT bag model for CFL quark matter.In our calculation results,we find that with the increase of the CFL energy gap there exists a transition behavior,which goes from the hadron star range through the transition range into the CFL quark star range.The observation data of PRS J1614-2230 are in the hadron star range(withΔ<40MeV).We also find that with hyperons the equation of state(EOS)for the hybrid star matter with the CFL quark matter core has a small change,which can be disregarded.

Influence of σ^(* )and φ Mesons on (A) Hyperon ^(1)S_(0) Superfluidity in Neutron Star Matter

Within the framework of the relativistic mean field theory,we investigate the ^(1)S_(0) superfluidity (SF) of A hyperons in neutron star (NS) matter including σ^(*) and φ mesons.The energy gap of ∧ hyperons is calculated with the Nijmegen one-boson-exchange potentials for a (∧∧) pair. The parameter set we use is in line with the recent experimental data △B_(∧∧) ~ 1.01 ± 0.20_+0.18-0.11 MeV.It is found that with σ^(*) and φ mesons the pairing energy gap △F of ∧ hyperons and the corresponding SF critical temperature T_(C∧) are suppressed.In addition the NS mass range of ∧ hyperon SF is enlarged obviously.

Direct Urca Processes with Hyperons in Cooling Neutron Stars

In the relativistic mean field approximation,the relativistic energy losses of the direct Urca processes with nucleons(N-DURCA)and hyperons(Y-DURCA)are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the Y-DURCA processes on the N-DURCA processes,and the total neutrino emissivity of neutron star matter.The results show that the existence of hyperons decreases the abundance of protons and leptons,and can sharply suppress the neutrino emissivity of the N-DURCA processes.

A Possible New Effect of Self-Consistency in the Relativistic Hartree-Fock Approximation

A new effect of self-consistency in the relativistic Hartree-Fock(HF)approximation suggested previously is con firmed by a renormalized calculation with the on-shell renormalization conditions.Two self-consistency schemes,ne requiring self-consistency in the HF potential(scheme P)and the other in the baryon propagator(scheme BP),are studied.It is pointed out that the on-shell renormalization conditions make the self-consistency require-ment in scheme P automatically satisfied.Our calculated results show that scheme P is a good approximation to scheme BP for the calculation of the baryon propagator and the self-consistency in scheme BP diminishes the continuum part of the spectral representation for the baryon propagator,while scheme P yields a baryon propagator which is the same as the HF result contributed by the single particle part of the above spectral representation alone.Further,it is demonstrated that the region of validity of the quasi-particle approximationmay depend on the renormalization conditions.

^(1)S_(0) Nucleon Superfluidity in Neutron Star Matter

We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interaction which is considered by exchangingδmeson on the nucleon superfluidity.It is found that theδmeson leads to a growth of the nucleon^(1)S_(0)pairing energy gaps in a middle density range of the existing nucleon superfluidity.In addition,when the densityρB>0.36 fm^(-3),the proton^(1)S_(0)pairing energy gap obviously decreases.The density range of the proton^(1)S_(0)superfluidity is narrowed due to the presence ofδmesons.In our results,theδmeson not only changes the EOS and bulk properties but also changes the cooling properties of neutron stars.

马钢9~#高炉炉况失常分析与处理

通过调整、控制漏水冷却壁、调整装料制度、更换布料溜槽,使高炉生产逐步恢复正常水平,各项指标逐步优化。

预制舱内屏柜安装固定及更换方案研究分析

本文针对比较常见的智能变电站屏柜式预制舱,分别从预制舱内屏柜靠墙安装和不靠墙安装这两种形式对屏柜的安装固定方案提出了切实可行的方法,进而可以确保屏柜安装固定的牢靠性;同时也提出来整屏更换技术方案,为后期屏柜更换能顺利进行提供了技术保障。

中国春玉米高产纪录的创造与思考

2020年中国农业科学院作物栽培与生理创新团队在新疆奇台创造24948.75 kg/hm2的玉米产量,刷新全国玉米高产纪录。研究团队采取玉米密植高产栽培技术,在膜下滴灌、水肥一体化生产条件下,4月14日播种,宽窄行70 cm+40 cm配置,播种密度135000株/hm2,产量最高的品种是MC670,收获穗数129630穗/hm2,穗粒数549.4粒,千粒重378.0 g,单穗粒重193 g。本文总结高产纪录玉米田生产过程的主要管理环节和高产群体的主要指标,为玉米高产提供参考。

遮阴对不同密度条件下玉米子粒含水率的影响

在大田条件下设置全生育期遮阴试验,通过测定成熟期子粒含水率,分析遮阴对玉米子粒含水率的影响。结果表明,在CK(自然光)、S1(自然光的85%)和S2(自然光的70%)处理下,各品种的子粒含水率表现为郑单958最高、先玉335次之、登海618最低。在S3(自然光的50%)处理下,登海618比先玉335子粒含水率平均高出4.36%。遮阴后玉米子粒含水率呈升高趋势,遮阴程度越大子粒含水率越高,其中,S1、S2和S3处理的子粒含水率分别比CK平均高出2.79%、4.43%和23.83%。遮阴后弱光胁迫导致玉米成熟延迟,与CK相比,S1、S2和S3遮阴处理成熟期平均推迟了4.0、4.0和6.5 d,可能是导致子粒含水率升高的原因。因此,在阴雨寡照频发和种植密度较高的区域或年份,建议选择熟期更早、脱水快的品种以达到机械粒收的子粒水分要求。

微塑料对微藻的毒性效应研究进展

微塑料(MPs)污染已经成为全球的持久性污染问题,引起了世界范围内的广泛关注。目前的研究表明,微塑料对水环境中的初级生产者微藻具有一定的毒害作用,同时,微塑料与其他污染物结合还可能产生更为严重的联合毒性效应,进而影响水体中食物链的稳定性,并对生态系统的健康带来潜在的风险。因此,开展微塑料对微藻毒性效应的研究十分必要。本文介绍了已公开发表的相关研究及成果,总结了微塑料对微藻的机械损伤、遮蔽效应、氧化损伤、吸附和团聚等致毒机理,并对未来微塑料对微藻毒性的研究方向做了简要分析与展望。