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Farquhar, and E. Recent impact experiments and model calculations have demonstrated that condensed sulfuric acid aerosols cannot form and persist over long periods following asteroid impacts The process leading to the extinction of the dinosaurs and various marine groups such as the ammonites and most planktonic foraminifera, accompanied by the survival of mammals, birds, crocodilians and other species, is therefore unknown.
Soot is a strong light-absorbing aerosol that can have a significant climatic influence 21 , 22 and the atmospheric lifetime of soot particles is longer on the scale of years in the stratosphere, although they are efficiently removed from the atmosphere by precipitation about a week in the troposphere 22 , However, the amount of soot in the stratosphere, the coincidence of the extinction and stratospheric soot and the climatic influence are unknown.
Soot contains polyaromatic hydrocarbons PAHs , such as coronene 26 , which form from the incomplete combustion of hydrocarbons. We estimated the total amount of soot ejected by the impact using the combusted five- to six-ring PAHs [coronene Cor , benzo e pyrene BeP , benzo g,h,i perylene Bpery ] that remained in the stratosphere.
The amount of the stratospheric soot estimated here includes the soot from both wild fires and impact target rock. Coronene, a six-ring PAH, is a hydrocarbon-derived geochemical diagnostic for combustion. The presence of both coronene and glass spherules in the coarse deposits implies that the impact induced extensive combustion. By contrast, low coronene content 0. Stratigraphic variation in organic molecules derived from combustion and land plants, the Carbon Preference Index CPI and stable carbon isotope ratios.
Cadalene and long-chain n -alkanes are according to Mizukami et al. The map shows the paleolocations of the impact site and the sections evaluated. The base map is according to Courtillot et al.
The carbon preference index CPI 32 , 33 , 34 values of n -alkanes were used to distinguish between crude oil and dead organisms.
The CPI of mature n -alkanes is 1 oil is mature 32 , 33 and the CPI of immature n -alkanes derived from plants is high The CPI values from the ejecta beds at Beloc decreased from 7 in the first unit to 1 to 2 in the second and third units, increased to 5 in the lower part of the Danian marlstone, decreased to a minimum of 3 in the Ir layer and then increased to 5 in the Danian limestone Fig.
These values show that the primary source of n -alkanes in the second and third units of the coarse ejecta deposits was crude oil and that the n -alkanes in the Ir layer were sourced from both crude oil and dead organisms. The low CPI values suggest that the organisms from which the oil was derived were older than the plants at the time of the impact. The land plant biomarker cadalene is concentrated within and just below the Ir layer, with levels four-fold higher than those in the Maastrichtian deposits, also implying that land vegetation was devastated Fig.
The peak in cadalene was also recognized at the K-Pg boundary in Caravaca, Spain 36 , implying semiglobal devastation of land plants. Because the proportion of soot ejected into the troposphere and stratosphere by the impact is unknown 37 , the amount of soot ejected into the stratosphere has not been determined previously.
These estimates did not include rapid removal processes within several days in the stratosphere, probably due to coagulation between BC and other larger-sized materials e. However, because we estimated the mass of the BC ejecta from soluble five- to six-ring PAHs falling from the stratosphere during the few years after the impact, the amount of stratospheric BC, which could have caused climate change over several years, did not change.
We performed global climate model calculations to quantify the climate change caused by BC equivalent to soot injection for three quantities of BC see Methods.
The BC ejected into the stratosphere spread around the globe within a few months and was gradually deposited on the surface over the following five years Fig. The sudden cooling of the surface temperature weakened the hydrologic cycle, resulting in an abrupt and significant decrease in precipitation Fig.
The temperature and precipitation gradually recovered within 10 years after the impact and the recoveries decreased over the following years. We found that these climate changes strongly depended on latitude in every BC ejection scenario Fig. The temperature cooling was dominant in the mid-high latitude regions due to the presence of large amounts of BC in the stratosphere in those regions.
On the other hand, the cooling was milder in the low latitude regions. However, precipitation substantially decreased on land in those regions over several years after the impact Figs 2 , 3 , 4.
Monthly anomalies from the control experiment no ejection case are shown on the left axis with filled circles a—d and the ratios relative to the control experiment are shown for shortwave radiation and precipitation on the right axis with open squares b , d. Meridional distributions of pre-industrial climate conditions and climate changes caused by the black carbon BC injection. Monthly anomalies from the control experiment are shown for the amount of BC b—d and temperature j—l.
The ratios relative to the control experiment are shown for shortwave radiation f—h , precipitation n—p and soil moisture r—t. For comparison, the absolute values of the control experiment are shown a , e , i , m , q. Regions without data correspond to those with no sunlight or the ocean. The scale for the no ejection case is different from the others. The BC emission in the no ejection case is mainly from biomass burning.
The reductions in surface shortwave radiation due to the BC ejection led to cooling of the ocean on a global scale Fig. Although the response time of the seawater cooling after the impact was slower than that of the surface air temperature and precipitation over land Fig.
The maximum cooling of surface waters appeared 2—6 years after the impact and the cooling recovered gradually, taking more than a decade.
Monthly anomalies from the control experiment no ejection scenario are shown. The regions with seawater temperatures below zero at the 2-m water depth in the control experiment were excluded for the estimation of the anomalies and the year averages to exclude the sea ice area. Meridional distributions of pre-industrial seawater temperature and seawater temperature changes caused by the black carbon BC injection.
Monthly anomalies from the control experiment are shown for the three BC scenarios b—d , f—h , j—l , n—p , r—t , v—x. The regions with seawater temperatures below zero at the 2-m water depth in the no ejection control scenario were excluded for the estimation of the anomalies to exclude the sea ice area.
For comparison, the absolute values of the control experiment are shown a , e , i , m , q , u. Regions without data correspond to the sea ice area. The scale for the no ejection scenario is different from the others. We assumed that the combusted PAHs in the coarse-ejected sediments were transported from the troposphere and those in the superjacent fine sediments were sourced from the stratosphere and land.
Dead organisms and crude oil present at the end of the Cretaceous were mixed in the ejecta. This is indirect evidence of the presence of very large amounts of crude oil in the target rocks at the end of the Cretaceous.
The crude oil was combusted during the impact, as evidenced by carbon cenospheres from Canada, Denmark and New Zealand The consistency supports the use of the model results. For the estimated land surface air temperatures, dinosaurs and tropical plants 45 could have survived only at the low latitudes in the Tg ejection case, may have survived only in the equatorial area in the Tg ejection case and could not survive at any location in the Tg ejection case on land Table 1 ; survival only in summer means extinction.
Although small mammals and reptiles could have lived underground where it is warmer, the dinosaurs did not. The different habitats of the dinosaurs and small mammals and reptiles would also have been key factors in determining their extinction or survival These ammonites should have inhabited between —m and 0-m water depths.
The habitat depths of ammonites changed with ontogenetic stage juveniles, middle phase and adults These temperatures are supported by oxygen isotope data of late Cretaceous ammonite shells 51 , 52 , 53 , The warm water ammonites could not survive after the impact Table 2.
The mild water ammonites could not survive after the impact in the Tg and Tg BC cases. The cool water ammonites survived upon migration to shallower parts in these cases. This is consistent with evidence that those ammonites that survived briefly into the Paleocene and the nautilids that survive to the present day, were significantly more widely distributed than were those that disappeared at the end of the Cretaceous 8.
The cooling of seawater could have disturbed the physiology and food web of the shallow marine dwellers, such as planktonic foraminifera, ammonites, inoceramids and marine reptiles, which could have led to their extinction.
Cooling due to stratospheric soot aerosols could have caused the extinction of shallow dwellers that inhabited —0-m water depths Table 2. Temperature minima occurred within 3—6 years after the impact in m water depths in oceans but within 1—3 years on land. Extinctions in oceans should have followed land plant devastation and extinction of the dinosaurs. In fact, fossil records show that the widely distributed ammonites briefly survived after the fall of Ir 7.
The deep-dwelling cool-water ammonites first suffered from the cessation of photosynthesis and then from the decrease in seawater temperature. They may have survived the temperature change but not the lack of photosynthesis and resulting lack of a food source. Sulfuric acid rain may have also contributed to the marine extinction Sulfuric acid rain near the impact site was carried by ocean currents, which may have resulted in a global decrease in pH in the surface waters within several years after the impact.
The abrupt, significant decrease in precipitation obtained by the model calculations could apply to the paleoclimate because the distribution and amounts of precipitation in the late Cretaceous do not differ substantially from those of the present day 41 , 42 Fig. The decreasing cover and size of vegetation patches resulted in further losses of soil and water, which led to further vegetation loss The herbivorous dinosaurs ate the decreased number of plants, resulting in the disappearance of vegetal food, similar to overgrazing leading to desertification today 63 , 64 , which could have led to the extinction of the dinosaurs.
Survival of freshwater-dwelling vertebrates such as crocodilians is dependent the availability of food, such as birds, mammals, fish, reptiles turtles, snakes , amphibians and macroinvertebrates and the base of the food webs being plant detritus 6 , The riverine communities could have survived because their organic carbon was derived from detritus 6 , 65 and water sourced from the middle latitudes had sufficient precipitation.
Dinosaurs and warm-mild water ammonites could have become extinct, while the crocodilians survived in the Tg soot ejection case Tables 1 and 2. The diminishing photosynthesis and food-web collapse in oceans may have killed the cool-water deep-dwelling ammonites.
Our results show that the stratospheric aerosols did not induce darkness, in contrast to previous assumptions. The surface cooling was milder than previously thought. Sufficiently colder climates at mid—high latitudes caused extinction of the dinosaurs and crocodilians at mid—high latitudes; the drought accompanied by mild cooling at low latitudes on land led to extinction of the dinosaurs and allowed survival of the crocodilians at low latitudes. The mild cooling with diminishing photosynthesis in the oceans could have caused extinctions of marine organisms such as ammonites, inoceramids and most planktonic foraminifera, while allowing the survival of deep-sea organisms.
The sufficiently colder climates at mid—high latitudes and drought with milder cooling at low latitudes on land, as well as the limited cessation of photosynthesis in global oceans occurred a few months to 2 years after the impact, followed by surface water cooling in global oceans within 2 to 6 years after the impact.
Tree species such as peach, cherry and citrus have exhibited signs of air pollution induced injury with inhibited or shortened flowering period, early leaf abscission and premature dropping of fruits. Chromosomal breakage and chromosome bridges were predominantly recorded at metaphase and anaphase respectively.
In view of the cytotoxic effects of cement kiln dust, it can also act as a mutagen. The characteristics of plants for effective pollution control have jotted down by Kumar et al.
Trees having thick and fleshy leaves with petioles flexible and capacity to withstand vibration are suitable. Dust pollution is of localized importance near roads, quarries, cement works, and other industrial areas.
Apart from screening out sunlight, dust on leaves blocks stomata and lowers their conductance to CO 2 , simultaneously interfering with photo system II. Air pollution is the presence of high concentration of contamination, dust, smokes etc. Car emissions, chemicals from factories, dust, and pollen and mold spores may be suspended as particles. Ozone, a gas, is a major part of air pollution in cities. These materials come from various sources, such as, various industrial processes, paved and unpaved roadways, construction and demolition sites, parking lots, storage piles, handling and transfer of materials, and open areas.
Some air pollutants are poisonous. Inhaling them can increase the chances of health problems. In fact, dust when inhaled can increase breathing problems, damage lung tissue, and aggravate existing health problems. In addition to health concerns, dust generated from various activities can reduce visibility, resulting in accidents. Various foliar types in plants exhibit differences; stickier leaves perform better in collecting more air-borne particles; some leaves possess greater surface stiffness and coarseness, which concern their adhesiveness for the particulates.
The morphological feature of the leaf is a determinant factor for the crown area. Selection of tree species along the roadside needs to address the followings issues, viz. In relation to the present scenario of urban environmental pollution, there is a research need for changing the approach of planting trees and other species. This is an open access article distributed under the terms of the, which permits unrestricted use, distribution, and build upon your work non-commercially.
Withdrawal Guidlines. Publication Ethics. Withdrawal Policies Publication Ethics. Home HIJ Responses in plants exposed to dust pollution. Review Article Volume 1 Issue 2. Keywords: dust pollution, particulate matters, plant response. Mineral composition of dust In a study conducted by Chatson et al. Figure 2 Good filtering effects of loose plantations. Figure 3 Small filtering effects of the thick plantations.
Rapid growth. Capacity to endure water stress and climate extremes after initial establishment. Differences in height and growth habits. Pleasing appearances. Providing shade. Large bio-mass and leaves number to provide fodder and fuel. Ability of fixing atmospheric Nitrogen. Improving waste lands. Heavier branches and trunk of the trees also deflect or refract the sound waves.
Ecological effects of particular matter. Environment International. Das TM. Monitoring and control of air pollutants through plants. In: Ray M, et al, editors. Recent research in Ecology and pollution. Butz EL. Plants that will withstand pollution and reduce it.
Health Guidance for Better Health. Agrawal S, Tiwari S. Flora and Fauna. Impact of granite mining on some, plant species around quarries of Bangalore district. Poll Res. Singh RB. The increase was partly offset by the fact the same aerosols and clouds also reduced the amount of sunlight reaching the Earth so that the total level of photosynthesis fell.
But hazy skies meant that the photosynthesis that did happen was more efficient. The net effect was a 10 per cent increase in the net amount of carbon stored by the land even after the drop in photosynthesis was taken into account. Plants perform better when they are being illuminated from several directions at once by light reflected off clouds and airborne particles, rather than under intense sunlight from a single direction.
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